Download Measurements on Carbon Sink Benefits of Coastal Shelterbelt and the

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Measurements on Carbon Sink Benefits of Coastal Shelterbelt and the
Interference Analysis in Guangdong Province of China
GAO Lan, LI Yi
College of Economics and Management, South China Agriculture University, China, 510642
Abstract: Through the econometric studying on carbon sink benefits, the result show that the Coastal
Shelterbelt System in Guangdong plays an active role in the carbon fixation and climate change
mitigation, which is important to the development of low carbon economy in Guangdong Province.
However, a variety of factors from natural environment and human activities will affect performance of
the carbon sink about Coastal Shelterbelt; as a result, it is difficult to reach the its ideal level of
effectiveness. This paper examines the route of interference factors acting on the carbon sink of Coastal
Shelterbelt, and provides ideas and methods for regional ecological construction and sustainable
development.
Keywords: Coastal Shelterbelt, Carbon Sink Benefits, Nature Interference, Human Interference
1 Instruction
Since entering the modern industrial society, along with a large number of mining and fossil fuel use,
concentrations of CO2 and other greenhouse gases in atmospheric continue to rise, which is the main
features of global climate change and is breaking the heat balance of the Earth's surface, changing the
structure and function of land ecosystems, threatening human survival and health. So, how to prevent
further warming of global climate and resolve a series of serious ecological problems have become the
focus of attention by all the countries in the world.
In order to reduce the accumulation of CO2 in the atmosphere, there are only two ways: reducing the gas
emissions (carbon source), or increasing the absorption of greenhouse gases (carbon sinks). The latter
could be realized mainly through the photosynthesis of forests and plants. As the principal of terrestrial
ecosystems, forest concentrates about 85% of the terrestrial biomass, stores 72%~98% of the organic
carbon in terrestrial ecosystems (about 11.8PgC ) and increases year by year( 0.178PgC per year)[1][2].
On the other hand, harvesting of forest will release carbon which had been fixed, and then become a
major carbon source of atmospheric CO2. Therefore, the vegetation and soil of the forest ecosystems
plays a "sink - Library - source" role in the global carbon cycle, having an irreplaceable function for
carbon fixation.
Guangdong Province is one of the most economically developed provinces in China. Building a
"Ecological province" has been regarded as an important development goal by Guangdong Province for
a long time. To this end, a number of ecological projects, such as water conservation forest, coastal
shelterbelt and nature reserves construction, have been put into practice and obtain significant results.
Among them, the coastal shelterbelt construction is one of the projects which have the largest
investment, most extensive coverage area and maximum numbers of participants. This paper is targeted
to the coastal shelterbelt in Guangdong and will calculate its carbon sink benefits after completing Phase
II of the project. The study can provide references for carbon sink measurement on the coastal
shelterbelt and other reforestation projects
2 Project Overview
The primary purpose of coastal shelterbelt construction project in China is disaster prevention and
mitigation and maintenance of Homeland Security. The implementation of Phase (1991 ~ 2000) has
achieved preliminary results. But the construction content is single, construction standards and
investment criteria are low, particularly is that the project is suspended after 2000 because of insufficient
Ⅰ
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attention. Until the end of 2004, the Indian Ocean tsunami triggered peoples’ reflection about a shortage
of ecological construction in coastal areas. And then, the State Forestry Administration introduced the
"Planning of the National coastal shelterbelt Phase II "(2006 ~ 2015) and related legislation officially in
2007. New phase of the project tries to gain a key breakthrough in the target location, system layout,
contents and levels and so on.
Guangdong Province is located in the south of Chinese Mainland, with a coastline of 5796.8km, which
is the longest coastline of the provinces in China. Based on the phase , construction of Phase II of the
coastal shelterbelt will extend from shallow waters to inland, composed by. three building levels:
mangrove forest for wave dissipation, coastal forest and the deep shelter belt
Ⅰ
Figure 1 Three Components of Coastal Shelterbelt Construction
Project area distributes along the province's coastline and is narrow-band-like, covering 17 coastal
prefecture-level cities, 60 counties (cities, districts), land area 83038.6hm2, accounting for 46.2% of the
total area of the province. In the area, there are complex topography, many rivers and lakes, vast seas,
diverse climate and important stopover and wintering ground of international migratory. Meanwhile, the
project area is the most developed economy and the most dynamic regions in Guangdong Province,
including Pearl River Delta and three special economic zones Shenzhen, Zhuhai and Shantou,
concentrating 65.5% of the population of the province, accounting for 94.4% GDP of the province.
