Understanding the variation of soil physico-chemical properties along slope position gradients is essential for vegetation restoration and reconstruction, but how slope positions impact the soil physico-chemical properties in the secondary vegetation of hilly regions is poorly understood. To address these uncertainties, we examined the changes in soil physico-chemical properties and their relationships along the slope position gradient in secondary vegetation of the hilly region in Guilin, southwest China. The results showed that except for the soil water content, soil total phosphorus and soil total potassium which reached the highest value at the footslope, other soil physico-chemical properties reached the highest content in the middle slope, and most of the soil physico-chemical properties showed the lowest content in the upper slope or footslope. Moreover, Pearson’s correlation analysis revealed that there were no significant correlations between most of the soil physico-chemical properties and that the correlations between soil physico-chemical properties were not consistent across different slope positions. Additionally, the principal component analysis showed that the first 4 principal components together explained 84.32% of the total variation and might be interpreted as the change of soil total nitrogen, soil organic matter, soil available nitrogen, soil available potassium, soil water content and soil total potassium. Overall, our results strongly demonstrated that slope positions showed significant effects on most of the soil physico-chemical properties and would provide an important reference for the formulation of restoration strategies in different slope positions to facilitate vegetation restoration and reconstruction and the sustainable development of the ecological environment in the hilly region.

Interspecific variation in plant functional traits is the basis of species coexistence in natural ecosystems. However, intraspecific variation is extremely important to community assemblage as well. Here, we quantify leaf trait variation within and across 32 dominant shrub species within two different leaf forms (16 evergreen species and 16 deciduous species) in subtropical evergreen and deciduous broadleaf mixed forest in the Karst topography of Guilin, southwest China. Results showed that leaf area (LA) and leaf thickness (LT) of evergreen species were significantly lower than those of deciduous species, whereas specific leaf areas (SLA) and leaf dry matter content (LDMC) showed the opposite pattern. For SLA and LA, the majority variance was found among species (50.82% vs. 65.01%) and little was found within species (22.98% vs. 27.89%), whereas the largest variation was within species (44.87% vs. 48.2%) with little among species (40.73% vs. 43%) for LDMC and LT. The large variability of LDMC and LT within species may reflect niche differentiation and the importance of intraspecific variation on species coexistence. Our results will help design conservation strategies for this unique subtropical evergreendeciduous broadleaved forest ecosystem.

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