Diversity And Pollination Behavior Of Flower-visiting Insects In Degraded Typical Steppe With Different Enclosure Durations In Inner Mongolia

We studied the diversity,timing characteristics,frequency of flower-visiting insects,pollination behavior and influencing factors on a degraded typical grassland with three enclosure durations in Xilinguole,Inner Mongolia.Experimental treatments included plot A(enclosed in 1983),plot B(enclosed in 1996)and plot C(free grazing).the results showed that:(1)A total of 2131 individuals,183 species belonging to 7 orders and 71 families were collected from the 3 plots.1133 individuals of 154 species belonging to 7 orders and 60 families were from plot A,847 individuals of 158 species belonging to 6 orders and 158 families were from plot B,and 151 individuals of 21 species belonging to 3 orders and 13 families were from plot C.Plot A had the greatest individual number of the flower-visiting insects,plot B had the highest richness,while plot C had both the lowest individual number and richness.(2)The Shannon diversity index(3.12),Pielou evenness index(0.86)and Margalef richness index(7.16)were the highest in the plot B in July.The Berger-Parker dominance index(0.15)was the highest in plot C in June.The change trend of Shannon diversity index in different months was consistent with that of Pielou evenness index,but contrary to that of Berger-Parker dominance index.(3)The Jaccard community similarity was the highest between the plot A and plot B(0.25)and the lowest between the plot A and plot C(0.16).(4)The dominant pollinators species varied with plots and months and in flower-visiting frequency.The frequency of pollinators is inversely proportional to the residence time.Wind speed,temperature,humidity and light intensity all affect the frequency and residence time of pollinators.