Modelling the Response of Vegetation in North-East China Transect to Global Change

Abstract

Biogeographical models relating large-scale patterns of climate and vegetation provide a way of simulating vegetation response to global change. While scaling down these models to regional or landscape scale, climatic factors are not the only components that affect vegetation patterns; other environmental components, such as topography and parent materials, also play important roles in vegetation classification. Elevation and quaternary geology are applied as indices of topography and parent materials, along with climatic index of moisture (MI), to classify vegetation and then predict the response of vegetation in North-East China INTRODUCTION There are two approaches for development of models of global vegetation: bottom-up and the top-down. The topdown approach utilizes current equilibrium models of global vegetation patterns by relating large-scale patterns of climate and vegetation (Smith, Leemans & Shugart, 1994). This top-down approach modifies global vegetation models by defining functional types of vegetation. While scaling down global or continental models (e.g. Holdridge Life Zone Classification, Holdridge, 1967) to regional or landscape level, vegetation is affected not only by large-scale climatic factors but also by other regional environmental components, such as topography and soil parent materials. Topography alters local water balance and parent materials dominates local nutrient cycling. They are therefore useful indicators of vegetation classification in predicting vegetation response to global change. North-East China Transect (NECT) lies between 42-46? latitude and 106-134? longitude, covering an area of 700,000 km2. It has a sharp and very sensitive environmental gradient from coastal east to interior west; for example, transition of climate (primarily precipitation ranging from more than 1300 mm to less than 150 mm), soil (organic matter, C/N, efficient water, various ionic ? 1995 Blackwell Science Ltd. Transect to global change. The model is based on a vegetation classification decision rule system established by statistical analysis of environment: vegetation relationships. The classification has been validated and gives general vegetation response patterns and sensitivities to global change.