Effects of disturbance frequency, species traits and resprouting on directional succession in an individual-based model of forest dynamics

Background/Question/Methods Succession theory focuses on the position of species along the shade-tolerance gradient and their ability to colonize recently disturbed patches and has for decades overlooked resprouting as a key trait in community patterns. We study how different species traits interact with disturbance frequency to change species dominance in the canopy, focusing on the effects of resprouting ability. We develop an individual-based model that simulates the dynamics of three species – paper birch, white pine and sugar maple, characterized by different successional strategies, as observed in northern Minnesota forests. We test (i) how different disturbance frequencies, (ii) sugar maple resprouting, and (iii) paper birch resprouting change successional patterns. Results/Conclusions We show that three disturbance frequency classes produce three different outcomes, each dominated by a different species, with lower disturbance frequency favoring later successional species. The importance of resprouting ability on success in the canopy depends on the species' other life-strategy traits. Sugar maple is able to dominate the community at all disturbance frequencies when resprouting, whereas the inclusion of resprouting for paper birch does not change the successional patterns. White pine is indirectly favored by sugar maple's resprouting ability, excluding paper birch from the community at disturbance frequencies that would see paper birch dominance in the absence of resprouting. Our results confirm the recent interest of taking into account resprouting, as it can bend succession directionality, and thus change community composition in response to disturbance. This has wide consequences for predicting forest diversity patterns, as well as invasion phenomena in a changing world.