Browsing by Author "Duncan, Sally L."

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Ecological History vs. Social Expectations: Managing Aquatic Ecosystems
(2009) Reeves, Gordon H.; Duncan, Sally L.
"The emerging perspective of ecosystems as both non-equilibrium and dynamic fits aquatic ecosystems as well as terrestrial systems. It is increasingly recognized that watersheds historically passed through different conditions over time. Habitat conditions varied in quantity and quality, primarily as a function of the time since the last major disturbance and the legacy of that disturbance. Thus, to match the effects of historical processes, we would expect a variety of conditions to exist across the watersheds in a region at any time. Additionally, watersheds have different potentials to provide habitat for given fish species because of variation in physical features. This developing ecological understanding is often preempted by social desires to bring all watersheds to a 'healthy' condition, which in turn is reflected in a common regulatory approach mandating a single condition as the long-term goal for all watersheds. Matching perceptions and regulations to the way aquatic systems actually change and evolve through time will be a major challenge in the future."
Integrating Ecological and Social Ranges of Variability in Conservation of Biodiversity: Past, Present, and Future
(2010) Duncan, Sally L.; McComb, Brenda C.; Johnson, K. Norman
"Historical range of variability has been proposed as a concept that can be used by forest land managers to guide conservation of ecosystem functions and biodiversity conservation. The role of humans in historical range of variability has remained somewhat murky and unsettled, even though it is clear that humans have been, are, and will continue to be forces of disturbance and recovery in forested landscapes. We attempt to develop concepts that integrate the ecological and social forces affecting landscape variability. Toward that end, we present a conceptual framework that places 'range of variability' into a broader context and integrates the ecological and social forces affecting landscapes past, present, and future. We use two terms to aid us in understanding the utility of historical range of variability as a context and future range of variability as a point of comparison: (1) the ecological range of variability is the estimated range of some ecological condition as a function of the biophysical and social forces affecting the area and (2) the social range of variability is the range of an ecological condition that society finds acceptable at a given time. We find it is important to recognize that future range of variability represents a constantly emerging and changing set of conditions, and that the more humans push a system to depart from its historical range of variability domain,the less likely it becomes that historical range of variability processes will prove useful as benchmarks in recovering a system."
Is there Potential for the Historical Range of Variability to Guide Conservation Given the Social Range of Variability?
(2009) Thompson, Jonathan R.; Duncan, Sally L.; Johnson, K. Norman
"Using the historical range of forest conditions as a reference for managing landscapes has been proposed as a coarse-filter approach to biodiversity conservation. By emulating historical disturbance processes, it is thought that forest management can produce forest composition and structure similar to the conditions that once supported the native biota. A recent project was designed to integrate social and ecological findings to investigate the important relationships between the state of ecological understanding of a region, the state of the region's biodiversity, and the state of the region's social understanding of how it might be managed for biodiversity conservation into the future. The project relied on established concepts of the historical range of variability (HRV) and developed the concept of the social range of variability to help explain the interaction of social and ecological assessments, particularly their interaction to create future ranges of variability. The Oregon Coast Range, where a rich history of HRV research has been completed starting with paleoecological reconstructions of the historical fire regime, was one of five sites in the United States that were selected as case studies. We found land development and impending climate change to be major hurdles impeding the use of the HRV as a management regime. We also found that the complexities and uncertainties of management preclude the use of any single tool to tackle landscape-scale challenges and suggest that land management needs to become a continuous process of negotiation."
The Past and Future of Colorado's Forests: Connecting People and Ecology
(2009) Binkley, Dan; Duncan, Sally L.
"The future composition, structure, and dynamics of forests in Colorado will develop in response to both ecological and social factors. Key ecological factors that shaped forests in the past included a great diversity of climatic conditions that results from complex topography and a broad range of elevations, as well as legacies of long-term climate changes and responses of plant and animal species. The influence of direct and indirect human impacts has steadily increased over the past two centuries, changing most forests. A workshop examined how goals of sustaining ecosystems and biodiversity will depend on a confluence of ecological and social changes. Key themes from the workshop included an acknowledgment that the sheer complexity of factors and interactions will limit our ability to shape the future, and that effective combinations of ecology and societies will depend in large part on the use of creative narratives that allow us to communicate productively among people with incredibly different knowledge and perspectives. These insights from Colorado’s forest landscapes and communities will likely resonate with other regions."
Range of Variability in Southern Coastal Plain Forests: Its Historical, Contemporary, and Future Role in Sustaining Biodiversity
(2009) Mitchell, Robert J.; Duncan, Sally L.
"Historical range of variation (HRV) has been used as a conceptual tool to determine appropriate management actions to sustain or restore diversity of ecological systems. This concept has come into question for both biological and social considerations, and the southeastern United States is a good model system to test its utility. Southeastern Coastal Plain upland pine savannas and woodlands and their associated wetlands are among the most diverse communities in temperate North America, having both high levels of species richness and large numbers of endemic flora and fauna. However, this diversity is intimately linked with disturbance regimes. Maintaining frequent fire, varied in season based on changing management objectives through time, is the most important management tool for sustaining biodiversity. Moreover, the landscape has been molded by a long history of intense land use that has altered both the biological and the social landscape in which management occurs, and threatens the native diversity. Management must anticipate likely trends and adopt strategies that provide flexibility for managers to deal with the future, both socially and ecologically. In the Southeast, the most dominant trend is associated with urbanization and forest fragmentation, which results from urban sprawl. This issue joins others fire and smoke, logging, access, in-holdings, and the uncertainty of scientific models, for example as matters of major concern to the public. Ultimately, it is the public that eventually grants or withholds social permission to manage. We explore, here, the potential and the limitations for how history can inform future management. Rather than being used as a specific management tool, we find that one purpose for which HRV may be well suited is serving as a broad communication framework to help diverse publics understand the concept of landscape dynamics. This approach would provide the fundamental background material for stakeholders to understand how ecological conditions and social acceptability interact through time to mold and constrain future possible ranges of variability."