There are also complete industry categories, strong sense of commodity economy and a high degree of
export-oriented.
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Figure2 The coverage of Coastal Shelterbelt Construction in Guangdong
According to “Planning of the Guangdong coastal shelterbelt Phase II” (2006~2015), this paper evaluate
the carbon sink benefits of coastal shelterbelt in Guangdong after 10 years construction (2006~2015),
with a discount rate of 7% on a baseline of 2005.
3 Estimation on Carbon Sink Benefit
At present, the main methods for estimating carbon sink are: biomass method, method of accumulation,
biomass inventory method, eddy covariance method, box-type method [3]. The biomass method was used
most commonly. It is estimated by the use of biomass and carbon content in the product of dry matter to
calculate carbon storage in forest ecosystems. There are many advantages of this method, such as direct
clear, technically feasible, and strong comparative.
3.1 Biomass assessment
Forest biomass is defined as all the weight of dry matter accumulated in forest plant in unit time,
including the biomass in main storry arbor species, undergrowth arbor species, shrub layer and
herbaceous layer. Biomass per plant is made up of biomass in the stem, branch, leaves, roots and other
organs. Unit of biomass is different in different types of biomass. Therefore, the types of forest plant and
their biomass formed by the coastal shelterbelt construction must be made clear at first. According to the
plan, the quantity of coastal shelterbelt construction Phase II in Guangdong is that Mangrove Forest
26676.9 hm2, Coastal Backbone Forest Strip 37093.4 hm2 and Deep Shelter Belt 577246.8 hm2.
According to the ecosystem monitoring and evaluation for Guangdong forest, we use the biomass
models to estimate biomass in forest plant biomass and utilize different variable model estimation to
calculate biomass of different forest layers. Model variables for biomass in main storry arbor species are
DBH, tree height of sample plot and sample trees. Model variables for biomass in undergrowth arbor
species are canopy density, average height and average diameter. Model variables for biomass in shrub
layer are shrub cover, average height, average diameter, etc. And then, model variables for biomass in
herbaceous layer are herb cover, age, height, etc. This paper measures the biomass per unit area of forest
vegetation of forest land in Guangdong Province comprehensively.
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Table 1 Biomass Statistics of Woodland Per Unit Area
Species group
Total
Main storry
Sample
Biomass
number
Subtotal Trunk Branch
Leaf
100.0
69.8
36.1
12.4
6.9
Shrub
layer
Field
layer
5.3427
7.6746
1.5894
11.1
15.9
3.3
Root
1712 48.3479 33.7412 17.4767 6.0106 3.3588 6.8951
Proportion
Undergrowth
14.3
Pine
395
39.0604 24.2552 13.6148 4.1408 2.9628 3.5368
2.9702
9.8317
2.0033
Cedar
197
50.1461 37.7961 18.5401 6.0417 6.7620 6.4523
3.4522
6.8889
2.0089
Broad-leaved
475
78.6284 56.0263 28.2476 10.9092 3.8501 13.0194
10.7684
10.2475 1.5862
71
34.5453 25.6137 13.7359 4.0916 4.0561 3.7300
1.7612
5.6045
1.5659
152
56.6782 37.9868 20.0185 6.4414 3.7383 7.7885
7.6300
9.1263
1.9350
Eucalyptus
85
29.1394 19.5011 12.5598 1.7975 1.1295 4.0143
2.9268
5.2687
1.4428
Bamboo
78
66.5559 54.7116 26.3012 9.8874 4.9565 13.5663
4.9219
5.8185
1.1040
Economic forest
259
5.3260
1.0075
1.3279
0.6429
Mixed
coniferous
Mixed
broadleaf-conifer
2.3478 1.2939 0.3431 0.3095 0.4012
Species selections of the three layers of coastal shelterbelt construction in Guangdong are as follows:
Mangrove Forest building based on shrubs mangrove, with fine tree species of Sonneratia apetala,
Kandelia candel, Aricennia marina, Aegiceras corniculatum,etc, classed as broad-leaved forest;
Coastal Backbone Forest Strip composed of the Casuarina equisetifolia L mainly, assisted by Taiwan
Acacia, Pinus caribaea, slash pine, etc, classed as mixed coniferous forest; Deep Shelter Belt made up of
