Browsing by Author "Theobald, David M."

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Framework for Evaluating Land Use Planning Alternatives: Protecting Biodiversity on Private Land
(2002) Theobald, David M.; Hobbs, N. Thompson
"Planning activities by local government often seek to identify areas of land that offer particularly high value for conserving biotic resources. Because private land is being developed rapidly, there is heightened concern about identifying these areas. Although general principles on setting priorities for habitat protection are emerging, substantial ambiguity remains about how to implement these principles. Here, we offer a general modeling framework for evaluating how planning alternatives could affect Critical Habitat. The framework contains four components: stakeholder involvement, spatial modeling of Critical Habitat and development patterns, analysis of alternative scenarios, and evaluation and monitoring. We illustrate this approach using a case study from Summit County, Colorado, USA."
Landscape Patterns of Exurban Growth in the USA from 1980 to 2020
(2005) Theobald, David M.
"In the United States, citizens, policy makers, and natural resource managers alike have become concerned about urban sprawl, both locally and nationally. Most assessments of sprawl, or undesired growth patterns, have focused on quantifying land-use changes in urban and metropolitan areas. It is critical for ecologists to examine and improve understanding of land-use changes beyond the urban fringe-also called exurban sprawl-because of the extensive and widespread changes that are occurring, and which often are located adjacent to or nearby 'protected' lands. "The primary goal of this paper is to describe the development of a nationwide, fine-grained database of historical, current, and forecasted housing density, which enables these changes to be quantified as a foundation for inference of possible ecological effects. Forecasted patterns were generated by the Spatially Explicit Regional Growth Model, which relates historical growth patterns with accessibility to urban and protected lands. Secondary goals are to report briefly on the status and trend of exurban land-use changes across the U.S., and to introduce a landscape sprawl metric that captures patterns of land-use change. In 2000, there were 125 729 km2 in urban and suburban (<0.68 ha per unit) residential housing density nationwide (coterminous USA), but there were slightly over seven times that (917 090 km2) in exurban housing density (0.68-16.18 ha per unit). The developed footprint has grown from 10.1% to 13.3% (1980 to 2000), roughly at a rate of 1.60% per year. This rate of land development outpaced the population growth rate (1.18% per year) by 25%. Based on model forecasts, urban and suburban housing densities will expand to 2.2% by 2020, whereas exurban development will expand to 14.3%."
Note on Creating Robust Resistance Surfaces for Computing Functional Landscape Connectivity: A response to: Rothley. 2005. 'Finding and Filling the 'Cracks' In Resistance Surfaces for Least-Cost Modeling'
(2005) Theobald, David M.
From introduction: "I agree with Rothley and others that these cracks are potentially problematic for landscape connectivity analyses, and I join them in cautioning conservation scientists to create valid models when generating spatial data inputs to cost-weighted analyses. However, I disagree as to the cause and the ubiquity of these cracks. I also provide a few additional procedures that will eliminate potential problems resulting from the misspecification of resistance surfaces and minimize possible additional artifacts arising from any correction processes. This note is intended to continue the important discussion about developing useful methods for computing functional landscape connectivity."