From the text (p. 247)...'Alteration of ecosystem processes is increasingly being recognized as a significant threat to biodiversity. Disruption of fire regimes, for example, affects 14% of listed species. About half of these species are threatened by fire suppression, and the others are vulnerable to controlled or uncontrolled fires. (p. 253) Finally, our analysis of biodiversity threats underscores the serious management challenges that conservationists face in their efforts to save imperiled species. A high proportion of imperiled species is threatened either by fire suppression within their fire-maintained habitats or by the spread of invasive alien species. Both types of threats must be addressed through hands-on management of the habitat, such as pulling up invasive plants and trapping alien animals or using prescribed fire to regenerate early successional habitats. Although the Endangered Species Act prohibits actions that directly harm listed animals and, to a lesser extent, listed plants, it does not require landowners to take affirmative actions to maintain or restore habitats for listed species. Thus, a landowner is not obliged to control alien species, undertake a program of prescribed burning, or do any of the other things that may be absolutely necessary for the long-term survival of a majority of our endangered species. In fact, it may be possible for a landowner to rid himself of an endangered species 'problem' by literally doing nothing and waiting until the habitat is no longer suitable for the species in question.'