Response Of Soil Ciliate Community To Various Grazing Intensity In Swamp Meadow In Maqu, Gannan, Gansu

To obtain a better understanding of the responses of soil ciliate community tovarious grazing intensity, seasonal research of the soil ciliate community across threesampling sites (full year without grazing, seasonal grazing and full year grazing) ofswamp meadow in Maqu, Gannan, Gansu was undertaken using the non-flooded Petridish method, live observation and protargol impregnation from April2011to February2012. Investigate the responses and reasons of the soil ciliate community in variousgrazing intensity, propose a suitable grazing management system for swamp meadowin Maqu, Gannan, Gansu. Main results listed as follows.1.The results of measurement on physical and chemical factors of soil showedthat with the grazing intensity enhanced, the temperature of soil increased; the watercontent of soil decreased; the pH of soil rising slightly; the organic matter content andtotal nitrogen content of soil decreased, seasonal grazing sampling site declined byless extent than full year grazing sampling site compared with full year withoutgrazing sampling site; the total phosphorus and available phosphorus content of soilwas not signiifbcant change; the inorganic nitrogen content of soil has no obviousdifference also.2.A total of107species were identiifed in swamp meadow in Maqu, Gannan,Gansu, belonging to8classes,17orders，31families and40genera based on thetaxonomic information system of Lynn,2008.3.The community of soil ciliate during various grazing intensity was studied, themain results are as follows:The results showed that the species distribution of soil ciliate had obviousdifference in various sampling sites. The full year without grazing and seasonalgrazing sampling sites have high similarity, which have low similarity between thefull year grazing sampling site.The results of compare on community composition of soil ciliate among varioussampling sites indicated that modest seasonal grazing has little impact on the stabilityof the soil ciliates community composition, but overgrazing makes soil ciliatescommunity composition simpliifcation.The dominant group and dominant species of soil ciliates were changed during various grazing intensity. Sporadotrichida was the dominant group in the full yearwithout grazing and seasonal grazing sampling sites, whereas Colpodida was thedominant group in the full year grazing sampling site. Dominant species of soilciliates in seasonal grazing sampling site increased and complicated than full yearwithout sampling site. Dominant species in full year grazing sampling site reducedand simplify.The peaks of species numbers, species density and species diversity index wereappeared in seasonal grazing sampling site, which showed that the ciliates diversity inthis sampling site was higher，the soil environmental condition in this sampling sitewas better.With the grazing indensity enhancement, the proportion of carnivores was up andthen descended，the proportion of omnivores has a rising trend, and the proportion ofbacterivores changes not obviously.The results of study on cluster analysis of environmental factors and speciesdistribution showed that full year without grazing and seasonal grazing two samplingsites were very similar to the each other, but were minimum similar to the full yeargrazing sampling site.4.The correlation analysis between compositional parameters of soil ciliatecommunity and physical and chemical factors of soil indicated there was extremelyobvious positive correlation between species numbers and water content, soil organicmatter (p<0.01), there was obvious correlation between species numbers and totalnitrogen (p<0.05).The density was mostly inlfuenced by water content, soil organicmatter, total nitrogen and total phosphorus content, which was incorporated that therewas extremely obvious positive correlation between density and water content, soilorganic matter and total nitrogen (p<0.01)， there was obvious positive correlationbetween density and total phosphorus (p<0.05).There was extremely obvious positivecorrelation between species diversity index and water content, soil organic matter(p<0.01), there was obvious correlation between species diversity index and totalnitrogen (p<0.05)5.In conclusion, soil ciliate community in seasonal grazing sampling site showedthe highest species numbers, species density and species diversity, sort of seasonal grazing> full year without grazing> full year grazing. Consequently, according theindicator of soil ciliates on environment, seasonal grazing intensity more conducive tothe reproduction of soil ciliate community, meet the intermediate disturbancehypothesis，which is the appropriate grazing intensity in experimental conditions.