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Deforestation of Tropical Rainforests - A Case Study of Madagascar
Abstract
In Madagascar, one of the world’s poorest countries, pressures on tropical
rainforests and other ecosystems are accelerating and having a dramatic impact on
Madagascar’s biodiversity, much of which is not found anywhere else in the world.
There have been limited attempts to conserve this great ecological treasure.
Introduction
Figure 1 World map – Madagascar
Considered a ‘megadiversity’ country, Madagascar is among the world's most
biologically diverse places, with incredibly high levels of endemic plants and
animals.
Figure 2 Vegetation in rainforest areas is dense, diverse and highly specialised
Figure 3 Madagascar’s endemic species
Known
Endemic Known
Endemic
mammal mammal bird
bird species
species species
species
105
84
202
104
Known higher
plant species
9000
Endemic
higher plant
species
6500
Madagascar has been described as a living laboratory of evolution. More than 150
million years ago, Madagascar split from Africa creating the world's fourth largest
island. Madagascar is an island continent and as such has evolved a range of plants
and animals adapted to its own conditions. Much of Madagascar’s flora and fauna is
endemic – 98 per cent of Madagascar's land mammals, 92 per cent of its reptiles,
68 per cent of its plants and 41 per cent of its breeding bird species do not exist
anywhere else. Madagascar is home to all of the world's lemurs (primate species),
all of which are endangered, and two-thirds of the world's chameleons. Plant
species include orchids, pitcher plants and the Madagascan rosy periwinkle (which
contains the most effective known treatment for childhood leukaemia).
However, large-scale deforestation has taken place since the 1970s and less than
10 per cent of the island's original forest-cover remains. Over 300 species of its
plants and animals are threatened with extinction.
Figure 4 Levels of endemicism in Madagascar
Deforestation in Madagascar
Since 1896 when Madagascar became a French colony, the Malagasy forests have
been rapidly depleted.
Figure 5 Remaining primary vegetation
Figure 6 Loss of forest cover
Logging has occurred for:
 shifting cultivation
 grazing
 fuel wood gathering
 economic development
 cattle ranching and
 mining.
Many forests were destroyed in the search for precious woods such as ebony and
rosewood. Other forest products such as raffia, beeswax, honey, lichens, and
camphor were gathered for export. In addition to crops, the construction of railroads
and their operation relied heavily on timber, intensifying the demand for wood.
Until 1950, most deforestation was done by farmers on a very small scale.
However, since 1950, deforestation has increased dramatically. Owing to the
extreme debt incurred by the Malagasy government, the country is exploiting its
wood resources to pay off money owed to northern countries. The extent of the
eastern rainforests at colonisation was 11.2ha. Only 7.6 million ha remained by
1950. By 1985 the eastern rainforests of Madagascar covered only 3.8 million ha.
Thus, in 1985, only 50 per cent of the rainforests that existed in 1950 still remained,
which is 34 per cent of that which originally existed. This amounts to an average
rate of clearance of 111,000ha (1.5 per cent) per year between 1950 and 1985.
Estimates of the extent of the remaining eastern rainforests have ranged from 2.5 to
6.9 million ha. In addition, it is estimated that approximately 165,000ha of forest are
currently cleared per year. Deforestation costs Madagascar between $100-$300
million per annum in decreased crop yields and the loss of productive forests.
Deforestation in Madagascar is directly related to the introduction of cash cropping.
After Madagascar became a colony in 1896, many people fled to the forests and
survived for years as shifting cultivators. At the same time, the colony's
agricultural production was geared primarily for export. Coffee, rice and beef were of
particular importance. The Central Highlands became the primary irrigated ricegrowing region for both subsistence and export crops. Coffee, which remains the
island's major export crop, was planted on the east coast – the region with the
largest remaining forest cover. Soil erosion rates on coffee plots are nearly double
those of lowland subsistence plots because broad expanses of bare soil under the
coffee bushes are particularly vulnerable to violent storms during the rainy season.
Heavy soil erosion still resulted in subsistence areas as steep slopes were cleared
for this purpose – areas removed from the most fertile land reserved for the cash
crops.
