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Andreas Wilkes
Southeast Asia
Working Paper
Towards Mainstreaming Climate Change in Grassland
Management Policies and Practices on the
Tibetan Plateau
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Towards Mainstreaming Climate Change in Grassland
Management Policies and Practices on the
Tibetan Plateau
Andreas Wilkes
ICRAF China 2008
ICRAF Working Paper No.67
Correct citation:
Wilkes A. 2008. Towards Mainstreaming Climate Change in Grassland Management Policies and Practices on the
Tibetan Plateau. WP number 67. Beijing, China, World Agroforestry Centre – ICRAF China. 43p.
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Summary
Background: The Qinghai-Tibet Plateau covers an area of about 2.5 million km2. 52% of the Plateau’s land area
is grassland. These grasslands provide ecosystem services of national, regional and global importance. Driven by
a combination of climate change impacts and unsustainable management practices, half of the Plateau’s grasslands
are estimated to be degraded or desertified. The Plateau’s grasslands also provide the livelihood basis for 5 million
pastoralists, many of whom live in poverty. Grassland degradation – due either to unsustainable management
practices or to the impacts of climate change – undermines the basis of pastoral economies. Based on a review
mostly of the Chinese language literature, this paper describes observed and predicted climate change, and impacts
of both climate change and anthropogenic factors on grasslands. It ends with suggestions for future policy related
research.
Observed and predicted temperature change: From 1955 to 1996 average annual temperatures on the Plateau
rose by of 0.16 ℃/decade, much higher than the rate of increase for the northern hemisphere as a whole. The rate
of increase in winter minimum temperatures (0.32-0.33 ℃decade) has been particularly rapid. Temperatures have
risen more rapidly at higher altitudes and in the northwest Plateau. Most predictive models suggest an increase in
temperature of 2-2.7 ℃ by 2050 compared to the 1990s.
Observed and predicted precipitation change: Trends in precipitation are more diverse across the Plateau. On
average, precipitation has increased by 3.4 mm/decade, mostly due to an increasing trend in winter precipitation,
while summer rainfall has decreased slightly. Some research finds correlations between rainfall and elevation, while
others point to regionally specific changes in the seasonality of precipitation. Northeast Tibet and the eastern Plateau
regions are experiencing decreasing summer rainfall with increasing winter precipitation. These seasonal changes
are of particular importance for grassland vegetation. The level of confidence in predicted trends in precipitation is
lower than for temperature, but is expected to increase in the SE and central Plateau regions.
Impacts of climate change on grasslands: As temperatures change, the location of climate belts on the Plateau
will change. Permafrost currently covers around half the Plateau area, but is predicted to largely disappear,
accelerating desertification. Some studies report changes in plant community structure, and in areas of permafrost
transition, total loss of vegetation and ecosystem functions has been observed. Warming over the last 20 years has
benefited vegetation growth in arid steppe and desert areas, but the currently most productive grasslands are not
among areas that are predicted to benefit from global warming. Grassland productivity is highly correlated with
precipitation, and more productive vegetation types of the eastern Plateau are experiencing declining precipitation
trends. Some field studies report diminution of average grass height and declining yield, due declining summer
(growth season) rainfall and a shortened growth season.
Anthropogenic influences on grasslands: Scientists generally concur that overgrazing is pervasive across the
Plateau. High grazing intensities is correlated with declines in vegetation height, coverage and aboveground
biomass, as well as soil organic matter and nutrient content. Some research has suggested that overgrazing has been
driven and exacerbated by grassland management policy, as grassland contracting has restricted herd mobility.
Towards climate change mainstreaming in grassland management policy: This paper argues for concerted
efforts to develop incentive systems for sustainable grassland management and to plan appropriate adaptation
measures. Such efforts will have to promote multidisciplinary research and strengthen links between research and
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policy. There is a particular need to strengthen social science research on pastoral economies and grazing systems.
Given the relative lack of solid social science research, integrating the results of top-down modeling with bottomup studies of adaptation practices and vulnerability will require innovation of new institutional arrangements for
multidisciplinary research and for linking in-depth and participatory local research processes with wider regional
studies and planning processes at different levels.
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Content
1.Introduction………………………………………………………………………………………………....…..…1
2.Grasslands of the Tibetan Plateau…………………………………………………………………………….….3
3.Observed and predicted climate change on the Plateau…………………………………………………………...6
3.1 Observed temperature changes………………………………………………………………………………..…..6
3.2 Predicted temperature changes…………………………………………………………………………………....7
3.3 Observed precipitation change………………………………………………………………………………..…..7
3.4 Predicted precipitation changes……………………………………………………………………………..…….8
3.5 Summary……………………………………………………………………………………………………..…...8
4.Impacts of climate change on grasslands…………………………………………………………………………..10
4.1 Impacts on the distribution of vegetation types……………………………………………………………….....10
4.2 Impacts on grassland productivity…………………………………………………………………………….…11
4.3 Impacts on plant communities and biodiversity…………………………………………………………….…...13
4.4 Impacts on ecosystem functions…………………………………………………………………………..…......14
4.5 Grassland carbon cycles…………………………………………………………………………………..…......14
4.6 Summary…………………………………………………………………………………………………….…..17
5.Anthropogenic influences on grasslands…………………………………………………………………….……...19
5.1 Impacts on grassland vegetation…………………………………………………………………………….…...19
5.2 Impacts on grassland carbon cycles…………………………………………………………………………......21
5.3 Summary…………………………………………………………………………………………………….......22
6.Towards mainstreaming climate change in grassland management policies…………………………………...24
6.1 Multidisciplinary learning to create incentives for sustainable grassland management…………………………25
6.2 Learning across multiple scales for adaptation planning………………………………………………...…..….26
6.3 Summary………………………………………………………………………………………………….....…..29
References……………………………………………………………………………………………...……….......31
Working papers in this series…………………………………………………………………………………...…39
1.Introduction
The Qinghai-Tibet Plateau covers the Chinese provinces of Tibet A.R. and Qinghai, and parts of Gansu, northwest
Sichuan and northwest Yunnan. The total land area of the Plateau is around 2.5 million km2, accounting for about
26% of China’s land area (Zhang et al. 2002). The average altitude of the Plateau is above 4000 masl, and lying
between 26º and 40º latitude, the Plateau is characterized by cold temperatures, averaging -5.3 ℃ to -10.8℃ in
winter with an annual average of less than 2℃. As the world’s ‘Third Pole’, the Plateau is one of the most sensitive
areas to global climate change. While average surface temperature globally has risen by 0.3-0.6℃ per decade, over
the last 50 years the average temperature on the Plateau has increased by 0.16 ℃ per decade (Shi 2001). Warming
has also been observed earlier on the Plateau than elsewhere in China (Li, Gao, Yang et al. 2005). This not only
makes the Plateau a sensitive indicator of global climate change but also suggests that impacts on the Plateau’s
ecology may be more severe than elsewhere.
Grasslands are the dominant vegetation type across much of the Plateau, covering some 1.3 million km2, or 52%
of the Plateau’s land area (Sheehy et al. 2006), accounting for around 40% of China’s grasslands. The Plateau
grasslands are one of the world’s largest continuous grassland areas, with a diversity of vegetation types including
arid deserts, semi-arid steppes, alpine meadows and wetlands (ibid.). The Qinghai-Tibetan Plateau has critical
influences on regional weather systems and hydrological cycles (Huang and Zhou 2004; Wang, Zheng and Song
2002; Xu et al. 2007). Parts of the Plateau, such as the source region of the Yellow, Yangtze and Mekong Rivers
have been singled out for their contribution to national environmental security. China initial communication on
climate change (NDRC 2007) stressed the importance of China’s grasslands for mitigating continued climate
change. Wang Genxu and others (2002) estimate that the Plateau’s grasslands store some 25% of China’s soil
carbon. Driven by a combination of climate change impacts and unsustainable management practices, around
half of the Plateau’s grasslands are already reported to be degraded or desertified. Degradation and increasing
desertification of grasslands exposes a greater percentage of soil surface. Hot dry soils retard the accumulation of
organic matter, further inhibiting plant growth, and desiccated soils are more prone to wind erosion. Grassland
degradation also releases greenhouse gases into the atmosphere, and thus contributes to further global climate
change (Schlesinger et al. 1990). On a large scale, desertification on the Plateau has the potential to influence wind
systems with impacts across East Asia (Luo et al. 1986, Liu Xiaodong et al. 1989, Li and Ding 2006). Thus, the
sustainable management of the Plateau’s grasslands is of great significance for mitigation of accelerated global
climate change and the maintenance of ecosystem services that are critical to both China and the wider Asian
region.
The Plateau’s grasslands are the basis for pastoral and agropastoral livelihoods of more than 5 million people.
Grassland-dependant livestock raising is the primary source of cash and non-cash income for the majority of the
Plateau’s inhabitants. Average incomes in pastoral areas of the Plateau are less than two thirds the average for
China’s rural inhabitants, and the incidence of poverty in many pastoral areas is high. A declining natural resource
base – due either to unsustainable management practices or to the impacts of climate change – undermines the basis
of pastoral economies. Sustainable management of the Plateau’s grasslands is therefore important not only to the
mitigation of further global climate change and the maintenance of regionally important ecosystem functions, but
also to the sustainability of pastoralist livelihoods and culture in this region.
Although scientists have done a lot to further understanding of climate change impacts on the Plateau and its
grasslands, current grassland management policies and practices are still largely based on initiatives begun many
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years ago. As China moves towards the identification of climate change mitigation and adaptation strategies,
grassland management policies and practices must contend with competing objectives. In many recent discussions
among scholars and decision makers in China, one recurring issue has been whether large areas of the Plateau
should be rezoned to reflect a prioritization of their ecosystem functions over their potential as a basis for animal
husbandry and socio-economic development (Yan et al. 2004). National grassland policy as a whole has also been
shifting towards a conservation focus rather than a focus on the sustainable socio-economic development of pastoral
regions themselves. Thus, climate change impacts on the Plateau’s grasslands is a clear domain in which there are
diverse stakeholders with diverse perspectives and interests, as well as varying capacities to influence the outcomes
of decision-making processes.
It is in this context that this paper aims to contribute to the development of strategies for the mainstreaming
of climate change considerations in grassland management policies for the Plateau region. Based mainly on
the existing Chinese language literature, this paper summarizes the state of knowledge on climate change on
the Plateau (Section 2), research on the impacts of climate change on Plateau grasslands (Section 3) and of
anthropogenic impacts on the Plateau’s grasslands (Section 4). Available evidence suggests that there will be both
losers and winners from climate change. Warmer temperatures, when accompanied by increasing precipitation,
will result in increased productivity of grasslands in some areas of the Plateau. Especially in the eastern Plateau,
warming combined with declining summer precipitation will probably continue to result in declining grassland
productivity. Melting of permafrost will hasten desertification of large areas of the Plateau and the concomitant
loss of other grassland ecosystem services. Grassland degradation and desertification on the one hand further
contributes to global warming and the loss of critical ecosystem functions, and on the other hand places stress on
animal husbandry production and pastoral livelihoods. China has already prioritized the conservation of grassland
ecosystems in its programmatic statements on climate change adaptation, and grassland conservation programmes
are already underway across the Tibetan Plateau. This paper finds that further policy relevant research is required
in order to mainstream climate change concerns in grassland management policy. In particular, it suggests that
policy relevant research must develop innovative institutional arrangements for the integration of natural and social
sciences disciplines and for linking in-depth and participatory local research processes with wider regional studies
and planning processes at different levels.
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2.Grasslands of the Tibetan Plateau
The Tibetan Plateau is the world’s largest and topographically most complex high plateau. It has a unique position
in global climate and climate change processes. Research shows that early summer warming from the Plateau
landmass has effects that extend all the way into the troposphere above the northern hemisphere (Qu et al.
2004). The Plateau is important in atmospheric circulation processes affecting the northern China plains and the
development and evolution of the East Asian Monsoon (Qu et al. 2004). Vegetation cover on the Plateau also has
impacts on atmospheric circulation and water cycling through the effects of reflection rates on surface energy, wind
drag, evaporation and soil moisture (Luo et al 1986, Liu et al. 1989, Li and Ding 2006) which influence rainfall in
the Yangtze watershed and the transport of moisture to inland China (Wang, Zheng and Song 2002). With almost 1
billion people living in river basins originating on the Tibetan Plateau, the hydrological importance of the Plateau’s
glaciers, other cryogenic features and their roles in regional hydrological processes have attracted much attention (Xu
et al. 2007). The Plateau’s grasslands also play important roles in regulating these processes.
