Overview of the Use of Natural Variability Concepts in Managing Ecological Systems

Abstract

Natural resource managers have used natural variability concepts since the early 1960s and are increasingly relying on these concepts to maintain biological diversity, to restore ecosystems that have been severely altered, and as benchmarks for assessing anthropogenic change. Management use of natural variability relies on two concepts: that past conditions and processes provide context and guidance for managing ecological systems today, and that disturbance-driven spatial and temporal variability is a vital attribute of nearly all ecological systems. We review the use of these concepts for managing ecological systems and landscapes.We conclude that natural variability concepts provide a framework for improved understanding of ecological systems and the changes occurring in these systems, as well as for evaluating the consequences of proposed management actions. Understanding the history of ecological systems (their past composition and structure, their spatial and temporal variability, and the principal processes that influenced them) helps managers set goals that are more likely to maintain and protect ecological systems and meet the social values desired for an area. Until we significantly improve our understanding of ecological systems, this knowledge of past ecosystem functioning is also one of the best means for predicting impacts to ecological systems today.These concepts can also be misused. No a priori time period or spatial extent should be used in defining natural variability. Specific goals, site-specific field data, inferences derived from data collected elsewhere, simulation models, and explicitly stated value judgment all must drive selection of the relevant time period and spatial extent used in defining natural variability. Natural variability concepts offer an opportunity and a challenge for ecologists to provide relevant information and to collaborate with managers to improve the management of ecological systems.

Lantana camara invasion in a heterogeneous landscape: patterns of spread and correlation with changes in native vegetation

“…Studies that track the long-term response of native community diversity, abundance, evenness, population demography, and relative dominance to invasive species are rare, and valuable (Strayer et al 2006). The principal advantage of long-term studies is that they do not require making assumptions about the past condition of a site, unlike studies that substitute space for time (Johnson and Miyanishi 2008;Landres et al 1999). However, the frequency of monitoring confounding site conditions such as disturbance, determines the quality of data collected through long-term observations.…”

The Role of Paleoecology in Restoration and Resource Management—The Past As a Guide to Future Decision-Making: Review and Example from the Greater Everglades Ecosystem, U.S.A

“…The role that paleoecology could play in addressing these issues was recognized as scientists and resource managers debated (1) what constitutes an appropriate baseline or reference condition for restoration given the extent of anthropogenic alterations to natural systems; (2) how to account for processes that occur infrequently or very slowly over decadal to centennial timescales and (3) what are the appropriate spatial and temporal scales for understanding ecosystems (Davis, 1989;Swetnam and Betancourt, 1998;Landres et al, 1999;Swetnam et al, 1999;Jackson and Overpeck, 2000;Jackson, 2001;Flessa, 2002). The U.S. National Academy of Sciences Committee on Restoration of Aquatic Ecosystems published a report in 1992 (NRC, 1992) that discussed the need for baseline studies and identified paleoecology as a method for obtaining information on the historic condition of ecosystems.…”

“…The U.S. National Academy of Sciences Committee on Restoration of Aquatic Ecosystems published a report in 1992 (NRC, 1992) that discussed the need for baseline studies and identified paleoecology as a method for obtaining information on the historic condition of ecosystems. By the end of the 1990s, the value of historical information on ecosystem variability and the use of paleoecology to obtain this information were increasingly recognized as essential components in resource management decisions (Landres et al, 1999;Millar and Woolfenden, 1999;Parsons et al, 1999;Swetnam et al, 1999).…”

Perspectives on biogeomorphology, ecosystem engineering and self-organisation in island-braided fluvial ecosystems

“…It is also recognised that the failure to maintain the diversity of natural processes has been a major cause of ecosystem degradation (Landres et al, 1999;Francis, 2009). For instance, attempts to control the natural variability of fluvial ecosystems inevitably lead to ecosystem degradation, and often pose a substantial risk to humans (for example the many problems associated with the management and prediction of flood risks; Apel et al, 2004).…”