SOIL AND NEEDLE C:N:P STOICHIOMETRY AND NUTRIENT RESORPTION AT DIFFERENT GROWTH STAGES OF PINUS MASSONIANA PLANTATIONS IN SUBTROPICAL CHINA

Abstract

Stoichiometry and nutrient resorption are key indicators for assessing nutrient use efficiency in plants, particularly in nutrient-limited environments. However, the dynamic changes of these metrics in plantation ecosystems remain poorly understood. This study investigates nutrient use efficiency in Pinus massoniana plantations in Guangxi, China, focusing on the dynamics of carbon (C), nitrogen (N), and phosphorus (P) in soil and needles across different growth stages. Results show that soil C:N and C:P ratios increased with plantation growth, while the soil N:P ratio remained stable. Needle analysis revealed high C content, and low N and P contents, reflecting efficient nutrient utilisation and carbon storage. The N:P ratio in green needles suggested an initial co-limitation of N and P, with a shift towards increasing N limitation as the plantation matured. While needle N resorption efficiency (NRE) showed no significant variation across growth stages, the P resorption efficiency (PRE) and PRE:NRE ratio declined, indicating a reduction in P limitation over time. These findings provide new insights into nutrient dynamics in plantation ecosystems in subtropical China, offering valuable guidance for sustainable forest management practices.