Responses of stoichiometric characteristics of C, N, and P in leaves and roots of three desert plants to nitrogen addition in extreme arid areas

Studying the ecological stoichiometric characteristics of plant carbon (C), nitrogen (N), and phosphorus (P) in response to N addition is of great significance for predicting plant adaptation to global change. Compared with forest and grassland ecosystems, relatively few studies on the ecological stoichiometry of plants in desert ecosystems exist. Three dominant perennial plants, Alhagi sparsifolia, Tamarix ramosissima, and Populus euphratica, in the southern edge of the Taklimakan Desert were selected to study their C, N, P, and stoichiometry response in leaves and roots to different N addition levels 0, 3, 6 g·(m²·a)⁻¹. The results showed that: 1) N addition and experimental period (month) independently or interactively affected the nutrient status in leaves and roots of A. sparsifolia, except for root C content (P < 0.05). The leaf and root N contents of T. ramosissima were affected by their interactions (P < 0.001), which had significant effects on the nutrient content in leaves and roots of P. euphratica (P < 0.05). 2) The stoichiometric ratios of C, N, and P in the leaves and roots of A. sparsifolia were significantly affected by N addition and the experimental period (P < 0.05), which had no significant effect on the C ꞉ P ratio in leaves of T. ramosissima (P > 0.05). In contrast, P. euphratica was affected by their interactions, except for the root C ꞉ P and N ꞉ P ratios (P < 0.01). 3) Among the three species, A. sparsifolia had the most significant correlation with soil nutrient status, followed by P. euphratica and T. ramosissima. The results showed that the responses of nutrient changes to short-term N addition were different in plants, reflecting that they had different adaptation strategies to environmental changes, which can provide suggestions for desert vegetation restoration and nutrient management.