Population trends and the environment
Population growth didn't become a factor in forest degradation in Madagascar until
1940, when vaccines were introduced that lowered the death rate. During the next
40 years the population increased rapidly from 4.2 to 9.2 million. This put a
significant strain on the natural resources and estimates show that 4 million
hectares
of
forests
were
cleared
during
this
40-year
period.
Madagascar’s population is poor and still growing very rapidly. This creates great
pressure on the land to provide for the population. With an average GDI (gross
domestic income) per head of US$870 a year and a foreign debt that nearly equals
its gross national product, the island is ranked amongst the poorest nations in the
world.
The island's average population growth rate ranks among the highest in Africa at
3.03 per cent per year. The population of around 16.5 million is expected to reach 28
million by 2025. Madagascar's exploding population is damaging the economy and
the environment.
Figure 7 Key data for Madagascar
Population in 2002
Crude birth rate
Life expectancy
Literacy
Land use
Population below the poverty line
Population growth rate
Crude death rate
Total fertility rate
16.47 million
42.4 per thousand
55.7 years
Males 88%,Females 73%
Arable 4.4%, Permanent crops 0.9%, Other
94.7%
70%
3.03%
12.15 per thousand
5.77 children per woman
GDP per head
$870
Source of GDP
Agriculture 34%, Industry 11%, Services 55%
Source: CIA World Fact Book, 2003
Much of Madagascar’s population is rural, and farming is having an adverse impact
on the environment. The cattle culture is especially strong in central and southern
Madagascar. Unfortunately, too many cattle on too little land have disastrous effects
on natural habitat. Heavy grazing as well as slash-and-burn agriculture cause severe
erosion even where human populations are comparatively sparse. The soils of
western Madagascar have been degraded to the point where the native dry forests
and thickets seem unable to regenerate. Exotic weeds are invading, leading to a
savanna-like landscape.
However, it is not just farming that is causing problems. In 2003, the world’s largest
mining company, Rio Tinto Zinc, announced plans to mine ilmenite (a mineral used
to make paint and toothpaste) in a 6000ha site near Port Dauphin on the southern
coast. The mining could last for up to 60 years. The company believes it will bring
much needed investment to Madagascar - there are plans for a new port and
breakwater, roads and storage facilities. It will certainly attract migrants, and these
may have a detrimental social impact (Port Dauphin has about 3000 unemployed
young men already) as well as creating negative environmental impacts such as
deforestation to make charcoal.
Protecting the landscape – National Parks in Madagascar
National Parks and reserves were first established by the French colonial
government in Madagascar in the 1920s. Today they account for just 3 per cent of
Madagascar’s land area, and only a small percentage of this land is actively
protected.
Figure 8 National Parks in Madagascar
There are three categories of national park:



Parc National – where farming, hunting, logging and human habitation are
prohibited
Reserve Speciale – special reserves to protect less threatened species.
People can live in these areas but hunting, farming and logging are banned
Reserve Naturelle Integral – fully natural reserves where access is permitted
only for authorised research.
Most parks and reserves are managed by ANGAP (translated as the National
Association for the Management of Protected Area), an NGO established in 1991.
Parks and reserves managed by other organisations, such as WWF, are planned to
be handed over to ANGAP in the near future.
Ranomafana National Park
Ranomafana National Park (RNP) is a large area (435km2) of primary rainforest in
southeastern Madagascar (see Figure 8 for location).
It was established in 1991 following the discovery of a previously unknown primate,
the Golden Bamboo Lemur, in 1986. The Park, on the edge of Madagascar's High
Plateau, is extremely mountainous, with elevations ranging from 600 to 1400m. Until
1986, the steepness of the slopes had preserved parts of the park from exploitation
– one-third of the park had been selectively logged, while the remaining two-thirds is
undisturbed. The range of altitudes allows for many different forest types, from
lowland rainforest to cloud forest and high plateau forest.
Climate
Madagascar’s climate is subtropical, with rainfall averaging 2,300-4,000mm
annually. Monthly rainfall is highest from December to March (400mm) and lowest
from May to October (90mm). Temperatures range between 18-20C, with lowest
and highest recorded temperatures in the area being 7oC and 37oC, respectively.