different types of forests such as soil and water conservation forests, water conservation forests,
protection forests, etc, with Hibiscus tiliaceus, Schima superba, Acacia confuse, Acacia auriculaeformis,
etc as the dominant tree species, belonging to mixed coniferous and broadleaf forest. Through the Phase
II of forestation, total biomass per year of coastal shelterbelt will be achieved:
Ⅱ
Table2 Biomass per Year of Coastal Shelterbelt Construction Phase in Guangdong
total biomass per year
biomass
Increment in forest
Type
Forest Properties
hm2/ a
t/ hm2·a
t/hm2
Mangrove
Broad-leaved
78.6284
2667.69
209756.2
Coastal Backbone
Mixed coniferous
34.5453
3709.34
128140.3
Forest Strip
Mixed
Deep shelter belt
56.6782
57724.68
3271731
broadleaf-conifer
Proportional relationship between carbon fixation and oxygen making of forest is determined by
chemical reaction equation of photosynthesis. And then, following the actual forest area, the annual
volume growth and the weight of branches and roots, the number of CO2 fixation by forest could be
calculated. Formula using this method is as follows:
n
YC= a·
∑S V
i
i
i =1
Where: YC is the amount of carbon fixation of coastal shelterbelt biomass (million t);
a is the amount of carbon fixation of dry matter per 1t(t);
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Vi is the output of coastal shelterbelt per area (t/ hm2)
Si is calculated area of coastal shelterbelt(hm2)
According to above formula, carbon fixing and oxygen releasing of coastal shelterbelt in Guangdong are
calculated as:
Table3 Balanced Schedule for Oxygen and Carbon of Coastal Shelterbelt in Guangdong
CO2 absorption
O2 releasing
carbon storage
Total biomass per
Forest belt
year
CO2=1.6123Wi
O2=1.1724 Wi
C=0.4399Wi
Mangrove
209756.2
338181
245918.2
92083
Coastal Backbone Forest
128140.3
206620
150245.8
56258.9
Strip
Deep shelter belt
3271731
527433
3835777.4
1436289.9
PS: 1.6123, 1.1724 and 0.4399 are coefficients of assimilation CO2, release O2 and carbon storage per ton of forest
plants respectively.
3.2 Value Assessment
Currently, there are considerable controversies on the economy method of physical quantity conversion
of CO2 fixation at home and abroad, representative views of which include: industry cost method,
planting cost method, carbon tax method, and the greenhouse effect loss method. The first method is
adopted in this study. According to the carbon sink per unit area and unit volume of the forest, the
industrial costs of CO2 transformation (1,200 yuan / t), and the market approximation coefficient of the
0.2, calculation formula is as below:
V1=Y×P×r × 1+i n
= 338181+206620+527433 ×1200×0.2×1.0710=50621.9×104 yuan/a
Similarly, the formula of the oxygen effective is:
（
（ ）
）
（ ）
V 2=Y×P×r× 1+i n
= 338181+206620+527433 ×1800×0.2×1.0710=75932.9×104 yuan /a
PS: The forest oxygen benefit of Guangdong coastal shelter is calculated by industrial oxygen cost1,800
yuan/t and the market approximation coefficient of the 0.2.
（
）
Ⅱ
Through the coastal shelterbelt construction phase in Guangdong, carbon sink benefits will reach
506.219 million yuan / a, with oxygen release efficiency 759.329 million yuan / a. Thus, it can be seen
that construction of coastal shelterbelt could not only play an important role to defense typhoons,
tsunamis and other natural disasters, safeguard the land security, but also help to strengthen the carbon
sink capacity, develop the trade in carbon sink, and enhance regional response to climate change.
4 Interference Factors Acting on Achievement of Carbon Sink Benefits
Although the construction of coastal shelterbelt has great sink benefits, but its achievement must meet
two basic conditions: quantity and quality. Both of them must conform to the corresponding building
requirements. But in reality, various disturbances from nature and social, which influence the
construction of the project deeply, will lead to carbon sink benefits of coastal shelterbelt in Guangdong
difficult to reach the ideal level.
