Vegetation Succession Following Clearcutting of Lowland Hawaiian Rainforest on the Island of Hawai'i.

This study evaluates the secondary successional pathways of Hawaiian lowland rainforest following anthropogenic disturbance. Whereas primary succession on lava flows has been well studied in Hawaii, secondary successional dynamics on disturbed habitats in the presence of nonnative species has been poorly researched and documented. Our study was based on two vegetation sampling efforts conducted on 200–400-year-old lava flows 2 and 27 years following a 400-hectare clearcutting operation in the Puna District of the southeast quadrant of Hawaii Island. Intact forest adjacent to the clearcut area provided a baseline to compare against succession dynamics in the clearcut area. The most important trees of the uncut primary forest, based on frequency, density, and dominance, were keystone Hawaiian forest species Metrosideros polymorpha , followed by Psychotria hawaiiensis, Psidium cattleianum, Ciboteum glaucum , and Cibotium chamissoi. Whereas early successional nonnative species dominated the initial vegetation colonizing the clearcut site, M. polymorpha, P. cattleianum , and Cibotium species were also present. Twenty-seven years later we found the clearcut site colonized by two distinct secondary forest types: M. polymorpha -dominated forest and Falcataria moluccana -dominated forest. Whereas M. polymorpha maintained a similar level of dominance in uncut primary forest and M. polymorpha -dominated secondary forest stands, it was nearly absent from F. moluccana -dominated secondary forest stands. Results demonstrated that the keystone Hawaiian native tree species can effectively reestablish across disturbed landscapes, but are unable to outcompete in areas where fast growing nonnative trees become established. This underscores the critical need to suppress early nonnative tree establishment in disturbed habitats if the objective is to reestablish Hawaiian native forests. [ABSTRACT FROM AUTHOR]