Climate Warming, Changing Disturbance Regimes, and Forest Resilience
Wednesday, August 13, 2014: 1:30 PM-5:00 PM
203, Sacramento Convention Center
Jill F. Johnstone
Monica G. Turner
Jill F. Johnstone
The frequency, severity, and extent of natural disturbances are changing profoundly as climate continues to warm, and these changes pose serious challenges to scientists, land managers, and society. How forest ecosystems will respond to novel disturbance regimes interacting with warmer climate is poorly understood but incredibly important to anticipate. Observations of past forest change and predictions from ecological theory suggest that, against a backdrop of changing environmental conditions, disturbances can trigger rapid change in forest ecosystems. Novel disturbance regimes may disrupt forest ecosystems and the processes that maintain them, and initiate new pathways of change by affecting post-disturbance community assembly and succession. Furthermore, changes to one disturbance regime may alter the likelihood or severity of another (i.e., linked disturbances) or produce compound disturbances that alter ecosystem resilience (i.e., the capacity of the system to recover following disturbance). The combination of changing climate conditions, altered disturbance regimes, and sensitivity of successional pathways to initial conditions creates a strong potential for rapid and non-linear shifts in forest ecosystem states. The aim of this session is to explore the mechanisms, dynamics, and implications of disturbance-mediated changes in forest resilience across different forest ecosystems. Presentations will tackle questions such as: What is the role of climate change in altering disturbance regimes and post-disturbance ecosystem recovery? How do disturbances interact across forest landscapes? What are the key thresholds, non-linearities, or leverage points in forest system dynamics? Under what conditions do disturbances trigger state changes in forest ecosystems? Examples will be drawn from a range of forests with an emphasis on northern and temperate forests of North America. We aim to identify commonalities that may lead to a more explicit framework for anticipating and managing forest state changes likely to occur with continued climate warming. The set of presentations will begin with an overview of disturbance dynamics and climate change, followed by presentations that address complementary topics that explore the nature of changing disturbance regimes, altered successional trajectories, and mechanisms that may underpin qualitative changes in forest landscapes. The session will conclude with perspectives on how our understanding of forest responses to changing disturbance regimes should influence our strategies of forest management. As the evidence for changing disturbance regimes accumulates around the globe, it is timely and important for us to consider how we can best anticipate the potentially dramatic impacts on forest ecosystems.