Study On The Diversity Of Insects In Yudaokou Semiarid Steppe Of Hebei Province

From July to September 2003 and from May to June 2004, investigation of the diversity and distribution of insects was made from the Yudaokou Natural Reserve in North Hebei, got 10 orders, 122 families, 332 genera, 427 species and 18,295 specimens by means of net trap associating with plastic cup and lamp in total. The diversity of insects from the plate is studied systematically for the first time. Insect taxa, distribution, diversity and its fluctuations are studied. Diversity of insect community from different habitats is analysed, the comparability of spots is contrasted, and cluster analysis is made. The results show:1. The biology complexity and the first trophic level are poor, energy flow can not support more species and restrict niche differeniyiation of species. Insect distribution pattern looks humdrum.2. The degenerate meadow, the low and damp meadow and the Melilotus suaveolens meadow approach niche-preemtion hypothesis, their ecological environments deteriorate relatively by using the species-abundance analysis. The curve of the month community species-abundance of the protected meadow and the crested wheatgrass meadow are changeful. The protected meadow likes the transition style between niche-preemtion hypothesis and log-normal hypothesis, but approaches niche-preemtion hypothesis on a general tendency. This indicates the protected meadow is getting well, though character of original degenerate plot shows here still, the habitate shows bad. The curve of the month community species-abundance of the crested wheatgrass meadow approach log-normal hypothesis unconspicuously, whose environmental condition is better. Interference , protection from mankind and heterogeneity of plant community enhance the environmental quality and make habitat well.3. Diptera population size is bulky. Species of Coleoptera are abundant. Micro-insects occupy more proportion. The insects appear coevolution with climate and geography obviously.4. Composition of insect community and popilation size have disparate style in different niches. Species richness show: protected meadow > degenerate meadow >melilotus suaveolens meadow > crested wheatgrass meadow > low and moist meadow. Population size show: protected meadow > crested wheatgrass meadow > low and moist meadow> degenerate meadow > melilotus suaveolens meadow.5. According to the statistic of insects specimen got by trapping, quantity of species of beetles living on the ground shows: degenerate meadow > melilotus suaveolens meadow > protected meadow > crested wheatgrass meadow > low and moist meadow. The quantity of insects specimens from different plots show degenerate meadow > protected meadow > melilotus suaveolens meadow > crested wheatgrass meadow > low and moist meadow.6. According to the calculation of index, Shannon—Wiener index and Simpson index of plots show: protected meadow > crested wheatgrass meadow > melilotus suaveolens meadow > degenerate meadow > low and moist meadow. The evenness shows: protected meadow > crested wheatgrass meadow > melilotus suaveolens meadow > degenerate meadow > low and moist meadow. The dominant index shows: low and moist meadow > degenerate meadow > melilotus suaveolens meadow > crested wheatgrass meadow > protected meadow.