Abstract: It is essential to predict the impacts of climate change on ecosystem functioning. The effects of environmental factors on the functional traits of the dominant plant species are becoming more obvious with the increasing warming and drying in the Loess Plateau. In this study, using the redundancy analysis, we examined the effects of soil and topographic factors on the functional traits of nine plant species in a grassland in the loess hilly region of Northwest Shanxi. Our results showed that soil and topographic factors played a key role in affecting the functional traits of dominant species, but did not affect that of nondominant species. Soil water content and available phosphorus content were the key soil factors affecting the functional traits of the dominant species. Soil water content was positively correlated with the height of the dominant species but negatively correlated with the relative branch number. Soil available phosphorus content was positively correlated with leaf nitrogen content, dry weight per plant and specific leaf area of dominant species, but negatively correlated with leaf carbon/nitrogen ratio and leaf dry matter content. Altitude is the main topographical factor affecting the functional traits of dominant species. It was positively correlated with leaf dry matter content and relative branch number of dominant species, and negatively correlated with plant height, leaf carbon content, and leaf area. Our results suggest that plant species in loess hilly areas would change resource use strategies to adapt to the environment of reduced soil moisture and nutrients under future warming and drying climate.

Key words: loess hilly area, functional trait, soil factor, topographic factor, redundancy analysis.