Landscape ecology deals with the patterning of ecosystems in space. Methods are needed to quantify aspects of spatial pattern that can be correlated with ecological processes. The present paper develops three indices of pattern derived from information theory and fractal geometry. Using digitized maps, the indices are calculated for 94 quadrangles covering most of the eastern United States. The indices are shown to be reasonably independent of each other and to capture major features of landscape pattern. One of the indices, the fractal dimension, is shown to be correlated with the degree of human manipulation of the landscape.

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Energy development has been occurring in the intermountain western United States for over a century, yet few studies have attempted to spatially quantify the impacts of this disturbance on native ecosystems. We used temporal remotely sensed data for the Pinedale Anticline Project Area (PAPA) in western Wyoming, a region that has experienced increased natural gas development within the past 10 yr, to quantify the spatiotemporal distribution of Wyoming big sagebrush Artemisia tridentata, natural gas development, and other landcover types. Our analyses included 5 Landsat Thematic Mapper (TM) images of the PAPA over a 22‐yr period (1985–2006). We determined whether Wyoming big sagebrush spatiotemporal patterns were associated with natural gas development or other landcover types. We also developed a footprint model to determine the direct and indirect impacts of natural gas development on the distribution of Wyoming big sagebrush habitats. Over the 22‐yr period, we observed an inverse relationship between the amount of Wyoming big sagebrush habitat and natural gas development. During this time, Wyoming big sagebrush habitat declined linearly at a rate of 0.2% yr−1 (4.5% total net loss), whereas natural gas development increased exponentially at a rate of 20% yr−1 (4800% total net increase). Our evaluation indicated that, by 2006, natural gas development directly impacted 2.7% (1750 ha) of original Wyoming big sagebrush habitat. Indirect impacts, quantified to account for degraded habitat quality, affected as much as 58.5% (assuming 1000‐m buffers) of the original Wyoming big sagebrush habitat. Integrating assessments of the direct and indirect impacts will yield a better elucidation of the overall effects of disturbances on ecosystem function and quality.

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SUMMARYInsect herbivores colonizing cyanogenic and acyanogenic white clover plants were investigated. With the exception of aphids, the herbivores studied were infrequent visitors and failed to discriminate between the two phenotypes. Aphids, however, were two to three times more abundant on acyanogenic than cyanogenic plants. Evidence of visible insect feeding damage was identical for both phenotypes. The evidence suggests that the trait of cyanogenesis confers protection against herbivory by aphids and, possibly, other insects. Such protection would be most important at the seedling stage, but feeding of the insects studied would not lead directly to seedling mortality of either phenotype. Instead, mortality of weakened seedlings may result from other causes later in the season.

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This paper develops a method for studying noninfinitesimal operational units, with the Thunen location and land use model. With constant returns to scale and perfect divisibility of nonland inputs, all operational units would occupy only a point on the landscape. The present model uses increasing returns to scale to generate large operational units, called "plantations," and studies the comparative statics. The setting of the model is an agricultural operation in which some processing of raw crop must be conducted prior to shipment to market. The processing is assumed to have increasing returns to scale.