Response of C:N:P in the plant-soil system and stoichiometric homeostasis of Nitraria tangutorum leaves in the oasis-desert ecotone, Northwest China

Nitraria tangutorum nebkhas are widely distributed in the arid and semi-arid desert areas of China. The formation and development of N. tangutorum nebkhas are the result of the interaction between vegetation and the surrounding environment in the process of community succession. Different successional stages of N. tangutorum nebkhas result in differences in the community structure and composition, thereby strongly affecting the distribution of soil nutrients and ecosystem stability. However, the ecological stoichiometry of N. tangutorum nebkhas in different successional stages remains poorly understood. Understanding the stoichiometric homeostasis of N. tangutorum could provide insights into its adaptability to the arid and semi-arid desert environments. Therefore, we analyzed the stoichiometric characteristics of N. tangutorum in four successional stages, i.e., rudimental, developing, stabilizing, and degrading stages using a homeostasis model in an oasis-desert ecotone of Northwest China. The results showed that soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) contents and their ratios in the 0-100 cm soil depth were significantly lower than the averages at regional and global scales and were weakly influenced by successional stages in the oasis-desert ecotone. TN and TP contents and C:N:P in the soil showed similar trends. Total carbon (TC) and TN contents in leaves were 450.69-481.07 and 19.72-29.35 g/kg, respectively, indicating that leaves of N. tangutorum shrubs had a high storage capacity for C and N. Leaf TC and TN contents and N:P ratio increased from the rudimental stage to the stabilizing stage and then decreased in the degrading stage, while the reverse trend was found for leaf C:N. Leaf TP content decreased from the rudimental stage to the degrading stage and changed significantly in late successional stages. N:P ratio was above the theoretical limit of 14, indicating that the growth of N. tangutorum shrubs was limited by P during successional stages. Leaf N, P, and N:P homeostasis in four successional stages was identified as strictly homeostasis. Redundancy analysis (RDA) revealed that soil acidity (pH) and the maximum water holding capacity were the main factors affecting C:N:P stoichiometric characteristics in N. tangutorum leaves. Our study demonstrated that N. tangutorum with a high degree of stoichiometric homeostasis could better cope with the arid desert environment.

Automated summary

Nitraria tangutorum nebkhas in different successional stages exhibit significant variations in vegetation and soil stoichiometric characteristics, strongly impacting soil nutrients and ecosystem stability. Changes in leaf carbon, nitrogen, and phosphorus contents and ratios throughout succession stages suggest limitation in shrub growth due to high N:P ratios surpassing theoretical limits of 14.