Table 1: Grassland area of administrative units on the Tibetan Plateau
Administrative
unit
Tibet
Qinghai
Sichuan
Gansu
Yunnan, Diqing
China
Total land area
(million ha)
120
72
48
39
2.387
960
Grassland area
Grassland
(million ha)
% of
admin.
unit area
% of
China’s
grassland
8 2 .0 5
36.47
20.87
17.90
0.8256
393
6 8 .1
50.5
43.0
39.4
34.6
41.7
2 0 .9
9.3
5.3
4.6
.002
100
Useable
grassland
(million ha)
7 0 .5
31.6
17.9
16.1
0.59
331
Source: Statistical yearbooks for various provinces
Grasslands are the dominant vegetation type across the Plateau, covering more than half of the Plateau’s total land
area. Previous studies have classified these vegetation types into either 12 or 17 categories (Sheehy et al. 2006 p.
145), with alpine meadow and alpine steppe together accounting for almost 75% of the total grassland area of the
Plateau (table 2). The distribution of grassland vegetation types across the Plateau depends on features such as soil
type, rainfall, temperature and altitude, but is heavily influenced by precipitation patterns. Precipitation is highest
in the southwest of the Plateau, with a general decline in precipitation gradients in a northwesterly direction. In
general the distribution of grassland vegetation types follows this SE-NW gradient (figure 1). Alpine meadow,
found in areas with >400 mm annual precipitation, is mainly located in the eastern part of the Plateau, while alpine
steppe and deserts are found in areas with lower annual precipitation. The average primary productivity (biomass
yield) of different grassland types is also influenced by summer rainfall. Wang Genxu et al. (2002) has estimated
that the soils of grasslands on the Plateau contain about 33.5 Pg of carbon, equivalent to approximately 23% of
China’s soil carbon. Seventy per cent of this carbon is stored in the soils subtending alpine meadows and alpine
steppe vegetation.
Table 2: Grassland vegetation types of the Tibetan Plateau
Vegetation type
Temperate meadow steppe
Temperate steppe
Temperate desert steppe
Alpine meadow steppe
Alpine steppe
Alpine desert steppe
Area (km2)
2100
38 330
-39680
56 260
377 620
86 790
% of total area
0.16
2.92
0.74
4.28
28.75
6.61
Table 2: Grassland vegetation types of the Tibetan Plateau
Vegetation type
Temperate meadow steppe
Temperate steppe
Temperate desert steppe
Alpine meadow steppe
Alpine steppe
Alpine desert steppe
Temperate steppe desert
Temperate desert
Alpine desert
Tropical tussock
Tropical shrub tussock
Temperate tussock
Temperate shrub tussock
Lowland meadow
Temperate mountain meadow
Alpine meadow
Marsh
Total
Area (km2)
2100
38 330
9680
56 260
377 620
86 790
1070
20 840
59 670
90
280
10
1400
11 680
60 670
586 520
210
1 313 220
% of total area
0.16
2.92
0.74
4.28
28.75
6.61
0.08
1.59
4.54
0.02
0.10
0.88
4.61
44.64
0.01
99.93
Source: Adapted from Sheehy et al. 2006
Much of the Plateau’s grasslands are degraded. Studies in Qinghai report that of the province’s total grassland area
of 316 100 km2, 23% (73,000 km2) is moderately or severely degraded (Cui et al. 2007). Of this, 48 600 km2 lies
within the source region of the Yellow River and 12 100 km2 within the source region of the Yangtze River. Soil
erosion in these two river source areas totals more than 100 000 tonnes of silt each year. A total of 125,200 km2 in
Qinghai is desertified, and expanding at a rate of 10 km2 per year (ibid.). Tibet A.R. has a total land area of 1 202
232 km2, of which grasslands cover 820 5l9 km2, or 68%. Grassland surveys conducted in the second half of the
1980s found that the total area of degraded grasslands was 114 280 km2, equivalent to 17.2% of the total usable
grassland area. Of this degraded grassland, 64,627 km2 (56.6%) was lightly degraded, 36 352 km2 (31.8%) was
moderately degraded and 13 302 km2 (16%) was severely degraded (Liu, Fan and Zhou 2002). Since the conduct
of that survey, degradation has continued. Government statements now estimate that the total degraded area
Source: Hou 1979
Figure 1: Distribution of major vegetation types on the Tibetan Plateau
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covers 426,666 km2, or more than half of Tibet’s total grassland area (Xinhua 2005). The China Geological Survey
estimates that since the 1970s, the desertified land area of the Plateau has increased by 8.3% from 467 332 km2
to more than 500 000 km2 at the turn of the century (China Geological Survey 2006). Wang Genxu et al. (2002)
estimate that over the last 30 years almost 3 Pg of soil carbon has been emitted to the atmosphere due to grassland
degradation on the Plateau. Thus, the health of the Plateau’s grasslands is of great importance to mitigating
accelerated global climate change.
In addition to their ecological importance, the Plateau’s grasslands are the basis for pastoral and agropastoral
livelihoods of more than 5 million pastoralists. With diverse ecological environments, natural resources, cultures
and degrees of market access, livelihood patterns across the Plateau are quite diverse. This diversity is reflected in
grazing and livestock management systems, herd structures and sources of income. Chinese official income data
includes the imputed value of agricultural and livestock products that are consumed by rural households without
entering the market. Even so, average incomes in pastoral areas of the Plateau are less than two thirds the average
for rural inhabitants nationwide. In 2002 the incidence of poverty in Qinghai was more than 30% (Liu 2003).
Sheehey et al. (2006) identify the decline of natural resources capacity to support animal production as the major
stress on pastoral society and economy on the Plateau. The Plateau’s pastoralists are often poor, constrained in their
range of livelihood options and thus potentially vulnerable to climate change. Examining the impacts of climate
change on grasslands of the Plateau is highly relevant to understanding how the Plateau’s pastoralists are being
affected by and adapting to climate change.
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3.Observed and predicted climate change on the Plateau
3.1 Observed temperature changes
Several studies have been conducted on trends in temperature change across the Plateau. In general, trends in
the last 30 to 50 years have been towards higher temperatures, particularly in winter. Shi Yafeng (2001) analysed
data for 97 meteorological stations on the Plateau between 1955 and 1996, and found an average decadal rise
in temperature of 0.16℃/decade, much higher than the rate of increase for the northern hemisphere as a whole,
which increased by 0.4℃in total between the 1960s and 1980s. The rate of increase in winter temperatures on the
Plateau (0.32-0.33 ℃/decade), mainly due to increases in average minimum temperatures, has made the greatest
contribution to increases in average annual temperatures (Shi 2002, Niu et al. 2005). Summer temperatures have
changed to a lesser degree. On average, winters in the 1990s were 1.5℃ warmer than in the 1960s, while summer
temperatures have only increased by 1.1℃ over the last 40 years (Li 2005).
Studies of periodic variation in temperature trends all report that while the 1950s were a relatively warmer period,
the mid-1960s to mid-1980s were a relatively colder period, but since the mid- to late-1980s rates of warming have
been increasing (Li 2005, Li and Kang 2006, Cai et al. 2003). The warming trend has been relatively consistent
across the whole of the Tibetan Plateau because most of the Plateau lies within the 0.8 isobar (Wu et al. 2005).
Table 1 shows the relationship between average increases in temperature and altitude based on analysis of 66
meteorological stations across the Plateau and surrounding areas. The table shows that across the Plateau spring and
summer average temperatures have seen slight decreasing or increasing trends at different altitudes, while autumn
and winter temperatures have uniformly been rising. The rate of change in autumn and winter temperatures has
been higher as elevation increases.
Table 3: Average annual increase in temperature at different altitudes in Plateau and surrounding
areas1961-1990
Units: oC/decade
Altitude
(m)
<500
500-1500
1500-2500
2500-3500
>3500
No. of
stations
34
37
26
38
30
Spring
-0.18
-0.11
-0.17
-0.01
0.12
Summer
-0.07
-0.02
0.03
0.02
0.14
Autumn
0.08
0.16
0.15
0.19
0.28
Winter
0.16
0.42
0.46
0.63
0.46
Ann. av.
change
0.00
0.11
0.12
0.19
0.25
Source: Liu and Hou 1998
Thus, there has been great variation in the rates of warming in different locations on the Plateau. Some areas such
as Lhasa have experienced temperature increase rates as high as almost 0.6 ℃/decade, while others, such as Anduo
and Tuotuohe in the Three Rivers Source Area have seen smaller increases of 0.1-0.3 ℃/decade (Li 2005). Li and
Kang (2006) report an analysis of both spatial and temporal trends which found that the warming trend began
earliest in the southeastern Plateau stations of Linzhi and Bomi and then spread eastwards and northwards. The rate
of increase in temperatures has been strongest in the northwest area of the Plateau, followed by the northeast, with
only a weak trend in the central-south area (Yang et al. 2000). Li, Zhu and Qin et al. (2003) offer an explanation of
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geographical differences in the extent of warming trends, suggesting that the main atmospheric cold front routes,
which are determined by topographical features of the Plateau, have been associated with lower than average trends
in change in minimum temperatures.
With rising temperatures, the number of frost days has decreased by 17 days while the number of warm days
(temperature >15 ℃) has increased by 9 days. Record breaking minimum temperatures are becoming much rarer
while record breaking high temperatures are increasing in frequency (Liu et al. 2005). In early January 2007, 10
stations in the Lhasa area reported record high temperatures, some 2 ℃ higher than normal for that time of year and
the three highest historical winter averages in both Tibet and Qinghai have all occurred since the turn of the century
(China Meteorological Bureau 2007).
3.2 Predicted temperature changes
Based on the results of general circulation models, the IPCC (2001) reports on regional impacts of climate change
predicted an increase in mean surface temperatures for temperate Asia of between 1.0-3.5 ℃by the year 2100 in
response to a doubling of CO2 concentration, with more pronounced increases in winter than in summer. However,
the same report notes that the confidence in future climate projections for the Plateau area remains low. All GCM
simulations project a warming trend for the Plateau in response to increased concentrations of greenhouse gases,
but these models do not represent well some of the characteristics of climatic change – such as relationship with
elevation – that have been observed in recent decades. This is probably due to their coarse spatial resolution and
inadequate treatment of physical processes – such as snow albedo – characteristic of topographically complex areas
such as the Plateau (Liu and Chen 2000: 1740). Modeling the effects of a 1% increase in CO2 concentration per
year, Zhang et al. (2004) predict that initially temperature increases will be slow, but as concentration levels rise,
the rate of temperature change will increase. By 2010, average temperatures on the Plateau are predicted to increase
by 0.2 ℃, by 2030 by 1.8 ℃ and by 2050 by 2 ℃. Other models also report the same accelerating trend, with
predicted increases as high as 2.2-2.7℃ by 2050 compared to the 1990s (Ding 2002). These predicted increases are
much higher than those predicted for China as a whole, and much higher than the global average increase of 0.4 - 1.2
℃ predicted through 2050 by the IPCC (IPCC 2001).
3.3 Observed precipitation change
Research on precipitation trends in recent decades on the Plateau points to a general increase in precipitation – on
average 3.4 mm/decade – mostly due to an increasing trend in winter precipitation, while summer rainfall has seen
a slight decrease (Niu et al. 2005, Li 2005, Wu et al. 2005). Although some researchers refer to an overall trend of
warming and drying on the Plateau (Shi 2001), in fact compared to the relatively uniform trends in temperature
across the Plateau, there has been much more geographical variation in precipitation trends (Li 2005, Wu et al.
2005).
Li Dongliang (2005) found that increases in precipitation are related positively to the altitude of the monitoring
station, with a clearer increase in precipitation in southwest Tibet than in northeastern Tibet. For example, Linzhi
and Bomi have received increasing rainfall at a rate of increase of 60 mm/decade, while Hainan in Qinghai
province has been receiving lower rainfall at a rate of -57 mm/decade. Li and Kang (2006) report a general trend
in decreasing precipitation across much of the Plateau, and especially in the Yalong Zangbo region, while average
rainfall has increased in higher altitude areas in the southeast, south and northern areas of the Plateau. There are
also significant changes in the seasonality of rainfall. For example, in northeast Tibet and the Gansu-Sichuan-7-
Qinghai border area, although total annual precipitation is increasing, summer rainfall is decreasing, while winter
rainfall and snowfall are increasing (Niu et al. 2005). These seasonal changes are of particular importance for
grassland vegetation.
