Spatial-temporal Dynamic Of Soil Macrofauna Communities In The Zoigêalpine Meadow

Soil fauna are the important role in terrestrial ecosystems that directly orindirectly modulate the availability of resources to other species, by causing physicalstate changes in biotic or abiotic materials. The spatial and temporal variability of soilfauna is likely to be crucial to understand soil community dynamics and food webs,especially in variable systems as alpine meadow ecosystem. In order to disclose thecompositions of taxa and functional groups, diversities of soil macrofauna communityand their Spatio-temporal variations, the alpine swampy meadow, grassland meadow,degraded meadow and sandy meadow four typical habitats in Zoigêmeadow, locatedin eastern edge of Qinghai-Tibetan, was selected and six plots in size of50m×50mwere established with permanent labels. The investigations were conducted in thesamples on April, May, July and October from2009to2011(except May in2009). Allthe individuals of soi1macrofauna found during the research period classified into2phylums,6classes,22orders,97families. Paradoxosomatidae, Doratodesmidae,Curculionidae larvae and Scarabaeidae larvae were the dominant taxonomic groupsaccounting for24.25%,21.26%,23.35%and9.31%of the total individuals of soilmacrofauna community, respectively. The dominant groups and the communitystructures of soil macrofauna in four meadows were different. Both the dominantgroups and rare groups had no significant changes, but the density of community wasincreased in the degraded process of alpine meadow. Generally, the spatial differencebetween swampy meadow and grassland meadow was small, both of which had agreat various with degraded meadow. The temporal difference of four habitats was notremarkable. The results of principal component analysis (PCA) and repeated measureANONA analysis showed that the effects of both habitat changes and temporalchanges on community density was significant (p <0.01), which manifested asdegraded meadow> swampy meadow> grassland meadow> sandy meadow andautumn (Ocotober)> summer (July)> spring (May)> winter (April), respectively. Thisshowed the impact of degradation and desertification of Zoigê alpine meadow ecosystem on soil macrofauna community density had significant seasonalcharacteristic. Soil macrofauna biomass had significant spatial and seasonal variations,performanced degraded meadow> grassland meadow> swamp meadow> sandymeadow and October> April> July> May separately, but the annual change ofbiomass was relatively stable.The richness index, Shannon index, Simpson index and Pielou index of fourcommunities had significant spatial and seasonal differences (except for Simpsonindex), and all of them in sandy meadow were the smallest. Richness index andShannon index were maximum in the degraded meadow and in July and minimum inApril. Simpson index and Pielou index were maximum in grassland meadow andminimum in2010. Simpson was maximum in the April and minimum in May, whichwas opposite to Pielou index.The biomass and density of detritivore, predator, herbivore and omnivore soilmacrofauna functional groups of four communities had significant spatial andseasonal differences, and the minimum were in sandy meadow. Detritivore andpredator soil macrofauna of degraded meadow were maximum, and maximum in Julyand minimum in April. The densities of herbivore and omnivore functional groups indegradation meadow and grassland meadow were higher than other stagesrespectivelly; both of them were higher in May and July and lower in October.Additionally, the vegetation and soil condition of the alpine meadow had strongimpact on soil macrofauna community diversities and weak impact on the communitydensity and biomass. The responses to the environmental factors varied with differentfunctional groups. The density of omnivore functional group responded significantlyto vegetation, but that of herbivore and predator functional groups respondedsignificantly to soil environmental factors and detritivore functional group respondedsignificantly to the content of potassium (K) and phosphorus (P) in soil. We found thetime lag effect of temperature and humidity on the soil macrofauna communitydensity. According to the results of correlation analysis, the temperature and humiditywere the main climate factors that affected the seasonal changes of diversities anddensity of soil macrofauna community in alpine meadow, which, however, had a weaker impact on the four functional groups of soil macrofauna. All results abovesuggested that the taxonomic compositions, individual densities, communitydiversities, biomass and density of functional groups of the soil macrofaunacommunity, in alpine meadow ecosystem on the eastern edge of Qinghai-Tibetanplateau, were sensitive to the change of habitats and seasons.