4.1 Natural interferences
The natural environment is important condition for growth and regeneration of plants and suitable
natural conditions is conducive to carbon cycle in the forest communities. Various kinds of interferences
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from natural, such as natural disasters, loss of soil nutrients, disease and pest injury and so on restrict the
carbon sink function of coastal shelterbelt. Natural interferences consist of endogenous interferences
(such as soil nutrients decreased, topography and location impact, single tree structure, etc.) and
exogenous interferences (such as typhoons, invasive species, pests and diseases), of which the main
types are as follows:
(1) Soil Nutrient Loss
Because of different soil types provided with different physical and chemical properties, their abilities to
absorb and store carbon are not the same. The nutritional status and nutrient flows of different soil types
are likely to affect the relative amount and absolute amount of carbon accumulation in vegetation and
soil plantations [4]. Sandy soil of eastern and western coastal in Guangdong province accounts for 22%
of the entire coastline, and coastal sandy site is extremely degraded. Adverse weather conditions such as
drought and high winds not only led to scarcity of local native species, but also are difficult to exotic
species adapt. Casuarina shelter forest plants in the barren sandy soil both defense typhoon and consume
soil fertility strongly. Meanwhile, moisture imbalance of the sand can cause slow-growing and then
decline, dry and die of Casuarina forest. Therefore, the survival rate of Casuarina backbone forest is low
and it is almost impossible to achieve corresponding biomass.
(2) Natural Disasters
Typhoon is a high frequency of natural disturbances in coastal areas of Guangdong, often accompanied
by heavy rains. Studies suggest that there is a negative correlation between precipitation and the carbon
density of forest vegetation when precipitation exceeds 3200mm [5]. Furthermore, typhoon and other
natural disasters will cause great damage to forest communities’ structure, leading to numerous
impairment and deaths to individual trees, and increasing nutrient loss of forest ecosystem. There are
average 4 to 6 - up to 7- typhoons per year landing (40% of the national total) on Guangdong Province,
which would undermine the upper structure of forest communities seriously, and then make the carbon
density and carbon stocks declined.
(3) Alien Attack
Research on carbon storage of the forest vegetation concluded that the organic carbon storage in native
species is the largest of all tree species, and native species forestation is favorable to carbon
accumulation [6]. However, in the field survey in project area, we found that the Sonneratia apetala
introduced from Bangladesh with fast-growing characteristics and high timber income has become the
preferred mangrove tree species, widely distributed in South China coast; crowd out the living space of
kandelia candel and other native mangrove species. In addition, in Pearl River Delta area, mangrove
wetlands also face invasive threats from Spartina alterniflora Loisel and other alien species. Large-scale
planting of exotic fast-growing species such as Foreign Pinus, Eucalyptus , caused a large area disappear
of natural vegetation and a lot of main native species extinction, and thus lead to biological diversity
dropped in the higher levels of food chain and the carbon cycle imbalance.
(4) Warming and Sea Level Rise
As important types of natural disturbance, climate warming and sea-level rise caused by the warming
and regional land degradation are great threat to the coastal shelterbelt, especially to the mangrove
wetland. Many scholars believe that the role of the temperature on carbon storage of forest vegetation is
bigger than rainfall and temperature rise will increase the release the carbon from forest soil and reduce
carbon stocks of forest [7]. Sea level rise due to climate warming will also lead to coastal erosion, tidal
flat narrowed, coastal vegetation space diminish,and then result in degradation of mangrove wetlands,
reed and a variety of wetland vegetation die. Geological records show that the average temperature of
the Pearl River Delta increased from 14 ~ 16 ° C in the past 32 000 years to the current 22 ° C, the
growth rate of nearly 50 years even up to 0.3 ° C per decade, showing a very significant climate
warming law. Warming and Sea Level Rise will influence the coastal forest ecosystems and their carbon
sink function for a very long time in the future.
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4.2 Human Interference
Project area situated in the coastal zone with high active economic has always been strongly influenced
by human activities. Human interference, as represented by reclamation, sewage, logging and other
activities, directly and indirectly lead to a series of ecological environmental deterioration such as the
damage of shelter artificial ecosystem, functional decline, shrink of biodiversity, decline in biological
productivity, land productivity recession, loss of forest resources and so on. All of them make the
carbon sinks and protection efficiency of coastal shelterbelt hard to gain.
(1) Reclamation
Historically, reclamation in the Pearl River Delta has great significance for solving the population
pressure, promoting commercialization of agriculture, and driving regional economic at the time. But
after entering the 20ec80s, reclamation with the purpose of aquaculture emerged disorder and excessive
state, a large area of mangroves, tidal flats and shallow wetlands are artificially modified. Since the
beginning of 21st century, urban construction and real estate development encroach on wetlands and
woodlands further, resulting in large area of mangrove, casuarina and other forest decline.
