Available soil nutrients and water content affect leaf nutrient concentrations and stoichiometry at different ages of Leucaena leucocephala forests in dry-hot valley.
Purpose: The carbon (C), nitrogen (N), and phosphorus (P) concentrations of leaves can reflect soil nutrient supply conditions and changes in soil. An understanding of species adaptability and nutrient use efficiency in extreme ecosystems can help land managers choose effective methods to improve management and community structure of introduced plants which may induce biological invasion and limit the regeneration of native species. Materials and methods: We selected the Leucaena leucocephala forests in three ages (9, 15, and 26 years old) in the Jiangjiagou Gully to study the relationships between (i) soil factors and forest age and (ii) leaf nutrient concentrations. Soil factors and leaf nutrients were measured in nine sampling quadrats of 10×10 m of each plot. We used ANOVA to examine differences in leaf variables and soil factors at different ages of L. leucocephala forest. Pearson's correlation analysis and linear regression analysis were conducted to identify the relationships between soil factors and leaf variables. Then, we used analysis of covariance to examine combined effects of forest ages and soil factors on leaf variables. Results and discussion: Leaf N was significantly correlated with available P, while leaf P was significantly correlated with both available P and available N. Leaf N and P had no significant relationship with soil total N and P. Leaf C:N:P stoichiometries had a higher significant correlation with total N, available N, and soil water content. Conclusions: Our findings illustrate that available N and available P are the main limitations for L. leucocephala, though available P imposed a stronger limitation than available N. Moreover, soil water content played an indispensable role on nutrient accumulation and the soil ecological environment. Our results provide useful information to improve L. leucocephala community structure and reduce soil degradation in a dry-hot valley.