99th ESA Annual Meeting (August 10 -- 15, 2014)

OOS 48

Understanding the Structure and Function of Fire Maintain Ecosystems: Honoring the Research Influences of Dr. Robert Mitchell

Frequent low-intensity fires maintain the structure and function of ecosystems with an evolutionary history of chronic fires whereas fire suppression transforms the structure and modifies the function. Fires burn as much as 4 million km2 globally and release as much as 2-3 Pg of C annually, effecting ecosystem to global carbon dynamics. Fire also influences carbon dynamics by altering the structure of the above- and belowground allocation and investment of plant C due to changes in life form (woody trees and shrubs versus grasses). These structural ecosystem changes lead to functional alteration, such as reduction in C4 carbon fixation. While climate, particularly temperature and moisture, sets limits on the distribution and productivity of the world’s biomes, fire resets systems far from their physiognomic limits. Fire’s impact is fully expressed in humid grasslands and savannas; if fire is suppressed, vegetative structure moves from a C3/C4 savanna to closed canopy shrubland, causing a concomitant loss of biodiversity. Future suppression could extend the global area of closed canopy shrub/forest lands from 27% to 56% and have subsequent consequences on biodiversity. The influence that fire—or the lack of fire—exerts on ecosystem structure and function identifies it as a key management tool to conserve species and regulate ecosystem development. This is true especially of forest management where silviculture and fire are intimately linked through the interaction of spatial and temporal controls on litter production and resulting fire behavior. Understanding the influence of structure and function is a necessity for enhancing our ability to adaptively manage dynamic ecosystem that are maintained by fire. Dr. Robert Mitchell dedicated his life to contributing toward a better understanding and appreciation of the structure and function of ecosystems maintained by fire. The objective of this oral session is to bring together a series of researchers that focus their studies on understanding the structure and function of fire-maintained ecosystems with an emphasis on ecosystem carbon dynamics, resource allocation patterns, restoration leading to enhanced biodiversity, and ecological management practices. Included in this session are a small but representative sample of the numerous students and colleagues fortunate enough to have worked with Bob in his life-long commitment to science, management, policy, and mentoring. Understanding the complex linkages between these fields of ecological study becomes even more important with growing anthropogenic pressures across the globe that may hinder fire management activities and ultimately change the ecosystems that are maintained by fire.