Ecological resilience and complexity: A theoretical framework for understanding and managing British Columbia's forest ecosystem in a changing climate

At global, regional, and local scales, forest managers are faced with unprecedented pressures to supply forest resources for human consumption while still maintaining a diverse array of other ecosystem services essential to human well-being. While this alone has posed major challenges to forest management, global climate change presents a new range of daunting challenges. The potential for major ecosystem changes as well as uncertainties about the degree and rate of climate change necessitates a major shift in thinking about forest management. Recent scientific literature proposes new approaches to forest management that focus on “managing for ecological resilience,” with the idea that it provides a tenable framework for achieving sustainability goals when environments are changing and the future is uncertain. The concept of ecological resilience has been used to guide the management of ecosystems degraded by human land use activities, and managing for resilience is a commonly discussed approach for countering the negative impacts of climate change. This document summarizes the theoretical literature on ecological resilience and complexity, and describes how this evolving body of science can begin to guide the management of forest ecosystems in a changing climate. Ecological resilience describes the capacity of ecosystems to absorb disturbance without collapsing into a qualitatively different state. While research is still under way to develop a structured understanding of the mechanisms regulating ecological resilience, scientists propose that key ecological processes, operating across varying scales of time and space (e.g., seedling survivorship, forest succession, periodic natural disturbances, propagule dispersal that facilitates species range shifts), generate the complexity needed to maintain ecosystem resilience to environmental change. Maintaining and enhancing biological diversity across multiple scales may play an important role in preserving ecosystem services if it generates redundancy in the ecological processes that confer ecological resilience (i.e., conserves key ecosystem functions). Adapting forest management frameworks to climate change involves actions that minimize the risk of adverse climate-change impacts and capitalize on its benefits. Managing for resilience advocates diverse and novel actions that help cope with uncertainties about future forest conditions and reduce both societal and ecological vulnerabilities to climate change. While societal adaptations to climate change include the development of policies to encourage adaptation, modifying wood processing technologies, and revising expectations of resource use and conservation objectives, management to maintain ecological resilience involves deliberate, on-the-ground forest practices that maintain ecosystem complexity across multiple scales of time and space, and facilitate gradual ecosystem change in response to climate change. In this report, we present some examples of the kinds of on-the-ground actions that could be undertaken to begin the process of managing for ecological resilience to climate change. They include: facilitating tree species (and population) migration and range shifts; developing forest harvest, regeneration, and stand-tending activities that maintain or enhance ecosystem complexity and response diversity to environmental change, such as the forest structures generated by past disturbance regimes; planting broader mixesof trees across landscapes to help reset successional trajectories; promoting landscape connectivity; and retaining or restoring areas that may be buffered against climate change. Managing for ecological resilience is in its infancy and the technical details about how to implement this new approach to forest management will depend on ecosystem type and evolve as the science integrating resilience, complexity, and biodiversity evolves and more information about the impacts of climate change on ecosystems becomes available through field monitoring programs and quantitative modelling research. Resilience-based ecosystem management, especially when it takes into account changing climate conditions, represents a profound shift in the way the Ministry of Forests and Range will approach how forest ecosystems are managed, and poses challenges to many existing practices and policies in British Columbia. Involving a more diverse array of forest practices than traditional forest management approaches, it will require setting landscape-level management objectives for desired future forest conditions and making decisions regarding how to cope with unexpected and undesirable management outcomes. Transitioning to resilience-based ecosystem management also requires an understanding of complex ecological and social feedbacks, but an awareness of this, and an openness to work with complexity scientists, forest ecologists, climatologists, forest geneticists, and others can help to make this transition.