| Clonal plants play an important role in maintaining community stability,conserving species diversity and nutrient cycling,and are able to adapt to most heterogeneous habitats due to their unique functional traits,but further research is still needed on the stoichiometric characteristics of clonal plants and their drivers.The inland river wetlands in the semi-arid and arid regions of northwest China are not only fragile and sensitive areas for ecological environment,but also important bases for biodiversity conservation and key dependencies for building ecological barriers.So it is necessary to systematically carry out the spatial variation of the chemometric characteristics of Phragmites australis populations in the northwest inland wetland.P.australis,as a dominant species in northwest inland wetlands,plays an important role in maintaining the ecosystem function and structure of northwest inland wetlands by virtue of its unique physiological characteristics,diverse reproduction methods,plastic morphological features and strong resistance to stress.The study of spatial variation in the stoichiometric characteristics of the clonal plant P.australis and its driving forces can help to understand the effects of heterogeneous habitats on plant survival and growth as well as the response mechanisms of plant physiological and ecological processes to habitats.In view of this,this paper used the clonal plant P.australis from the Dunhuang Yangguan wetland as the object of study,and divided the P.australis population into three different sampling gradients of wetland,salt marsh,and desert habitats according to the distance of the P.australis population from the reservoir and its population characteristics,aiming to elucidate the stress adaptation of P.australis to the growth environment from the perspective of the changes of plant nutrients distribution in whole plant and clonal components,and to provide a theoretical basis for further understanding of the response mechanism of clonal plants to heterogeneous environment.The aim was to elucidate the stress adaptation of P.australis to the growing environment from the perspective of changes in the distribution of nutrients between whole plant and clonal components,and to provide a theoretical basis for further understanding of the response mechanisms of clonal plants to heterogeneous environments.The main results of the study are as follows:(1)From wetland,salt marsh to desert habitat,soil water and soil N contents showed a significant decreasing trend(P<0.05),while soil salinity,soil bulk weight and soil pH showed a gradual increasing trend.In the wetland habitat,the higher the water content,the greater the soil C,N and N:P values.Soil pH showed a significant negative correlation with soil N(P<0.05);In salt marsh habitat,soil salinity showed a significant negative correlation with soil N and a significant positive correlation with soil C(P<0.05).In desert habitat,soil water showed significant positive correlations with soil P,C:P and N:P.Soil water was closely related to soil stoichiometric characteristics.(2)P.australis can adapt to heterogeneous environments by changing nutrient partitioning strategies,as evidenced by a significant decrease(P<0.05)in whole plant N and P contents and no significant change(P>0.05)in C content,and a significant increase(P<0.05)in whole plant C:P and N:P from salt marsh to desert habitat.P.australis adapt to stressful environments by changing nutrient partitioning patterns among different components,as evidenced by N and P were invested more in underground components(rhizomes and roots)for survival growth,and N and P utilization efficiency of leaf and stem components was increased.Meanwhile,the proportion of C,N and P of leaves to the whole plant was greater in three habitats.(3)In three habitats,the whole P.australis plant and each component C-N,C-P,and N:P-C showed significant anisotropic growth relationships(P<0.05),but the C-N,C-P,and N:P-C anisotropic growth indices of the whole reed plant and each component differed among habitats.In the wetland habitat,the whole plant showed a significant positive correlation between N and P(P<0.05).In salt marsh habitat,whole plant C content of P.australis increased with increasing P content,and stem C showed a significant positive correlation with N(P<0.05).In desert habitat,there was a significant positive correlation between whole plant N and P.Leaves,stems,rhizomes,and roots showed a significant negative correlation between N and P(P<0.05).(4)Relative importance and redundancy analyses showed that soil elements,water,pH,salinity and bulk weight were the main drivers of P.australis stoichiometric trait assignment in both whole plant and component dimensions,respectively.In wetland habitat,soil bulk weight and C were the most important factors influencing variation in whole plant stoichiometric characteristics of P.australis,while soil bulk weight,C and P were the direct environmental factors driving changes in stoichiometric characteristics of different components of P.australis.In salt marsh habitat,relative importance and redundancy analyses indicated that soil P and N played an important driving role in the stoichiometric characteristics of the whole P.australis plant and different components.In desert habitats,soil water was the most important environmental driver of spatial variation in the stoichiometric characteristics of whole plant and different components. |
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