The Influence of Land Use History on Current Abundance of Invasive Species in Forests

Land use history influences the composition of current forests dramatically. As regulations in Massachusetts related to protecting rivers have changed, land use in the early 1970s along rivers transitioned away from agriculture and toward forests. The succession of these forested areas over the past 50 years may be different from forests that were already established at the same time. I hypothesized that there is a greater abundance of invasive plant species in forests that were being used for agriculture than those already forested. This hypothesis was based on the ability of invasive species to outcompete native species when there are disturbances in the ecosystems and high levels of resources such as light and nutrients. I also predicted that native, early-successional trees would be more abundant at recent agricultural sites due to the shorter amount of time that these forests had for succession. At four sites in the Connecticut River Watershed, I surveyed current forests with two different land use histories, those that had been agriculture in 1970 and those that were forested. I measured the distribution and abundance of native and invasive plants in transects 60m long and 2m wide. Both hypotheses were supported by the data from the sites surveyed in the study. Current forests that had been used for agriculture in 1970 had much greater abundance of invasive plants (about 36% compared to about 20%), and more native, early-successional trees.