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Extinction rate estimates for plant populations in revisitation studies: Importance of detectability

Conservation Biology

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Abstract

Many researchers have obtained extinction-rate estimates for plant populations by comparing historical and current records of occurrence. A population that is no longer found is assumed to have gone extinct. Extinction can then be related to characteristics of these populations, such as habitat type, size, or species, to test ideas about what factors may affect extinction. Such studies neglect the fact that a population may be overlooked, however, which may bias estimates of extinction rates upward. In addition, if populations are unequally detectable across groups to be compared, such as habitat type or population size, comparisons become distorted to an unknown degree. To illustrate the problem, I simulated two data sets, assuming a constant extinction rate, in which populations occurred in different habitats or habitats of different size and these factors affected their detectability The conventional analysis implicitly assumed that detectability equalled 1 and used logistic regression to estimate extinction rates. It wrongly identified habitat and population size as factors affecting extinction risk. In contrast, with capture-recapture methods, unbiased estimates of extinction rates were recovered. I argue that capture-recapture methods should be considered more often in estimations of demographic parameters in plant populations and communities.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Extinction rate estimates for plant populations in revisitation studies: Importance of detectability
Series title:
Conservation Biology
Volume
18
Issue:
2
Year Published:
2004
Language:
English
Contributing office(s):
Patuxent Wildlife Research Center
Description:
570-574
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
570
Last page:
574
Number of Pages:
5