Precipitation only measures inputs of water. The Plateau is a region of high solar radiation and evaporation rates are
high (Yang and Piao 2006). Considering both input and evaporation gives measures of humidity which are a better
indicator of plant growth conditions. Niu et al. (2005) examined trends in humidity over almost 40 years (1961-1998)
and found that the southeast, southwest and the Tarim basin are all areas of increasing relative humidity, while the
northeast, Qilianshan and the Gansu-Sichuan-Qinghai border area are all becoming drier.
Overall, the area of the Himalaya-Tibetan Plateau region covered in snow each year is decreasing, especially at
lower elevations (Rikiishi and Nakasato 2006). The length of the snow covered season is also shortening. Compared
to the 1960s, at the turn of the last century the snow covered season was 23 days shorter. However, there is also
great geographical variation. In areas where increasing annual precipitation is driven mainly by winter precipitation,
this translates into heavier winter snowfalls, with negative implications for livestock survival in the winter months
(van Wageningen and Sa 2001: 10). Based on analysis of government and newspaper reports, Hao et al. (2002)
suggest that the northeast Plateau region is one of the main areas of snow disaster in China, and that the frequency
of snow disasters has been increasing in recent decades. However, confidence in this conclusion is low because of
the nature of the data sources analysed.
3.4 Predicted precipitation changes
The IPCC regional climate change impacts report (IPCC 2001) notes that the level of confidence in predicted trends
in precipitation for Temperate Asia are much lower than for temperature – which as already noted is itself not high.
Modeling the effects of increases in CO2 concentration using a GOALs model, Zhang et al. (2004) predict a 15%
increase in rainfall for western China as a whole by 2080. To 2010 little or no increase in rainfall is predicted for
the northern Plateau, but increases of 50-100 mm are predicted for the south and southeast. Between 2010 and 2030
the model predicts increases of 50-100 mm across the Plateau, and by 2050 increases are expected to rise along a
SE-NW gradient, with increases of 200 mm in the SE, declining in a NW direction with no or little increase in the
NW.
3.5 Summary
Significant changes in temperature and precipitation have been observed on the Tibetan Plateau. In general the trend
is towards rising temperatures, especially since the late 1980s, and increasingly so at higher altitudes and latitudes.
The magnitude of temperature changes observed in the Tibetan Plateau (0.16 ℃/decade) have been larger than
the average changes for the rest of China (0.04 ℃/decade) and the globe as a whole (0.03-0.06 ℃/decade). These
changes on the Plateau have been observed to occur earlier than comparable changes in other areas of China (Li et
al. 2005). This suggests the importance of monitoring changes on the Plateau to understand not only future expected
trends in other areas, but also to better understand the impact of changes in the Plateau on atmospheric, climatic
and hydrological systems elsewhere. By contrast, general trends in precipitation are less clear, with significant
differences between regions and with different patterns in seasonal change occurring in different locations.
In general, warmer temperatures may imply benefits for the net primary productivity of grasslands on the Plateau
-8-
(Xu and Liu 2007). Temperature increases in late autumn and winter may have little benefit for vegetation growth.
But lengthening of the growing season due to fewer frost days and more warmer days may have positive benefits.
Seasonal dimensions of changes in precipitation also have major implications for impacts on grasslands, as spring
and summer rainfall are important for plant growth. In many areas, however, increased total precipitation is due to
increased winter rain and snowfall, so benefits for grasslands cannot be assumed.
Most studies of climate change on the Plateau focus on examination of long term trends. Another significant feature
of climate factors on the Plateau is their high inter-annual variation. This feature of the Plateau climate is of great
importance for grass growth and winter climate conditions, and has a most direct impact on livestock production.
But with increased attention to understanding longer term trends, little research to date has focused on climate
variability on the Plateau.
Table 4: Summary of climate changes on the Tibetan Plateau
Changes in climate
phenomena
Temperature change
Observed changes (degree
of confidence)
Rising average temperatures
1.6 ć/decade (high)
Rising winter temperatures
0.32-0.33 ć/decade (high)
Total precipitation
Increasing precipitation 3.4
mm/decade (high regional
variation)
Regional variation in trends:
increases of 200 mm in SE, little
or no increase in NW by 2050 (low)
Snowfall
Decline in number of days of
snow cover (low)
Increasing occurrence of
snow disaster (low)
Increase in snowfall with
increasing winter precipitation (low)
Decrease in snow covered days (low)
-9-
Predicted changes
(degree of confidence)
2-2.7 ć by 2050 (low)
Faster rise in winter than average
temperatures (low)
4.Impacts of climate change on grasslands
Around half the Plateau’s grassland area is reported to be degraded and/or desertified. Until recently scholarly and
official documents all agreed that overgrazing has been the primary cause. In recent years, however, the impact of
climate change on grasslands has become widely acknowledged, although separating the effects of climate change
and anthropogenic factors remains difficult. Observed impacts of climate change have been reported in relation
to grassland productivity, plant community composition and the distribution of plant communities, as well as on
grassland soils and whole grassland ecosystems.
Several studies have been conducted of the adaptive mechanisms of grass species to the special characteristics
of the Plateau, such as cold, lower levels of oxygen and higher levels of ultraviolet light (Wang, Ren and Hu et
al. 1998). There are no reports of the predicted impact of climate change on particular grassland species, but in
general climate change can be expected to lead to shifts in the geographical distribution of plant communities, in
situ adaptation (evolution) and/or disappearance of species. Grass growth is particularly responsive to temperature
and moisture, so a changing climate can also be expected to have strong impacts on the health of grassland plant
communities.
4.1 Impacts on the distribution of vegetation types
The current distribution of vegetation types is strongly influenced by climatic factors such as temperature and
precipitation. Precipitation zones in particular are closely related to the distribution of grassland types on the
Plateau. Alpine meadow in areas with > 400mm annual precipitation is mainly found in the eastern part of the
Plateau, while alpine steppe and desert vegetation types are found in areas with <400 mm annual precipitation.
Together these two grassland types account for more than two thirds of the Plateau’s vegetation cover. As average
temperatures and precipitation trends change, the area suited to growth of different vegetation types can be expected
to shift.
Zhao et al. (2002) show that with long term changes in temperature, the geographical location of different climate
belts on the Plateau will change, with a shrinking of the frigid zone in the east and southeast and a westward shift
in the semi-frigid zones and temperate zones. The distribution of vegetation types is also strongly affected by
rainfall. Despite the difficulties in modeling the responses to vegetation distribution to climate change, current
published predictions suggest some general trends. Modeling of changes in the distribution of vegetation biomes in
response to IPCC A2 and B2 scenarios (Weng and Zhou 2005), suggests that large areas of Plateau tundra biome
will transform to temperate grass and shrublands, with an overall decrease in the area of tundra. Ni (2003) reports
predicted responses to warming and doubling of CO2 concentration using a BIOME3 model. Results suggest that
climate change will cause a large reduction in the area of temperate desert and alpine steppe, with an increase in
the forested area, temperate shrubland and meadow and temperate steppe, and a general northwestward shift of
all vegetation zones. The author explains the increase in meadow, shrubland, and steppe biome areas as being due
to increased temperature and water stress favoring C4 grasses over C3 woody plants. Zhang et al. (1996), whose
model only included temperature and precipitation factors, predicted similar shifts but contrary to Ni (2003)
predicted a decrease in the alpine meadow area.
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Table 5: Predicted changes in area of Plateau biomes in response to climate change
Biome
Current
predicted land2
area* (thou. km )
Cold temperate conifer forest
Temperate deciduous broad leaved forest
Warm temperate evergreen broad leaved forest
Tropical seasonal and rain forest
Temperate shrubland / meadow
Temperate steppe
Temperate desert
Alpine meadow / shrubland
Alpine steppe
Alpine desert
Ice / polar desert
Total
183.61
7.50
45.28
2.50
139.17
83.06
246.94
252.50
755.00
597.22
210.28
2523.10
Predicted
land area after
climate
change
448.61
49.44
60.56
9.17
315.83
254.17
104.72
299.44
547.78
411.39
21.94
2523.10
% change in
land area
+244
+659
+133
+366
+227
+306
-58
+119
-28
-31
-89
0
Note: *land area covered by different biomes as predicted by BIOME3
Source: Adapted from Ni (2003)
Another significant feature of the Plateau is permafrost – permanently frozen subsoils. Permafrost has decisive
functions that influence vegetation, soil erosion processes and surface and underground water flows. Meadow and
shrublands tend to occur in the non-permafrost or seasonally frozen areas, while permanently frozen areas are
characterized by alpine steppe and desert (Ni 2003). Permafrost covers an area of about 1.2 million km2 (Nan et
al. 2004), or around half of the land area of the Plateau. About 30% of the total permafrost area is currently located
in the central and northwestern parts of the Plateau (Ni 2003). With warmer temperatures, the boundary between
permanent and seasonal permafrost is predicted to shift northwards by 1-2º latitude. Eventually, it is predicted
that permanent permafrost will largely disappear from about 70% of the Plateau (Ni 2003). Experts predict that,
given the cumulative impact of the warming trend in recent decades on the accumulation of energy, even if aboveground temperatures do not continue to rise, over the coming 30 to 40 years the trend in permafrost thawing will
continue at about the same rate. Currently, the transitional area of permafrost thawing covers an area of more than
44 303 km2 (9.61% of land area) in the western and northern Tibetan Plateau, but this area is predicted to reach a
total of 47 762 km2 by 2030 (Li et al. 2005). IPCC (1996) suggests that once temperatures have increased by 2℃,
permafrost will basically disappear. Disappearance of permafrost will accelerate desertification on the Plateau for
reasons described in Section 3.4 below.
4.2 Impacts on grassland productivity
The net effects of these shifts in the geographical spread of different vegetation types depend also on changes in
productivity that will be brought about. Overall, research tends to suggest that much of the Plateau’s grasslands may
benefit from warmer temperatures. However, precipitation trends, including changes in their seasonality also have
a crucial impact on grassland productivity. And precipitation trends are not only more varied across the Plateau, but
also more difficult to predict.
Remote sensing research on the Plateau as a whole reports that grasslands have benefited from global warming
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(Luo et al. 2004). Changes in NDVI (a proxy indicator for vegetation cover) across the plateau between 1982-1999
suggests that grassland vegetation cover has benefited from climate change due to an earlier onset of the growing
season in spring and accelerated growth during the growing season due to higher spring temperatures (Yang
and Piao 2006). However, that paper also noted different responses occurring in different vegetation types. For
example, NDVI of alpine meadows shows significant increase in the summer and a lagged correlation with
precipitation, while alpine and temperate steppe neither show significant summer increases in NDVI nor significant
correlations with climatic variables. Xu and Liu (2007) reports results of a study of the correlation between
NDVI and temperature (1982-2002), finding that across the Plateau grassland vegetation in May-June is highly
correlated with increases in temperature in April-May. Their study also found that areas with low NDVI (taken to
represent low vegetation coverage) have relatively stronger responses to temperature change, suggesting that the
least productive grasslands my actually benefit most from global warming trends. Positive correlations between
NDVI and temperature were found to be highest in the northern Plateau (from the eastern Kunlun Mountains to
the southwestern Qilian Mountains) and in the south (northern edge of the Himalayas eastward to the Hengduan
Mountains), an area covering 39% of the Plateau. These areas are both areas of high elevation (where temperature
increases have on average been largest) and areas of low NDVI. In terms of vegetation types, bare grassland, shrubs
and alpine grassland with a low vegetation coverage show more sensitive responses to global warming than other
types of vegetation. But the authors also caution that while the largest percentage increases in vegetation (between
6-10%) may occur in these areas, the absolute increase in NDVI (0.005 – 0.01) is not large. Also, areas currently
with the most productive grasslands are not all among those that will benefit from warming. So the implications of
these findings for future increased grassland productivity on the Plateau may be limited.
While these studies suggest that a large proportion of the Plateau’s grassland area may benefit from future global
warming, grassland productivity is also heavily influenced by precipitation, which was not considered by Xu and
Liu (2007). Piao et al. (2004) show that for China’s grasslands as a whole, above-ground biomass has a stronger
correlation with precipitation than it does with temperature, and that this correlation is stronger at higher altitudes.
In this regard, it should be noted that areas of the eastern Plateau where more productive vegetation types, such as
alpine meadow, are widely distributed are areas of declining average precipitation, while many areas experiencing
increasing precipitation are typified by lower productivity grassland types.
The complex changes in temperature and precipitation trends as well as variation in changes in their seasonality
across the Plateau lead several studies to identify adverse impacts of climate change on grasslands in the region.
Most of these studies have been undertaken in the eastern Plateau, while comparable research elsewhere on the
Plateau is mostly lacking. The eastern Plateau is generally an area of higher rainfall, more productive vegetation
types, but also subject to warming and drying trends in recent decades. Several studies in this region suggest that
changes in temperature trends in the spring sprouting season and autumn end of growth season, as well as decreases
in summer precipitation, are having adverse effects on grasslands.
