Difference in leaf and root stoichiometric characteristics of Quercus rehderiana Hand.-Mazz. in forests with rocky and non-rocky desertification in Southwest China

Quercus rehderiana Hand.-Mazz. is a genus of Quercus in the Fagaceae family, which widely distributed in Guizhou Province in Southwest China. It has important ecological significance in soil and water conservation, species diversity maintenance, and climate regulation. To date, the researches on stoichiometric characteristics of Quercus mainly focus on leaves, and few studies on roots. However, the difference of leaf and root stoichiometric characteristics of Quercus between in forests with rocky and non-rocky desertification are still unclear. In this study, we compared leaf (15 individuals) and root (9 individuals) carbon (C), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) concentrations and their stoichiometric ratios in five 20 x 20 m quadrants of forests with rocky and non-rocky desertification. The aim was to find their resource strategies of adaptation to nutrient deficient soil environments in forests with rocky desertification. Our results show that leaf P and K concentrations in forest with non-rocky desertification were significantly higher than those in forest with rocky desertification, Ca and Mg concentrations were opposite. Root N, Ca and Mg concentrations in forest with rocky desertification were significantly higher than that in forest with non-rocky desertification, P and K concentrations were opposite. The N:P of leaves were greater than the threshold value of phosphorus (16) both in forests with rock and non-rocky desertification. Leaf P concentration was positively correlated with N concentration in forest with non-rocky desertification. Root N concentration was positively correlated with P concentration in forest with non-rocky desertification. C concentration of leaves and roots in forest with rocky desertification was negatively correlated with Ca concentration. In conclusion, leaf and root showed an obvious difference in nutrients and stoichiometric characteristics between in forests with rocky and non-rocky desertification. The growth of Q. rehderiana both in forest with rocky and non-rocky desertification was mainly limited by P. The trade-offs and synergies of nutrient absorption and utilization by different plant organs are both similar and different in different forests. Therefore, proper addition of N and P nutrients in plant growth period can promote plant growth and development, and help to improve the stability of forest ecosystem. The research results have practical significance for the vegetation restoration and protection in forests with rocky desertification.