The Domestic Benefits of Tropical Forests: A Critical Review Emphasizing Hydrological Functions

摘要: The authors critically review the literature on net domestic (within-country) economic benefits of protecting tropical forests, focusing hydrological and production nontimber forest products. (The does not consider other important classes benefits, including global all kinds, ecological which do have instrumental value, existence value forests.) Their main conclusions: (1)The level from preservation is highly sensitive to alternative land use local climatic, biological, geological, circumstances. When agroforestry or certain types tree crops, natural forests may yield no benefits. (2)The are poorly understood likely be variable. They also fewer than popularly assumed: Deforestation has been shown associated with large-scale flooding. Tropical deforestation generally higher, lower, dry season flows. Although it plausible that should affect precipitation, magnitude even direction effects unknown, except in special case cloud "harvest" passing moisture. link between downstream sediment damage basic topography geology. Where transport slow - as large, low-gradient basins impacts manifest themselves distant future, so present small. Steep near reservoirs marine fisheries, hand, can cause substantial if cover severely disturbed. But only a few pioneering studies examined economics reservoir sedimentation, improved models both dam function needed. (3) most impressive point estimates based products often atypical cases faulty analysis. domesticated synthetic substitutes exist, product-related rents for will usually driven toward zero.