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1.
A comparison of satellite data and landscape variables in predicting bird species occurrences in the Greater Yellowstone Ecosystem,USA 总被引:6,自引:0,他引:6
Saveraid Erika Hasler Debinski Diane M. Kindscher Kelly Jakubauskas Mark E. 《Landscape Ecology》2001,16(1):71-83
We compare the accuracy of predicting the occurrence of 11 bird species in montane meadows of the Greater Yellowstone National Park ecosystem, in the states of Montana and Wyoming, USA. We used remotely sensed, landscape, and habitat data. The meadow type, as determined from the remotely sensed data, was highly correlated with abundances of six of the 11 bird species. Landscape variables significant in predicting occurrence were selected using a stepwise multiple regression for each bird species. These variables were then used in a multiple regression with the variable meadow type. As expected, the abundances of the generalist species (American Robin, Dark-eyed Junco, White-crowned Sparrow, Brewer's Blackbird, and Chipping Sparrow) were not strongly correlated with landscape variables or meadow type. Conversely, abundances of the Common Snipe, Common Yellowthroat, Lincoln's Sparrow, Savannah Sparrow, Vesper Sparrow, and Yellow Warbler were highly correlated with meadow type and landscape variables such as percent cover of willow (Salix spp.), graminoid, woody vegetation, sagebrush (Artemisia spp.), and graminoid and shrub biomass. The results from our study indicate that remotely sensed data are applicable for estimating potential habitats for bird species in the different types of montane meadows. However, to improve predictions about species in specific sites or areas, we recommend the use of additional landscape metrics and habitat data collected in the field. 相似文献
2.
The purpose of our study was to compare the number, proportion, and species composition of introduced plant species in forest
patches situated within predominantly forested, agricultural, and urban landscapes. A previous study suggested that agricultural
landscape context does not have a large effect on the proportion of introduced species in forest patches. Therefore, our main
goal was to test the hypothesis that forest patches in an urban landscape context contain larger numbers and proportions of
non-native plant species. We surveyed the vegetation in 44 small remnant forest fragments (3–7.5 ha) in the Ottawa region;
15 were situated within forested landscapes, 18 within agricultural landscapes, and 11 within urban landscapes. Forest fragments
in urban landscapes had about 40% more introduced plant species and a 50% greater proportion of introduced plant species than
fragments found in the other two types of landscape. There was no significant difference in the number or proportion of introduced
species in forest fragments within forested vs. agricultural landscapes. However, the species composition of introduced species
differed among the forest patches in the three landscape types. Our results support the hypothesis that urban and suburban
areas are important foci for spread of introduced plant species. 相似文献
3.
Over the past decade, the urban–rural gradient approach has been effectively used to study the ecology of cities and towns
around the world. These studies have focused on understanding the distribution of plants and animals as well as ecosystem
processes along gradients of urbanization that run from densely urbanized inner city to more rural exurban environments. We
reviewed 300 papers investigating urbanization gradients that were published in peer-reviewed journals between 1990 and May
2007. Sixty-three percent of the papers investigated the distribution of organisms along urbanization gradients. Only five
papers addressed the measures used to quantify the urbanization gradient itself. Within the papers addressing the distribution
of organisms, 49% investigated the responses of birds to urbanization gradients, and <10% of the papers investigated more
cryptic organisms. Most of these studies utilized a variety of broad measures of urbanization, but future advances in the
field will require the development of some standardized broad measures to facilitate comparisons between cities. More specific
measures of urbanization can be used to gain a mechanistic understanding of species and ecosystem responses to urbanization
gradients. While the gradient approach has made a significant contribution to our understanding of the ecology of cities and
towns, there is now a need to address our current knowledge gaps so that the field can reach its full potential. We present
two examples of research questions that demonstrate how we can enhance our understanding of urbanization gradients, and the
ecological knowledge that we can obtain from them. 相似文献