| The expressway has made great contributions to China's economic development,and it has also exerted a profound impact on the structure and function of grassland ecosystems.This article selects the Caragana korshinskii forest beside the Qingyin Expressway(Yanchi County,Ningxia)as sampling site.In May,August and October 2016,sampling sites were set up at 0m,30 m,60m,100 m,150m and 200 m away from the highway respectively.The community composition and diversity of ground-active arthropods at different spatial distances were investigated by trapping method.Combined with soil physical and chemical properties,soil heavy metal analysis and ground herbaceous vegetation investigation,the distribution characteristics and influencing factors of ground-active arthropods community structure in the roadside Caragana korshinskii are studied to provide scientific basis for the management and utilization of artificial Caragana korshinskii forest lands,biodiversity conservation and soil quality assessment.1.The farther away from the expressway,the more significant differences of the soil physical and chemical properties in the artificial Caragana intermedia have,and it also shows some seasonal characteristics.The performance of different indicators is also different.For example,the soil pH only showed that the 60 m sampling point in spring was significantly smaller than other sampling sites(P<0.05).The soil water content at the 0m and 200 m sampling sites in summer were only significantly higher than that at the sampling sites of 60 m,100m and 150m(P<0.05).The content of organic carbon and total nitrogen was only significantly higher than that sampled at the 60 m,100m,150 m and 200 m sampling sites(P<0.05)in the autumn at the 30 m sampling sites.The Soil Zn content was significantly higher at sampling sites of 60 m and 150 m than sampling sites of 0m,30 m and 100 m in spring,and it was significantly higher at sampling sites of 0m,30 m and 60 m than sampling sites of 0m,30 m and 100 m in summer,in autum it was significantly higher at sampling sites of 60 m and 150 m than sampling sites of 0m,30 m and 100m(P<0.05).The soil Cd content at the 0m and 200 m sampling sites in autum were only significantly higher than that at the sampling sites of 60 m,100m and 150m(P<0.05).2.The further away from the expressway,the crown width and height of the Caragana korshinskii and the characteristics of the herbaceous vegetation on the ground have also changed significantly.The crown of Caragana korshinskii shrubs at 200 m sampling sites was significantly larger than those at the sampling sites of 30 m,60m and 100m(P<0.05).The height of Caragana korshinskii shrubs at 0m and 200 m were significantly higher than those at 100 m and 60m(P<0.05).The characteristics of the herbaceous vegetation are also affected by the expressway,and in different seasons,the situation is also different.For example,in spring,the number of plant species at 0m sampling point is significantly higher than that at the 150 m sampling point,while in summer,the one at 0m is significantly lower than that at the 200 m sampling point(P<0.05).3.The farther the distance is from the expressway,the number of individual arthropods on the ground has changed significantly.The number of individuals with ground-active arthropods in the spring was significantly higher than 0m,60 m,and 100 m sampling sites in spring.In summer,the numberat the 60 m sampling sites is significantly lower than that at other sampling sites,and the autumn performance at 150 m is significantly higher than the 0m and 200 m sampling sites.On the whole,the Shannon-Wiener diversity index of the arthropods on the ground gradually increase with the increase of the distance from the expressway,and the Shannon-Wiener diversity index of the ground-active arthropods at 200 m is significantly higher than that of the 30 m sampling sites(P<0.05).The similarity index of ground-active arthropods is higher in spring and autumn and lower in summer,indicating that the summer highway had the greatest impact on the composition of ground-active arthropods at each sampling point.RDA analysis has shown that particle size distribution,electrical conductivity,and herbaceous vegetation differences at different sampling sites are the major environmental factors affecting ground-active arthropods.4.The ground-active arthropods functional group includes four functional groups: omnivorous,herbivorous,predatory and sacrificing.The main functional groups are predatory and herbivorous groups.The number of individuals,groups,and biomass of each functional group is affected by the freeway in different seasons.For example,in spring,the number of herbivores is significantly higher at 30 m than that at the 0m sampling point;while in summer,the biomass of herbivores at 200 m,100m sampling point is significantly higher than the 0m and 60 m sampling sites.The predatory and predatory animal biomass in autumn is significantly higher than the 30 m sampling point in the 150 m sampling point.Herbivores are negatively affected by heavy metal Cd,but also by the mechanical composition of the soil and the number of herb groups.Predator animals are also affected by the mechanical composition of the soil,but they are affected much more by soil moisture content and electrical conductivity.Comprehensive analysis shows that the ground-active arthropods community is affected by the interaction of high speed and seasonal changes.The number of individuals,the number of clusters,and the diversity of the ground-active arthropods community are fluctuating in different seasons with increasing distance from the expressway.The number of individuals,groups,and biomass of each functional group fluctuate in different ways.It has been shown that ground-active arthropods have complex response patterns under the dual influence of highway and seasonal changes.Particle size distribution,soil water content,electrical conductivity,soil Cd,herbaceous taxa,and mean height are important factors affecting the distribution of ground-active arthropods community. |
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