The growing season is therefore year-round. Sometimes the wet season brings
cyclones, which can have a tremendously destructive impact on the trees of the
forest causing extensive tree blow-downs, flooding and river channel changes.
Soils
Soils at RNP are mostly red clay oxisols, developed from parent rock with
extremely low levels of nutrients. These soils are considered some of the most
naturally infertile in the world, with high iron and aluminium concentrations but little
phosphorus.
Figure 9 Soils in the rainforest are usually red in colour – indicating the presence of
iron oxides
The accumulation of iron and aluminium gives the soil a red colour and in some
cases the concentration of aluminium may form bauxite nodules. The soils are often
deep, due to high rates of chemical weathering, heavily leached, due to the high
rainfall totals, and infertile, since most of the nutrients are held by the plants. Under
sustained hot and wet conditions, fine clay and silicate particles are removed in
suspension, while Nitrogen (N), Calcium (Ca), Magnesium (Mg) and Potassium (K)
are carried away in solution.
Most rainforests have infertile soils but those in Madagascar are worse. This is due
to the combination of high rainfall, high elevations and steep slopes, which, in turn,
is reflected in slow tree growth and lower fruit productivity.
Vegetation and biodiversity
The vegetation in rainforests shows many adaptations, for example





it is evergreen, enabling it to photosynthesise year round
it is layered, and the shapes of the crowns vary with the layer, in order to
receive light
there are buttress roots to stabilise the trees
some plants have drip tips to shed water, others have saucer-shaped leaves
to trap water
some trees are heliophytes and seek the light; others are sciophytes and
live in the shade
Figure 10 Tropical rainforests are a mosaic of species and layers
Figure 11 Light is limited below the canopy
Figure 12 Canopy trees are very tall and their foliage is limited to the tree tops
Rainforests are very productive ecosystems: the Net Primary Productivity
(NPP) is approximately 2200g/m2/yr, and the stored energy, or biomass is
45kg/m2. The ecosystem is diverse, with as many as 200 species of tree per ha,
which includes hardwoods like teak, mahogany and yellow wood. The tropics is
the richest area for biodiversity – tropical forests contain over 50 per cent of the
world’s species in just 7 per cent of the world’s land. They account for 80 per
cent of the world’s insects and 90 per cent of primates.
The biological richness of Ranomafana National Park is extremely high. The
diversity of tree species on 1ha plots at Ranomafana amounts to 105 different
known species. This makes it fall somewhere in the middle, in terms of
rainforests, in between lower elevation rainforests in Colombia, South America,
with 197 species, and lowland rainforests in Gabon, Africa, with 99 species. The
lush vegetation contains most of Madagascar's endemic plant families.
Endangered species include golden bamboo lemur, greater bamboo lemur,
aquatic tenrec, Madagascar Serpent Eagle, and the Madagascar Fish Eagle.
RNP contains most species found in the threatened eastern forest corridor of
Madagascar.
Fauna
Of the species which have a diversity among the highest in the world are:
 primate species, with 12 species in five families, which are all endemic – the
Park is home to 12 lemur species, several of which are extremely rare, and
 land-snails.
The park contains over one-third of Madagascar's birds (118 species), rare
carnivores, amphibians and reptiles (68 species) including the world's smallest
chameleon.




More than 80 per cent of the spider species collected have been unknown to
science.
Frogs are distinguished by high species diversity.
Nine species of chameleon have been recorded.
There are several species of endemic crayfish in the park, and their closest
relative may live in Tasmania.
Nutrient cycles
The nutrient cycle in the tropical rainforest is one that is easily disrupted.
Tropical rainforests have been described as ‘deserts covered by trees’. Despite
some of the world’s most luxuriant vegetation, tropical rainforests are found on
some of the world’s least fertile soils. This paradox is explained by the closed
nature of the nutrient cycle. Once the vegetation is removed, nutrients are
quickly removed from the system by intense rainfall creating infertile conditions,
even deserts.
Figure 13 The nutrient cycle
The threats to tropical rainforests
One of the main threats to biodiversity is deforestation. Tropical forests are
being destroyed at a rate of over 11 million ha/year (or 21ha/minute). This is
due to a combination of shifting cultivation, commercial logging, cattle
ranching, plantation farming, road clearance and urban development. However,
there are natural causes of deforestation such as drought, climate change
(which can cause drought), and lightning (the main natural cause).