Kobresia communities are the dominant species on the majority of the Plateau’s alpine meadow grasslands. Ren
(2005) studied changes in Kobresia grasslands over the last 20 years, finding that degradation has been rapid,
with decreasing vegetation cover, changes in community structure and emergence of weed species. That study
suggests that increasing temperature with declining summer precipitation has caused a diminution of average
grass height from 8 cm to 3 cm and a decline in yield of between 50-80%. Research in southern Qinghai (Xu et
al. 2001) suggests that the rate of increase in temperature during the spring season is slowing so that the grass
sprouting period has become extended or delayed, while temperatures are dropping faster in the autumn so that
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vegetation dries out faster. Overall the length of the growth period each year is decreasing, with observable impacts
on productivity. Under fenced enclosure conditions, comparisons of grass height by species with data from the
late 1980s show that grasses in southern Qinghai are now 30-50% shorter (Zhang et al. 1999). During the summer
months grasses are entering their elongation and reproduction stages and have higher water requirements, but
in southern Qinghai summer rainfall is decreasing, with significant impact on grass yields (Xu et al. 2001). In
general most precipitation is concentrated in the summer months (June to September). The overall trend is towards
decreased summer rainfall, but in some areas spring rainfall is also decreasing with negative effects on grass growth
(ibid.). In semi-arid and arid areas of the Plateau winter precipitation is increasing, while summer precipitation
is decreasing, and winter and autumn temperatures are falling while the spring temperature rise is slowing, again
leading to a shorter grass growth season (Wang, Li, Pan et al. 2004). These field observations are supported by
recent experimental warming studies conducted in northern Qinghai. Klein et al. (2007a) report that experimental
warming of alpine meadow and alpine shrublands by 1-2℃ resulted in declines in biomass by more than 10% in
the former with no significant net effects on biomass in the latter. In both rangeland types, palatable plant biomass
– largely Graminoids – decreased. However, some studies report that although the growing season is delayed, net
primary productivity and the timing of the peak growing season are not affected (van Wageningen and Sa 2001 p.
14-15).
Scientific studies are not the only source of information on climate change impacts on grasslands in the Three
Rivers Source Area. An anthropological study (Zhang and Li 2005) reported that among 200 herders interviewed in
the Yangtze River source area, almost 85% reported obvious climatic changes, and more than 55% reported obvious
impacts on grasslands, including changes in precipitation (15%), changes in grass quality (13%), changes in
grassland area (10%) and changes in frequencies of animal disease epidemics (13%). The vast majority of herders
agreed that there is a link between climate change and grassland degradation or desertification. Herders were found
to be more sensitive to climate changes in the warm season than in the winter because the warm season is the grass
growth period on which their livestock depend. Herders report that in the past the warm season was 3-4 months
long, but now it is less than 3 months. Later sprouting of grass impacts on livestock growth, calving or lambing and
milking. Climate change impacts on grasslands in this area are thus of direct relevance for animal husbandry and
herding communities’ livelihoods.
4.3 Impacts on plant communities and biodiversity
Field studies in the alpine steppe-alpine meadow transition zone have revealed the impacts of climate change
through changes in the diversity, richness and evenness of grass communities (Wang, Li, Pan et al. 2004). Warmer
and drier climate is causing the transition of K. humilis communities to Stipa purpurea steppe in the region south
of the Tongtianhe with a concomitant decline in biomass and carrying capacity (ibid.). While these trends represent
adaptations of plant communities to climate change, from a rangeland management point of view, declining
biomass and decreasing nutritional value of plant communities represents degradation.
There are also indications that declining summer precipitation may have adverse implications for biodiversity.
Studies have found that species richness correlates strongly and positively with growing season precipitation, while
species richness is also positively related to productivity (Yang et al. 2004). The implication is that decreasing
summer precipitation will have impacts on both species richness and biomass. Experimental warming of alpine
meadows in northern Qinghai (Klein et al. 2007b) shows a strong effect on species richness (a decline of 26-36%),
with species loss higher in drier experimental sites.
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The impacts of warmer and drier climates on permafrost also have major implications for vegetation. Wang, Li,
Pan et al. (2004) report that in an area of permafrost thawing soil desiccation has led to regressive plant community
succession (from Kobresia sp. to Carex sp .) with a decrease in biomass of 33%. Research on alpine marsh in
Northern Qinghai – an area of rising air temperature (0.157℃/decade) and decreasing precipitation (-18.59 mm/
decade) – finds that climate change has induced an increase in potential evapotranspiration, melting of permafrost
and transformations in vegetation. Marsh meadow (dominated by the cold- and wet- adapted Kobresia tibetica ) is
succeeding into typical alpine meadows. While this has led to increasing indices of species diversity, hyrophilic
plants are becoming replaced by neutral plant communities (such as Kobresia capillifolia), but vegetation cover and
biomass have declined greatly (Li, Zhao, Zhao et al. 2003).
4.4 Impacts on ecosystem functions
Permafrost is an important feature of ecosystems on the Tibetan Plateau. Past changes in seasonal temperature have
had clearly observable impacts on permafrost. The length of the frozen period has shortened, the permafrost area
has declined, and the depth of frozen soil has decreased. In affected areas, permafrost transitions into seasonally
frozen soil. The transition to a seasonally frozen soil results in a fall and eventual disappearance of the underground
water table and desiccation of surface soils, with vegetation being unable to absorb water from the available soil,
resulting in low vegetation cover and biomass, desertification and salination of soils. Melting of permafrost causes
hummocking of soil-vegetation formations, and these hummocks typically sustain low levels of vegetation cover
and biomass productivity. On severely affected thawed permafrost vegetation cover is only 10-20%, with bare earth
and scree accounting for the remainder (Xinhua 2004). Change in hydrological processes in permafrost further
adversely affects wetlands, energy and radiation balances.
Permafrost currently covers an area of about 1.2 million km2 (Nan et al. 2004), or approximately 50% of the land
area of the Plateau. In Qinghai Province, the area of stable permafrost has decreased by 4.5%, while the area of
unstable permafrost and permafrost in transition has increased by 2.8%. The area of seasonally frozen soils has
increased from 38.1% to 41.6% of the province’s land area (Xinhua 2004). Currently, the transitional area of
permafrost thawing covers an area of more than 44 303 km2 (9.61% of land area) in the western and northern
Tibetan Plateau, and this is predicted to increase to 47 762 km2 by 2030 (Li et al. 2005). IPCC (1996) suggests that
if temperatures increase by 2℃ – as is predicted for the Plateau – permafrost will basically disappear.
Studies in the Three Rivers Source Area (Wang, Wang, Cheng and Li 2006) have found strong evidence of
degradation of whole grassland ecosystems, including decreases in vegetation cover and soil erosion, such that
when vegetation cover falls below 50% the water retention properties of soil are basically lost, and nitrogen and
soil organic matter decreases rapidly. These changes – combined with glacial retreat and permafrost melting – are
having major impacts on the hydrological functions of the area as a whole (Run and Yang 2001).
4.5 Grassland carbon cycles
Wang Genxu et al. (2002) estimate that the organic carbon content of soils subtending grasslands on the QinghaiTibet Plateau total 33.5 Pg. Most of this carbon (23 Pg) is stored in meadow and steppe soils, representing almost
one quarter of China’s total organic soil carbon and 2.5% of the global pool of soil carbon. This clearly points to
the potential importance of grasslands in the Plateau in limiting global climate change. But given the sensitivity
of grasslands on the Plateau to climate change and human disturbance it is also important to examine whether
-14-
predicted trends will turn the Plateau’s grasslands into a net source of carbon dioxide and a contributor to global
climate change. This is a relatively recent area of research in which the relationships between many variables
are still relatively uncertain because of the wide range of environmental and management conditions that affect
grasslands in different areas.
The main source of carbon in grassland ecosystems is carbon fixed through plant photosynthesis. Climate clearly
has major impacts on biomass of different types of vegetation in different climate zones, with some vegetation types
being affected more by growing season precipitation and average temperatures than others (Han 2002). However,
much more carbon is stored underground in grassland ecosystems than is present in above-ground biomass. For
different types of grassland across northern and western China, the ratio of below-ground to above-ground biomass
has been found to vary between 2.75 and 22, depending on the grassland type in question. Research on three types
of vegetation in northern Qinghai shows that Kobresia humulis alpine meadow has a ratio of 7.92, alpine Kobresia
pygmaea prairie meadow has a ratio of 15.21, while alpine marsh meadow has a ratio of 21.59. The vast majority
(68-75%) of this underground biomass lies in the 0-30 cm soil layer (Huang et al. 1988). In Qinghai Kobresia
meadow, 90% of plant biomass lies in the 0-10 cm topsoil layer, so a significant proportion of vegetation-soil
biochemical cycles occurs within the soil.
The soil carbon pool accounts for about 90% of the total carbon stored in grasslands (Li and Chen 1998). The
main sources of organic carbon in the soil pool are plant remains and decomposition of the litter layer. Soil carbon
density is mainly dependant on soil types (in particular their moisture content), varying between 4.86-17.99 kg/
m2 depending on the type of soil (Qi et al. 2003). Some studies find even higher carbon densities than in forest
soils at the same latitude (ibid. p. 346). Carbon densities are much higher in the surface soil (0-20 cm) layers than
in deeper soil layers (Wang and Chen 1998). Climatic variables influence soil carbon stocks through their effects
on vegetation and through their influence on the rate of decomposition of soil organic matter. Thus, precipitation
has been found to have a clear positive correlation with soil organic carbon, while the influence of temperature
is somewhat more complex, having a beneficial effect within suitable temperature ranges (Wang Shuping et al.
2002). Research also finds that vegetation types have different speeds of litter decomposition which influence the
accumulation of soil carbon (Wang and Chen 1998). The roles of litter in grassland carbon cycles on the Plateau
is greatly under researched (Qi et al. 2003 p. 346). The accumulation of leaf litter can strongly influence grassland
ecology by causing a decline in surface soil temperatures, increases in soil moisture and decreases in soil pH, all
of which affect seed sprouting and community growth (Guo and Zhu 1988, Pei et al. 1996, Guo 1989). Scurlock et
al. (2002) find that when the underground dynamics of dead matter are accounted for in measurements, net primary
productivity is 2-5 times higher than when measured by more conventional indicators that ignore the effects of
litter. Clearly the significance of these underground dynamics differs between ecoregions and grassland types.
In grassland ecosystems, net ecosystem productivity (that is, the amount of carbon sequestered) is very small
compared to the size of fluxes, so there is great potential for changes affecting fluxes to change the net flow of
carbon, and for grasslands the therefore shift from being a CO2 sink to a CO2 source. The main factors determining
the amount of carbon sequestered in soil are: (i) the rate of input of organic matter; (ii) the decomposability of the
organic matter inputs; (iii) the depth in the soil at which the organic C is placed; and (iv) the physical protection of
carbon in soil structures (Jones and Donnely 2004).
Plant photosynthesis is central to CO2 fluxes in grasslands. Research has identified regularities in daily and seasonal
changes in the release of CO2 to the atmosphere in grassland ecosystems (Qi et al. 2003), because rates of CO2
emission are closely related to daily photosynthesis and seasonal plant growth patterns. But a large proportion of the
carbon that enters grassland soils is returned to the atmosphere through respiration of roots and soil organisms. Soil
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respiration of CO2 is affected mostly by soil temperature which also affects soil microbial activity. Soil moisture
only has a major impact where soil moisture is a limiting factor (Cui et al. 1999, Zhang et al. 2001a, Li et al. 2000).
Wang Genxu et al. (2002) estimated the total soil carbon pool of grasslands in the Qinghai Tibet Plateau to amount
to 33.52 Pg. Of this, almost 70% (23.24 Pg) is contained in alpine meadows and alpine steppe soils. Because of
differences in climate and soil types, large differences were found between Qinghai and Tibet in terms of carbon
content per unit area (see table 6). Alpine steppe has a relatively low organic carbon content compared to alpine
meadow, but because the area of alpine steppe is very large (6526 X 104 ha) it also contains a significant amount of
carbon. Marshes were found to have high levels of soil organic carbon but their total area is limited. By comparison,
cultivated land and forest soils in the Plateau were estimated to contain a total of 15.65 Pg of organic carbon, less
than half the carbon of the region’s grasslands (Wang Genxu et al. 2002 p 213).
