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1.
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
2.
We surveyed birds in patches of native eucalypt forest and in surrounding exotic matrix (Radiata pine forests) in south-eastern
Australia. Our objectives were: (1) to examine the influence of the width of native forest patches and the age of surrounding
pine forests on bird occurrence in patches of native forest; and (2) to verify the relationship between the use of the surrounding
pine matrix and bird species response to variation in width of patches of native forests. A total of 32 study sites (boundaries
between eucalypt and pine forests) were surveyed. Birds were counted by the area search method within 0.5-ha quadrats. Data
were analysed using generalised linear models. Wide patches of eucalypt forest supported higher species richness and greater
numbers of birds, such as foliage searchers and nectarivores, than narrow patches. Matrix age also influenced the occurrence
of some species in native patches. The abundance of species in wide and narrow patches of native forest was related to their
use of the matrix. This was true for native forests surrounded by old but not by young pine forests. We suggest that management
in wood production landscapes take into account both characteristics of native patches and the surrounding matrix. Negative
impacts of fragmentation in managed landscapes might be reduced by promoting matrix types that are suitable for bird species. 相似文献