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We sampled 35 lakes in northern Wisconsin to determine the presence of Orconectes rusticus, the rusty crayfish, and related this pattern to several parameters pertaining to potential invasion routes that could influence
the distribution of these crayfish in the lakes. The presence of rusty crayfish in lakes was positively related to an index
of human use and negatively related to the length of stream connections to other lakes containing the crayfish. Humans appear
to act as vectors allowing crayfish to travel along discontinuous routes that otherwise would be inaccessible to them, and
thus, provide crayfish with spatially discontinuous corridors that increase the probability of movement by channelizing the
space between lakes. In contrast, streams correspond closely to the traditional definition of terrestrial corridors, in that
they are spatially continuous. This distribution pattern suggests colonization operating via two corridors with two spatial
scales, making management of the invasion of rusty crayfish complex. 相似文献
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Faith R.?KearnsEmail author N. Maggi?Kelly James L.?Carter Vincent H.?Resh 《Landscape Ecology》2005,20(1):113-125
Freshwater research and management efforts could be greatly enhanced by a better understanding of the relationship between landscape-scale factors and water quality indicators. This is particularly true in urban areas, where land transformation impacts stream systems at a variety of scales. Despite advances in landscape quantification methods, several studies attempting to elucidate the relationship between land use/land cover (LULC) and water quality have resulted in mixed conclusions. However, these studies have largely relied on compositional landscape metrics. For urban and urbanizing watersheds in particular, the use of metrics that capture spatial pattern may further aid in distinguishing the effects of various urban growth patterns, as well as exploring the interplay between environmental and socioeconomic variables. However, to be truly useful for freshwater applications, pattern metrics must be optimized based on characteristic watershed properties and common water quality point sampling methods. Using a freely available LULC data set for the Santa Clara Basin, California, USA, we quantified landscape composition and configuration for subwatershed areas upstream of individual sampling sites, reducing the number of metrics based on: (1) sensitivity to changes in extent and (2) redundancy, as determined by a multivariate factor analysis. The first two factors, interpreted as (1) patch density and distribution and (2) patch shape and landscape subdivision, explained approximately 85% of the variation in the data set, and are highly reflective of the heterogeneous urban development pattern found in the study area. Although offering slightly less explanatory power, compositional metrics can provide important contextual information. 相似文献