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A model of arctic tundra vegetation derived from topographic gradients 总被引：10，自引：0，他引：10
We present a topographically-derived vegetation model (TVM) that predicts the landscape patterns of arctic vegetation types in the foothills of the Brooks Range in northern Alaska. In the Arctic there is a strong relationship between water and plant structure and function and TVM is based on the relationships between vegetation types and slope (tan ) and discharge (), two independent variables that can be easily derived from digital terrain data. Both slope and discharge relate to hydrological similarity within a landscape: slope determines the gravitational hydrological gradient and hence influences flow velocity, whereas discharge patterns are computed based on upslope area and quantify lateral flow amount. TVM was developed and parameterized based on vegetation data from a small 2.2 km2 watershed and its application was tested in a larger 22km2 region. For the watershed, TVM performed quite well, having a high spatial resolution and a goodness-of-fit ranging from 71–78%, depending on the functions used. For the larger region, the strength of the vegetation types predictions drops somewhat to between 56–59%. We discuss the various sources of error and limitations of the model for purposes of extrapolation. 相似文献
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Ramesh Raja Segaran Megan Lewis Bertram Ostendorf 《Urban Forestry & Urban Greening》2014,13(2):315-324
Urban stormwater management is undergoing a transition from centralised hydrologically efficient systems to collections of dispersed, multi-functional elements. In response to a better understanding of impervious surface areas, the adoption of water sensitive urban design is promising for new large urban developments. However, spatial and economic constraints prohibit its adoption in established urban areas. We explore the potential for improvement to stormwater quality if 10% of existing parks in an established urban catchment are reserved for stormwater filtration. Spatially explicit hydrologic modelling is used to model the effects of parks in an existing urban catchment in South Australia as networks of bioretention devices. The allocation of 10% of parks that cover less than 16% of the landscape for bioretention devices may result in a 62% reduction (7.8 tonnes per year) of nitrogen from stormwater. The sources and destinations of stormwater pollutants are mapped to explore the strength and weaknesses of park size and distribution within each sub-catchment. Large parks situated lower in the catchment along the main trunk, and distributed smaller parks higher along the secondary stormwater network are shown to be effectively located. The potential for increasing the utilitarian value of many public parks by demonstrating the capacity for significantly improving urban stormwater quality is illustrated in this exploratory model. Opportunities for targeted improvements to stormwater quality are examined in the discussion. 相似文献
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Relationships between a terrain-based hydrologic model and patch-scale vegetation patterns in an arctic tundra landscape 总被引：4，自引：0，他引：4
Implicit in the relationship between vegetation patterns and landforms is the influence of topography on the water regime at the patch scale. Hence, based on the numerous process-based studies linking plant structure and function to water in the arctic, we hypothesize that the general pattern of arctic landscapes can be explained by a mesotopographic variable such as water drainage. In this paper, we test this hypothesis by examining the spatial relationship between patterns of vegetation and the water regime in a small watershed in northern Alaska. Using gridded elevation data, we develop a model (T-HYDRO) to generate a 2-dimensional water flow field for the watershed and compare this to vegetation patterns as given by 1) a vegetation map developed from aerial photographs in conjunction with extensive field sampling; and 2) a normalized difference vegetation index (NDVI). Our results show that it is possible to account for about 43% of the spatial variance in NDVI, which supports our hypothesis. In spite of its limitations, the correspondence of patterns presented in this paper provides encouraging evidence that we can find simple approaches to stratify landscapes and that it is possible to overcome the frequently made assumption of spatial homogeneity in ecosystems modeling. 相似文献
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