Re-establishment of three dominant herbaceous understory species following fine-scale disturbance in a Catskill northern hardwood forest

At the landscape scale, herbaceous understory plant species are limited in return to forested settings by dispersal. At fine-scales, microhabitat characteristics are known to be important in determining the distribution of herbaceous understory plant species. Fine-scale manipulative experiments to determine responses of understory species to disturbance, however, are few and limited to Europe and the Pacific northwest. The Unified Neutral Theory of Biodiversity (UNT) predicts that species enter disturbed habitat in abundances proportional to their neighboring abundance. I assessed the reestablishment of dominant understory plant species (Dryopteris intermedia, Lycopodium lucidulum, and Oxalis acetosella) following small-scale disturbance in a Catskill northern hardwood forest. While reestablishment of all species was significantly and positively correlated with the presence of each species in surrounding areas indicating the importance of dispersal limitation of reestablishment, rates of recovery were species specific. Reestablishment of O. acetosella was far greater than that of the other species. In fact, no sexual reproduction was observed for D. intermedia and L. lucidulum. Cover of D. intermedia and L. lucidulum was significantly and positively correlated with pre-disturbance cover but this was not true for O. acetosella, indicating that for the pteridiophytes, habitat quality (as well as dispersal) was an important factor in reestablishment. Reestablishment therefore was influenced by dispersal and habitat characteristics, was species specific, and did not follow the predictions of the UNT. Thus, small-scale disturbance can have an important effect on the composition of the herbaceous community in northern hardwood forests.