Nathaniel E Roth

Assessing Ecological Condition, Vulnerability, and Restorability of a Conservation Network Under Alternative Urban Growth Policies

ABSTRACT: Landscape connectivity is vital to the ecological health of many landscapes, and identification of linkages in working landscapes that are somewhat, but not irreversibly, degraded is needed. Assessment of the current ecological condition of habitat linkages can be used to determine appropriate management activities, including restoration. Forecasting the future ecological condition of identified linkages under multiple human-use scenarios can identify future patterns of vulnerability and degradation, and thus aid in prioritization of conservation and restoration actions. We forecast the ecological condition of a modeled conservation network of cores and habitat linkages in the San Joaquin Valley, California, a highly developed agricultural area. We assessed current and projected future impacts from modeled urban growth representing seven regional urban growth policy scenarios to determine conservation and restoration priorities. We characterized current ecological condition of the linkages using a clustering algorithm that compared vegetation type, length, and major road and canal crossings. The modeled urban growth forecasts were overlaid on the ecological network to identify expected impacts. A threat index was calculated for individual network components and for component clusters, and revealed significant impact differences between the various urban growth scenarios. The linkages most threatened by urban conversion were those that are currently the most ecologically degraded, suggesting that a significant future conservation issue in this working landscape will be the loss of restoration opportunities rather than loss of intact wildlife linkages. This study presents an approach for incorporating regional conservation design with urban growth policy analysis for working landscapes.

Adapting Travel Models and Urban Models to Forecast Greenhouse Gases in California

This paper reviews the California Global Warming Solutions Act, which motivates both urban modeling by countywide agencies and the modeling of energy use in buildings and travel and the resultant greenhouse gases (GHGs). The authors identify principles for urban models and travel models, as applied to countywide land use plans and transportation plans. Two urban models, UPlan (a simple one) and PECAS (a complex one) were developed by the authors and are outlined here. The energy use and GHG impacts calculator, which will take as an input floor space data from UPlan or PECAS, is described. The methods used in this calculator and how it will be applied within the two urban models are described. The UPlan implementation is described in detail and an example given. Finally, the limits of UPlan are identified and an explanation for how PECAS may be able to perform all of the economic evaluations called for in the California Climate Act is provided.