While several studies on the process of invasion often focused on single factors or on the general explanation of ‘disturbance,' recent work has attempted to move towards a more mechanistic understanding of the factors that promote plant community invasion. Manipulative experiments provide a means for discerning causal relationships and interactive effects of environmental factors in promoting invasion. This dataset contains the results of multifactor manipulative experiments in forest communities, which compared factors influencing early seedling establishment for native and invasive woody plants. In an earlier study, we found that in Long Island, NY, invasion patterns are correlated with forest community type (pine barrens or hardwood), light availability, and soil N and Ca. Therefore, we conducted manipulative field experiments in two different years to determine the relative importance and interaction of experimental gaps and N and Ca addition in pine barrens and hardwood forests in promoting invasion. We used seedlings of seven common native and invasive species in the first experiment, and 16 native and invasive species paired phylogenetically in the second experiment. This was done in the years 2000 and 2003 respectively.