Areas of greatest plant diversity are in LEDCs where the pressure on the
remaining habitat is greatest. Reduced diversity may eliminate options to use
untapped resources for agriculture, industry and medicine. Currently less than 5
per cent of the world’s rainforests are protected. Scientists argue that each
country should protect at least 10 per cent of their habitat and up to 20 per cent
of key habitats such as rainforests.
The value of rainforests
Figure 14 The value of tropical rainforests
Industrial uses
Charcoal
Ecological uses
Watershed protection
Subsistence uses
Saw logs
Flood and landslide
Fodder for agriculture
Pulpwood
Soil erosion control
Pit sawing and saw
milling
Plywood and veneer
Climate regulation e.g. CO2
and O2 levels
Special woods and ashes
Gums, resins and
oils
Fuelwood
and charcoal
Building poles
Industrial chemicals
Rearing silkworms
and protection
Medicines
Genes for crops
Tourism
Weaving materials
and dyes
Beekeeping
Fruit and nuts
Rainforests are important for a number of reasons. They serve as the earth's
lungs, producing the oxygen we breathe and removing C02 from the
atmosphere. Two-thirds of all of the world's plant and animal species live only in
the tropics. The loss of tropical rainforest is the leading cause of the extinction
of species on a global scale.
Medicines derived from tropical rainforest plants include:
 curare (used as a muscle relaxant during surgery)
 diosgenin (used for birth control pills, arthritis, asthma)
 quinine (used for malaria, pneumonia) and
 vincristine/vinblastine (used for Hodgkin's disease, leukaemia and other
cancers).
Over 2000 tropical plants have been identified by scientists as having anticarcinogenic properties. Worldwide, the commercial value of medicines based
on natural products is over US$20 billion a year. However, over 60 per cent of
the world’s population still depend on traditional medicines and most of these
are derived from plants.
Agriculture has benefited from rainforests; for example, tea, coffee, bananas,
oranges, lemons, peanuts and pineapples all originate from these regions.
Valuable wood such as teak and mahogany is used to build furniture, while
lower quality wood is used to make plywood and fibreboard. However, forestry
has many negative impacts and modern machinery can cut down forested
land at an alarming rate.
Forestry
practise
Planting
Clear felling
Figure 15 Potential environmental impacts of forestry
Water
Soil
Landscapes
Accumulation of
litter from acidifying
tree species - soil
acidification;
groundwater
acidification
Cultivation of
productive waterdemanding tree
species reducing
groundwater
availability
Bare land after
clear felling -water
Accumulation of
litter from acidifying
tree species - soil
acidification
Uniform planting major changes in
form, colour and
texture arising from
sharp boundaries of
forest stands
Nature and
wildlife
Plantation of
monoculture and
introduced tree
species uniformity, loss of
biodiversity
Bare land after
clear felling -wind
Large clearances
scarred landscapes
If dead or
decaying wood
erosion increased
sediment and
organic matter
loads eutrophication,
sedimentation
Draining
Weeding,
cleaning,
thinning
Pesticide and
fertiliser
application
Heavy
machinery use
Lowering of
groundwater level
reducing water
availability
Oxidation of organic
soils - soil
acidification,
groundwater
acidification
Use of herbicides groundwater
pollution
Leaching of applied
substances groundwater
pollution
Soil erosion increased sediment
load in surface
waters
Oil leakage/spills water pollution
Recreation
Soil sealing increased runoff,
decreased
infiltration to
groundwater
Increased use of
water - reduction of
water availability
and pollution
through effluent
from tourist centres,
camping grounds
etc.
