Allocation strategies of two dominant conifer species in heterogeneous environments on eastern margin of the Tibetan Plateau

The stability and functioning of montane forest ecosystems are critically regulated by the stoichiometry of carbon (C/SOC), nitrogen (N/TN), and phosphorus (P/TP) in the vegetation–soil system. However, the seasonal dynamics of plant resource allocation strategies and their environmental drivers remain incompletely understood. This study investigated these strategies and their driving factors in two dominant conifers, Picea crassifolia (Qinghai spruce) and Juniperus przewalskii (Qilian juniper), in the Qilian Mountains by systematically analyzing C, N, and P dynamics in plant organs and soils. The results revealed that: (1) the soil SOC and TN contents are higher in Qinghai spruce forests, whereas TP content is lower than in Qilian juniper forests; (2) the seasonal fluctuations in organ C content for both species are not significant, but N and P contents change markedly. Qinghai spruce grows under a low N and P pattern, while Qilian juniper maintains stable growth with a high N and high P pattern; (3) climatic factors have a greater impact on element contents in Qinghai spruce organs, whereas soil properties more significantly affect Qilian juniper. This study reveals significant differences between the two species in element allocation strategies and ecological adaptability, providing a scientific basis for differential management of montane forests.