Deforestation of Tropical Rainforests - A Case Study of Madagascar
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.
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
Figure 2 Vegetation in rainforest areas is dense, diverse and highly specialised
Figure 3 Madagascar’s endemic species
Known Endemic Known Endemic Known higher Endemic
mammal mammal bird bird species plant species higher plant
species species species species
105 84 202 104 9000 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:
fuel wood gathering
cattle ranching and
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 rice-
growing 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
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
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
Figure 7 Key data for Madagascar
Population in 2002 16.47 million
Crude birth rate 42.4 per thousand
Life expectancy 55.7 years
Literacy Males 88%,Females 73%
Land use Arable 4.4%, Permanent crops 0.9%, Other
Population below the poverty line 70%
Population growth rate 3.03%
Crude death rate 12.15 per thousand
Total fertility rate 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
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
Figure 8 National Parks in Madagascar
There are three categories of national park:
Parc National – where farming, hunting, logging and human habitation are
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.
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 18-20C, 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 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
Figure 9 Soils in the rainforest are usually red in colour – indicating the presence of
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
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
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
The park contains over one-third of Madagascar's birds (118 species), rare
carnivores, amphibians and reptiles (68 species) including the world's smallest
More than 80 per cent of the spider species collected have been unknown to
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.
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,
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 Ecological uses Subsistence uses
Charcoal Watershed protection Saw logs
Flood and landslide Fodder for agriculture Gums, resins and
Pulpwood Soil erosion control Fuelwood
Pit sawing and saw Climate regulation e.g. CO2 Building poles
milling and O2 levels
Plywood and veneer Special woods and ashes Weaving materials
Industrial chemicals Beekeeping
Rearing silkworms Fruit and nuts
Genes for crops
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
Over 2000 tropical plants have been identified by scientists as having anti-
carcinogenic 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.
Figure 15 Potential environmental impacts of forestry
Forestry Water Soil Landscapes Nature and
Planting Accumulation of Accumulation of Uniform planting - Plantation of
litter from acidifying litter from acidifying major changes in monoculture and
tree species - soil tree species - soil form, colour and introduced tree
acidification; acidification texture arising from species -
groundwater sharp boundaries of uniformity, loss of
acidification forest stands biodiversity
Clear felling Bare land after Bare land after Large clearances If dead or
clear felling -water clear felling -wind scarred landscapes decaying wood
erosion increased and water erosion removed - loss of
sediment and plant and animal
organic matter Use of vehicles - species which
loads - compaction depend on this
eutrophication, loss of
sedimentation Sudden decrease in biodiversity
Draining Lowering of Oxidation of organic Drying of land Lowering of water
groundwater level soils - acid-sulphate causing changes in table - loss of
reducing water formation - soil plant communities wet forests and
availability acidification and landscape wetlands high in
Oxidation of organic
soils - soil
Weeding, Use of herbicides - Increased Removal of Removal of
cleaning, groundwater frequency of vehicle greenery -uniformity understorey, an
thinning pollution use -erosion and important habitat
compaction for many species
- loss of
Pesticide and Leaching of applied Fertilisation in Changes in plant Release of
fertiliser substances - waterlogged communities and chemical
application groundwater conditions - hence landscape pesticides -
pollution denitrification poisoning of non-
greenhouse gas target species
contribution to Fertilisers
climate change applications -
changes in plant
Heavy Soil erosion - Increased Increased
machinery use increased sediment frequency of vehicle frequency of
load in surface use - soil vehicle use -
waters compaction and disturbance of
Oil leakage/spills -
water pollution Oil leakage/spills
Soil sealing -
Recreation Increased use of Trampling leading Infrastructure Increased
water - reduction of to erosion and development number of visitors
water availability compaction (access roads, in forests -wildlife
and pollution recreation centres disturbance
through effluent etc.) -changes in
from tourist centres, landscape Recreational
camping grounds infrastructure
etc. development -
Grazing and Overdensity of Overdensity of Overdensity of Overgrazing and
browsing grazing/browsing grazing/browsing grazing/browsing browsing
animals - soil animals soil animals - soil (overpopulation
erosion and erosion and erosion and of game) -
compaction - compaction changes in damage to young
increased sediment landscape plants, trees and
load, decreased habitats
Every day 100 species become extinct (four species per hour) due to tropical
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
Sandification is a process of selective erosion. Raindrop impact washes away
the finer particles of clay and humus, leaving behind the coarser and heavier
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
Figure 16 Impacts of deforestation
Hydrosphere Atmosphere Biosphere
increased runoff increased turbidity increased sedimentation
increased discharge leads to O2 content reduced less CO2 absorbed
CO2 released from decaying reduction in shading (more increased evaporation
woody material direct sunlight on forest floor)
loss of biomass decrease in habitats decrease in species diversity
rapid soil erosion leads to increased leaching
loss of nutrients
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.
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
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.
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.
gives details of the Living Planet index, a measure of global biodiversity and its
change over time. This is updated annually.
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.