The Dynamics of Change in Alaska's Boreal Forests: Resilience and Vulnerability in Response to Climate Warming

University Of Alaska Fairbanks Campus, Fairbanks AK

Investigators

Abstract

The cornerstone of the Bonanza Creek (BNZ) LTER research has been the state factor approach, which allows prediction of ecosystem properties based on independent controls such as climate, parent material, topography, potential biota, and time and interactive controls, i.e., processes internal to ecosystems that both affect and respond to ecosystem processes. The intellectual merit of the proposed research involves expansion of this theoretical framework to address processes underlying ecosystem resilience and vulnerability. Our objective is to identify factors that buffer systems from radical changes in structure and functioning (resilience) vs. factors that might precipitate changes to alternative states (vulnerability). This requires an extension beyond the assumptions of steady state dynamics to ask under what conditions changes in drivers might trigger a fundamental change in the nature of boreal ecosystems. The central question of our research is: How are boreal ecosystems responding, both gradually and abruptly, to climate warming, and what new landscape patterns are emerging? We study the dynamics of change in several steps. (1) Climate sensitivity of physical and biological processes to temporal variation in the environment, which defines the limits of resilience to climate change; (2) changes in the successional dynamics caused by changes in climate and disturbance regime, which define the points in the adaptive cycle of disturbance and recovery at which ecosystems are most vulnerable to change; (3) threshold changes that are likely to cause the boreal forest to function in a qualitatively new way and (4) integration and synthesis in which we integrate these modes of climate response across multiple temporal and spatial scales and explore their societal consequences. The research design combines long-term observations, long-term experiments, and process studies to identify ecological changes and to document controls over ecosystem processes and successional dynamics in three landscape units: floodplains, uplands, and wetlands. We test hypotheses about controls over ecosystem dynamics by manipulating selected interactive controls. These plot-level studies are extended to larger spatial scales (watersheds, regions, and the state of Alaska) in a hierarchical research design, using extensive measurements, remote sensing, and modeling. Temporal scales of the research span hours (weather), years (growth, populations), successional cycles (stand-age reconstructions), and millennia (vegetation and climate reconstructions). We explore societal consequences by identifying past and potential future changes in ecosystem services that boreal forests provide both locally (e.g., subsistence resources) and globally (e.g., carbon sequestration). Involvement in LTER cross-site comparisons enables us to understand boreal processes in a broader context. To make this information available and useful to a broader community, we work closely with schools, community outreach programs, the broader scientific community, and resource managers through collaborations, outreach, and webbased data management. Information management emphasizes secure archival of the information we have collected, promotion of its use in synthesis, and development of web-based databases to facilitate its use by the scientific community.