Root nutrient capture and leaf resorption efficiency modulated by different influential factors jointly alleviated P limitation in <i>Quercus acutissima</i> across the North–South Transect of Eastern China

Abstract

Soil and climatic conditions are known to have close associations with plant morphological and stoichiometric traits at a regional scale along latitudinal gradients; however, how latitude drives biotic and abiotic factors affecting plant nutrient acquisition to accommodate environmental nutrient deficiency remains unclear. We quantified soil, root, leaf, and leaf litter nitrogen (N) and phosphorus (P) concentrations to determine the potentially limiting nutrient and the simultaneous responses of root capture and leaf resorption to nutrient deficiency in seven <i>Quercus acutissima</i> forests across the North–South Transect of Eastern China. The results showed that the mean leaf and root N:P ratios in <i>Q. acutissima</i> were 21.58 and 20.23, respectively, which markedly exceeded the P limitation threshold of 16 for terrestrial plants. The mean leaf litter N and P were 10.63 mg/g and 0.51 mg/g, respectively, indicating that P resorption proficiency was relatively higher than N resorption proficiency. N displayed higher stoichiometric homeostasis than P in the leaf. The leaf and root N:P ratios showed a quadratic variation that first decreased and then increased as latitude increased, whereas the phosphorus resorption efficiency and root-soil accumulation factor of P displayed the opposite trend. Partial least square path modeling (<i>PLS-PM</i>) analysis demonstrated that root nutrient capture and leaf nutrient resorption were regulated by different influential factors. Overall, these findings provide new insights into plant strategies to adapt to environmental nutrient deficiency, as well as the scientific basis for predicting the spatial and temporal patterns of nutrient acquisition in the context of climate change.