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Potter Deborah U. Gosz James R. Molles Manuel C. Scuderi Louis A. 《Landscape Ecology》1998,13(4):203-214
Landscape Ecology - We investigated the question “Is there a relationship between seasonality in precipitation and vegetative cover in Pole Canyon, NM?” GIS and statistical methods were... 相似文献
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The feeding preferences and consumption rates of the exotic woodlouse Armadillidium vulgare were measured on litters from the autochthonous Rio Grande cottonwood and the exotic Russian olive. When offered a choice between five litter types (green and shed leaves of Russian olive and cottonwood, and fruits of Russian olive), the isopods consumed more of the exotic plant litter (green leaves and the fruits of Russian olive) than of the autochthonous cottonwood. When offered only one diet, consumption rates of green leaves and fruits of Russian olive were again the highest. Feeding was related with N and C:N ratios of the litter, with highest consumption of diets with low and high C:N ratios and lowest consumption of diets with intermediate C:N ratios. The N content was highest (and C:N ratios lowest) on isopods feeding shed leaves of Russian olive. Growth was not related to the amount or the C:N ratio of the food consumed, being highest for animals feeding on shed leaves of cottonwood. Our results show that the consumption patterns and the C and N body composition of the exotic woodlouse A. vulgare are altered when fed with Russian olive litter, suggesting that the replacement of the autochthonous cottonwood by the exotic Russian olive may negatively affect the maintenance of the population of these exotic detritivores in the area. 相似文献
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Past studies of the Rio en Medio, New Mexico, U.S.A., have shown significant changes in water quality and in invertebrate communities below the Sante Fe Ski Area. The present study was undertaken to determine how far downstream the effects of the ski area extend.. The concentration of every major nutrient except SO4 was found to increase below the ski area and the only mechanism for recovery seemed to be dilution by downstream tributaries. Increased sediment loads below the ski area were also recorded. Peaks of sediment transport were associated with snow melt and summer rains. Much of the increased sediment below the ski area appeared to settle out in the upper reaches of the Rio en Medio. Composition and diversity of stream insects appeared to be little affected. However numbers and biomass of invertebrates were significantly reduced below the ski area. These reductions were attributed to the effects of increased sediment load. Some recovery of invertebrate production was recorded at distances of 700 to 2200 m below the ski area. 相似文献
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