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Trees cast shade on homes and buildings, lowering the inside temperatures and thus reducing demand for power to cool these buildings during hot times of the year. Drawing from a large sample of residences in Auburn, Alabama, we develop a statistical model that produces specific estimates of the electricity savings generated by shade-producing trees in a suburban environment. This empirical model links residential energy consumption during peak summer (winter) months to average energy consumption during non-summer/non-winter months, behaviors of the occupants, and the extent, density, and timing of shade cast on the structures. Our estimates reveal that tree shade generally is associated with reduced (increased) electricity consumption in the summertime (wintertime). In summertime, energy savings are maximized by having dense shade. In wintertime, energy consumption increases as shade percentage in the morning, when outdoor temperatures are at their lowest, increases. [Copyright &y& Elsevier]

Abstract: We explore the consequences of including both general and specific controls for spatial autocorrelation in country-level models of species imperilment. A general spatial autocorrelation term constructed as a binary contiguity matrix aggregates an unknown number of possible influences, some of which exert a negative impact on species imperilment in the referent country, others of which exert a positive impact. Adding spatial dependency measures that are based on specific cross-border effects can substantially change not only the size and statistical significance of the general spatial dependency term but also the size, sign, and/or statistical significance of the explanatory variables. [Copyright &y& Elsevier]

Abstract: Modeling the determinants of species'' ecological fragility using country-specific data may be complicated by the fact that factors that influence species imperilment may extend or operate beyond arbitrary political boundaries. Following McPherson and Nieswiadomy [McPherson, M.A. and Nieswiadomy, M.L., 2005. Environmental Kuznets curve: threatened species and spatial effects. Ecol. Econ. 55: 395–407.], we confirm the advisability of controlling for spatial autocorrelation in models focusing on imperilment of birds, mammals, reptiles, amphibians, and vascular plants. We also compare the performance of different definitions of the spatial dependency. Although our a priori expectation was that measures that more accurately reflect the degree of spatial interaction between countries, such as the percentage of shared border, would be superior to a measure of simple adjacency, in fact we find that the simple adjacency measure outperforms the other measures in most cases. [Copyright &y& Elsevier]

Using the Environmental Scorecard ratings of Congressmen and Senators published annually by the League of Conservation Voters, we explore empirically whether political support for pro-environment legislation, aggregated across each legislative body, is sensitive over time to changing economic conditions — that is, whether there is a political trade-off between economic conditions and the environment. Using LCV scorecard ratings from 1970 to 2008, we find evidence, consistent across both the House and Senate, that political support for the environment is related to per capita income, but this general tendency can be decomposed into sharp differences by party. [Copyright &y& Elsevier]