A Study On The Insect Diversity Of Different Exclosure Period In Degraded Typical Steppe Of Inner Mongolia

In this paper,by chessboard method,the author preliminary investigated the insect community composition,community diversity and time dynamics,community stability,the relationship between insect community and environment factors in different exclosure period(enclosed for 32years,enclosed for 19years,unenclosed)on of typical degraded steppe in the Inner Mongolia Grassland.The results of study showed that as follows.(1)25020 insects specimens belonging to 8 orders,70 families were collected.The order Diptera(25 families),Hemiptera(14 familiies),Coleoptera(14 familiies),Hymenoptera(9 Families)are dominant.The dominant family of the A is Psyllidae,Cicadellidae.The dominant family of the B is Psyllidae,Membracidae.The dominant family of the C is Psyllidae,Membracidae and Cicadellidae.(2)The number of individuals in the sample is sorted that:A(9447)>B(9282)>C(6291);The richness index is the highest of A(126),C plot(107)is the lowest,the difference between three kinds of plots were significantly;The diversity index of A plot is the highest(3.8581),C plots is the lowest(2.8594),the difference bwtween A and B was not significant,C is significantly different with both Aand B;Evenness index of A plots is the highest(0.7977),C plots is the lowest(0.6119),the evenness of C was lower than A,B plot significantly;dominance index C plots is the highest(0.1395),A plot is the lowest(0.0333).The difference between three samples was significant.(3)The insect community in the plot showed obvious seasonal dynamic changes.The number of insects,species richness,diversity index and evenness index were the highest in the A sample,followed by the B plot and the lowest in the C plot.The dominance of the C species was higher than that of the A and B plots(except May).(4)In different enclosure years,the number of natural enemies group:A>B>C,the number of Phytohagous group:C>B>A;the number of Neutral insect group:C>A>B.The community stability is:A>B>C,and influenced by the seasons.(5)Analysis of insect community and environmental factors showed that plant height had the greatest impact,followed by plant cover,plant species and plant degrees.