and water erosion
removed - loss of
plant and animal
species which
depend on this
loss of
biodiversity
Use of vehicles compaction
Sudden decrease in
water demand
following clear
felling -waterlogging
Oxidation of organic
soils - acid-sulphate
formation - soil
acidification
Drying of land
causing changes in
plant communities
and landscape
Lowering of water
table - loss of
wet forests and
wetlands high in
biodiversity
Increased
frequency of vehicle
use -erosion and
compaction
Removal of
greenery -uniformity
Fertilisation in
waterlogged
conditions denitrification
greenhouse gas
emission contribution to
climate change
Changes in plant
communities and
hence landscape
Removal of
understorey, an
important habitat
for many species
- loss of
biodiversity
Release of
chemical
pesticides poisoning of nontarget species
Fertilisers
applications changes in plant
communities
Increased
frequency of
vehicle use disturbance of
wildlife
Increased
frequency of vehicle
use - soil
compaction and
erosion
Oil leakage/spills
soil pollution
Trampling leading
to erosion and
compaction
Infrastructure
development
(access roads,
recreation centres
etc.) -changes in
landscape
Increased
number of visitors
in forests -wildlife
disturbance
Recreational
infrastructure
development increased
groundwater
abstraction
affecting tree
growth
Grazing and
browsing
Overdensity of
grazing/browsing
animals - soil
erosion and
compaction increased sediment
load, decreased
infiltration to
groundwater







Overdensity of
grazing/browsing
animals  soil
erosion and
compaction
Overdensity of
grazing/browsing
animals - soil
erosion and
changes in
landscape
Overgrazing and
browsing
(overpopulation
of game) damage to young
plants, trees and
habitats
Every day 100 species become extinct (four species per hour) due to tropical
deforestation.
At the current rates, 5-10 per cent of tropical forest species will become
extinct every decade.
Rainforests are being destroyed 40 per cent faster today than 10 years ago.
At the current rates of deforestation, all tropical forests in the Philippines and
Madagascar will be destroyed within 20 years.
Every year about 40 million hectares of rainforest are completely destroyed
Almost 90 per cent of West Africa's rainforest has already been destroyed
Asia lost almost a third of its tropical forest cover between 1960 and 1980 the highest rate of forest conversion in the world.
The effects of deforestation
Deforestation disrupts the closed system of nutrient cycling within tropical
rainforests. Inorganic elements are released through burning and are quickly
flushed out of the system by the high intensity rains.
Soil erosion is also associated with deforestation. As a result of soil compaction,
there is a decrease in infiltration, an increase in overland runoff and surface
erosion.
Sandification is a process of selective erosion. Raindrop impact washes away
the finer particles of clay and humus, leaving behind the coarser and heavier
sand.
As a result of the intense surface runoff and soil erosion, rivers have a higher
flood peak and a shorter time lag. However, in the dry season river levels are
lower, the rivers have greater turbidity (murkiness due to more sediment), an
increased bed load, and carry more silt and clay in suspension.
Other changes relate to the climate. As deforestation progresses, there is a
reduction in the water that is re-evaporated from the vegetation and so the
recycling of water diminishes. Thus meaning annual rainfall is reduced, and the
seasonality of rainfall increases. Evapotranspiration rates from savanna
grasslands are estimated to be only about one-third of that of the tropical
rainforest.
Figure 16 Impacts of deforestation
Hydrosphere
Atmosphere
increased runoff
increased turbidity
increased discharge leads to
O2 content reduced
flooding
CO2 released from decaying
reduction in shading (more
woody material
direct sunlight on forest floor)
loss of biomass
decrease in habitats
rapid soil erosion leads to
increased leaching
loss of nutrients
Biosphere
increased sedimentation
less CO2 absorbed
increased evaporation
decrease in species diversity
Management
From its establishment in 1991 until 1998, Ranomafana National Park was
operated by the Institute for the Conservation of Tropical Environments (ICTE)
at the State University of New York at Stony Brook. On 30 June 1998
management of the park was transferred to the national park service of
Madagascar, ANGAP (Association pour la Gestion des Aires Protégées).
ANGAP maintains a staff of approximately 80 to manage the park, including a
Park Manager, Chief Financial Officer, and Heads of Tourism, Conservation,
Ecological Monitoring, Conservation Education, and Community Relations.
Park organisation
The Ranomafana National Park and its surrounding communities are the focus
of an integrated conservation and development project (ICDP) funded in part by
the US government and private foundations. The Ranomafana National Park
Project (RNPP) was developed in response to Madagascar's 15-year National
Environmental Action Plan. The goals of the RNPP were to:

establish Ranomafana National Park

promote sustainable development for villagers affected by the park and

conserve the biodiversity of the park.
