| Agricultural ecosystem is the main type of landscape ecosystem in the lower reaches of the Yellow River, human activity is the main interference factors of agricultural ecological system. Different landscape types, distribution of biodiversity larger differences. Landscape heterogeneity is an important feature of the landscape pattern, has a significant impact on the landscape function process. Landscape heterogeneity impact on biodiversity, landscape heterogeneity effect at the same time, the structure and function of landscape, previous research on attention of many plants, animal diversity attention slightly less.We investigated dynamics of ground-dwelling spider diversity in different habitats and their seasonal dynamic characteristics in the lower reaches of the Yellow River. The trap method was adopted to ditch, forest land, farmland, hedge four habitat of spiders after sampling, a field investigation was conducted in May, July, September, and November, 2014. Analyzed the Spider community structure and spatial distribution and seasonal dynamic. Based on the principle of landscape ecology, the technology of geographic information system, Fragstats4.1 support, with five competition models related to 12 variables to analyze the relationship between the spider communities and supergene, application of redundancy analysis in Canoco4.5(RDA), obtained the spider role appropriate scales and index and different habitat types significantly. The results as followed.(1) 2014 April, September July, November, collected 5,468 headed spider through the trap method were identified, belonging to 10 families and 19 genera 21 species. The common groups were:Lycosidae, Gnapphosidae, Linyphiidae, Thomisidae, Theridiidae. Different seasons in different habitats, species composition vary, but the common types of relatively large, the dominant species is relatively concentrated, the common species are Pardosa astrigera, Pirata piratoides, Trochosa ruricola, Alopecosa albostriata, Gnaphosa kansuensis, Hitobia unifascigera, Drassylus shaanxiensis, Erigone prominens,Ummeliata feminea, Xysticus eohippiatus, Achaearanea asiatica, Enoplognatha japonica.(2) The difference of habitat and human disturbance degree determines the composition and distribution of ground spiders in the very great degree. The spider community in the hedge is relatively stable, providing quality library resources for farmland of spider community. Farmland harvest has spider community quantity differences, hedges become spider refuge. The fall winter season woodland habitat spider total individuals tend to rise, probably due to more litter, which protect the soil animal hibernation, and litter storage capacity big, can increase the heat capacity, reduce soil heat dissipation speed, small amplitude of temperature variation. Spring ditch total habitat spider individual highest, caused by this reason is quite likely the spring cold more, and ditches happens to avoid the cold, this is an effective way to avoid the cold for the spider.(3) The spider community in the different habitats of a difference, through the SPSS double factor variance analysis found that habitat, season and their interaction on the spider community in the study area is extremely significant difference(P<0.01).(4) Between different habitat types of spider community diversity is influenced by soil factors influence is different. Between different habitat type soil factors significantly for the characteristic of spider community diversity have significant influence. In order to study the habitats of the three trench, woodland, hedges found, although there are composed of the same spider species, but affected by different soil factors in different degree.(5) There are differences between landscape heterogeneity and biodiversity at different scales, according to research the optimal scale of different objective selection. Ditch habitat, determine its in the 100 m scale and diversity of spider community had the strongest correlation, accounted for 55.8%. PR index, Shannon index of diversity(SHDI) and the spider community evenness degree of E, H’,D, Shannon dominance diversity are positively correlated, the reason may be patch richness degree is big, the landscape type diversity is conducive to the diversity of spider community. The area is the main agricultural area of production, planting wheat, habitat type is single, the current between the adjacent farmland was very close, in order to protect the biological diversity, can be a certain buffer zone is arranged in the farmland patches.(6) In this study, through the statistics of the diversity of spider community and ordering effects and environmental factors and landscape factors, reflects better the structure of spider communities in different habitats in the environment. The results found that the less human disturbance, vegetation is rich, complex ecological environment, great heterogeneity environment, species richness of spider, diversity index and evenness of high. Therefore, in agricultural production should be avoided a single large area of cultivation, keeping more around other plants or in the cultivation of farmland windbreak forest, shade trees to increase the landscape heterogeneity. Thus indirectly improve yield and food security, in the service of mankind. |
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