Housing development is eroding the value of protected lands

Natural areas such as National Forests and National parks are highly desirable locations for housing development. Unfortunately, this development can degrade the ability of the natural areas to protect their resources. Dr. Eric Wood has found that development in and around natural areas leads to declines in avian species of greatest conservation concern and increases in synanthropic avian species.

Many people - including many ecologists - dream of a home or cabin in the wilderness as an escape from urban life. The downside of this dream is strong development pressure on inholdings and along the boundaries of National Forests, National Parks, and other protected areas. Is it possible that the appeal of these areas is leading to the degradation of the resources they were designed to protect? Eric Wood, a postdoctoral researcher in the SILVIS lab is considering just this question. 'Housing growth inside and on the boundaries of protected areas has dramatically increased over the last half-century or so. We really have no idea what that is doing to biodiversity within the protected area', notes Eric. In order investigate this question, he is comparing the composition of bird communities within, on the boundaries of, and outside of protected areas, and relating this community composition to the level of development. Eric's research is showing two different stories, one in the western United States, and one in the East.. 'Housing [density] adjacent to protected areas is highest in the east', said Eric (Fig. 2).


Wood's study design and maps of housing density throughout the United States from 1970 to 2010.
From 1970 to -2010, Eric found a strong negative correlation between housing in inholdings and abundance of species of greatest conservation need (SGNC) and land cover affiliates (e.g., species associated with the dominant land cover of a BBS route - such as forest breeders in forested regions) in three of four regions of the United States (Fig. 3). Synanthropes, species closely associated with human development, showed a strong positive relationship with inholding development in these same regions (Fig. 3).


Relationship (regression coefficient) of housing density and the proportional abundance of species of greatest conservation need (SGCN), land cover affiliates (e.g. forest breeders in forested regions, etc.), and synanthropes in four regions of the United States from 1970 to 2010.
Eric also found that housing development along the boundaries of protected areas had a negative effect on SGCNs and no effect on synanthropes within the protected area. This appears to show that synanthropes are mostly affected by development patterns locally, while SGCNs are influenced by land use both locally and over very broad areas. Eric's analysis shows that in the western United States, the relationships between housing developments and birds are similar, but much weaker in strength (Fig. 3). This is because, in comparison to the East, housing development in and around protected areas in the West is relatively low. This doesn't mean there is no cause for concern though, as growth rates for development in the West are very high. It seems likely that what has already happened in the eastern United States is now in progress in the West. This means that it is important to keep these effects in mind as development continues. Eric has several suggestions how to remedy this situation. First, non-developed lands outside of high-priority protected areas should remain undeveloped as much as possible. Where there is development, it is possible that better planning, such as concentrating development in fewer, dense clusters may have less impact. Lastly, public land managers must educate nearby landowners through outreach about the risks development poses to natural areas, for example the spread of exotic invasive species or depredation of birds by pet cats. Eric is now using historical sources of bird and land use data to examine how these trends in development and their effects on the bird community have changed over time.
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