Floristic diversity in the experimental watersheds of the Hubbard Brook Experimental Forest, New Hampshire, USA

Complete abundance-annotated botanical inventories of managed and unmanaged forested areas provide critical baseline data for the long term monitoring of floristic diversity. Such data are essential in identifying species at risk of local or regional extirpation, in tracking rates of exotic invasion, and in the evaluation of species diversity effects arising from natural and anthropogenic disturbance. The reaction of forest herbaceous species to disturbance, and their subsequent recovery rates, have been little studied to date. This study documents the complete floras of seven experimental watersheds of the Hubbard Brook Experimental Forest, compares their relative floristic characters, and provides baseline data for long term diversity monitoring at the Hubbard Brook Experimental Forest. The two watersheds having undergone experimental clearcuts in the recent past were found to differ significantly in elements of the herbaceous understory. These differences were not reflected in tree data and suggest that forest management policies based on tree recovery times may underestimate true floristic recovery periods, and threaten diversity over the long term.