RELATIONSHIPS BETWEEN A TERRAIN-BASED HYDROLOGIC MODEL AND PATCH-SCALE VEGETATION PATTERNS IN AN ARCTIC TUNDRA LANDSCAPE

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 str ucture and function to water in the arctic, we hypothesize that the ge neral pattern of arctic landscapes can be explained by a mesotopograph ic variable such as water drainage. In this paper, we test this hypoth esis by examining the spatial relationship between patterns of vegetat ion and the water regime in a small watershed in northern Alaska. Usin g gridded elevation data, we develop a model (T-HYDRO) to generate a 2 -dimensional water flow field for the watershed and compare this to ve getation patterns as given by 1) a vegetation map developed from aeria l photographs in conjunction with extensive field sampling; and 2) a n ormalized 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 corre spondence of patterns presented in this paper provides encouraging evi dence that we can find simple approaches to stratify landscapes and th at it is possible to overcome the frequently made assumption of spatia l homogeneity in ecosystems modeling.