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Ecosystem Profile: Indochina
The combination of economic development and an increasing human population is creating unprecedented pressures on the region's natural resources, and overexploitation has now reached critical levels in many areas. This is compounded by the lack of effective planning and management systems to control these pressures. The principal responsibility for the management of natural resources and biodiversity rests with government institutions but these often lack the financial resources, technical expertise, and political will to fulfill this responsibility effectively. Rapidly increasing levels of consumption have led to massive increases in natural resource exploitation and conversion of natural habitats to other land uses. The two over-riding immediate threats facing the region's plant and animal species are habitat loss and overexploitation of plant and animal species. One or both of these are the principal threats to nearly all globally threatened species in the region.
Probably less than 5 percent of the Indo-Burma Hotspot is covered by forest in pristine condition, while mildly damaged yet ecologically functional forest covers another 10 to 25 percent (van Dijk et al. 1999). The hotspot ranks in the top 10 hotspots for irreplaceability, and in the top five for threat. In the cases of many species, sites and even landscapes, these threats are immediate and severe (e.g. Duckworth et al. 1999, Baltzer et al. 2001, Nooren and Claridge 2001, Tordoff 2002).
Unregulated, unsustainable, unreported, and generally illegal overexploitation has driven many animal species in the region to the verge of extinction in the wild, and severely suppressed populations of others (e.g. Nash 1997, Nooren and Claridge 2001, Oldfield 2003). There are several inter-related causes, including subsistence needs, recreation, and incidental, opportunistic exploitation. However, trade demand from both domestic and international markets is often a key factor driving overexploitation. Trade demand is a particularly significant factor in the case of certain species, especially ones used in the manufacture of traditional medicines. For instance, a recent re-evaluation of the global threat status of turtles in Asia (a significant proportion of which occur in Indochina) resulted in 18 species being assessed as Critically Endangered and 27 as Endangered, primarily as a result of trade-driven exploitation (van Dijk et al. 2000, Stuart and Thorbjarnson in press).
Trade-driven overexploitation is impacting animal populations throughout Indochina. Prior to the 1990s, the greatest pressures were placed on animal populations in China, which is the major market for wildlife products in the region. During the 1990s, the focus of pressure shifted to populations in Vietnam, then Lao P.D.R. and, finally, Cambodia, as the economies of these countries opened to international trade, infrastructure developments linked previously remote areas to outside markets, supplies of wildlife products in China became depleted and domestic demand for wildlife products increased. Although populations of certain high-value animal species appear still to be more healthy in parts of Cambodia than in Vietnam, Lao P.D.R. and southern China, there are strong indications that populations of the highest-value species, such as tiger, have already undergone precipitous declines as a result of trade-driven hunting.
Limited resources, manpower, capacity, and motivation among enforcement agencies mean that overexploitation of animal species continues largely unabated. Incentives to hunt these species are often high for rural people, particularly where there is an actual or perceived trade demand. The values of some species have risen to the point that even formerly secure populations in more affluent areas are heavily trapped, as in the case of Chinese three-striped box turtle in Hong Kong (Lau 2003). Many target species have been reduced to such low levels that traders now acquire wildlife and wildlife products from further afield, even outside the region. For example, most pangolins found in trade in Vietnam recently have been in shipments from Malaysia and Indonesia (TRAFFIC Southeast Asia - Indochina in litt. 2003).
Conservation action is required in a number of thematic areas, at site, landscape, national, and international levels, if populations of species threatened by overexploitation are to be secured. Site-based action is required to reduce pressure on wild populations. A particularly important site-based action may be control of indiscriminate snaring, which frequently results in the capture of species other than those targeted by hunters, with potentially devastating consequences for ground-dwelling species, notably saola. Other important actions include control of domestic and international trade in wildlife and wildlife products. Animals at greatest risk from trade based on current knowledge include pangolins, primates, bears, cats, civets, cervid deer, wild cattle, rhinoceroses, Asian elephants, turtles, crocodiles, monitor lizards and numerous snake species.
The threat posed to plant species from overexploitation for local consumption and trade is potentially as massive as that to animal species. However, very little accurate information has been published on the impacts of overexploitation on plant species in the region. Thousands of plant species in the region have documented uses in human societies, from decoration to construction, and from food to traditional medicine. Of an estimated 4,200 to 4,500 plant species in the forests of Hainan Island, more than 2,900 species are used locally, for timber trees, medicinal plants, rattans, and wild fruit (Davis et al. 1995). Overexploitation of plants does not, therefore, only have implications for biodiversity but also for rural livelihoods, as forest products form an important component of the livelihood strategies of many households.
