Variation of leaf functional traits and adaptive strategies of dominant woody species in rocky desertification habitats in karst area.

To clarify the response of leaf functional traits of dominant woody plants in karst areas to variations of soil characteristics across different rocky desertification habitats, we used the method of substituting space for time to examine the characteristics and variation of nine leaf functional traits of five dominant tree species and three domi-nant shrub species in typical primary forest (the early stage of rocky desertification with extremely weak rocky desertification characteristics), secondary forest habitat (the middle stage of rocky desertification with weak rocky desertification characteristics), and rocky desertification habitat (the late stage of rocky desertification with high rocky desertification characteristics), and analyzed the adaptation strategies of those species to habitat change. The results showed that compared with the primary forest habitat, soil water content in the rocky desertification habitat decreased significantly by 60.4%, and soil carbon and nitrogen contents, C:N, and N:P decreased significantly by 72.8%, 35.8%, 55.1% and 56.7%, respectively. Across the three habitats, leaf water content and specific leaf area of dominant tree species were lower than those of shrub species, while leaf dry matter content and leaf carbon content were higher. Among these traits, the variation of specific leaf area was the largest, and that of leaf carbon content was the smallest. The overall variations of leaf traits of shrubs were higher than that of tree species. There were general correlations among leaf traits. The specific leaf area and leaf water content were significantly negatively correlated with leaf dry matter content. Soil water content accounted for 48.6% of the variation in leaf traits, being the main soil factor affecting the variation of karst dominant woody plants. In the dry and barren rocky desertification habitat, leaves presented a combination of high leaf water content, high specific leaf area, low leaf thickness, low leaf dry matter content, low leaf carbon content and low leaf N:P. They adopted a "fast investment-benefit" resource acquisition strategy. In contrast, the combination of leaf traits in the relatively humid and nutrient-rich primary forest habitat was opposite to that in the rocky desertification habitat, adopting a "slow investment-benefit" resource conservative strategy.