Table 6: Soil carbon storage in Plateau grasslands
Grassland type
Alpine meadow
Alpine steppe
Marsh
Source: Wang Genxu et al. 2002
Carbon content per unit area
(kgC/m2 )
Q in g h a i
53.127
16.224
49.877
Tib e t
29.049
8.9575
56.462
Total organic carbon storage
(10 8 t C)
Q in g h a i
108.102
25.434
15.352
Tib e t
54.410
44.414
4.448
Soil carbon can be emitted by natural soil respiration (including plant root respiration, mycorrhizal respiration
and microbial decomposition), or by land use changes that influence organic matter decomposition. Based on
measurements of carbon fluxes in four locations, Wang Genxu et al. (2002 p. 213-4) suggests that because of low air
pressure and CO2 content in the atmosphere on the Plateau, in the summer months when temperatures rise grassland
soils are a net emitter of CO2, while in the winter they are a sink. On this basis they estimate that grassland soils
emit 1.17 Pg of carbon per year, which is equivalent to more than 3% of the total carbon stored in grassland 0-0.65
m soil profiles.
Other site specific studies of CO2 fluxes in grasslands on the Plateau typically find that they are a weak but
important carbon sink. A study by Kato et al.(2006) of CO2 fluxes in a Kobresia alpine meadow in Qinghai
estimated net ecosystem productivity (NEP) at 78-193 g C per m2per year. NEP was mainly affected by temperature
via its effects on biomass growth. Yan et al.(2006)estimated that netCO2 absorption varied between 0.257kg CO2/
m2and 0.153kg CO2/m2 in two consecutive years in an alpine steppe meadow, with variation determined largely
by net evapotranspiration. Li et al. (2006) measured net CO2 absorption of 0.231and 0.275kg CO2/m2 in two
consecutive years, or an average of 0.253kg CO2/m2. Net carbon sequestration was calculated to be 63.1 and 74.9 g
C/m2. The size of CO2 fluxes were found to be most strongly related to growing season temperatures. These studies
were based on empirical measurements, and although these studies all report grasslands to be a net carbon sink,
they also identified a range of climatic and environmental factors that influence rates of absorption and emission.
Modeling of CO2 fluxes on a larger scale also shows great variations in soil organic content over the last 30 years.
Zhang et al. (2006) estimated that rates of variation in soil organic content were higher for ecotypes with higher soil
organic carbon content. These rates of variation also increased in the 1990s, suggesting that sequestration of carbon
in grassland soils is sensitive to climate change. Modeling suggests that in some areas of the Plateau, soil organic
content has declined over the last 40 years, mainly due to warming temperatures (ibid). However, general trends are
difficult to identify, as soil organic content has different responses to warming in different ecotypes and even in the
-16-
same ecotype in different locations.
Climate influences both the above and below-ground processes which drive carbon cycles and carbon sequestration
in grasslands. Where climate change does not induce changes in ecosystems and key ecosystem properties,
increases in temperature may result it a loss of soil organic carbon because of higher decomposition rates (Lu and
Zheng 2006). Carbon dioxide concentration in the atmosphere is predicted to increase. Some argue that this will
cause a ‘fertilization effect’, from which grassland productivity will gain. However, both modeling and field studies
suggest that the Plateau’s grasslands may in fact suffer from elevated atmospheric carbon dioxide levels. Shaw et
al. (2002) suggest that elevated carbon dioxide may suppress root allocation, thus offsetting the positive effects
of increased temperature, rainfall and nitrogen deposition on net primary productivity. On the other hand, higher
temperatures may increase net primary productivity and thus the provision of organic inputs to soil carbon cycling
processes. The net result of higher temperatures will depend also on interaction with other site specific factors such
as rainfall and soil types.
From existing research it appears that grassland soils of the Plateau – perhaps especially already degraded
grasslands – have considerable potential for carbon sequestration. In addition to the question of the impacts of
climate change on carbon sequestration rates, it is also important to know whether grassland soil carbon will
become saturated. Little research has been done on this question, but research elsewhere suggests that after a
saturation level has been reached, continued maintenance of the management practices that led to the accumulation
of carbon is required (Soussana et al. 2004).
4.6 Summary
Remote sensing research suggests that past climate change has benefited grasslands across a large proportion of the
Plateau. However, it appears that much of this benefit has accrued to areas with initially lower vegetation cover and
lower productivity. The vast majority of published field studies have been undertaken in the eastern Plateau, much
of which has been both warming and drying. Many of these studies report adverse impacts on the productivity of
grasslands as well as changing plant community composition leading to declining vegetation cover and biomass.
This growing body of work provides evidence that independent of management practices, climate change itself has
contributed to grassland degradation in many areas of the Plateau. Precipitation appears to play a major role in these
dynamics, but precipitation trends are difficult to predict. Comparable studies from other areas of the Plateau are
lacking.
Climate change is expected to lead to major shifts in the distribution of vegetation types across the Plateau,
including expanded desertification due to permafrost melting. Modeling generally suggests that the Plateau’s
grasslands will gain from these changes, but the interrelationships between the many factors affecting grasslands
are not only poorly understood, but also difficult to model reliably. Grassland carbon cycles are even less well
understood. Studies suggest that the Plateau’s grasslands contain a significant proportion of China’s soil carbon.
At a minimum, therefore, maintaining vegetation cover is of great importance for limiting the contribution of the
Plateau’s grasslands to further global climate change.
Changes in grassland productivity and plant community composition have direct impacts on animal husbandry.
Given the wealth of information emerging on climate changes in recent decades, as well as documented impacts on
grasslands, it is noticeable that there have been no studies of how herding communities and households have been
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adapting grazing practices to accommodate these changes.
Table 7: Impacts of climate change on grasslands of the Plateau
Observed changes
Vegetation
distribution
Vegetation
productivity
Grassland
biodiversity
Net increase in vegetation cover
across Plateau, especially in north and
south and areas of low vegetation
cover
Decrease in height and yields in
eastern Plateau
Declining species richness in areas of
permafrost thawing / regressive
succession
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Predicted changes
No rth wa rd s h ift o f a ll ve g e ta tio n
zones
Increase in temperate and alpine
grass/shrubland area, decrease in
alpine steppe and deserts
Net increase due to shift towards
more productive vegetation types
Declining productivity where
precipitation declines
Increasing biodiversity where
rainfall is increasing
Declining biodiversity where
precipitation is declining
5.Anthropogenic influences on grasslands
Grassland responses to climate change are taking place against a background of continued human use. Overgrazing
has long been blamed for degradation of the region’s grasslands. Across the diverse ecological zones of the Plateau,
there is a diversity of grazing, livestock management and household economic systems (see Sheehy et al. 2006).
But in all these systems grasslands are the basis of pastoral livelihoods. A degrading natural resource base has direct
impacts on livestock production systems.
5.1 Impacts on grassland vegetation
Across the Plateau, studies of land use change report significant location specific impacts on grasslands from such
activities as conversion to arable land or past efforts to cultivate grasslands for forage production (Wang, Long and
Ding 2004). But studies show that less than 3% of the Plateau’s total area has been converted to arable land (Zhang
and Ge 2002). Land use change studies generally highlight the conversion of grassland to desert and other nonproductive uses. For example, although Pan and Wang (2004) report that between the 1980s and 2000, in the Three
Rivers Source area the land used for construction increased rapidly, its overall percentage of land use was still very
low. By comparison, shifts in the quality of grasslands, including desertification, affected a much larger area (see
also Pan et al. 2004). In addition to the impacts of climate change, overgrazing is the most commonly cited driving
force.
Government statistics suggest that the Plateau has about 60-70 million head of livestock, which is three times
higher than the figures for the 1950s (Wang and Zheng 1999). While officials may have incentives for overreporting
increases in livestock numbers to demonstrate growing local economies, anecdotal evidence suggests that
government reports of livestock numbers may even greatly underestimate actual numbers. Local reports from
across the Plateau almost unanimously suggest that grasslands – especially winter grasslands – are overstocked.
For example, in the Three Rivers Source Area, winter pastures in Maxin, Dari and Gande counties are reportedly
overgrazed by 37-280%. That is, current stocking levels are 1.4 to 4 times higher than the theoretical carrying
capacity of winter grasslands; summer grasslands in these areas are overstocked by about 80% relative to theoretical
carrying capacity (Wang and Chen 2001). Grassland surveys conducted in the late 1980s in the Three Rivers Source
area found that of the region’s 162 600 km2 of grasslands, moderately or severely degraded grasslands covered 35
700 km2 (Yan et al. 2003). Continued overgrazing since then can only have had more adverse impacts.
Several studies have been undertaken of the impacts of overgrazing on grasslands in the Plateau region. These
studies have identified a range of effects on plant communities and soil systems. In general, grazing restricts
the growth of Gramineae (grasses) and Cyperaceae (sedges), with clear correlations being reported in several
studies between degree of grazing intensity and the height, coverage, biomass and leaf area index of plants (Han
et al. 1991). In Potentilla shrublands in northern Qinghai, strong negative correlations have also been found
between grazing intensity and below-ground biomass (Liu et al. 1999). Grazing intensity has also been found to
be associated with changes in plant community structure (Zhou et al. 2002). As grazing intensity increases, the
proportion of biomass due to non-palatable plants increases (Han et al. 1993). However, the association between
grazing intensity and other measures of biodiversity, such as species richness, evenness and diversity is not strictly
unilinear, and depends very much on the properties of individual species within plant communities. Zhou et al. (2004)
reported results of monitoring of the effects of an 18 year experiment with different grazing densities in a Potentilla
shrubland in northern Qinghai. Results show that long term heavy grazing simplified the alpine shrub community
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and decreased the standing aboveground biomass, especially palatable plants. The heights, total coverage and dead
material coverage of plant communities was inversely related to the stocking rate. As grazing intensity increased,
the dominant shrub and grass species were replaced by less palatable and nutritious forbs, so the index of rangeland
quality decreased. This suggests that long term heavy grazing plays a major role in grassland degradation. However,
the study also found that under moderate grazing conditions, live shoot coverage was greater than in other plots.
Other studies have also found that light and moderate grazing stimulates both above and below-ground growth (Dong
et al. 2006, Wang Wenying et al. 2006); that species diversity is higher in moderately grazed plots than in lightly or
heavily grazed plots (Wang Wenying et al. 2006); and that exclosure of grasslands for several years may lead to a
deterioration of grassland quality due to dominance of non-palatable forbs (Miehe et al. 2004). A study combining
experimental warming of alpine meadows and shrublands with clipping (to simulate the effects of grazing) also
suggested that light grazing (30% of biomass was clipped) may serve to counter the adverse effects of warming on
grassland biomass (Klein et al. 2007b).
Several studies have reported impacts of overgrazing on soil system properties and processes. Grazing reduces soil
surface coverage, which impacts on soil temperatures and physical properties. In a study on sub-alpine meadows
in the Qilian Mountains, An et al. (2003) found that as grazing intensity increased, soil organic matter decreased,
soil pH value increased, soil N and P content decreased. Where grasslands had degraded to very low vegetation
coverage rates, the total DNA of soil microorganisms reduced. Dong et al. (2005) studied the effect of stocking
rates on soil physical characteristics in a mixed sown pasture (Elymus natans+Puccinellia tenuora ) in the Yangtze
and Yellow Rivers source region over two years. The study found that as stocking rates increase, the water contents
of soil strata decrease. Soil bulk density and hardness increased. These studies show that the health and stability
of grassland ecosystems depends on soil system functions, and that overgrazing causes rapid decrease in these
functions. Gan et al. (2005) compared different degrees of grazing intensity in sub-alpine meadows in NW Sichuan.
The study found that organic matter decreased significantly in grazed sites compared to a non-grazed control plot.
Soil organic contents were 39%, 45% and 48% less in lightly, moderately and heavily grazed sites than in a nongrazed control plot. Total P, available P, available K and available N all increased over these gradients, with more
significant degradation of nutrients in surface soil (0-10 cm) layers than in deeper soil.
Several studies have also compared the vegetation and soil properties of grasslands at different degrees of degradation
and the interactions between soil and plant community changes. Wang Wenying et al. (2006) showed that as the
degree of degradation increased, Kobresia pygmaea which reproduces by clone in an alpine environment gradually
disappears while seed reproducing species (such as Ligularia virgaurea, Aster alpinum, Leontopodium nourn etc)
develop rapidly. The study found a significant positive correlation between vegetation cover and soil water content,
particularly in the surface (0-20 cm) layers. In a study in the Three Rivers Source area, Wang et al. (2005) found
that grassland degradation changes soil hydrological processes. As the coverage of vegetation decreases, soil
moisture retention decreases, and soil water filtration occurs more rapidly. This process is accompanied by a change
in dominant species to species more adapted to drier soils, a decrease in average height of vegetation and more
severe soil erosion. Shang et al. (2006) reports that different degrees of degradation are also correlated with declines
in soil microorganism presence and diversity, and with shifts in the dominant species of microorganisms.
