Social and ecological aspects of conservation development as a strategy for biodiversity conservation on private lands

Abstract

Private lands harbor a large proportion of the world’s biodiversity, and they are also facing widespread threats from extractive land uses, anthropogenic disturbances, and land conversion for residential and commercial development. With decreased funding and support for public land acquisition and management, developing effective and economically viable tools for conservation on private lands is increasingly important. One method is conservation development (CD), an alternative to residential sprawl designed to decrease negative environmental impacts by clustering houses in a small portion of a property while preserving the remaining land as protected open space. Although CD makes up approximately one-fourth of all of the private lands conserved in the U.S., little research has assessed where and why this tool is implemented, long-term management of CD open space, or specific positive or negative effects on wildlife communities. I conducted a thorough investigation of CD as a private land conservation strategy using a variety of methods. In chapter one, I investigated CD’s ability to successfully protect animal populations by examining bird and mammal occurrence in 14 CD subdivisions (range: 14-432 ha) in Northern Colorado, USA. Using point count and camera trap data in an occupancy modeling framework, I evaluated the relative importance of 9 subdivision design factors (e.g. housing density, proportion of CD preserved, total area of the protected space) and 14 stewardship factors (e.g. mowing, livestock, native vegetation cover) in influencing the richness of human-sensitive and human-adapted species and probability of use by 16 birds and 6 mammals. I found that bird and mammal species richness and habitat use were associated predominantly with design characteristics that maximize the natural or undisturbed land area both within and surrounding the development (e.g., proportion of CD preserved, total area of the protected space, proportion of natural land cover types at large scales). Habitat use by birds was frequently influenced by local habitat composition and quality, and several bird and mammal species had decreased habitat use in areas with increased localized disturbances such as the presence of humans and mowing in the open space. In chapter two, I used Social Network Analysis (SNA) to examine participation of individuals and companies (actors) in CD implementation. Using data gathered from public county records, I quantified actor participation in CD subdivisions in six counties in Colorado, USA. I examined and compared the patterns of actor participation in CDs among counties and identified the individuals and organizations that were most consistently associated with the implementation of CDs within each county. I found that social networks of actor participation in CD differed among counties, and network characteristics varied depending on the population of the county, the total number of CDs in the county, and the total number of actors in the network. My results also showed that the most highly connected actors that were consistently involved in the implementation of many CDs were biological and geological consultants, surveyors, engineers, and planners. In chapter three, I formally assessed the content of management plans and conservation easements for existing CD subdivisions in six Colorado counties. I quantified the proportion of CDs with management documents. I also examined the land uses and stewardship activities that were prohibited, permitted, encouraged or required in the protected open space of existing CDs. I determined which activities and practices were most and least frequently addressed in these documents in order to prioritize strategies to improve CD as an effective private land conservation tool. More than two-thirds (69%) of 302 CDs had documents on file that included guidelines and regulations for the long-term stewardship of the protected land. However, CD management documents rarely mentioned issues relating to wildlife habitat improvement, species-specific monitoring and management, homeowner education, and access to the open space by domestic pets. This research identifies several key design and stewardship factors that influence the conservation value of CD open space for birds and mammals, and the key actors and actor types in CD implementation. These findings can inform the strategies used to communicate recommendations to improve CD effectiveness at achieving conservation objectives. This research also examines the current strengths and weaknesses in the documents that guide stewardship of CD subdivisions. Using these findings, I made recommendations for critical guidelines and regulation that should be included in management documents to attain conservation benefits. By incorporating characteristics that promote the persistence of sensitive animal species on private lands, CDs have strong potential to balance the housing needs of growing human populations with the preservation of diverse and abundant animal communities. With direct application to improving the way that CDs are designed, developed and managed, my findings could enhance the potential of CD to sustain native biodiversity on private lands.