| The community of soil ciliates in Qingcheng County,Gansu Province after ten years of converting cultivated lands into forestlands was studied by using non-flooded Petri dish method,observation in vivo and directing-culture counting method from April of 2015 to January of 2017.Two converted forestlands are mixed multiple-species forest and monoculture economic forest.The structure of understory plant community was investigated at the same time.Soil physic-chemical factors including soil temperature,soil water content,soil porosity,p H value,electric conductivity,soil porosity,contents of soil total nitrogen,total phosphorus,total potassium,available nitrogen,available phosphorus,available potassium and organic matter in different plots were also measured.⑴Analysis of plant community composition exhibited that a total of 35 species belonging to 2 phyla,3 classes,17 orders,21 families and 31 genera.There were 18 families,27 genera and 31 species in mixed multiple-species forest(APR)and 12 families,19 genera and 20 species in monoculture economic forest(A).It was also found that the plant species diversity of mixed forest is far higher than economic forest.⑵Test results of physic-chemical factors showed that content of soil moisture,soil porosity,organic matter and total nitrogen in restoration soils were significantly higher than that in cropland(P<0.05),but the plots APR is higher than A.Soil pH in restoration soils was decreased slightly compared to the cropland.Content of total phosphorus,available nitrogen,available phosphorus and available potassium of cropland in fertilizer seasons were significantly higher than that in restoration soils(P<0.05),but the plots APR is higher than A.The content of total potassium has no significant difference in various sampling plots(P>0.05).Cluster analysis of soil physic-chemical factors in various sampling plots indicated that the soil environmental conditions in restoration plots is different to cropland plots.⑶Analysis of soil ciliates community composition showed that 127 ciliates identified in 4 collection plots belonging to 10 classes,21 orders,34 families 52 genera.Distribution of ciliates in various collection plots indicated that 101 species distributed in plot APR,which had the most species,then 79 species distributed in plot A,62 and 49 species distributed in plot CK1,CK2,respectively,and the CK2 had the lest species.Vegetation restoration was beneficial to increase the number of families,genera and species of soil ciliates.The dominant group Colpodidade in cropland soils is substituted by Sporadotrichina in restoration soils.The number of dominant species was also increased with the vegetation restoration.Species such as Urosoma gigantean,Nassula gracilis,Colpoda cucullus,Colpoda reniformis,Colpoda colpidiopsis,Colpoda henneguyi and Colpoda inflata has a broad ecological niche in soil ecological system.Cluster analysis of species distribution in various sampling plots indicated that the distribution of soil ciliates in restoration soils is different to cropland.⑷ The correlation analysis between structural parameter of soil ciliates community and plants community indicated that the complexity of ciliates community is closely associated with the plants.The results of Redundancy analysis of environmental factors and characteristic parameters of soil ciliates community exhibited that soil organic matter,total nitrogen,soil porosity and temperature were the main driving factors for the changes of soil ciliate communities.Grey correlation analysis of soil environmental factors with the species number,density and diversity index of soil ciliates in each season showed that soil organic matter,total nitrogen,available nitrogen,soil porosity and water content were important to soil ciliates.⑸Seasonal dynamic changes of soil ciliate species number were accord with the changes of soil moisture and temperature of study area. |
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