New study analyses biggest threats to Southeast Asian biodiversity

Southeast Asia is a global biodiversity hotspot — but with about 4 billion people living in the region, the pressures on that biodiversity are severe.

Mekong river diversity
The Mekong River has the highest freshwater diversity in the world which is under threat by 78 planned dam constructions. Image: Pierre Le Bigot, CC BY-NC-ND 2.0

Southeast Asia is a global biodiversity hotspot — but with about 4 billion people living in the region, the pressures on that biodiversity are severe.

Deforestation rates in Southeast Asia are some of the highest anywhere on Earth, and the rate of mining is the highest in the tropics. The region also has a number of hydropower dams under construction, and consumption of species for traditional medicines is particularly pronounced.

These issues are not unique to Southeast Asia, of course, as they are symptomatic of those facing tropical regions around the globe.

But a new study published in the journal Ecosphere analysing all of the threats to Southeast Asia’s biodiversity concludes that the region “may be under some of the greatest levels of biotic threat.”

“Of all regional threats the two main drivers of biodiversity loss in the Asian tropics are hunting and trade, and habitat loss,” Alice Hughes, an associate professor in landscape ecology and conservation with the Chinese Academy of Sciences and the study’s author, told Mongabay.

Hughes found that, region-wide, Southeast Asia has lost 14.5 per cent of its forests in the last 15 years and may have already lost more than 50 percent of its original forest cover. Some areas, including parts of Indonesia, are projected to lose up to 98 percent of their forests by 2022 and the habitat for wildlife that it represents.

The main drivers of this forest loss is conversion for agriculture: rubber, oil palm, and pulp and paper plantations have proliferated throughout Southeast Asia, which now supplies significant amounts of each of these commodities to the global market — indeed, for both palm oil and acacia-based pulp and paper, Southeast Asia is the source of nearly 90 percent of the global supply.

The pace of land conversion is not set to slow anytime soon, either — the total area used for rubber plantations alone is projected to expand by between 4.3 and 8.5 million hectares (10.6 and 21 million acres) by 2024 in order to meet growing demand.

Habitat loss is also driven by the construction of dams, and Southeast Asian countries plan to build scores in the coming years. There are currently 78 dams planned for the Mekong Delta that, if built, are projected to reduce the number of migratory fish by 20 to 70 per cent while flooding terrestrial habitats and causing regional droughts.

“The Mekong has the highest freshwater diversity in the world, and the potential extinction of so many species represents a global catastrophe,” Hughes noted in a piece for The Conversation earlier this month.

“The drainage of Asia’s wetlands presents a further set of dangers, particularly due to their importance to more than 50 million migratory wading birds that depend on them for migration and breeding,” Hughes added.

“Around 80 per cent of Southeast Asian wetlands are threatened by conversion to agricultural land or development by drainage. Up to 45 per cent of intertidal wetlands have already been lost. This has so far caused population reductions of up to 79 per cent in some wading species.”

Without urgent and immediate action to counter and ameliorate these threats we can expect to see the extinction of large numbers of species in the coming decades.

Alice Hughes, associate professor in landscape ecology and conservation, Chinese Academy of Sciences

The second of the top two threats to Southeast Asian biodiversity identified by Hughes in the study is hunting and the illegal wildlife trade. (Another study published last September actually found hunting to be an even bigger threat to the region’s biodiversity than deforestation.)

Wildlife collection in the region is driven by bushmeat hunting and the use of wild animals and their parts in traditional medicine, for ornamental purposes, and for the pet trade.

“The intensity of demand has resulted in the loss of all mammals of over [two kilograms] in the majority of unprotected forests across the region, whilst many bird and herptiles are under major threat as pets, and for zoos and aquaria,” Hughes said.

Many of Southeast Asia’s most threatened ecosystems harbor exceptionally high levels of endemism. Take, for instance, karsts, landscapes underlain by limestone that have eroded, producing ridges, towers, sinkholes, and other characteristic features capable of harboring multiple site-endemic species.

Southeast Asia has an estimated 800,000 square kilometers (about 309,000 square miles) of karst, and there are estimates that up to 90 per cent of cave-dependent species in China have yet to be formally described by scientists.

Yet karst ecosystems are under threat, mainly due to cement production — another threat to Southeast Asia’s biodiversity that shows no sign of abating any time soon.

Cement production has grown exponentially in recent years, and three of the top five global exporters of limestone are in Southeast Asia: India, Vietnam, and Malaysia, which collectively produce nearly 20 percent of global cement exports.

“As karsts are under-represented in protected areas — and given the majority of karst-dwelling species are limited to a single site — there is no way of knowing how many species go extinct annually as a consequence,” Hughes notes.

There are numerous other drivers of biodiversity loss in Southeast Asia, including climate change, disease, invasive species, pollution, and urbanization, but, in the short-term, none represent the same level of threat to the same number of species as habitat loss and hunting and trading of wildlife, according to Hughes.

Compounding the problem is the fact that none of these drivers of biodiversity loss occur in a vacuum. In fact, many of the threats “act in synergism,” Hughes writes in the study, “and the outlook for any species or habitat reflects the complex interaction of a number of these issues.” Which, she suggests, is all the more reason to understand each driver in its specific context when creating solutions.

In the study, Hughes makes a number of recommendations for combating these threats to biodiversity in the region. For many ecosystems and some taxa, she argues, further research is needed to develop appropriate priorities for conservation, especially in the wake of rapid habitat degradation and destruction. Better enforcement and monitoring is also needed in order to enforce existing regulations to protect habitat and prevent the exploitation of endangered species.

And while new technologies allow habitat destruction and wildlife trade to be monitored at ever-higher temporal and spatial resolutions, more effort is required to make the use of these technologies standard practice.

“Southeast Asia’s biodiversity has never been more threatened,” Hughes said. “Without urgent and immediate action to counter and ameliorate these threats we can expect to see the extinction of large numbers of species in the coming decades.”

This story was published with permission from

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