Elevation pattern of resource allocation in Picea crassifolia Kom. and its coupling mechanism with soil factors in Helan Mountains, China

Environmental heterogeneity in soil fertility induced by elevation gradients affects trade-offs in tree survival strategies. In arid and semi-arid ecosystems, especially in subalpine coniferous forests in the northwest of China, tree nutrient partitioning strategies and their interactions with the soil environment need to be further explored in depth. We set up three sample plots at different elevations in Helan Mountains, and collected and measured the C, N and P contents of all organs and soil samples of to explore the nutrient partitioning of Qinghai spruce (Picea crassifolia Kom.) and its coupling with soil. N and P contents in plants and soils showed a synchronized pattern of decreasing and then increasing with elevation, while C only changed synchronously at low to middle elevations. The allocation strategies of different elements among organs varied across the elevation gradient. Plants at middle elevation allocated more N and P to thick roots and less to branches and leaves compared to those at low and high elevations. Plant stoichiometric characteristics have a close response and influence relationship with soil stoichiometric characteristics, as elevation increased, the number of plant organ types that significantly responded to soil nutrient changes increased, and at the same time, and the effect of soil C content on the stoichiometric characteristics of plant showed an enhanced trend. This study elucidates the elevation patterns and driving mechanisms of plant-soil stoichiometric characteristics in montane forest ecosystems, which will contribute to better targeting of forest and tree management and conservation from the perspective of plant nutrient partitioning.