ECOLECON: A spatially explicit model for ecological economics of species conservation in complex forest landscapes.
详细信息
文摘
ECOLECON is a spatially-explicit, object-oriented, and individual-based computer simulation model for species conservation in forested landscapes. It consists of both ecological and economic components. Ecological components include information on habitat selection, demography, and dispersal of the species being modeled. Economic components contain forest growth and yield functions, timber prices and forest management costs. The model is capable of predicting population dynamics, spatial distribution, extinction probability, as well as future landscape structure, and economic income from timber harvest. Since ECOLECON is interactive and easy to use, it is a useful tool for research, education and forest management.;Simulation results illustrated that on hypothetical pine forests, landscape structure and rotation lengths play important roles in determining both the population size of Bachman's Sparrow (Aimophila aestivalis) and the economic revenues from timber harvest. When rotation length was shorter than 80 years, population size had a negative linear relationship with rotation lengths. Land expectation value was maximum when rotation length was 20 years. Increases in the amount of mature habitat resulted in increasing sparrow population size but decreasing annual net income under current tax and market conditions. Thus, the goals of maximizing short-term economic return and maximizing the sparrow population size are in conflict. Fragmentation of a small amount of mature habitat resulted in a lower population size, but fragmentation of large amount of mature habitat resulted in larger population size, compared to non-fragmentation. The spatial location of patches of mature habitat also caused large differences in population size. Larger stand sizes produced higher economic revenues, but the effect of stand size on population size was confounded by the overall composition of the landscape, especially the amount of mature habitat.;When coupled with a geographic information system (GIS), ECOLECON was used to simulate the impacts of a forest management proposal on the annual gross income and population dynamics of Bachman's Sparrow on specific landscapes of the Savannah River Site, South Carolina. Among the three harvesting methods considered, random harvesting resulted in the lowest population size and the lowest economic income, clustered harvesting yielded the highest sparrow population size and an intermediate amount of annual gross income, while harvesting the oldest stands first had the highest economic income and supported an intermediate population size. Both harvesting the stands in clusters and harvesting the oldest stands first allowed the sparrow population size to reach and exceed the minimum management goals proposed by the U.S. Forest Service, but the sparrows experienced a long transition period with a very low population size. Thinning and periodically burning middle-aged stands could increase total amount of suitable habitat for Bachman's Sparrow, thus increasing the average sparrow population size and realizing the minimum management objective sooner.