DoD Biodiversity Conservation Handbook
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Chapter 2: Understanding Conservation Science; By  Bob Unnasch

Assessing Threats to Biodiversity

Otis Air National Guard

Freshwater pond at Otis Air National Guard Base, Cape Cod, Massachusetts. Military lands often contain extensive wetlands that are protected under state and federal laws. (Photo: Douglas Ripley)

Measurement of threat status has gained increasing attention among practitioners and students of conservation (e.g., Salafsky and Margoluis 1999B, Hockings et al. 2001, Margoluis and Salafsky 2001, Ervin 2002). Clearly, without reduction in the threats to biodiversity, those species and ecosystems that are the focus of conservation efforts will rapidly degrade and disappear. Yet, regardless of its importance, measuring threat status is insufficient on its own, for several reasons. Most significantly, a focus on threat status alone must assume that there is a clear, often linear, relationship between a threat and the ecological condition of biodiversity. This runs counter to recent evidence of the non-linear dynamics of ecosystems and threshold effects (e.g., Scheffer et al. 2001). Secondly, a singular focus on threats can lead to a "zero-tolerance" approach to threat activities in human influenced landscapes. Under most circumstances, this is unrealistic. Thus, it is preferable to link threats assessment to ecological integrity of viability assessments.

Here, a threat is defined as something negatively impacting a key ecological attribute. Conservation and management actions work to abate these impacts. Thus, there is a direct (and, it is hoped, clearly understood) linkage between the actions of the managers working on threats and the benefits to the ecological integrity and viability of targets of biodiversity.

Proceed to Next Section: Regional Conservation Planning

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Bob Unnasch is Senior Conservation Scientist, The Nature Conservancy

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