Long term heavy grazing may influence the properties of grassland plant communities, and may drive plant
community succession. Changes in vegetation cover, soil harness and water retention may create the conditions for
irreversible degradation. ‘Black beach’ is a form of degraded grassland which in the 1990s covered an estimated
total area of more than 7000 km2, or 16% of the total degraded area on the Plateau (Shang 2001). Black beach is
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characterized by large soil particles, weak water retention properties and low vegetation cover. Some researchers
have stressed the role of climate change and permafrost melting in the formation of black beach, suggesting that
overgrazing is an aggravating factor, while others stress the causative role of overgrazing itself (Zhou et al. 2004,
van Wageningen and Sa 2001). Once vegetation cover has decreased and soils become desiccated and hardened, the
conditions for rodent infestation are created, with further destructive impacts (van Wageningen and Sa 2001).
Population growth is often given as a reason behind overstocking. But some researchers have discussed the
contribution of grassland management policies to overstocking and overgrazing. In particular, in the early 1980s
before collective management of grasslands was reformed, livestock were contracted to households and stocking
levels increased rapidly across the Plateau. Subsequently, grasslands were contracted to households in most areas.
In some cases, this was a ‘paper exercise’ and grassland management continues in practice along traditional
methods. In other areas, grasslands have been fenced off, and some argue that this itself is adverse for the rational
utilization of grassland resources across space and time, thus contributing to excessive grazing in specific locations
(Li et al. 2007, Zhao and Long 2007). Herder households have been encouraged to sedentarize and livestock
mobility across the landscape has decreased and the recovery period for pastures has shortened (Feng et al. 2005).
Several international observers and scholars have criticized Chinese grassland management policy (Wu and Richard
1999, Banks et al. 2003, Williams 2002). Most reports of the impacts of these grassland management policies are
based more on anecdotal evidence. A comprehensive evidence-based study on the impact of contracting and fencing
on grassland vegetation funded by the EU is currently underway (Yan and Waters-Bayer 2007).
5.2 Impacts on grassland carbon cycles
Although climate change may also be a significant cause of grassland degradation, in the short term climate is
not an available management tool, while grazing management policies and practices are. Almost all papers on
sustainable grassland management on the Plateau recommend the implementation of sustainable stocking rates.
Grassland productivity is affected by climatic factors, which vary considerably across the Plateau. Given a lack of
existing data, and limited staff capacities, calculating theoretical carrying capacity at the local level has been found
difficult to put into practice (Li 2007). The concept of carrying capacity itself has also been debated. Following
debates about African arid grassland ecosystems, some have argued that grasslands on the Plateau are nonequilibrium systems to which the concept of carrying capacity is not well suited (Wu and Luo 2004). Others have
stressed that ecological carrying capacity is not a sufficient reference for pastoral livestock production systems, in
which economic goals are also important (Wu and Luo 2004, Dong et al. 2002).
Retention of carbon in grassland soils is strongly influenced by management and anthropogenic disturbances. Since
most soil organic carbon is stored in the upper layers, factors that impact on vegetation cover and soil erosion are
key influences. Wang Genxu et al. (2002 p. 214-5) suggests that conversion of grasslands to arable land plays a
relatively small role in carbon dynamics on the Plateau. By contrast, grasslands cover around 90% of land area, and
almost 20% of grasslands are moderately or severely degraded. Of the estimated 3.02 Pg of carbon lost due to land
use change between 1986-2000, 98% was due to grassland degradation.
Pan et al. (2004) studied the impacts on land cover change in the Three Rivers Source Area. In this area they
found that land cover changes with important implications for soil carbon storage were not limited to conversion
of grassland to arable land. In the research area, over 1986-2000, 23% and 34% of alpine marsh were converted
into alpine meadow or steppe. Other important land cover changes included the conversion of more than 20% of
-21-
meadow and steppe with high vegetation coverage into steppe and meadow with low vegetation coverage, and
an increase in desertified land. They estimate that together, these changes led to a loss of 336.6 Gg of soil organic
carbon over the 15 year study period. A significant contribution to this was due to the loss of alpine marshes. Ren
and Lin (2005) focuses on the impacts of land cover change in the Three Rivers Source Area between 1986-2000.
Over this period soil organic matter content declined by more than 11% while CO2 emission levels only declined
by about 9%. Thus the area is becoming a net source of atmospheric CO2. Arable land increased by only 11.78 km2,
leading to a release of 16 500 t of CO2, while the grassland area decreased by 2929 km2, causing a release of 7.6
million tones of CO2. A disproportionate amount of this CO2 release has been due to the loss of marshes, although
the area of marsh only changed from 7.28% of total area in 1986 to 5.63% in 2000.
Overgrazing impacts on plant biomass and thus the availability of organic inputs to carbon cycling processes.
Overgrazing can also accelerate soil respiration causing a loss of soil organic carbon. Research in Inner Mongolia
shows that long term overgrazing caused a loss of 12% of carbon stocks in the 0-20 cm soil layer (Li and Chen
1997). Overgrazing in the growth season causes changes in soil physical properties which further constrain the
development of individual plants, with direct impacts on grassland carbon sink production (Wang 1996, Li et
al. 1999). However, it is also clear that compensatory growth occurs in response to a certain degree of grazing
(Wang, Wang and Li 1998) so adopting suitable grazing densities are important. Moreover, there is evidence
from elsewhere that exclosure of grasslands from grazing may have negative impacts on the sequestration of
soils because excluding grazing may cause the immobilization of carbon in excessive plant litter and a change in
dominant vegetation to plants whose root systems are conducive to soil organic matter formation and accumulation
(Reeder and Schuman 2002). Soil carbon may be increased by grazing if this causes a higher annual shoot turnover
and a redistribution of carbon between plants and soil due to changes in plant species (ibid). Wang and Chen
(1998) and Wang Shuping et al. (2002) show that the release of CO2 from soils is lower in grazed than in ungrazed
grasslands, and lower in heavily grazed than in lightly grazed grasslands. Grazing intensity has clear associations
with soil organic matter. Partly this is because of the impacts of grazing on soil system properties and partly because
as grazing intensities increase the proportion of carbon returned to the soil decreases. However, some other research
reports contradictory findings (Wang et al. 2001, Li and Lin 2000, Zhang et al. 2001a).
Several studies have been undertaken comparing soil carbon stocks in sites of different degrees of degradation.
Wu and Theissen (2002) compared light, moderate and heavily degraded grassland sites in Gansu, finding that
organic carbon is reduced by a third. Zhou et al. (2005) also found correlations between degree of degradation and
soil organic matter, especially in surface layers. Cao et al. (2004) suggest that lack of soil nutrients in degraded
grasslands is the main driver of changes in dominant plant populations towards those more suited to low nutrient
availability.
Management practices which eliminate disturbance to soil carbon in established pastures would clearly have a
great impact on carbon sequestration. Increasing grass production by reseeding, fertilization and irrigation, as well
as improvements in stocking densities and rotational grazing all have potential to increase soil organic matter. In
terms of increasing carbon sequestration, rehabilitation of already degraded grasslands have the greatest potential.
However, Jones and Donnely (2004) also cite studies finding that improved management of grasslands may
redistribute carbon in the soil profile without actually increasing the amount of carbon sequestered.
5.3 Summary
Existing reports mostly concur that overgrazing is a significant cause of grassland degradation and that overgrazing
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is pervasive on the Plateau. Research shows that overgrazing impacts on both plant communities and soil system
properties and drives processes of grassland degradation and desertification. These processes have positive
feedbacks to global climate change. Degradation and increasing desertification of grasslands exposes a greater
percentage of soil surface and soil temperatures increase. Hot dry soils retard the accumulation of organic matter,
further inhibiting plant growth, and desiccated soils are more prone to wind erosion. Soil particles are transported
into the atmosphere as dust which may trap reradiation and further exacerbate warming (Schlesinger et al. 1990).
Grassland degradation also releases greenhouse gases into the atmosphere, and thus contributes to further global
climate change.
Overgrazing retards grassland vegetation growth, with obvious impacts on livestock production. Overgrazing has
been found to impact on the growth of livestock themselves. Wang et al. (1991) report that as grazing intensity
increases, the body weight gain of Tibetan sheep decreases. Zhao and Wang (1988) suggest that this is because of
the impacts of different grazing intensities on plant community structure, with implications for the digestibility of
grazed biomass.
The extent to which past and current grassland management policies have been successful in addressing
overstocking is a particularly important question. Some observers suggest that past grassland management policies
across the Plateau have exacerbated overstocking and improper use of grassland and water resources (Yan and
Wu 2003). More recent efforts to address stocking rates directly have been found difficult to implement (Li 2007).
Carrying capacity of grasslands can also be increased by cultivating grass plots, and a great deal of work has been
done on this across the Plateau. However, deficiencies in the extension system (Bass et al. 2001) suggest that this
route to addressing the balance between livestock and available forage is not likely to bring about dramatic changes
in the immediate future. If the common assumption that overstocking is pervasive is correct, then alternative means
to addressing this issue – while also ensuring livelihood development for pastoral communities – must be found.
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6.Towards mainstreaming climate change in grassland management
policies
The notion of ‘abrupt climate change’ – a situation in which the climate system is pushed across a threshold and
enters a new state – has been raised in scientific and policy circles (National Research Council 2002). Lenton et al.
(2008) further develops the notion that changes in critical elements of the global climate system – ‘tipping elements’
– may trigger either rapid or gradual transition to a new climate system state. Ecosystems of the Tibetan Plateau
have several critical functions, including influences on atmospheric circulation and regional weather systems, and
hydrological processes that affect vast regions of China, South and Southeast Asia. Grasslands, covering more
than half of the Plateau’s land area, play key roles in mediating these processes. Official reports state that about
half of the Plateau’s grasslands are degraded to different degrees. Grassland degradation has positive feedbacks to
global climate change, through the release of methane and CO2, changes in carbon sequestration properties of soils,
changes in surface albedo and increases in atmospheric particle concentration which traps reradiation and further
exacerbates warming (Schlesinger et al. 1990). Both climate change (changes in precipitation and temperature
trends) and overgrazing are widely seen as potential ‘tipping elements’ affecting the Tibetan Plateau’s grasslands
and the global environmental services they provide.
The further relevance of the notion of climate system ‘tipping points’ is that it also relates to the extent to which
society recognizes, is willing and is able to respond to environmental change (Lenton et al. 2008, Scheffer et al.
2003). Often societies are slow in recognizing critical ecosystem changes, and even slower in developing effective
responses. An accumulation of scientific evidence is no guarantee of a societal response, nor is it a guarantee
of effective regulation of the causes of environmental change (see, for example, Kuhn 1962 and Latour 1987).
Institutional processes mediate the flow and interpretation of information, and also affect social actors’ incentives
to respond (Tompkins et al. 2005, Næss et al. 2005). While some have argued that centralized decision-making
systems incur lower transaction costs in responding and are therefore able to respond more rapidly to critical
ecosystem changes (Scheffer et al. 2003), such social systems may also face challenges arising, among other things,
from constraints on information flows, effects of unequal distributions of decision-making power, interest group
capture and so on. Processes of social learning are particularly important when problems and causes are complex.
China has responded rapidly to growing awareness of climate change and changing ecosystem services that are
already perceived as impacting on national and regional environmental security (NDRC 2007). Prevention of
desertification and grassland degradation has been highlighted in several of the Chinese government’s statements on
climate change impacts and adaptation needs (ibid and Lin et al. 2007). China’s Initial Communication on Climate
Change (NDRC 2004) stressed the important role of China’s grasslands in mitigating continued climate change and
highlighted declining grassland area and productivity as a key threat to China’s agricultural sector in the National
Climate Change Programme (NDRC 2007). This programme has incorporated the current National Grassland
Conservation and Utilization Plan (MoA 2007), which proposes by 2020 to put 60 million ha of grassland under
enclosure (retirement), cultivating 3 million ha of reserve grassland and establishing 18 million ha of improved
grassland across the Tibetan Plateau. As part of the Special Provision for the Development of the Western Regions
(xibu da kaifa ), between 2004 and 2010, central government will invest 75 billion RMB (ca. USD 10.7 billion) in
the establishment of the Three Rivers Source Area Nature Reserve, including investment in grassland retirement,
wetland conservation, ‘black beach’ rehabilitation’, rodent control and human resettlement (Yan et al. 2004).
