Deforestation of tropical rainforests — a case study of Madagascar

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

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.

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 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 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.

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

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 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

• 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

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.