Relationships between a terrain-based hydrologic model and patch-scale vegetation patterns in an arctic tundra landscape
Relationships between a terrain-based hydrologic model and patch-scale vegetation patterns in an arctic tundra landscape
复制标题
北极苔原景观中基于地形的水文模型与斑块规模植被格局之间的关系
作者：
B. Ostendorf;J. Reynolds
植被格局和地貌之间的关系隐含着地形对斑块尺度上水势的影响。因此，基于将北极植物结构和功能与水联系起来的大量基于过程的研究，我们假设北极景观的一般模式可以用中尺度变量（如排水）来解释。在本文中，我们通过研究阿拉斯加北部一个小流域的植被模式和水状况之间的空间关系来检验这一假设。利用网格化高程数据，我们开发了一个模型（T-HYDRO）来生成流域的二维水流场，并将其与以下植被模式进行比较：1)从航空照片和广泛的野外采样中开发的植被图；2)归一化植被指数（NDVI）。我们的研究结果表明，NDVI的空间方差可能占到43%左右，这支持了我们的假设。尽管存在局限性，但本文提出的对应模式提供了令人鼓舞的证据，表明我们可以找到简单的方法来分层景观，并且有可能克服生态系统建模中经常提出的空间同质性假设。
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.