In disturbance ecology, human land-use is often treated as a single type of landscape modification, though we know that there are many different types and patterns of human land-use each with differing levels of impact on ecological communities. This study focuses on land-use patterns in Massachusetts, asking how the patterns of land-use since colonial times affected the population genetic structure of beech (Fagus grandifolia). With the spread of colonial agriculture nearly 80% of what was nearly continuously forested land was transformed into pastures and fields, which were later abandoned and the forests returned. Townships experienced varying levels and patterns of deforestation. We compare how these patterns influence the genetic diversity and structure of the beech trees that recolonized abandoned sites. Samples of beech trees growing in previously deforested landscapes were analyzed using microsatellite markers to test for the severity and extent of genetic bottlenecks in their return onto formerly deforested plots.
Results/Conclusions
Preliminary results suggest the there is evidence of bottlenecks in the recolonized fields in Petersham, MA. Allelic diversity, for instance, is higher in woodlots, which were permanently forested, though often logged, than in reforested farmland. This study addresses important ecological and conservation questions about how the size and area of habitat patches may affect ecological dynamics. Perhaps more importantly, it demonstrates that human land-use cannot and should not be treated as one category of landscape modification, but rather has varying impacts based on the patterns of modification.