Such programmematic efforts clearly demonstrate that the accumulation of scientific evidence of significant
-24-
environmental change has translated into strong support for action at the most senior policy levels. Policy change,
however, is often driven by simplified and appealing policy narratives (Keeley and Scoones 1999). So there is no
guarantee that strong policy support for remedial action will translate into effective practices on the ground. As
the sections below discuss, there are particular knowledge gaps concerning sustainable management of Tibetan
Plateau grasslands. These knowledge gaps arise, in part, because of social distance and lack of effective co-learning
between scientists, policy makers and the herders whose grassland management practices are of such importance in
determining the outcomes for the Plateau’s grasslands. As this review paper has shown, Chinese scientists have a
strong basis in scientific methods and primary data on both climate change and Plateau grasslands. Further support
to mainstream climate change concerns in grassland management policies must also include a focus on support
to knowledge management and social learning processes across multiple levels with a view to promoting the
development of adaptation plans and support policies that reflect the needs of diverse stakeholders in sustainable
utilization of the Plateau’s grasslands.
6.1 Multidisciplinary learning to create incentives for sustainable grassland management
In principle, anthropogenic factors impacting on Tibetan Plateau grasslands are directly amenable to policy
intervention. Both scientific and policy communities in China agree that overgrazing is a principal driver of
grassland degradation across the Plateau. There is strong evidence that heavy grazing can cause degradation of
grassland vegetation and soils with resulting loss of ecosystem functions, while light or moderate grazing can
stimulate biomass production and maintain vegetation cover. Klein et al. (2007b) have even suggested that suitable
grazing levels may counteract the adverse effects of warming on grasslands in northern Qinghai.
Enforcement of sustainable stocking rates has been written into the Grassland Law (PRC 2002), but has proved
difficult to implement in practice. Constraints include the ability of local extension agents to undertake this work,
as well as the direct conflict between limiting herd sizes and herders’ livelihood goals (Li 2007). Payments for
environmental services (PES) schemes might provide one way of providing economic incentives for adoption
of more sustainable grassland management practices. Senior Ministry of Agriculture officials are aware that the
stocking rate enforcement provisions in the Grassland Law provide only negative sanctions for overstocking,
without providing positive incentives for herders to adopt sustainable stocking rates. A preliminary proposal
has been submitted to the Ministry of Finance for a mechanism to facilitate compensatory payments (Liu 2007).
In outline, this system would require herder households to sell off livestock in excess of estimated sustainable
stocking levels, and the government would pay households a compensation for the foregone annual income over
a guaranteed period of 10 years. With a rising trend in central government fiscal revenue as a share of GDP, and
foreign exchange reserves at over USD 1000 billion, it appears that the ability and possibly also willingness of
central government to pay for such an incentive mechanism are both in place.
However, many doubts about the outline proposal for a PES system remain. Existing natural science research on the
impacts of stocking densities on grassland ecosystems is relatively well developed, but integration of this growing
knowledge base with other disciplines has not yet occurred. In terms of identifying priority target areas for a PES
scheme, the scientific basis for mapping flows of ecosystem services already exists. But there is as yet no database
of stocking densities with which to map and identify geographical areas critically at risk from overgrazing. The
outline proposal for a grassland PES scheme suggests payment levels based on the central government’s current
ability to pay. But at the micro level very little is known about herders’ willingness to accept such payments. No
research has been published on price elasticity of livestock sales, and no in-depth studies can be found of household
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stocking decisions and household economies on the Tibetan Plateau. Unlike afforestation of trees, whose physical
location can be logged using GPS to verify compliance with compensation scheme requirements (Ma et al. 2006),
livestock are mobile. The PES scheme outlined in Liu (2007) does not define a monitoring scheme for a grassland
PES scheme, and workable methods for verification of the outcome of compensatory payments would be necessary
to persuade the Ministry of Finance to support such as scheme.
That an outline policy proposal has already been developed, yet these and other important questions have not been
adequately researched, points to major discontinuities between research and policy communities, as well as between
different research disciplines. There are few formal mechanisms for integrating scientific research into policy
making. Although some senior researchers sit on the Ministry of Agriculture’s academic advisory committee, their
role is only advisory, leaving a large gap between the provision of advice and development of policy. Furthermore,
there are no mechanisms in place to ensure provision of funding for policy relevant research prior to policy design,
either from academic funding bodies or from the Ministry of Agriculture itself. In other sectors, China has already
accumulated considerable experience of PES schemes. In particular, more than 7 years’ experience of implementing
the Sloped Farmland Conversion Programme, which compensates farmers for afforesting arable land on slopes
above 25 degrees (Xu et al. 2005, Xu et al. 2002), can provide many lessons of relevance to the design of a
sustainable and equitable grassland PES scheme. International experiences with PES schemes in grassland (DutillyDiane et al. 2007) and other sectors (Forest Trends 2006) can also make important contributions. There is clearly
a need, therefore, to develop institutional processes that support policy analysis to draw on existing information,
that facilitate multidisciplinary research on topics of policy relevance, and that link the accumulation of credible
scientific evidence with policy making.
Another potential source of financial incentives for sustainable grassland management practices might be carbon
finance programmes in which herders are rewarded for engaging in management practices that improve the CO2
sequestration of their grasslands. At present, grassland soil carbon sequestration programmes are not eligible
under the CDM. There is mounting pressure for a post-Kyoto agreement to include payments for sequestration
in existing forests, and this might be extended to other carbon sinks, including grasslands. In the absence of such
a global facility, voluntary carbon markets– which are predicted to reach a total value of USD 3 trillion by 2020
(Point Carbon 2008) – provide one alternative source of financing. In early 2007 the Chicago Climate Exchange
began to accept applications under a newly approved Rangeland Management Soil Carbon Offsets programme.
In this programme, payments to ranchers in the US can be made in return for engaging in sustainable rangeland
management practices, including sustainable stocking rates and rotational grazing. Some grassland types on the
Tibetan Plateau have been shown to sequester significant levels of CO2. This suggests the potential for developing
such projects as a way of providing incentives to herders to engage in sustainable management practices. However,
much work remains to be done in characterizing baselines, developing methodologies that both meet buyers’
requirements and that are implementable under realistic conditions, and investigating the economic and institutional
feasibility of such projects. Existing international experience both with grassland carbon cycle research and carbon
finance project methodology development can be drawn on to support the development of such projects on the
Tibetan Plateau.
6.2 Learning across multiple scales for adaptation planning
Mainstreaming climate change into conservation and development planning refers in general to the integration of
consideration of climate change mitigation and adaptation into ongoing sectoral and development planning and
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decision making (Mitchell et al. 2006). A basic feature of China’s government system is that responsibility for
planning and implementation of conservation and development actions is distributed between vertical line agencies
(such as grassland focused agencies subsidiary to technical animal husbandry bureaus at each level of government)
and various levels of local government each with their own ‘horizontal’ area of geographical jurisdiction (Chao
1991). In practical terms, grassland management policies and major programmes are set at national level and
implemented in grassland areas across the country in relatively standardized ways. For local governments, this
sometimes leaves them with little room for adjustment to local particularities in the implementation of these
national policies. Aside from implementing national programmes, local governments must develop plans for
locally suited projects and submit them to superior levels either within the ‘vertical’ technical line agency system or
within the ‘horizontal’ administrative system. Local governments therefore often face a conflict between pursuing
funding themes already announced at superior levels as against undertaking local assessments to design projects
that better reflect local needs, but which run the risk of not fitting with the funding priorities set by superior levels
of government. The ability of local governments and supporting stakeholders at other levels to generate or secure
funding for locally designed adaptation activities is a key determinant of how proactive governments can be in
developing adaptation plans. This implies that the support to adaptation planning on the Tibetan Plateau needs to
address concerns, perspectives and options available to decision makers located at different positions within the
technical and administrative systems, and to develop ways to embed evidence-based scientific research in decisionmaking processes across multiple scales.
From a sectoral perspective, climate change mainstreaming in grassland management policy implies a need to
support consideration in national level decision-making of (a) climate change impacts on grasslands, (b) climate
change impacts on policy-supported grassland management practices and (c) ways in which grassland management
programmes can support adaptation of herders to climate change at the same time as contributing to the mitigation
of climate change. As this review paper has shown, there is a growing body of scientific research on the impacts
of climate change on Plateau grasslands that enjoys significant support from national scientific research funding
bodies. Further research will undoubtedly enhance our understanding of climate change impacts. The current
national grassland management plan (MoA 2007) runs through 2020. With regard to the Tibetan Plateau, its
main programmes are grassland enclosure (retirement), natural grassland improvement and creation of grassland
reserves across the Tibetan Plateau, efforts that appear in general to be beneficial for counteracting the impacts
of and mitigating further climate change. To date, scientific research on the outcomes and impact of government
funded grassland management programmes has in general been relatively weak. For example, China has been
implementing a grassland retirement programme, tuimu huancao, since 2003. In this programme compensation is
provided to herder households who retire grasslands from use, restrict seasonal use and / or introduce rotational
grazing systems. Between 2003-2006 Qinghai planned to retire almost 3.5 million ha of grassland, and in Tibet
almost 7.5 million ha have been retired. Although monitoring of regrowth of above-ground biomass within
enclosed areas is a mandatory part of programme implementation, there have been few formal publications of
the results, and few studies on the impacts of enclosure on other grassland ecosystem functions. Furthermore, the
few published reports on the socio-economic impacts of the programme call for increased attention to the impacts
of the programme on household economies and the need for related investments to support transitions in animal
husbandry management practices in programme areas (Bao 2006). Research on the observed and predicted impacts
of climate change on these programmes is at an even earlier stage of development. In other countries research
results suggest that it cannot be assumed that grassland retirement will improve all ecosystem functions (Jones and
Donnely 2004). And although cultivation of grass plots has been shown to be beneficial for both above and belowground biomass and carbon sequestration (Ma et al. 2002, Ma et al. 2003, Ma et al. 2007), the large amounts of
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nitrate fertilizer applied in these treatments suggest a concern for the actual GHG sequestration potential of these
methods of grassland management. More focused research on climate change impacts on and socio-economic
impacts of the main grassland management programmes is due. The development of screening tools to assess
climate change mitigation and adaptation benefits of current programmes, as has been done for China’s water sector
(Tanner et al. 2008), is one way to promote consideration of climate change issues in national sectoral planning.
Consideration of climate change impacts in the grassland management sector will, therefore, involve not only better
integration between natural science and social science in the assessment of policy and programme options, but also
integration between research and policy communities so that the results of scientific research can better inform the
assessment, adjustment and further development of national policies and programmes.
As this review has shown, the datasets and methods to undertake integrated regional assessments of climate change
impacts on the Tibetan Plateau are being developed, though some challenges to Plateau-specific Regional Climate
Models remain to be overcome (Weng and Zhou 2005). Climate change impacts on grasslands also impact on
animal husbandry and pastoral livelihood systems. Integrated impact assessments (see Kelly and Kolstad 1999,
Patt et al. 2003) generally include the development of climate change scenarios and assessment of their biophysical
impacts. These aspects of current scientific knowledge are relatively more developed. Beyond that, it is also
necessary to investigate the socio-economic impacts of climate change induced environmental change and to
assess options for adaptation. While the state of knowledge from the natural sciences on climate change impacts
on Tibetan Plateau ecosystems has been growing, the 5 million or more pastoralists whose management practices
determine outcomes for grassland sustainability have been conspicuously missing from the picture. While there
are a few studies documenting traditional grassland management practices and responses to climate variability
(Gesangben and Duozang Caidan 2000), only one study has been identified focusing on herders’ knowledge of
climate change and its impacts on grasslands and animal husbandry (Zhang and Li 2005). No study is known of
how herders’ management practices are adapting to climate change. In pastoral systems in many other countries,
mobility is a key adaptation strategy (Hesse and Cotula 2006, Kipuri and Sorensen 2008, Batima 2006). Some
previous research on grassland tenure reform on the Tibetan Plateau has argued that contracting of grasslands has
reduced the options for mobility (Feng et al. 2005), though informal grassland rental markets have developed in
some areas (Richard et al. 2006). Climate variability has long been a characteristic of the Plateau. Again, there are
few systematic studies of how herders cope in the face of such risk events (but see Bass et al. 2001 and Xue 2005).
