Invasive species are a threat to biodiversity and ecosystem function. Southeast Michigan forests are seeing a substantial increase in invasive shrub density. Understanding how these species invade is important to controlling their spread and attempting to eradicate them. This research considered the impact of soil nutrient levels on the abundance and size of native and invasive shrubs at Walden West, an environmental preserve in southeast Michigan. Soil nutrient levels were measured from bulked samples in eight 400 square meter quadrats. All trees and shrubs were mapped, measured, identified, and tagged. Leaf samples were also taken and chemical analyses carried out to determine the relationship of leaf chemistry to soil chemistry in these species.
Results/Conclusions
Correlations between abundance and some soil nutrient levels were found. Calcium levels were of prime importance, although cation exchange capacity (CEC) and phosphorus levels were also significant predictors of species composition. Leaf chemistry is primarily driven by species identity but there are some environmental effects as well, though effect size is small. From these results, we can conclude that at least some species of invasive shrubs demonstrate a level of specialization on soil types within a given reserve, suggesting the possibility of source-sink dynamics and perhaps suggesting effective control strategies.