| In order to verifying the conservation effects by each other,two C.intermedia shrub sites with different planting years and patterns were selected(site 1 and site 2)in desert steppe in Yanchi County,Ningxia.Five microhabitats were set up of each site at the east and west sides under the canopy(SEi,SWi),at the canopy edge(SEe,SWe),and at the center of the belt(Gap).The community structure of herbaceous plant communities,functional characteristics of Agropyron mongolicum and their relationship with microclimate and soil factors were studied.The main results are as follows:(1)Artificial C.intermedia can improve the microclimate under the canopy and the edge of the shrub.The light intensity,soil temperature and surface temperature under the canopy and the edge of the shrub in site 1 and site 2 were significantly lower than those of gap(P<0.05)..(2)The soil physical and chemical properties of the 0-40 cm soil layer under the canopy of artificial C.intermedia were improved compared with gap,and the contents of soil organic carbon,total nitrogen,total phosphorus and total potassium under the canopy in site 1 and site 2 increased by13.93%-77.27%and 13.04%-77.28%respectively compared with gap;the number of soil microorganisms increased under the canopy and the edge of the shrub;7 phyla including Proteobacteria and Planctomycetes bacteria showed higher abundance under the canopy and the edge of the shrub(P<0.05).(3)Compared with gap,the average coverage,height and aboveground biomass of the plant community under the artificial C.intermedia increased by 32.11%-55.46%,24.80%-67.43%and 35.76%-186.37%,respectively(P<0.05);The aboveground biomass of Gramineae of the total aboveground biomass accounts for 72.12%-82.64%under the canopy.The dominant species of SWi,SEi,and SWe in site 1 were all A.mongolicum,and the SEe,Gap in sitel and five microhabitats in sitet 2 were all A.mongolicum and Artemisia scoparia as the dominant species.Redundancy analysis showed that light intensity and soil organic carbon were the main factors affecting herb diversity and productivity(P<0.05).(4)Compared with gap,the net photosynthetic rate of A.mongolicum leaves under the artificial canopy of C.intermedia increased;the nutrient content of leaves under the canopy increased overall,and the leaf length,leaf width,leaf area and leaf dry weight increased by 24.80%-156.93%,respectively.The root length,root diameter and root surface area increased by 19.40%-161.67%,respectively.Light intensity,soil organic carbon,soil total nitrogen,and soil total phosphorus were the factors that significantly affected the functional traits of leaves of A.mongolicum,and soil organic carbon was the factor that significantly affected the functional traits of roots of A.mongolicum(P<0.05).In conclusion,the artificial C.intermedia with different planting years and patterns both have certain nurse effect on the understory and canopy-edge herbs by improving the microclimate and soil environment,which can change the plant community structure,functional traits and photosynthetic physiological characteristics of A.mongolicum. |
