Study Of The Relation Between Grasshopper And Vegetation Community In The Upper Reaches Of Hei River

Grasshopper species spatial distribution pattern is the result of natural long-term adaptation,and a reflection ofthe relationship between grasshoppers and the environment. Grasshopperdisaster is a global biological disaster, the economic losses caused by locust disaster and thehuge influence will affect the natural ecosystem and socio-economic system. In recent years,with global climate change and the increase of extreme weather events and the inappropriatehuman activities, grasshopper disaster become increasingly rampant, therefore the study ofrelation between the occurrence and distribution of locusts and environmental factors wasreceiving more and more attention of people. At present the characteristics and spatialdistribution of grasshopper communities gradually received an in-depth research andinvestigation from the basic grasshopper species investigation and fauna graduallypenetrated into their diversity and the relationship of environmental factors, spatialdistribution pattern and factors of influence and so on. Grasshopper species spatialdistribution pattern is the result of natural long-term adaptation,grasshoppers and theenvironment, a reflection of the relationship between grasshoppers, grasshoppers is torecognize thespatial heterogeneity of grasshopper population dynamics of the occurrence anddevelopment an important theoretical basis,taking quantitative research of Heihe Riverupstream of the natural populations of grasshoppers spatial distribution pattern,analysis ofspatial distribution of dominant species of grasshoppers, grasshopper populations todetermine the spatial structure and spatial autocorrelation, for understanding the occurrenceand distribution of grasshopper environmental studies provide a theoretical basis to explain.Draws following conclusion through the research paper:(1)the spatial pattern of different age was aggregated distribution, with age, aggregationdegree turned to old dispersive larva from young aggregated larva, and scope of spatialdependence expanded gradually; The features of spatial autocorrelation trended to invertedU-shape that the peak was the forth age. The trend of spatial distribution focused inNortheast-Southeast and Northwest-Southeast and continuously increased with age, and thatthe trend of spatial distribution strengthened in Northwest-Southeast, while it weakenedgradually in Northeast-Southwest. Vertical differentiation was obvious at intermediateelevations.(2) the dominant five kinds of grasshoppers in this region’s semivariogram models are nonlinear models, showing aggregated distribution; different types of spatial dependencebetween samples of grasshoppers in the range of2.29—24.59m; in the grasshopperpopulation heterogeneity in the random part of the total due to spatial heterogeneityaccounted for15.77%—88.64%. Influenced by diet and habitat selectivity, the distributionpattern of grasshopper populations are flaky and patchy pattern of horizontal distribution intheir formation process. Scale dependence of the grasshoppers become diversified andcomplex distribution pattern of the characteristics of cross between different species ofgrasshoppers intercalation, the same kinds of grasshoppers was non-uniform spread of highand low values the overall balance of the formation of a plaque inlaid with complementarystructure, this distribution pattern reflects the grasshopper habitats and climate change on thediversity of adaptive structures.(3) the richness of grasshoppers distribute in a complex terrain of environments, indifferent topographical factors of elevation, slope, aspect, position, profile and plan.However it does not mean the distribution of grasshoppers equally affected by each factor, orhas an uniform distribution probability in the whole environmental range. The GAMmodeling indicates the distribution of grasshopper is controlled by the elevation and aspectbut not the slope as commonly reported. A map was produced in ARCGIS using a lookuptable generated in GRASP module. From this map it can be seen that grasshopper candistribute in most areas in study area, and its distribution centre locates in the west and northpart of the aspect, and the elevation region of2600-2700m.(4) the order that the density of grasshopper was influenced by topographical factors waselevation> aspect> profile> slope> plan> position. Grasshopper distribution was almostbalanced in the position plane of curvature and the gradient profile curvature, and presenteda two parabola distribution in aspect and slope,the evaluation, showing a “S” trend. On theregional distribution, there were higher density of grasshoppers in the whole regions, butthey were mainly located in the region with altitudes of2550–2650m, and mainlyconcentrated in the northwest and west asepct, which was consistent with actual observation.(5) the follow relationship of grasshopper community and vegetation communityshowed obvious regional, the follow relationship showed patch characteristics in differentaltitude scale. From the point of view of direction, in northwest-southeast upwardgrasshopper rich files space distribution showed obvious trend, showed negative correlation with vegetation richness, grasshopper density and richness showed negative correlation, therelationship of other index not obvious; in northeast-southwest upward, space distributiontrend of grasshopper density was obvious, showed positive correlation with vegetationrichness, richness and Vegetation height showed negative correlation, positive correlationwith vegetation richness, relationship of other index was not obvious.