A developing consensus from adaptation research in other countries is that for adaptation planning to link with
and support adaptation practices, it is essential to understand existing adaptation practices and the potential for
government interventions to either assist or hinder the development of increased resilience and adaptive capacity
among key actors (Tompkins et al. 2005 and Swanson et al. 2007). Given the extent to which pastoral economies
and livelihood strategies remain little understood by the scientific and policy communities, it will be necessary
to undertake in-depth socio-economic studies of how herders cope with climatic variability as well as longer
term climate change. In the almost total absence of other sources of information, studies of local knowledge and
practices will be a particularly useful source for informing decision makers of current adaptation practices and the
potential for actions to further support herder adaptation to increasing climatic variability and to longer term climate
change (Puri 2007, Turner 2007, Dekens 2007). Studies of livelihoods, coping strategies and related indigenous
knowledge can inform the development of indicators for vulnerability to climate related risks, on the basis of which
vulnerability can be mapped to assist in the targeted development of adaptation policies which support the resilience
and adaptive capacities of pastoral communities. Such research, again, will require multidisciplinary cooperation.
In-depth local case studies of indigenous knowledge of climate change and herders’ current adaptation strategies
should be linked to wider regional studies aiming to map vulnerability and adaptive capacities. Linking results of
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this research with planning of supportive policies for climate change adaptation will require the development of
strategies for the translation of knowledge across social and administrative levels for their consideration in regional
and sectoral adaptation planning.
6.3 Summary
The preceding sections of this paper have summarized a wealth of information on climate change trends across the
Plateau and the emerging knowledgebase on the impacts of climate change on grasslands and selected ecosystem
functions in the region. Available evidence suggests that there will be both losers and winners from climate
change. Warmer temperatures, when accompanied by increasing precipitation, will result in increased productivity
of grasslands in some areas of the Plateau. Especially in the eastern Plateau, warming combined with declining
summer precipitation will probably continue to result in declining grassland productivity. Melting of permafrost
will hasten desertification of large areas of the Plateau and the concomitant loss of other grassland ecosystem
services. Grassland degradation and desertification on the one hand further contributes to global warming and
the loss of critical ecosystem functions, and on the other hand places stress on animal husbandry production and
pastoral livelihoods. China has already prioritized the conservation of grassland ecosystems in its programmatic
statements on climate change adaptation, and grassland conservation programmes are already underway across the
Tibetan Plateau. This paper finds that further policy relevant research is required in order to mainstream climate
change concerns in grassland management policy.
Climate change is taking place against a background of pervasive overgrazing. Legal requirements for sustainable
stocking rates have proven difficult to implement. Grassland management stakeholders are now examining the
potential for payments for ecosystem services to provide incentives for sustainable grassland management as well as
supporting herders’ livelihoods. Potential sources of funding for such payments include a central government PES
scheme and carbon finance markets. In order for such schemes to be sustainable and equitable, multidisciplinary
research integrating knowledge of grazing impacts on grassland ecosystems with knowledge of herder household
economies and their likely responses to incentive payments is required.
Further research on and assessments of climate change impacts in grassland areas of the Tibetan Plateau and
development of adaptation strategies will also require multidisciplinary research. Adaptation in pastoral systems
relates to many more sectors and issues than just grassland science. In addition to impacts of biophysical changes
on animal husbandry, research should consider livelihood impacts and strategies in a broader sense, developing
an understanding of existing adaptation strategies, and assessing the effects of social policy in a range of sectors
as they relate to herder communities’ capacities to cope with increased short term climate variability as well as
adaptation to longer term climate change. Consideration of adaptations in grassland management practices relates
not only to questions of grassland ecology and animal husbandry, but also to household and regional economics,
and to the performance of extension service and social welfare systems (Bass et al. 2001). Adaptation research
should inform sectoral planning processes in the grassland management sector, as well as informing the planning
strategies of local governments at various levels. Because of the paucity of existing information on herders’ current
adaptive strategies, the results of in-depth local studies will have to link to wider regional studies and planning
processes at different levels. This suggests that a research strategy should be based on a combination of top-down
and bottom-up approaches to adaptation planning (UNFCC 2004).
Characteristics of the institutional arrangements of a society are among the core determinants of a society’s
vulnerability to climate change and their adaptive capacity (Adger 2001). Several studies have shown that
-29-
both institutions and social learning processes that are either hindered or facilitated by institutions are critical
determinants of adaptation responses (Tompkins et al. 2005, Næss et al. 2005, Adger 2001). China’s rapid
development and adoption of significant programmes on climate change mitigation and adaptation as well
as grassland conservation in part reflect the general centralized nature of decision-making in the country. A
review of how these policy innovations came about has yet to be done, but it suggests that both the national and
international scientific community can be crucial in bringing about major policy shifts of the type required for
addressing changes of the scale implied by massive degradation of Tibetan Plateau grasslands. Such shifts in policy
paradigm are, however, often driven by simplified policy narratives (Keeley and Scoones 1999). This review has
suggested that there are weak links between scientific research and the monitoring of impacts of major policies
and programmes. The grassland management sector in China appears to be characterized by weak links between
research and policy and in particular by weak links between natural and social science research. Within the
government system, there are also conflicts between lines of vertical command and horizontal control, and these
bureaucratic institutional arrangements will also influence incentives for developing adaptive responses to climate
change. New platforms, processes and institutional arrangements to facilitate social learning will have to emerge
for rapid and effective responses to climate change to be integrated into adaptive planning for the management of
Tibetan Plateau grasslands.
-30-
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WORKING PAPERS IN THIS SERIES
2005
1.
Agroforestry in the drylands of eastern Africa: a call to action
2. Biodiversity conservation through agroforestry: managing tree species diversity within a network of community-based, nongovernmental, governmental and research organizations in western Kenya.
3.
Invasion of prosopis juliflora and local livelihoods: Case study from the Lake Baringo area of Kenya
4. Leadership for change in farmers organizations: Training report: Ridar Hotel, Kampala, 29th March to 2nd April 2005.
5.
Domestication des espèces agroforestières au Sahel : situation actuelle et perspectives
6. Relevé des données de biodiversité ligneuse: Manuel du projet biodiversité des parcs agroforestiers au Sahel
7.
Improved land management in the Lake Victoria Basin: TransVic Project’s draft report.
8.
Livelihood capital, strategies and outcomes in the Taita hills of Kenya
9. Les espèces ligneuses et leurs usages: Les préférences des paysans dans le Cercle de Ségou, au Mali
10. La biodiversité des espèces ligneuses: Diversité arborée et unités de gestion du terroir dans le Cercle de Ségou, au Mali
2006
11. Bird diversity and land use on the slopes of Mt. Kilimanjaro and the adjacent plains, Tanzania
12. Water, women and local social organization in the Western Kenya Highlands
13. Highlights of ongoing research of the World Agroforestry Centre in Indonesia
14. Prospects of adoption of tree-based systems in a rural landscape and its likely impacts on carbon stocks and farmers’ welfare: The FALLOW Model Application in Muara Sungkai, Lampung, Sumatra, in a ‘Clean Development Mechanism’ context
15. Equipping integrated natural resource managers for healthy agroforestry landscapes.
16. Are they competing or compensating on farm? Status of indigenous and exotic tree species in a wide range of agro-ecological zones of Eastern and Central Kenya, surrounding Mt. Kenya.
17. Agro-biodiversity and CGIAR tree and forest science: approaches and examples from Sumatra.
18. Improving land management in eastern and southern Africa: A review of polices.
19. Farm and household economic study of Kecamatan Nanggung, Kabupaten Bogor, Indonesia: A socio-
economic base line study of agroforestry innovations and livelihood enhancement.
20. Lessons from eastern Africa’s unsustainable charcoal business.
21. Evolution of RELMA’s approaches to land management: Lessons from two decades of research and development in eastern and southern Africa
22. Participatory watershed management: Lessons from RELMA’s work with farmers in eastern Africa.
23. Strengthening farmers’ organizations: The experience of RELMA and ULAMP.
24. Promoting rainwater harvesting in eastern and southern Africa.
25. The role of livestock in integrated land management.
26. Status of carbon sequestration projects in Africa: Potential benefits and challenges to scaling up.
27. Social and Environmental Trade-Offs in Tree Species Selection: A Methodology for Identifying Niche Incompatibilities in Agroforestry [Appears as AHI Working Paper no. 9]
28. Managing tradeoffs in agroforestry: From conflict to collaboration in natural resource management. [Appears -39-
29. Essai d'analyse de la prise en compte des systemes agroforestiers pa les legislations forestieres au Sahel: Cas as AHI Working Paper no. 10]
du Burkina Faso, du Mali, du Niger et du Senegal.
30. Etat de la recherche agroforestière au Rwanda etude bibliographique, période 1987-2003
2007
31. Science and technological innovations for improving soil fertility and management in Africa: A report for NEPAD’s Science and Technology Forum.
32. Compensation and rewards for environmental services.
33. Latin American regional workshop report compensation.
34 Asia regional workshop on compensation ecosystem services.
35 Report of African regional workshop on compensation ecosystem services.
36 Exploring the inter-linkages among and between compensation and rewards for ecosystem services CRES and human well-being
37 Criteria and indicators for environmental service compensation and reward mechanisms: realistic, voluntary, conditional and pro-poor
38 The conditions for effective mechanisms of compensation and rewards for environmental services.
39 Organization and governance for fostering Pro-Poor Compensation for Environmental Services.
40 How important are different types of compensation and reward mechanisms shaping poverty and ecosystem services across Africa, Asia & Latin America over the Next two decades?
41. Risk mitigation in contract farming: The case of poultry, cotton, woodfuel and cereals in East Africa.
42. The RELMA savings and credit experiences: Sowing the seed of sustainability
43. Yatich J., Policy and institutional context for NRM in Kenya: Challenges and opportunities for Landcare.
44. Nina-Nina Adoung Nasional di So! Field test of rapid land tenure assessment (RATA) in the Batang Toru Watershed, North Sumatera.
45. Is Hutan Tanaman Rakyat a new paradigm in community based tree planting in Indonesia?
46. Socio-Economic aspects of brackish water aquaculture (Tambak) production in Nanggroe Aceh Darrusalam.
47. Farmer livelihoods in the humid forest and moist savannah zones of Cameroon.
48. Domestication, genre et vulnérabilité : Participation des femmes, des Jeunes et des catégories les plus pauvres 49. Land tenure and management in the districts around Mt Elgon: An assessment presented to the Mt Elgon improving livestock productivity.
51. Buyers Perspective on Environmental Services (ES) and Commoditization as an approach to liberate ES ecosystem conservation programme.
50. The production and marketing of leaf meal from fodder shrubs in Tanga, Tanzania: A pro-poor enterprise for à la domestication des arbres agroforestiers au Cameroun.
markets in the Philippines.
52. Towards Towards community-driven conservation in southwest China: Reconciling state and local perceptions.
53. Biofuels in China: An Analysis of the Opportunities and Challenges of Jatropha curcas in Southwest China.
54. Jatropha curcas biodiesel production in Kenya: Economics and potential value chain development for smallholder farmers
55. Livelihoods and Forest Resources in Aceh and Nias for a Sustainable Forest Resource Management and -40-
Economic Progress.
56. Agroforestry on the interface of Orangutan Conservation and Sustainable Livelihoods in Batang Toru, North Sumatra.
2008
57. Assessing Hydrological Situation of Kapuas Hulu Basin, Kapuas Hulu Regency, West Kalimantan.
58. Assessing the Hydrological Situation of Talau Watershed, Belu Regency, East Nusa Tenggara.
59. Kajian Kondisi Hidrologis DAS Talau, Kabupaten Belu, Nusa Tenggara Timur.
60. Kajian Kondisi Hidrologis DAS Kapuas Hulu, Kabupaten Kapuas Hulu, Kalimantan Barat.
61. Lessons learned from community capacity building activities to support agroforest as sustainable economic alternatives in Batang Toru orang utan habitat conservation program (Martini, Endri et al.)
62. Mainstreaming Climate Change in the Philippines.
63. A Conjoint Analysis of Farmer Preferences for Community Forestry Contracts in the Sumber Jaya Watershed, Indonesia.
64. The Highlands: A shower water tower in a changing climate and changing Asia.
65. Eco-Certification: Can It Deliver Conservation and Development in the Tropics?
66. Designing ecological and biodiversity sampling strategies. Towards mainstreaming climate change in grassland management.
67. Participatory Poverty and Livelihood Assessment Report, Kalahan, Nueva Vizcaya, the Philippines
68. Towards Mainstreaming Climate Change in Grassland Management Policies and Practices on the Tibetan Plateau
69. The Last Remnants of Mega Biodiversity in West Java and Banten: An In-Depth Exploration of RaTA (Rapid Land Tenure Assessment) in Mount Halimun-Salak National Park, Indonesia
-41-