Lack of data constrains assessments of the magnitude of this threat, but its effects on many groups of plants, for instance orchids, are potentially devastating. Plant species with high economic values are often particularly at risk, most notably timber species. Indochina's forests support a great diversity of commercially valuable timber species, including Erythrophleum fordii, Dalbergia spp., various members of the Dipterocarpaceae family (such as Dipterocarpus spp., Shorea spp. and Hopea spp.) and various conifers, most notably Fokienia hodginsii. Stocks of most timber species in the region have declined significantly over recent decades, although the implications of this for the long-term viability of populations of these species are not fully known. Other economically valuable plant species threatened by overexploitation include Aquilaria crassna, which is a source of agarwood, and Panax vietnamensis, which is used to produce a tonic; both of these species are threatened with extinction in Vietnam as a result of overexploitation (Tordoff et al. 2003). Demand from the traditional medicine trade is also a significant factor contributing to the depletion of Himalayan yew (Taxus wallichiana) populations in Yunnan Province, and the bulk movement of wild orchids Dendrobium spp. from Lao P.D.R. and Vietnam to China.
As human populations and levels of consumption increase, overfishing presents a growing threat to the region's freshwater fish diversity, with potentially significant indirect impacts on other species through, for example, depletion of food supply. The region's most productive freshwater fishery, Tonle Sap Lake, has seen the recent disappearance from catches of some of the larger, more valuable species, an overall decrease in average fish size and lower catches per unit effort (Baran et al. 2001). However, overfishing is not restricted to industrial-scale fisheries. The increasing incidence of poison, electric and, even, bomb fishing on a local scale (e.g. Chen 2003), as the region's rivers and non-flowing wetlands succumb to increasing pressure of human settlement, especially in conjunction with other threats, has the potential to cause drastic reduction in whole fish communities (Baltzer et al. 2001).
Forests are the key habitats for a high proportion of the region's globally threatened plant and animal species. However, the region's forests have been the focus of commercial logging for decades, which has had a massive impact on their extent and condition. While commercial logging usually degrades forest habitats, it is not always a direct cause of forest loss per se. However, the construction of logging roads often opens up forest areas to subsequent settlement and conversion to other land uses. Moreover, for some animal species, the direct effects of habitat degradation and loss may be compounded by increased susceptibility to hunting in small forest patches or in forests penetrated by roads.
Within Indochina, lowland evergreen and semi-evergreen forests have been the principal focus of commercial logging activities. Lowland evergreen forests have been so severely affected that few intact areas remain; all remaining blocks of lowland evergreen forest are of critical conservation importance. In 1995, less than 5 percent of the level lowlands in Thailand retained their forest cover (Stewart-Cox and Cubitt 1995). On Hainan Island, natural forest cover was 25.7 percent in 1956 but, by 1983, only 7.2 percent remained (Maxey and Lutz 1994). Loss of natural forest cover in China, Thailand and Vietnam was so extensive during the second half of the 20th century that, by the end of the century, the forestry industries of these countries had gone into substantial decline. In addition, decline of the national forest estates of these countries contributed to major environmental problems, such as flooding and landslides. For instance, floods in Nakhon Si Thammarat province in Thailand and catastrophic flooding in the Yangtze Basin in China were both instrumental in changing national policies towards logging of natural forests (Carew-Reid 2002, BirdLife International 2003a). Such problems led to nationwide logging bans in Thailand, Vietnam and China, in 1989, 1997 and 1998, respectively. While the observance of these bans has not been absolute, the pressures on natural forests in each country have declined substantially. However, because demand for wood products in each country continues to increase, and is not fully met by commercial timber plantations, these logging bans have contributed to increased pressure on natural forests in Lao P.D.R. and Cambodia. In Lao P.D.R., commercial logging continues in parts of the country, while, in Cambodia, although a nationwide moratorium was introduced in 2002, large parts of the national forest estate remain under timber concessions, and there are strong pressures to resume commercial logging operations.
