Tree cover and forest cover dynamics in the Mekong Basin from 2001 to 2011

Abstract

The Mekong Basin spanning large parts of continental Southeast Asia is endowed with rich natural resources that are increasingly under pressure as a result of rapid socio-economic development over the last decades. Particularly the forests in the region are threatened by large-scale infrastructure developments, the expansion of agriculture and trading of timber products. In view of these developments, this study provides an updated view of the current state of the forest resources in the region and the change they have undergone throughout the last decade. Annual maps of percent tree cover, herbaceous cover, and barren land for the years 2001–2011 were derived from 500 m MODIS data, and formed the basis for a tree cover specific identification of changes utilizing utilising long-term statistics on inter-annual prediction variability. Furthermore, the temporal patterns shown in the tree cover history of each pixel for the observation period, allowed a differentiation to be made between permanent forest cover conversions and temporary forest losses, as well as between areas of abrupt and more gradual forest dynamics. Average gross forest loss for the Lower Mekong Basin was estimated at a rate of 0.4% per year. When considering permanent forest losses only, the highest annual loss rates were evident for Vietnamese Basin area (1.1 %), followed by the respective national areas of Cambodia (0.7%), Laos (0.4%), and Thailand (0.2%). Extensive areas of forests and forest regrowth within Laos and Vietnam have been affected by temporal losses that have been mostly attributed to shifting -cultivation practices and the conversion of natural forests to forest plantations. Furthermore, it could be shown that temporal patterns of change may possibly reveal information about the underlying causes of forest cover reduction. Forest clearance related to large-scale mechanised clear cutting, e.g. by the agroindustry, generally showed very abrupt decreases in canopy cover, while forest losses related to small-scale agricultural clearings or more selective logging where characterised by more gradual decreases.