A Preliminary Study On The Diversity And Spatial Heterogeneity Of Grasshopper Under The Disturbance Of Grazing Chicken

Interference by changing the resources and environment condition influences thestructure and dynamics of biological communities, and impacts on diversity andspatial heterogeneity pattern of communities. Diversity and spatial pattern ofbiological communities may reflect influence of interference from outside influencefactors on the impact on communities, and reveal ecological adaptation strategies ofcommunities. Grasshopper is an important biological indicator. It changes ecologicalenvironment of grassland. Since its special biological characteristics, complexcommunity structure, unique environmental sensitivity and fast reconstruction of thecommunity that be able to make a rapid response to changes in the externalenvironment. The ecological strategies of grasshopper under the influence fromoutside environment decides to if endurance or adapt influence and subsistence.Competition and adaptation for limited resources form communities’ species diversityand spatial distribution pattern. Understanding the species diversity and spatialdistribution pattern of the grasshopper is an important theoretical basis to understandthe occurrence and development of dynamic characteristics of the grasshopperpopulations, and reveal the mechanism environmental studies of grasshopper.We carried out the experiments in alpine grassland of Qilian Mountain, fromJune26to July26,2012, analyzed the characteristic of species diversity and spatialheterogeneity variation of grasshopper under grazing chicken, and studied thediversity and spatial heterogeneity of grasshopper under the different strength ofchicken interference. To provide basic data and scientific basis for the further studythe relationship between grasshopper and environment as well as effectivemanagement of grasshopper. Draws following conclusion through the research paper:(1)No animal and lightly grazed plots of vegetation community had very similar,with weak similarity between the heavy grazing plots. The aboveground biomass,average height, average coverage and richness of vegetation community abovegroundbiomass, average height, average coverage and richness decreased with the increasingof grazing intensity.(2)Dominant species in no animal and lightly grazing of vegetation communityare Potentilla acaulis, Cyperaceae, Stipa.Krylovii, Leymus secalinus, Melissitusruthenicus, Heteropappus altaicus. Dominant position of Artemisia frigida and Alliumpolyrhizum increased in middle and heavy grazing, but dominant species of Melissitus ruthenicus decreased. Height, aboveground biomass and coverage of gramineousplants decreased with the increasing of grazing intensity, Stellera chamaejasme andAllium polyrhizum increased with the increasing of grazing intensity, Artemisia frigidashowed an upside-down “V” trend.(3)No animal and lightly grazed plots of grasshopper population had very similar,with weak similarity between the heavy grazing plots. The species richness, density,diversity and evenness of grasshopper population decreased with the increasing ofgrazing intensity, but dominance increased.(4)Dominant species in no animal and lightly grazing of grasshopper populationare Pararcyptera microptera meridionalis, Bryodema miramae, Chorthippus fallax,Oedaleus decorus asiaticus. The dominant species of Chorthippus dubius increased inmiddle grazing plot. The dominant species of Euchorthippus unicolor increased inheavy grazing plot, but Bryodema miramae and Chorthippus dubius decreased.(5)The spatial pattern of grasshopper community was aggregated distribution inall plots. The variation coefficient of grasshopper community in a variety of grazingintensity were different，and spatial heterogeneity of random-component was the mainpart of the total. The nugget of grasshopper increased with increase of grazingintensity, it implied that the grasshopper community had the nugget effect in lightgrazing and no grazing. The sill of grasshopper increased with increase of grazingintensity, it implied that the total spatial heterogeneity of grasshopper communityincreased with increase of grazing intensity. Spatial heterogeneity ofrandom-component in total spatial heterogeneity in no grazing, light grazing, middlegrazing and heavy grazing were70%,67%,51%and89%, it implied that spatialautocorrelation increased with the increasing of grazing intensity. The range ofgrasshopper community in a variety of grazing intensity was within a range of32.35-89.52m, and it was heavy grazing <middle grazing <light grazing <no grazing,it implied that the distance of spatial autocorrelation of grasshopper communityincreased with the increasing of grazing intensity.(6)Along with the increasing of grazing intensity, the density of Oedaleusdecorus asiaticus showed “U” trend.The spatial pattern of Oedaleus decorus asiaticuswas aggregated distribution in all plots. The variation coefficient of Oedaleus decorusasiaticus in a variety of grazing intensity were different，and spatial heterogeneity ofrandom-component was the main part of the total. The nugget of Oedaleus decorus asiaticus increased with increase of grazing intensity, it implied that the Oedaleusdecorus asiaticus had the nugget effect in heavy grazing and no grazing. The sill ofOedaleus decorus asiaticus increased with increase of grazing intensity, it impliedthat the total spatial heterogeneity of grasshopper community increased with increaseof grazing intensity. Spatial autocorrelation increased with the increasing of grazingintensity. The range of grasshopper community in a variety of grazing intensity waswithin a range of21.86-98.34m, and it was heavy grazing <moderate grazing <lightgrazing <no grazing, it implied that the distance of spatial autocorrelation ofgrasshopper community decreased with the increasing of grazing intensity.Either the chicken directly affect grasshopper or by changing the vegetationstructure indirectly affect grasshopper under grazing interference, the ultimately aretogether act on the grasshopper communities, change the grasshopper communitycomposition and spatial disturibution, impact of grazing interference of chickenimposed on grasshopper communities exceed the impact of other environmentalfactors in the same region, become a structural factors that impact grasshopper spatialheterogeneity.