Conversion of forest to cash crop plantations is a particularly significant cause of forest loss in the region. There has been extensive replacement of natural forests by a variety of cash crops, including sugar, tea and coffee in southern China (MacKinnon et al. 1996), and oil palm and rubber in peninsular Thailand (e.g. Wells 1999). Montane forests in Vietnam and Lao P.D.R. are being converted to coffee plantations (Eames 1995, Duckworth et al. 1999), and numerous other cash crops (for example, cashew nuts) have had significant localised impacts. As domestic and export demand for many commodities is likely to increase, remaining forests are becoming increasingly Vulnerable to conversion. For example, deciduous dipterocarp forests in Cambodia are being converted to teak and pulp wood plantations (BirdLife International 2003a). The use of fire to clear forest for plantations has had a particularly devastating impact in the late 20th century (BirdLife International 2003a). This is contributing to a reduction in species diversity in evergreen forests, and causing them to grade into more deciduous forest types (van Dijk et al. 1999). Even reforestation programs, which have been underway for some years in southern China and Vietnam, have a heavy focus on plantation of monocultures of eucalypts or pines, which are fire prone, nutrient depleting and ecologically sterile (MacKinnon et al. 1996, 2001).
Throughout Indochina, rural communities in upland areas practice various forms of shifting cultivation, typically involving rotational systems of swidden fields and regenerating fallows. While shifting cultivation is often cited as a cause of forest loss, there is significant variation in the forms of shifting cultivation practiced in the region, and not all forms have been historically, or are presently, destructive to forest. While, in some parts of the region, shifting cultivation has been correlated with forest degradation and loss, there is also evidence that, in other areas, shifting cultivation is being practiced with minimal impacts on biodiversity (E. Webb in litt. 2004). In order to resolve the on-going debate over the impacts of shifting cultivation on biodiversity, there is a need for additional information on which systems are compatible with conservation, and which may require modification.
Economic development and population growth have led to an intensification and expansion of permanent agriculture in many lowland parts of the region. Extensive drainage and conversion of wetlands, most notably seasonally inundated grasslands, has occurred to accommodate this. In the Mekong Delta of Vietnam, almost all natural grasslands have now been converted for intensive rice cultivation (Buckton et al. 1999). The formerly extensive wetlands in the Chao Phraya Basin of central Thailand have suffered the same fate (P. D. Round in litt. 2002). The region's low-intensity agricultural systems, which not only represent a rich tapestry of landscape, tradition and culture but also support biodiversity of considerable global importance, are also being fragmented into increasingly isolated pockets, as a result of agricultural intensification (P. D. Round in litt. 2002).
Intertidal mudflats in Indochina are the feeding areas of hundreds of thousands of migratory and resident shorebirds, at least 20 shorebird species occur in internationally significant numbers, and several areas qualify for Ramsar designation (Round 2000, Wetlands International 2002). Piecemeal conversion of intertidal mudflats through mangrove afforestation is a potentially serious threat to the most important areas for migratory shorebirds, including the Inner Gulf of Thailand and the Red River Delta of Vietnam (Pedersen and Nguyen Huy Thang 1996, Erftermeijer and Lewis 1999). Mangrove afforestation changes the nature of the substrate, and tends, therefore, to make intertidal mudflats unsuitable for bird species for which they are the preferred feeding habitat, such as Black-faced Spoonbill (Yu and Swennen 2001). The forces driving this form of conversion include the coastal protection, land reclamation, and aquaculture development agendas of national and local governments, and financial incentives from national forestry programs.
Aquaculture development is also driving the conversion of other coastal habitats. Throughout the coastal zone of the region, mangroves, lagoons, marshes, and other wetlands are undergoing widespread and rapid conversion to shrimp and fishponds. This has particularly affected coastal mangroves, including a number of Ramsar sites. It should be noted that traditionally managed, extensive aquaculture, such as is practiced at Mai Po Nature Reserve in Hong Kong, can provide valuable habitat for many waterbirds, including a number of globally threatened species (BirdLife International 2003a). However, various forces, including the need for aquacultural pond owners to generate rapid financial returns in order to repay loans for the construction and lease of ponds, are driving a shift from extensive aquaculture to unsustainable forms of intensive aquaculture, leading to die-back of mangrove and loss of habitat for many waterbirds.
