Agriculture, water, and ecosystems: avoiding the costs of going too far
The widespread impacts of draining and burning in Southeast Asian peatlands
Large parts of the tropical peat swamp forests in Southeast Asia have been seriously degraded, largely due to logging for timber and pulp (Wösten and others 2006; Page and others 2002). The process has been accelerated over the last two decades by the conversion of forests to agriculture, particularly oil palm plantations. Drainage and forest clearing threaten the stability of large tracts of forests in Indonesia and Malaysia and make them susceptible to re.
Attempts to clear and drain the forests and establish agriculture have high rates of failure. Under the Mega Rice Project in Kalimantan, Indonesia, large areas of forest were cleared and some 4,600 kilometers of drainage canals were constructed in an attempt to grow rice on a grand scale using emigrant workers from the heavily populated neighboring island of Java. The cleared land was un- suited to rice production, and the scheme was abandoned. In 1997 land clearing and subsequent uncontrolled res severely burned about 5 million hectares of forest and agricultural land in Kaliman- tan, releasing an estimated 0.8–2.6 billion tons of carbon dioxide into the atmosphere (Glover and Jessup 1999; Page and others 2002; Wooster and Strub 2002). The res created a major atmospheric haze, with severe impacts on the health of 70 million people in six countries. In addition, there have been economic effects on timber and agricultural activities, with the res compounding the loss of
peatlands through clearing and failed attempts to cultivate large areas for rice.
Rehabilitation of some degraded areas is under way, but it is a slow and difcult process trying to reestablish the hydrology and vegetation (Wösten and others 2006). At a regional level the Asso- ciation of Southeast Asian Nations (ASEAN) has taken an active interest in the problem through the ASEAN Peatland Management Initiative, facilitating the sharing of expertise and resources among the affected countries to prevent peatland res and manage peatlands wisely. The regional initiatives are linked with national action plans. Monitoring mechanisms are in place, and a policy of zero burning
for further land clearing has also been established, in particular for oil palm plantations.
Despite these steps, the problem of peatland degradation continues. The expansion of oil palm plantations is a major driver. The peat swamps are still being cleared and burned, undermining efforts to conserve and use the peatlands of Southeast Asia wisely and threatening the health of people lo- cally and regionally.
2003). Indeed, there are instances where the opposite occurs: where wetlands reduce low flows, increase floods, or act as a barrier to groundwater recharge. Given the wide range of wetlands, from entirely groundwater-fed springs and mountain bogs to large inland river floodplains, such variation should not be surprising.
Changes in water quality. Many factors contribute to changes in water quality. is sec- tion looks at nutrient loads, agrochemicals, and siltation.
Nutrient loading. e use of fertilizers has brought major benefits to agriculture, but has also led to widespread contamination of surface water and groundwater through run- off. Over the past four decades excessive nutrient loading has emerged as one of the most important direct drivers of ecosystem change in inland and coastal wetlands, with the flux of reactive nitrogen to the oceans having increased by nearly 80% from 1860 to 1990 (MEA 2005c). Phosphorus applications have also increased, rising threefold since 1960, with a steady increase until 1990 followed by a leveling off at approximately the applica- tion rates of the 1980s (Bennett, Carpenter, and Caraco 2001). ese changes are mirrored