The park is divided into a core protected zone of 41,500ha surrounded by a
peripheral zone in which some exploitation of the forest is permitted. The
peripheral zone contains more than 100 villages with over 25,000 residents in
total, most of whom are subsistence farmers.
The mission of the Ranomafana National Park is to:
 promote research on the biodiversity and conservation of Madagascar
rainforests, including populations, communities, and the ecosystem processes
they depend on
 promote formal and informal training at the undergraduate and graduate levels
for international students and Malagasy scientists
 conduct long-term monitoring research on the flora and fauna of the park
 share information with Malagasy policy makers and with scientists globally.
However, not everyone was happy with the establishment of the park.
Complaints have been made that the parks were set aside without the consent
of the local people. When the Ranomafana Forest was converted into a national
park in 1991, 80,000 peasants who relied upon the forest as their primary
source of income viewed the transformation as an economic disaster. However,
had this park system not been implemented, it is estimated that there would
have been absolutely no forest cover left in 2025.
Other possible solutions to deforestation in Madagascar
One of the most important schemes for reducing the impact of deforestation is
debt-swapping. This is a scheme, initiated in the USA, whereby bankers in
MEDCs agree to wipe out the debts of the LEDC country by allowing the debts
to be purchased at a fraction of their face value and then used to finance
conservation work. For example, the World Bank controls the operations of the
Rio Tinto Zinc mining subsidiary - no investment is permitted without
reassurance on ecological restoration.
Another scheme is to change current methods of farming. Palm trees help
rainforest soils. They bring nutrients into the soil and thrive on the nutrient weak
soil of the rain forests. These palm trees help stabilise the soil and thus prevent
erosion while palm oil provides a useful source of income. Replanting of
vegetables, hardwoods, 'charcoal' thorns, particularly in a tree nursery close to
the Montagne D'Ambre National Park, is being funded by the Worldwide Fund
for Nature (WWF) in return for the farmers themselves acting as wardens.
‘Wildlife corridors' are being planted to link some of the remaining areas of
woodland.
In addition, changes in the methods of harvesting timber i.e. selective logging
rather than clear-cut logging allow forests to regenerate naturally. Ideally
logging in rainforests needs to be halted completely to ensure their safety but
this is unlikely.
Other potential solutions are smaller in scale. For example, the World Bank
directly finances some of the work of the WWF which co-ordinates many of the
individual projects being carried out on the island using its own funds and
support from the World Bank and from UNISAID (the United States Agency for
International Development), which in turn has been particularly heavily involved
in financing the Montagne Ambre conservation project. The Montaign d'Ambre
National Park is on a small rainforested mountain in the far north of
Madagascar, surrounded by dryer lowland.
Conclusion
Deforestation of Madagascar’s rainforest has been severe and rapid - most of
the losses have occurred within the last 70 years, and local people are the
major cause of the destruction.
Rapidly growing population pressure combined with extreme poverty threatens
these unique natural assets of Madagascar. There are many threats to the
forest around the park. Slash and burn agriculture by subsistence farmers,
timber exploitation, conversion to rangeland, and cutting of wood for fuel and
forest products are widespread. Rainforest biomes are difficult to conserve on
account of their fragility, specialisation and the lack of speed with which they
can adapt to change. There is an urgent need to study Madagascar's
biodiversity, not the least of which is to learn how best to conserve it for future
generations. Madagascar is seen as conservation 'flagship'. If an area of such
outstanding beauty and wildlife significance cannot be saved there may be little
hope for less spectacular parts of the world. Protected land covers a very small
part of the country and even within these areas very few of the parks and
reserves are actively policed.
Further references
http://www.panda.org/livingplanet
gives details of the Living Planet index, a measure of global biodiversity and its
change over time. This is updated annually.
http://www.ran.org_center/factsheets
provides access to the Rainforest Action Network which has some excellent
factsheets on tropical rainforests, rates of deforestation, users of rainforests,
climate change and the rainforest, species extinctions, corporations in the
rainforest and many more.