Quantifying Risk of Tree Species Regeneration Failure and Ecosystem Transitions in Lower Elevation Forests

University Of Montana, Missoula MT

Investigators

Abstract

Ecological disturbances have the potential of causing transitions of low-elevation forests into other ecosystem types, consequently altering the position of lower treelines. Small shifts in these lower treelines can result in large changes in forested area, which will have profound ecological and economic impacts for society. These ecosystems already are experiencing dramatic changes due to widespread disturbance and climate-driven mortality with long-term implications for ecosystem services including water management, carbon stocks, and maintenance of connectivity for wildlife species. This research project will provide new perspectives, information, insights and approaches to advance basic understanding about the processes that maintain low-elevation forests and improve capabilities to forecast where and under what conditions these forests may be lost. The project will provide critical information for identifying vulnerable low-elevation forested regions, including those in the wildland-urban interface. The findings will provide a novel but tractable means of quantifying risk of regeneration failure and ecosystem transition in lower-elevation forests to guide future land use and management priorities in the wildland-urban interface of the western U.S. Project results will provide valuable information and insights for policy makers, governmental agencies, and resource administrators in assessing appropriate courses of action to minimize socio-economic and ecological impacts. Ecosystem transitions at lower elevation forests can occur because of both mortality of adult trees and regeneration failure after disturbance. Increases in temperature and the frequency of drought may prevent seedling regeneration at sites that adult trees can generally tolerate. The investigators will explore answers to the core question of how climate and ecological disturbances impact tree species emergence and regeneration in lower-elevation forests. They will identify regions prone to regeneration failure by linking fine-scaled physiological greenhouse studies to broad-scale observational data of species regeneration patterns as mediated through local and regional climate and hydrology models. It will assess geographic patterns in the demography of lower treelines by using forest inventory data, and mechanistic and correlative niche models of species distributions. The investigators will identify vulnerable areas for active management and improve basic understanding of processes governing the distribution of lower-treeline forests by bridging the disciplines of biogeography, biophysical ecology, and ecohydrology.