ECOLOGICAL AND ECONOMIC-EFFECTS OF FOREST LANDSCAPE STRUCTURE AND ROTATION LENGTH - SIMULATION STUDIES USING ECOLECON

ECOLECON is a spatially-explicit, object-oriented computer simulation model that simulates animal population dynamics and economic yield from timber harvests based on forest landscape structure and timber management schemes. The model has been parameterized to simulate the population dynamics and extinction probability of Bachman's Sparrow (Aimophila aestivalis), a species of management concern in southeastern pine forests. Simulations with ECOLECON have shown that forest landscape structure and management options such as rotation lengths influence both population sizes of the sparrows and economic returns from timber harvests. Sparrow population size and economic income were often maximized by different management strategies. For example, land expectation value reached a maximum when a rotation length was 20 years; however, whenever harvest rotation length was shorter than 80 years, sparrow population size had a negative linear relationship with rotation lengths. As the amount of mature pine habitat increased, sparrow population size increased, but annual net income decreased. Fragmentation of landscapes with only a small amount of mature habitat caused lower population sizes, but fragmentation of landscapes with a large amount of mature habitat resulted in a larger population size. Differences in placement of the mature habitat within the landscapes resulted in 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 amount of mature habitat. Simulation models such as ECOLECON provide a potentially powerful tool for balancing wildlife population needs and economic revenues through designing and managing forested landscapes.