| In order to understand the changes of grasshopper’s population dynamics in loess hilly-gully region of Yanan and provide more certain basis theoretical for it’s ecological restoration This study systematically investigate for characteristic of grasshopper population,which was carried on the area of ecological restoration in loess hilly-gully of Yanan.With the result of this study,we get 3396 grasshoppers which belongs to 6 families, 15 genera, 30 species.Based on studying the genera, species and diversities of grasshopper in different locations,different artificial restoration types and different restoration stages.And then this study analyzes dynamics of grasshopper populations. In the end,this study discusses the distribution of grasshopper pattern by the average density, concentration, and Fang Junbi these three indicators The results are as following:1、Dynamics of grasshopper populations in different locations Statistical analysis showed that species and genera of grasshopper is different in different location:to the number of families, genera and species distribution in different place,the most species were distributed in Bao Ta district(22)and Zhi Dan county(22),the most genera were distributed in Baota district(13) and Ganquan(13),But to the number of families which has no big difference; With the analysis of the grasshopper species diversity in different locations,the study showed that Zhidan county’s Shannon- Weiner index and diversity index are the highest, Ganquan county’s Simpson index is the highest, Yanchang county’s evenness index is the highest.2、Dynamics of grasshopper populations in different artificial restoration types The dominant species has a variety in different artificial restoration types: Callitamus abbreviatus,Oedaleus infernalis,Trilophidia annulata,Chorthippus albonemus are dominant species in artificial restoration forests; Atractomor phasinensis,Oxya adentata,Epacromius coerulipes,Oedaleus infernalis,Trilophidia annulata are dominant species in natural grassland; Atractomor phasinensis is dominant species in artificial restoration grassland; Atractomor phasinensis, Oedaleus infernalis are dominant species in the farmland. The distribution of the number of families, genera and species show : artificial recover the natural recovery of forest > grassland > grassland > farmland; The study of grasshopper species diversity shown that natural recovering grassland’s evenness index and Shannon- Weiner index are the largest,and the species richness index of artificial restoration forest is the largest, the dominance index of concentration of artificial recover grassland is the biggest. grasshopper population density is similar to the changes in number of family, genus and species. Grasshopper population in the artificial recovering forest is evenly distributed, the other three types is gathered.3、Dynamics of grasshopper populations in different restoration stage In the investigation we selected four artificial restoration of artificial recovering forest phase(5 a, 7 a, 9 a, 11 a),we get grasshoppers 753 which belongs to 6 families, 9 genera and 17 species. The result shows that the number of species is different in every restoration stage and the numbers is increasing along with the length of restoration stage’s increasing; Changes in species diversity in different recovery stages showed no significant differences, species richness and Shannon- wienner index is increasing along with the restoration stage’s increasing; Simpson advantage concentrated probability index and evenness index have no obvious change trend along with the length of restoration stage’s increasing; the grasshopper population density is increasing along with the increasing length of restoration stage.But the distribution of grasshopper showed that gathering degree is reduced along with the increasing of length of restoration stage gradually, with a declining trend.4、Dynamics of grasshopper populations In different stages of ecological restoration community succession The grasshopper species diversity is gradually rising along with the developing of community succession(succession in the farmland- grass- forest)in different stages of ecological restoration, the trend of which is belongs to the linear change. The population density of grasshopper in different ecological succession stage is increasing along with the developing of succession of farmland-grass – forest. The distribution of grasshopper populations is gather in farmland and grassland, it is evenly distributed in forest stage, and tends to distribute. randomly... |
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