Patterns of tree diversity in response to logging in Algonquin Provincial Park

Abstract

The acceleration of human disturbance on natural systems necessitates the understanding of the effects of disturbance on species diversity, in order to mitigate its impacts. The Intermediate Disturbance Hypothesis (IDH) provides a general framework for predicting how these effects will unfold, centered on the premise that diversity will be maximized at intermediate levels of disturbance, or after an intermediate amount of time has passed since the last disturbance. We investigated the impact of disturbance by logging in Algonquin Provincial Park, ON, Canada, on tree species diversity. We sampled 7 sites, with known times since the last logging event, ranging between 4 and 149 years. We found that species richness and diversity indeed peaked at an intermediate disturbance regime of approximately 80 years since logging. We also found that this maximum diversity was caused by a combination of early, pioneer, post-pioneer, sub-climax, and climax species. Our experiment shows that IDH is applicable to the mixed forests of Algonquin, and therefore, provided that sites are logged after a suitable amount of time has passed, it is possible to harvest trees and maintain diversity.