Winslow D. Hansen

Managing bark beetle impacts on ecosystems and society: priority questions to motivate future research

Summary 1. Recent bark beetle outbreaks in North America and Europe have impacted forested landscapes and the provisioning of critical ecosystem services. The scale and intensity of many recent outbreaks are widely believed to be unprecedented. 2. The effects of bark beetle outbreaks on ecosystems are often measured in terms of area affected, host tree mortality rates, and alterations to forest structure and composition. 3. Impacts to human systems focus on changes in property valuation, infrastructure damage from falling trees, landscape aesthetics, and the quality and quantity of timber and water resources. 4. To advance our understanding of bark beetle impacts, we assembled a team of ecologists, land managers and social scientists to participate in a research prioritization workshop. 5. Synthesis and applications. We identified 25 key questions by using an established methodology to identify priorities for research into the impacts of bark beetles. Our efforts emphasize the need to improve outbreak monitoring and detection, educate the public on the ecological role of bark beetles, and develop integrated metrics that facilitate comparison of ecosystem services across sites.

Generalizable principles for ecosystem stewardship-based management of social-ecological systems: lessons learned from Alaska

Human pressure could compromise the provision of ecosystem services if we do not implement strategies such as ecosystem stewardship to foster sustainable trajectories. Barriers to managing systems based on ecosystem stewardship principles are pervasive, including institutional constraints and uncertain system dynamics. However, solutions to help managers overcome these barriers are less common. How can we better integrate ecosystem stewardship into natural resource management practices? I draw on examples from the literature and two broadly applicable case studies from Alaska to suggest some generalizable principles that can help managers redirect how people use and view ecosystems. These include (1) accounting for both people and ecosystems in management actions; (2) considering historical and current system dynamics, but managing flexibly for the future; (3) identifying interactions between organizational, temporal, and spatial scales; (4) embracing multiple causes in addition to multiple objectives; and (5) acknowledging that there are no panaceas and that success will be incremental. I also identify next steps to rigorously evaluate the broad utility of these principles and quickly move principles from theory to application. The findings of this study suggest that natural resource managers are poised to overcome the barriers to implementing ecosystem stewardship and to develop innovative adaptations to social- ecological problems.

Social and Ecological Determinants of Land Clearing in the Brazilian Amazon: A Spatial Analysis

While tropical land clearing provides for the livelihoods of Brazilians from many socioeconomic backgrounds, it also affects climatological and ecological processes. To develop sustainable forest use, further study is needed to investigate the causes of tropical land clearing. This study uses spatial econometric techniques to estimate the effects of ecosystem productivity, measured by soil fertility and climate, and strategic interactions on municipal-level land clearing in the Brazilian Legal Amazon between 1975 and 1995. We find a negative relationship between soil fertility and land clearing. Furthermore, there is evidence of positive spatial interactions across municipalities. (JEL C31, Q24)

Meeting Indigenous Subsistence Needs: The Case for Prey Switching in Rural Alaska

Identifying coping strategies that Alaskan subsistence hunters use while responding to adverse conditions provides insights into their capacity to sustain traditional livelihoods. Previous qualitative research has suggested that subsistence hunters switch prey to cope with fluctuations in the availability of subsistence resources. We developed and quantitatively tested a predictive framework assessing whether 19 rural Alaskan communities used this strategy. We found, between 1993 and 2004, these communities rarely substituted one resource for another. Our lack of evidence for prey switching may reflect other complicating factors such as greater availability of groceries and increased formal employment opportunities. These results highlight the need for improved data collection on harvests, hunter effort, and socioeconomic characteristics to inform comprehensive models. Our findings characterize subsistence hunting systems in rural Alaska, providing regulatory agencies with a greater understanding of the systems they manage. This may facilitate more flexible management that balances conservation concerns with rural livelihoods.