LTER: Interaction of Multiple Disturbances with Climate in Alaskan Boreal Forests

The Bonanza Creek Long-Term Ecological Research program focuses on improving our understanding of the long-term consequences of changing climate and disturbance regimes on boreal forests. The overall objective is to determine the major controls over forest dynamics, biogeochemistry, and disturbances and how these factors interact in the face of a changing climate. The forest dynamics theme addresses successional changes in biotic populations and communities following disturbance, emphasizing the relative importance of historical legacies, stochastic processes, and species effects in determining successional trajectories and the sensitivity of the trajectories to climate. Changes in the carbon cycle during succession hinge on changes in forest dynamics and other element cycles, but also influence nutrient availability and microenvironment and therefore successional changes in forest dynamics. Regional and landscape controls over disturbance regimes focus on processes that are responsible for the timing, extent, and severity of disturbances. Our research design uses experiments and observations at intensive sites in three successional sequences (floodplains, south-aspect uplands, north-aspect uplands) to document the processes that drive successional change. We will establish the larger context for these intensive studies by studying two large regions, a relatively uniform region in interior Alaska and along a climate gradient from the warmest to the coldest areas in Alaska. Through synthesis we will address three important ecological issues. (1) How do species characteristics and diversity influence biogeochemistry and disturbance regime within ecosystems and landscapes? (2) How can we conceptualize spatial and temporal scaling as the basis for linking processes and patterns from ecosystems across landscapes? (3) How do positive and negative feedbacks that operate within ecosystems influence the sensitivity of ecosystems (i.e., their sustainability) to perturbations, such as changes in climate and disturbance regime?