The region is experiencing rapid economic growth and associated urban, industrial and infrastructure developments are having severe direct and indirect impacts on natural habitats. One of the key pillars of the economic development strategy of each country is the extension of the national road network. In Vietnam, for example, a second major north-south highway linking Hanoi with Ho Chi Minh City has been routed through the Annamite Mountains, bisecting several protected areas. At the regional level, major road networks are being created that link capital cities and major ports, such as the East-West Corridor linking the port of Da Nang in Vietnam with Bangkok, via southern Lao P.D.R. As well as causing direct loss and fragmentation of habitat, creating barriers to the dispersal of species such as gibbons, new roads open up previously inaccessible areas to settlement and habitat conversion. Moreover, new roads strengthen economic links between remote rural areas and urban centers, facilitating the expansion of wildlife trade networks and placing increased pressure on plant and animal populations.
Increasing regional demand for flood control, irrigation, and electricity generation is fuelling a wave of dam construction on large rivers. The reservoirs created often flood important terrestrial habitats, while artificially managed discharges cause major alterations to seasonal flow regimes and natural sedimentation processes. The dams themselves impact directly on fish migration routes and access to spawning grounds: most lack fish passes or strategies to maintain aquatic communities downstream (Dudgeon 2000b). The Yali Falls dam on the Sesan River in Vietnam, for example, has had serious deleterious effects on the river's fish and sandbar-nesting bird communities downstream in Cambodia (Baird et al. 2002, Seng Kim Hout et al. 2003). Another impact of dam construction is that displaced human communities are often relocated in areas where they clear or place additional pressure on natural habitats.
Mining and quarrying for ores, gems and construction materials is causing localised but significant habitat loss in the region. Quarrying of limestone for cement manufacture is a particular threat to limestone karsts, whose potential severity is greatest in smaller, more isolated karsts, such as those in the Kien Luong area in southern Vietnam, which also happen to be among the richest in terms of invertebrate endemism (L. Deharveng in litt. 2003). Mine access roads and temporary settlement by mine workers can also have serious indirect impacts, including increased levels of hunting by mine workers living in temporary camps in remote forest areas. Moreover, several mining techniques can lead to pollution of aquatic systems by sediment or toxic chemicals, with negative impacts on freshwater biodiversity.
Deliberate and accidental introduction of alien invasive species has occurred at a number of sites in Indochina (e.g. Dudgeon and Corlett 1994, Fellowes 1999, Li and Xie 2002), although the impacts on biodiversity have been little studied to date, and are, thus, poorly understood. Certain invasive species are problematic at certain sites, for example Water Hyacinth Eichhornia crassipes and Mimosa pigra in Tonle Sap Lake and inundation zone (MacDonald et al. 1997), Pricklypear Opuntia sp. at Khao Sam Roi Yot National Park in Thailand (J. Parr verbally 2003) and Mile-a-Minute Mikania micrantha in the New Territories of Hong Kong (Liu et al. 1997). However, there is little evidence that invasive species are leading to widespread declines of native species across Indochina, and their impacts are probably less severe than many other threats to biodiversity in the region.
Urbanization, industrialization and agricultural intensification are leading to increased levels of pollution throughout the region. Discharge of industrial waste into major waterways frequently occurs unregulated, and agrochemicals applied onto agricultural land rapidly enter river systems, wiping out sensitive organisms and causing their predators to desert and search food elsewhere. According to the Division of Agricultural Toxic Substances of the Department of Agriculture, imports of herbicides into Thailand trebled in quantity between 1987 and 1994 (P. D. Round in litt. 2002). Sewage treatment is still scarce in the region, and mass dumping of raw sewage is frequent (BirdLife International 2003a). With the intensification of agriculture as a major socioeconomic strategy, the extensive use of agrochemicals will pose many problems for species and ecosystems in the immediate future. As well as the direct impacts on species through toxicity, the severe declines in invertebrate abundance associated with high levels of pesticide use are one of the major factors contributing to the collapse of open country and peri-urban bird populations in agricultural landscapes throughout the region.
The underlying causes of the threats outlined above are often deep rooted and complex. Many have their origins in regional and global economic trends, on-going demographic changes and the socio-political history of the region. They may be becoming further compounded by the unpredictable impacts of climate change. A brief overview of major root causes follows.
Economic growth and ever-increasing consumption are the main underlying causes of habitat loss and degradation, and overexploitation of plant and animal species. All countries in the region are, to varying degrees, pursuing market-oriented economic policies and export-led development strategies, on the promise of strong economic growth and with the encouragement and support of external donors. This is especially notably in three critical sectors for biodiversity conservation: forestry, fisheries and agriculture.
