| [Back to front page] | Impacts of disturbance In recent years, it has become increasingly apparent that conservation of tropical forests cannot rely solely on protected area networks. After a couple of decades of rapid expansion in tropical protected areas, further expansion is probably limited. This view is reflected in the World Resources Institute’s Global Biodiversity Strategy, UNEP’s Global Biodiversity Assessment, and the work of many other authors. A comprehensive approach to forest conservation must therefore incorporate the sustainable management of land outside protected areas, and this requires an understanding of how human activities impact on forest resources. For the past three years, researchers from three countries - India, Thailand and Malaysia - have been working collaboratively under the auspices of CIFOR and IPGRI to investigate how human activities affect the genetic resources of forest plant species. This has been a multidisciplinary research project, involving not only research on genetic resources, but also on reproductive ecology and socioeconomic investigations of the communities living in and around the forest. In August 1997, members of the research team met in Bangalore, India, to review results of their studies, to draw conclusions about the impact of human activities on forest genetic resources, and to begin a process of communicating the results to forest managers and policy makers. The selection of sites within countries was made to cover as many different types of human activities as possible, while also allowing comparisons to be made amongst countries. Thus, in Malaysia, the main type of human activity was logging; in Thailand, as well as timber harvesting, the forests were also used for grazing and collection of NTFPs; and in India the main activities were grazing and NTFP collection. Preliminary results provide some interesting insights concerning the interaction between people and forest genetic resources. For example, the socioeconomic research in India indicated that, in general, it is the poorer households that maintain a greater reliance on the collection of NTFPs. Members of the wealthier households often have access to salaried income, which not only provides potential for greater income, but is also more dependable than seasonal NTFP collection, yields of which can vary widely from year to year. With the incorporation of many NTFPs into a market economy, there is a marked tendency for unsustainable harvesting, even when the harvesting is undertaken by indigenous communities which have traditionally relied on these products for their livelihoods. Consequently, regeneration of certain species is almost completely absent in areas of highly intensive harvesting, and genetic diversity of these species is consequently eroded. In contrast to NTFP collection, most other activities appear to have a much less obvious impact. Although the impacts of logging, based on the research done in Malaysia, were evident on all species sampled - not only on those which were harvested - the loss of genetic diversity did not exceed 24 per cent which was less than the percentage reduction in numbers of trees. Similarly, the harvesting of wood for construction and fuel in Thailand only had a significant impact at very high intensities of extraction. The research in Thailand also clearly demonstrated that the intensity of impact is dependent on the reproductive ecology of the species. Those species which are pollinated by weakly flying insects show increased levels of inbreeding as the density of reproductive individuals declines, while species affected by more strongly flying insects are less affected. Depending on the behaviour of pollinators, and the degree of host-pollinator uniqueness, there may also be clear thresholds in the intensity of disturbance that affect the mating system and, consequently, genetic diversity. Further comparative analyses across the three countries will
indicate the degree to which these findings are generalisable. Similarly, the integration
of research across all three disciplines involved will illustrate the processes which
determine the consequences of people-forest interactions much more clearly than would be
possible from examination of data from just one discipline.
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