Studies On The Structure And Dynamics Of Arthropod Community In Poplar Stand

Based on the thorough investigation,the dynamics of the arthropod communities of Poplar and interaction of main pests with its natural enemies were studied by means of community analysis,path analysis and cluster analysis.These provided theory foundation for SPM.1 The arthropod community was divided into four sub-communities,which were phytophages,predators,parasitoids and neutralities.The results were showed 58 species of arthropod belonging to 40 families and 35 species of phytophages belonging to 22 families; 19 species of predators belonging to 15 families.The relative abundance of phytophages was 0.8026.Notodontidae and Halticidae were dominant insects of phytophages.The relative abundance of predators was 0.0686.Micryphantidae and Tetragnathidae were dominant enemies of predators.Dominance and dominant concentration of total communities were 0.3020 and 0.1764 respectively.Dominance and dominant concentration of every sub-community showed parasitoids＞neutrality＞phytophages＞predators.2 The seasonal dynamics of sub-communities was in consistent with the total community;the tendency was from high to low,to high again.Hill diversity index was in relation to,individuals,dominance,dominant concentration,Pielou evenness and species richness.Hill diversity index was most relative with dominant concentration(-0.9455),species(-0.8902),Pielou evenness(0.9660) by path analysis.Principal components analysis coordinates analyzed indexes of communities;the results revealed diversity,individual number,species,species richness and diversity.were synthetic indexes of community construction.3 Diversity indexes of arthropod communities were analyzed by clustering and optimization partitions.D=1.47,Total community were divided into five stages:Ⅰ:3.21,4.25,9.23;Ⅱ:11.26,12.21;Ⅲ:10.26;Ⅳ:5.25,6.14,7.25,8.11,8.25;Ⅴ:6.25,7.11.The optimization partitions in the arthropod total communities were 3.21～4.25,5.26～8.25,9.23～10.26,11.26～12.21.The characteristic parameters of arthropod community were analyzed with the method of principal component analysis.For the three kinds of communities,the absolute values of normalized regressive coefficient of C,S,H,R had greater contribution.4 By dynamic analysis to the pests and the natural enemies of polar,there 36 species of pest which belonging to 22 families were invested.The main pest of poplar were Notodontidae and Halticidae,which numbers were 15904 and 2980.There total 22 specis of natural enemies sub-community which beloging to 16 families and the main predators were Micryphantidae and Tetragnathidae,their numbers were 884 and 804.5 The pests' dominant concentrations was obviously higher than natural enemies by dynamic analysic of dominant concentrations of the poplar pest and its natural enemy,which because the more pest species and obvious of the dominant pest species.The greater differences of dominant cocentration showed that phytophages at dominant position in the arthropod community of poplar.The low dominant concentration of natural enemy, mainly because of the more species and there were no obvious species,in other words that control of pests by natural enemies in the ecosystem of poplar was better.