Remote sensing applications for monitoring rangeland vegetation     

P.T. Tueller 《African Journal of Range and Forage Science》2013,30(4):160-167

Remote sensing techniques hold considerable promise for the inventory and monitoring of natural resources on range‐lands. A significant lack of information concerning basic spectral characteristics of range vegetation and soils has resulted in a lack of rangeland applications. To use remote sensing technology for measuring vegetation and soil changes on rangelands, certain things must be accomplished. First, the spectral characteristics of scene components must be determined for the various vegetation types. Second, determinations must be made of the appropriate kinds of remotely sensed data that should be used for the task. And finally, procedures must be outlined for acquiring the remotely sensed data that will measure changes in the range vegetation and soils. The interpretation of the remotely sensed data for such monitoring purposes will depend upon the use of various vegetation indices, pixel modelling and appropriate statistical tests. The parameters of interest for range condition must be identified and a means of measuring them either directly or indirectly developed. The paper describes an approach to the use of remotely sensed data to accomplish rangeland monitoring.  相似文献   

Empirical patterns of the effects of changing scale on landscape metrics   总被引：45，自引：2，他引：45  

Wu  Jianguo  Shen  Weijun  Sun  Weizhong  Tueller  Paul T. 《Landscape Ecology》2002,17(8):761-782

While ecologists are well aware that spatial heterogeneity is scale-dependent, a general understanding of scaling relationships of spatial pattern is still lacking. One way to improve this understanding is to systematically examine how pattern indices change with scale in real landscapes of different kinds. This study, therefore, was designed to investigate how a suite of commonly used landscape metrics respond to changing grain size, extent, and the direction of analysis (or sampling) using several different landscapes in North America. Our results showed that the responses of the 19 landscape metrics fell into three general categories: Type I metrics showed predictable responses with changing scale, and their scaling relations could be represented by simple scaling equations (linear, power-law, or logarithmic functions); Type II metrics exhibited staircase-like responses that were less predictable; and Type III metrics behaved erratically in response to changing scale, suggesting no consistent scaling relations. In general, the effect of changing grain size was more predictable than that of changing extent. Type I metrics represent those landscape features that can be readily and accurately extrapolated or interpolated across spatial scales, whereas Type II and III metrics represent those that require more explicit consideration of idiosyncratic details for successful scaling. To adequately quantify spatial heterogeneity, the metric-scalograms (the response curves of metrics to changing scale), instead of single-scale measures, seem necessary.This revised version was published online in May 2005 with corrections to the Cover Date.  相似文献