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Testing assumptions : the recent history of forest cover in Nakai-Nam Theun National Protected Area, Laos Robichaud, William G.


In Laos, as in much of Southeast Asia, swidden agriculture is commonly blamed as a primary driver of forest loss. The foremost policy initiative of the Lao Department of Forestry is to replace traditional swidden agriculture with other forms of rural livelihood. This has percolated down to donor-supported management planning for the largest nature reserve in Laos or Vietnam, Nakai-Nam Theun National Protected Area (NNT NPA) in the Annamite Mountains of central Laos. But 'swidden' is a collective term for a spectrum of cultivation strategies of varying intensity and environmental consequences, and its presumed deleterious impact on the forest cover of NNT NPA is an untested assumption. I tested the assumption by methods of historical ecology, plotting the patterns of NNT's forest cover and human settlement over the past several decades. Principal sources of data were topographic maps dating back to 1943, and Landsat images from 1976, 1989 and 2001. The analysis showed that, although NNT has been inhabited for hundreds and possibly thousands of years, it retained more than 95% forest cover until the mid-1960s. Subsequently, forest declined at 0.5%/year until the 1980s, followed by an increase of ca. 0.3%/year to the present day. Over the same period, forest cover declined in Laos as a whole at 1.7%/year, and in two protected areas near NNT at more than 3%/year. The earlier deforestation that occurred in NNT, to the 1980s, expanded little into the unbroken forest of the reserve, but was contained almost entirely within a swidden/forest mosaic whose boundaries already existed in the 1960s. At present, the main pressure on NNT's forest is from villages outside the reserve's northern border, not within. Two factors best account for the stability of NNT's forest cover in the face of increasing population. First, human settlement has been remarkably stable in NNT since at least the 1940s, with few changes in the number or location of villages. This stability places practical limits on the extent of forest clearance by the area's residents. Population density within the existing swidden/forest mosaic (about 1/5 of NNT's area) is probably still below carrying capacity for swidden livelihoods. Second, NNT has seen an unprecedented escalation in wildlife trade in the last twenty years. Income earned from wildlife trade may have allowed NNT's residents to purchase rice to feed growing populations, instead of clearing more forest to grow it. The implication for management is that swidden itself is not the primary threat to NNT's forest, growing human population is. Given limitations on agricultural intensification in NNT, in the absence of population stabilization efforts to suppress wildlife trade could stimulate an increase in swidden, and vice-versa.

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