Effects of environmental factors on plant functional traits across different plant life forms in a temperate forest ecosystem

Plant functional traits have been shown to vary with environmental conditions. However, we lack empirical data on how plant functional traits of different plant life forms respond to environmental factors. We studied the influence of environmental conditions on the distribution of plant functional traits in a Quercus wutaishanica forest with the aim of exploring the patterns of functional traits across different life forms and determining the driving factors of functional trait variation at fine spatial scales. We collected data on environmental factors (soil nutrients and soil moisture, canopy variables, topography) of 70 20 m × 20 m plots. Leaves were harvested from 26 species (4 tree species, 7 shrub species and 15 herbaceous species), and community-weighted mean (CWM) trait values for leaf area (LA), leaf mass per unit area (LMA), leaf carbon content (LCC), leaf nitrogen content (LNC), leaf phosphorus content (LPC), and leaf potassium content (LKC) were calculated. We also measured the height (H) of plants. The importance of biotic and abiotic factors in controlling plant functional traits was quantitatively assessed using redundancy analysis (RCA). Regression was used to determine relationships between CWM trait values and environment variables. We found that plant functional traits varied with life forms of plants. LA, LMA and LCC of trees were greater than those of the understory, whereas LNC, LPC and LKC of herbaceous were greater than those of trees. Responses of plant functional traits to environmental factors varied with different life forms. The combined effect of canopy, topography and soil factors had a greater impact on plant functional traits in understory layer than tree layer. General linear models showed that openness is the main factor affecting various functional traits of undergrowth plants, and the relationship between the element content in leaves of herbaceous plants and environmental factors is greater than that of shrub plants. The strong correlation of plant functional traits and environmental factors at fine spatial scales indicates that Q. wutaishanica forests have high spatial variability. Considering the variation of traits in different life form of plants and their interactions with biotic factors, it provides further insights into ecological mechanisms of shaping plant communities and driving plant community dynamics.