Scale dependent effects of environmental factors on vegetation pattern and composition in Horqin Sandy Land, Northern China

Understanding the relationship between vegetation-environment is very important to manage arid and semiarid ecosystems. However, information on how environment factors influence the vegetation patterns at different spatial scales in semiarid area ecosystem is lacking. We measured vegetation compositions and environment characteristics form 55 sample sites in grassland habitat (flood plain grassland, wet meadow, dry meadow) and sand dune habitat (fixed dune, semi-fixed dune, mobile dune) in Horqin Sandy Land. Multivariate analyses were used to examine the relationship between vegetation patterns and environment factors at the two scales of habitat and region. Vegetation cover, aboveground biomass, soil organic carbon (C), total nitrogen (N) and soil water content decreased from grassland habitat to sand dune habitat. Vegetation cover increased with the increase in soil water content in grassland habitat. Vegetation cover, species diversity and aboveground biomass increased with the increase in soil organic C, total N and EC in sand dune habitat. The most important complex gradient determining vegetation pattern and composition showed a region scale relationship with the combination of soil properties and topography features. Soil water content, EC and altitude were closely related to the vegetation distribution in grassland habitat, whereas soil organic C, total N and EC were significantly related to the vegetation distribution in sand dune habitat. Our results suggest that vegetation-environment relationships are dependent on the scale of observation. Thus, the interpretation of the vegetation pattern and composition in semiarid area needs to consider the spatial scales and habitats at which important environmental variables actually vary. (C) 2011 Elsevier B.V. All rights reserved.