Spatial and Temporal Dynamics of Disturbance Within and Between Forest Regions of the U.S.

Abstract

Forest disturbances play a critical role in shaping forest structure and influencing the ecosystem services that forests provide. However, the rates, patterns and consequences of disturbance remain largely uncertain. How do disturbance rates vary within and between regions and how vulnerable are forests to changes in disturbance? This research takes a tiered approach to quantifying the spatial and temporal patterns and impacts of disturbance within and between diverse forested landscapes of the contiguous U.S. First an intraregional characterization of the patterns and process of disturbance, as captured by over a quarter century of Landsat imagery was performed over the highly forested northeastern state, New Hampshire U.S. Next an inter- regional comparison of disturbance rates, trends and size distributions were conducted across three regions representing diverse forested landscapes in the U.S. with different dominant disturbance regimes. Finally, a framework was developed to assess the vulnerability of forested ecosystems to disturbance and how vulnerability

may change in the future. Results showed that disturbance is not homogenous but varies both spatially and temporally within and between regions. Further ecosystem vulnerability to disturbance varies strongly across the U.S., with western forests generally exhibiting greater sensitivity and vulnerability to disturbance under current climates. Under a potential climate scenario, the majority of U.S. forest area was estimated to increase in resiliency to disturbance, which may buffer some of the impact of intensified forest disturbance. The challenge and opportunities going forward is to continue to quantify and integrate the complex rates, patterns and processes of disturbance into ecosystem models and field study designs that link impact assessment of changes to ecosystem function and services.