Changes of land use and land cover caused by human activities have direct impacts on carbon storage
and carbon cycle in forest and soil. Land use such as digging ponds to breed shrimp in the forest zone,
converting forest land to arable land, urban construction and so on, will increase the atmospheric CO2
emissions, so that the "carbon sink" possessed of shelter originally would become "carbon source "
finally. Carbon emissions to the atmosphere from land use change are 1.6 Pg per year, taking up about
20% of the total emissions from human activities [8]. Long-term and continuous conversion use of land
and non-conversion use of land on the coastal shelterbelt will increase the carbon release from terrestrial
ecosystem and result in further increase of CO2 concentration in atmospheric.
(2) Sewage
Due to population growth, urban expansion and urbanization, the rapid development of industrial
production, various pollution discharges from industrial, agricultural pesticides, fertilizers, ship oil and
daily life are damaging the soil and water environment of coastal shelterbelt seriously in Guangdong.
Investigation shows, the amount of sewage quantity from land to sea in Guangdong coastal areas
reaches 440.6 billon ton, with total pollutant 3,549,000 ton (excluding offshore oil platform leak),
resulting in a large area of mangrove and casuarina saplings died. A large number of pollutions will not
only reduce the survival rate, but also destroy carbon cycle between forest and soil.
(3) Clear cutting, Selective Cutting and Illegal Logging
Continued growth in demand for wood stimulates the commercial logging of shelter. Growing illegal
logging is another important reason for forest structure and function damage. Although there are
expressly provides in the "Management regulations for Coastal Special Protection Forest” that firewood,
grazing, building tombs, quarrying, mining land, mining and other deforestation are prohibited in the "
Coastal Special Protection Forest” by the state. However, field survey in project area of Leizhou
Peninsula informed that many cases of illegally logging occur in local shelter area almost every day,
with the amount from several to tens or even hundreds of trees. Houghton and other studies [9] have
shown that carbon storage would fell by 35%, 50% and 15% respectively in tropical, temperate and
boreal forest after harvesting. Moreover, there will be a further loss of carbon storage if failure to restore
in time.
(4) Improper Manual Operation
Through acting on productivity and carbon cycling of forest and soil,Proper operation and management
can have a positive impact on carbon sink, storage, and emissions of forests thus affecting the effects of
plantations to mitigate the climate change. In fact, the species introduction, management and protection
issues, fuelwood collection , tourism development and other issues existing in the coastal shelterbelt
formed predatory on forest collectively, interfered the growth and carbon sink of shelterbelt. Mainly as
follows : because of the site environment and climate change, Casuarina species introduced by
Guangdong Province in the 60s of last century showed poor growth and inbreeding depression; In the
view of management and protection, net clearing for trees litters cut off natural circulation of forest
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ecosystem artificially, causing lower fat levels and productivity of woodland. Furthermore, fuelwood
consumption of the surrounding communities is also increasing year by year and shows predatory;
Finally, a large number of resorts, hotels, restaurants constructions and other tourism development
activities on the beach is eroding forest land. Existing extensive management of coastal shelterbelt will
not only cause a decline in forest productivity, but also lead to soil erosion and degradation, thereby
affecting carbon storage in forest plants.
In summary, various kinds of interferences are acting on coastal shelterbelt in Guangdong and will make
the carbon sink efficiency hard to achieve. Interference route is as follows:
Natural
Interferences
Forest area
Three systems of
coastal shelterbelt
Human
Interferences
Biomass
formation
Carbon sink
benefits
Forest stork
Fig3 Route of Interfere Factors Acting on the Carbon Sink Benefits of Coastal Shelterbelt
5 Conclusion
Forest ecosystems have enormous capacity to absorb carbon and stork carbon. Forest construction and
operation have become important measure of international communities to tackle climate change and
slow global warming. Coastal Shelterbelt Construction is an important forest ecological project in our
country. It not only plays an important role to defense maritime natural disasters, but also has significant
benefits of carbon sink. However, its function and role of carbon sinks are affected by many factors.
Once the quantity and quality of forest resources could not reach the construction requirements, the ideal
level of effectiveness will be reduced to different extents. Due to technical constraints, this paper only
analysis the interferences from natural and human acting on the carbon sink functions of coastal
shelterbelt qualitatively. Research methods and the accuracy need to be improved further.
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