| Precipitation can lead to changes in the dynamics of soil moisture,nutrients,and microorganisms,which directly or indirectly affect species diversity,primary productivity,and species competition in terrestrial ecosystems,with implications for ecosystem stability.Plant C:N:P stoichiometry patterns and the response of different organs to precipitation reflect trade-offs between resource acquisition and adaptation strategies to different habitats.Phragmites australis is a common perennial herb that is a dominant plant in arid zone wetlands.In this study,we quantified the stoichiometric characteristics of P.australis’ organs(leaves,stems,roots and flowers)and soil C,N and P chemistry under different precipitation gradients and the factors affecting them,using reed in the middle and lower reaches of the Shule River basin as the study target.The main results are as follows.(1)C,N and P contents of each P.australis’ organ increased significantly with increasing precipitation,while C:N,C:P and N:P decreased significantly with increasing precipitation.(2)The C,N and P contents of P.australis’ leaves and flowers were significantly higher than those of stems and roots;C:N and C:P of P.australis’ stems and roots were significantly higher than those of leaves and flowers;while the N:P situation varied among organs,with leaves being the highest,followed by flowers,then stems,and roots being the lowest;N:P of P.australis’ leaves(22.14)> 16,indicating that the growth of leaves was mainly limited by P,and N:P of stems and flowers(14.56,15.64)ranged from 14 to 16,indicating that stem and flower growth is limited by both N and P.Root N:P(6.84)< 14,indicating that root growth is mainly limited by N.(3)The dominant soil factors affecting P.australis’ leaf stoichiometry are soil active phosphorus,soil salinity and soil moisture;the dominant soil factors affecting P.australis’ stem stoichiometry are total soil nitrogen,total soil phosphorus and soil ammonia nitrogen;the dominant soil factors affecting P.australis’ root stoichiometry are total soil nitrogen,soil ammonia nitrogen,soil nitrate nitrogen,soil salinity and soil p H;the dominant soil factors affecting P.australis’ flower stoichiometry are soil active phosphorus,soil ammonia nitrogen and soil salinity.The dominant soil factors affecting P.australis’ flower stoichiometry are soil effective phosphorus,soil ammonia nitrogen and soil salinity.(4)Precipitation indirectly affects P.australis’ leaf C by affecting effective soil phosphorus and soil moisture,P.australis’ leaf N,P and N:P by affecting effective soil phosphorus,soil salinity and soil moisture,P.australis’ stem N by affecting total soil N and soil ammonia N,and P.australis’ stem P and N:P by affecting total soil phosphorus,total soil N and soil ammonia N.Precipitation has a direct effect on flower N,P,C:N and N:P.P,while precipitation also indirectly affects P.australis’ flower N by affecting soil salinity and soil ammonia nitrogen,P.australis’ flower P and C:P by affecting soil effective phosphorus and soil salinity,and P.australis’ flower C:N by affecting soil ammonia nitrogen,soil nitrate nitrogen and soil salinity.This study confirms that wetland hydrological conditions are important influencing factors for wetland ecosystems.When implementing ecological restoration projects for wetlands in the northwest arid zone,it is necessary to focus on the restoration and distribution of wetland water resources,and the restoration of wetland hydrological conditions can be achieved by constructing water diversion canals,reservoirs and other water conservancy projects.The effectiveness of nitrogen and phosphorus in arid wetland soils can be improved by applying appropriate amounts of nitrogen and phosphorus fertiliser to nutrient-poor sites in arid wetlands.Planting trees and grasses also have some significance for ecological restoration of wetlands,and higher quality plant species such as P.australis can be cultivated and planted in arid wetlands. |
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