| The unique morphological and physiological characteristics of Caragana korshinskii and Artemisia ordosica play an indispensible effect in the restoration and protection of desert ecosystem in the desert area of northwest China.They both play an important role in the process of material cycle,energy flow and information transmission as important shrub species for wind prevention and sand fixation in desert ecosystem.The present study was intended to explore the composition and diversity of arthropod community in the shrub canopy of C.korshinskii and A.ordosica in desert area,and provided scientific basis for the biodiversity protection of C.korshinskii and A.ordosica and the construction and management of artificial vegetation in northwest desert ecosystem.We Selected C.korshinskii and A.ordosica of the same size in Yuyang,Yanchi and Shapotou as the study objects.The study investigated the soil physicochemical properties under shrub,the nutrient content of branches and leaves and the canopy of arthropod community composition and diversity,and analysed the relationship between crude protein,crude lipid,total N,total K and total P in May,July and September 2020.The main results were as follows:(1)There were significantly higher the total N and crude protein of branches and leaves in C.korshinskii than A.ordosica(P<0.05)in the three study areas;whereas there were significantly lower the total K and crude lipid of branches and leaves in C.korshinskii than A.ordosica(P<0.05).The total P of branches and leaves in C.korshinskii was significantly lower than A.ordosica in Yuyang and Shapotou(P<0.05),but there was no significant difference between C.korshinskii and A.ordosica in Yanchi(P>0.05).There were significantly lower the soluble sugar of branches and leaves in C.korshinskii than A.ordosicain Yuyang and Yanchi(P<0.05),but there was no significant difference between C.korshinskii and A.ordosica shrubs in Shapotou(P>0.05).Correlation analysis showed that the total P of branches and leaves in C.korshinskii had significantly negative correlation with soil electrical conductivity and soil total N(P<0.01),and the crude lipid of branches and leaves in C.korshinskii had significantly negative correlation with soil total C and soil total N(P<0.01).The total N and crude protein of branches and leaves in A.ordosica had significantly negative correlation with soil pH and soil bulk density(P<0.01),but the total N of branches and leaves in A.ordosica had significantly positive correlation with soil water;the soluble sugar of branches and leaves in A.ordosica had significantly positive correlation with total soil C(P<0.01).(2)The dominant groups of C.korshinskii shrub were Cicadellidae and Pyralidae,while Formicidae was the dominant group of A.shrub.There were significantly higher the canopy arthropod abundance in C korshinskii than in Yuyang and Shapotou(P<0.05),but there was no significant difference in Yanchi(P>0.05).There was no significant difference in group number,Shannon index and Simpson index between C.korshinskii and A.ordosica shrubs in Yuyang(P>0.05),but there were significantly higher the richness of canopy arthropods,Shannon index and Simpson index in C.korshinskii than A.ordosica in Yanchi and Shapotou(P<0.05).The results of RDA analysis showed that total P and total K were the main limiting factors on the distribution of canopy arthropods community structure in C.korshinskii shrub,while total N was the main limiting factor on the distribution of canopy arthropods community structure in A.ordosica shrub.(3)According to the division of feeding habits,the canopy arthropods were divided into three trophic groups:predacious,omnivorous and phytophagous canopy arthropods,with 3,6 and 4 groups respectively,and 11.09%,53.26%and 35.6 5%accounted for the total richness of can opy arthropods respectively.There were significantly higher the richness of predatory in C.korshinskii than A.ordosica shrub in Yuyang(P<0.05),however,the values were opposite in Yanchi,but there was no significant difference between C.korshinskii and A.ordosica shrub in Shapotou(P>0.05).There was no significant difference of the richness of predacious and omnivorous canopy arthropods between C.korshinskii and A.ordosica shrubs in three study areas(P>0.05).There were significantly higher the richness of phytophagous canopy arthropods in C.korshinskii than A.ordosica shrub in Yuyang and Shapotou(P<0.05),while there was no significant difference between C.korshinskii and A.ordosica shrubs in Yanchi(P>0.05).There were significantly higher the abundance of phytophagous canopy arthropods in C.korshinskii than A.ordosica shrub(P<0.05).Correlation analysis showed that the abundance of omnivorous canopy arthropods in C.korshinskii had significantly negative correlation with total K of branches and leaves(P<0.01).The abundance of omnivorous canopy arthropods in A.ordosica had significantly negative correlation with total P of branches and leaves(P<0.01),but it had significantly positive correlation with soluble sugar of branches and leaves(P<0.01).Comprehensive analysis showed that the soil physicochemical properties under shrubs and nutrient content of branches and leaves were affected by shrub species and precipitation.As the amount of precipitation decreased,the richness of canopy arthropods was decrease-increased by the type of shrub.There were the abundance of canopy arthropods,Shannon index and Simpson index are less affected by shrub species except for Yuyang which has an abundant precipitation,while the abundance of canopy arthropods,Shannon index and Simpson index in canopy of Yanchi and Shapotou are affected by shrub species consistently,showing the aggregation effect of C.korshinskii shrub. |
