Forests in a changing climate [electronic resource] : social and ecological responses to yellow-cedar decline in the Alexander Archipelago, Alaska

Forest mortality related to climatic stress is expected to increase in future decades as a result of climate change. These dieback events can have cascading effects, affecting forest structure and community composition over time, as well as the ecosystem services that these forests provide to people. They often occur across land designations, posing challenges to resource managers and conservation planners to meet objectives for sustaining a population and the many uses and values people derive from forests. To understand the fine-scale, human-environment interactions that shape adaptation to the impacts of climate change, this dissertation addresses the following question: "What are the social and ecological responses to yellow-cedar decline, and how does the social-ecological system adapt?" This research centers on yellow-cedar (Callitropsis nootkatensis), a tree species experiencing widespread mortality associated with climate change in the Alexander Archipelago, Alaska. To date, adaptation has primarily focused on the adjustments in natural or human systems, but this dissertation highlights the fact that individuals (both members of the human and ecological communities) collectively construct a system response through their interactions as well as their abilities to exploit new opportunities and cope with losses. The first chapter focuses on understanding how forests affected by yellow-cedar decline develop over time. Fifty plots were established in remote forests to make comparisons in forest structure and community composition between healthy forests and forests affected by the dieback at different time points. Findings indicate a turnover from yellow-cedar to western hemlock (Tsuga heterophylla) dominated forests, an increase in functional plant diversity, and significant changes in the community composition of the understory. The observed temporal variations in regeneration, as well as changes in understory and overstory composition, emphasize the importance of considering the long-term effects of a species dieback associated with climate change. My findings suggest that directional ecological changes may not be unidirectional when taking into account a diversity of perspectives on ecosystem services. How people use and value the services forests provide, from material uses to intangible values, are also important factors in interpreting impacts of widespread forest mortality in the human dimension. The second chapter examines the social responses to the dieback through semi-structured interviews. It focuses on how knowledge of the dieback, attitudes about impacts occurring, and the use values that people derive from these forests were related to adaptive responses adopted by local forest users and managers. Knowing the dieback was associated with climate change led forest users to different forms of adaptation. Findings indicate that adaptation can occur from the bottom up as individual users and managers adapt their behaviors and practices in advance of policies. This research shows that managers and users may develop new ways of benefitting from the emerging ecosystem dynamics and adopt psychological forms of adaptation in response to the impacted system. Decision-making processes in resource management and conservation may need to evolve to adequately consider the diversity of direct uses, intangible values, and psychosocial factors affected by climate-related impacts occurring on both managed and protected lands. The third chapter links assessment of the current ecological condition of yellow-cedar and its future vulnerability in Glacier Bay National Park and Preserve to the perspectives held by resource managers and users on adaptive practices in protected areas and on actively managed lands. The interdisciplinary approach reveals: 1) a set of socially-feasible future adaptation strategies; 2) system-specific metrics that could better connect local ecological monitoring with management practices; and 3) the underlying views of protected areas and values that influence perspectives on adaptive management. This chapter provides a social-ecological framework to be used as a guiding tool for assessing when, where, and how to adapt practices in other systems experiencing climate change impacts across land designations.

Advisor: Dirzo Rodolfo primary advisor. Thesis advisor
Lambin Eric F. primary advisor. Thesis advisor
Ardoin Nicole M. (Nicole Michele) advisor. Thesis advisor
Hennon Paul E. advisor. Thesis advisor
O'Hara Kevin L. (Kevin Laughlin)