Forest biodiversity and timber extraction: an analysis of the interaction of market and non-market mechanisms

摘要

Forest ecosystems provide a range of products and services for human use, primarily due to the biodiversity inherent in them. From the ecological viewpoint, this diversity is of different kinds and has the potential to cater to human well-being in multifarious ways. However, the mix of services that is available to any economy from forests depends, in addition to their biological characteristics, on the nature of the economic regime within which they are exploited. Some commodities such as timber are extracted in a regime driven, in the main, by market forces. Others such as non-timber forest products may be extracted under a variety of arrangements, the range varying from open access to common property regimes. Services such as those of water cycle augmentation and micro-climate regulation are typically available to communities as free goods. It is hypothesized that this difference in institutional regimes has implications for the mix of products and services that are extracted in different ways. 1. Through its effect on the extraction efforts for the marketed product. 2. Because of policies, such as plantation, which are intended to increase the supply of the marketed product, typically, timber. 3. Through a change in biodiversity of the forest stock which in turn results in a decreased availability of the non-marketed products. The present paper studies conditions under which timber has been extracted from forests of the north Indian state of Uttar Pradesh (UP) during the 1975-2000 period to examine this proposition. It is postulated that extraction of timber at any point of time depends on the stock, the effort involved in extraction (as represented by the per unit cost of extraction), the biodiversity index (defined as a product biodiversity index) and a variable depicting ecological characteristics of the forests. Using a modified Gordon-Schaefer production function, and the assumption that forests are managed for "sustainable timber extraction", the reduced form equations are derived and estimated using data from Uttar Pradesh forests for the 1975-2000 period. The results suggest that, in the absence of variables representing the plantation area and biodiversity-corrected stocks, the explanatory power of the model is low, even though extraction is seen to be significantly impacted by effort. If, however, the ratio of plantation area and biodiversity-adjusted extraction are introduced as explanatory variables, interesting results with respect to the trend of extraction over time are obtained. As stocks of woody biomass increase, extraction increases. A decrease in biodiversity of the stock may be accompanied, under a certain set of circumstances, with a rising trend in extraction, and at a rising rate as explained above. However, an increased biodiversity may imply a decreasing trend in the extraction in the future provided that present extraction Y does not rise at a rate faster than the rate of increase in the biodiversity. These two results seen together are, we believe, significant. They point to the fact that policies aimed at increasing plantation increase short-run timber extraction. Further, if biodiversity increases, the impact on future extraction of timber depends on relative rates of change in biodiversity and extraction per unit effort. It is clear that trade-offs between timber extraction and existence of biodiverse forests providing a variety of goods and services.