Assessing Threats to Biodiversity
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
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