The trend of rapid economic growth across Asia over the past decade has increased regional demand for natural resources, particularly timber and cash crops, resulting in the degradation and conversion of natural habitats. Changes in food consumption patterns have exacerbated this trend, particularly an increase in animal protein consumption. For example, overall meat consumption in China increased by 117 percent between 1991 and 1998 (Tansley and D'Silva 1999), with dramatic implications for fodder demand and land use. Growing affluence among ASEAN nations is also resulting in an increasing demand for products such as paper and palm oil. Increasing levels of consumption in developed countries are also contributing to loss of natural habitats in the region, for example, the major export markets for shrimp farmed in aquacultural ponds in the region's coastal zones are Japan and western countries.
Many threats to biodiversity arise from situations where government agencies mandated to manage natural resources face limitations of personnel, resources, training and motivation. Capacity limitations are one of the major reasons why protected area systems in the region function so inefficiently. They continue to be plagued by a suite of management problems, ranging from low staff morale, lack of incentives for good performance, limited technical capacity, inappropriate budget allocations, and overemphasis on infrastructure development. Inadequate regulation of companies, illegal land clearance and encroachment of protected areas are other symptoms of capacity limitations.
Subsidies within the forestry and agriculture sectors have promoted increased production of a number of products linked to forest loss, including forest products and cash crops, and promoted agricultural intensification and the large-scale use of agrochemicals. Subsidies for tree planting have led to the afforestation of intertidal mudflats, grasslands and other natural non-forest habitats. Such perverse incentives may be direct, for example tax write-offs, grants or low-interests loans, or indirect, for example low land rents, low labor costs, construction of “free” access roads and other infrastructure, or weak environmental protection regulations.
Although biodiversity has important cultural, spiritual, recreational, and personal values, government policies frequently recognize natural resources only for their market value, particularly in developing countries, where the environment, including biodiversity, is severely undervalued. Indeed, the fact that quality of life is dependent upon a complex range of ecological functions that provide clean air, pure water, fertile soils and other ecosystem services, is seldom even considered. The undervaluation of ecological services in Indochina may be partly because dispersed services, such as carbon sequestration, although important globally, are of less significance to national governments, and partly because immediate gains from exploiting a natural resource are frequently more attractive to decision makers than long-term, theoretical benefits from its maintenance. Furthermore, many of the most important values of biodiversity may simply be unquantifiable.
A recent study estimated the combined value of 17 different ecosystem services, including climate regulation, water supply and food production, at between $16 and 54 trillion per year (Costanza et al. 1997): twice global gross national product. Forests and wetlands are particularly undervalued, when their full environmental and social value is taken into account (for example, nutrient cycling, climate regulation, erosion control and recreation). A number of recent projects, including the economic review of protected areas undertaken for the Lower Mekong Countries (ICEM 2003) and a review of the roles of natural vegetation in China (MacKinnon et al. 2001), have aimed to demonstrate the economic values of biodiversity.
Inappropriate systems of land ownership, particularly lack of land tenure and involvement in management of local communities, have been a key underlying cause of biodiversity loss. Large tracts of natural habitat under the nominal ownership of the state have frequently failed to retain their biological and ecological values. Land tenure is an important consideration in people's attitudes towards land use and significant in terms of habitat loss, especially deforestation. Unresolved land tenure arrangements can facilitate spontaneous settlement and conversion of forested areas. Many countries in the region are presently undertaking major reforms to their land policies, including the allocation of land to private owners. Unclear policies and lack of technical capacity within the government institutions involved have often meant that the land reform and allocation processes have further marginalized the poorer sections of rural communities, and exacerbated threats to biodiversity.
Global climate change is an emerging threat, which has manifested itself most tangibly in the increasing frequency, severity and geographic extent of regional droughts. Concern that the frequency and severity of El Niño events will increase with global warming renders many forests more susceptible to fire. The medium to long-term impacts of climate change on the region's biodiversity are currently far from being fully understood but clearly warrant careful scrutiny, given the devastating effects to date on the neighbouring Sundaland hotspot (BirdLife International 2003a). Although it is not possible to predict the precise effects with any degree of confidence, under any scenario of significant climate change, the spatial distribution of habitats and biotic communities is likely to change, as some habitats increase in area while others decrease.
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