Allocation Patterns and Strategies of Carbon, Nitrogen, and Phosphorus Densities in Three Typical Desert Plants

The densities of carbon, nitrogen, and phosphorus (C-N-P) reflect the adaptation and response of desert plants to hyper-arid environments. However, the allocation strategies for biomass and C-N-P densities among various plant life forms remain poorly understood. This study involved the collection of samples representing both aboveground and belowground biomass (to depths of 200 cm) from three desert plant species-both herbaceous and shrubby-and evaluating their C-N-P densities. The investigation focused on the distribution strategies and drivers influencing total C-N-P densities within the plant-soil system. The results indicated that the biomass of the shrub Tamarix ramosissima (8.88 ± 1.22 kg m^-2) was significantly greater than that of the herbaceous plants Alhagi sparsifolia (0.96 ± 0.15 kg m^-2) and Karelinia caspia (0.72 ± 0.09 kg m^-2). The total C density among the three species was observed as follows: T. ramosissima (9.26 ± 0.99 kg m^-2) > A. sparsifolia (6.21 ± 0.85 kg m^-2) > K. caspia (6.18 ± 1.12 kg m^-2). Notably, no significant differences were detected in the total N and P densities across the species. Additionally, for A. sparsifolia and K. caspia, the roots exhibited greater biomass and C-N-P densities. Further analysis revealed that soil pools accounted for 56.34-95.10% of total C density, 90.39-98.63% of total N density, and 99.86-99.97% of total P density in the plant-soil system. The order of total C-N-P densities was established as C > P > N, decoupling total P density from other environmental factors. Total C and N densities in the three plant species were predominantly influenced by soil physicochemical properties, with biotic factors and microbial biomass playing secondary roles. This study improves the understanding of C-N-P densities strategies of dominant vegetation for restoration and sustainable management in hyper-arid deserts.