Response Of Soil Ciliate Communities To Ecological Restoration After The Implementation Of The Conversion Of Cropland To Forest And Grassland Program

In order to understand the response of soil ciliate communities to the soil environmental changes after converting cultivated lands into forestlands,from March2014 to July 2015,the community characteristics of soil ciliates in three restoration sampling sites of different plant and two control sampling sites of Duoshi village in Tianzhu county of Gansu were studied by using non-flooded petri dish method,observation in vivo and culture direct counting method. As well as the physic-chemical factors(including pH value,soil temperature,soil water content,soil porosity,electrical conductivity,content of available phosphorus,available potassium,available nitrogen,total nitrogen,total phosphorus,total potassium and organic matter etc.)in different soil samples were investigated. The main research results are as follow:(1) With the returning of farmlands to forestlands, the soil water content,electrical conductivity, available phosphorus, total nitrogen and organic matter compared to the control sites were significantly increased. Content of available potassium and total potassium compared with the control sites was slightly increased.soil porosity and total phosphorus compared with the control sites were slightly decreased. Changes of available nitrogen content were not obvious.(2) A total of 66 plants were identified in this study,belonging to 2 phyla,3classes,19 orders,26 families and 55 genera. In the sampling site A1, Artemisia japonica was the dominant group. In the sampling site B2, Roegneria kamoji was the dominant group. Medicago ruthenica was the dominant group in site A2.According to the plant diversity index and evenness index: mixed forest(A1) > seabuckthorn forest(B1) > spruce forest(A2). And the dominance index was contrary to the species diversity and evenness index.(3) A total of 125 soil ciliate species were identified in this study,belonging to 9classes,19 orders,29 families and 34 genera.(4) The distribution of soil ciliate species in ecological restoration sites and control sites had significant differences. Cluster analysis showing,the distribution of the soil ciliate species distribution among two control soil sample were similar but had certain difference among the ecological restoration sites. After the conversion of cropland to forest,soil ciliate community tend to be complex.(5) The dominant species of soil ciliates were changed. Colpoda edaphoni,Colpoda inflate and Cohnilemebus fusiformis were the dominant ciliates in site A0.Colpoda edaphoni and Cohnilemebus fusiformis were the dominant ciliates in site B0.In the sampling site A1,Colpoda edaphoni,Colpoda inflata,Colpoda reniformis,Cohnilemebus fusiformis,Engelmanniella mobilis,Chilodonella uncinata,Euplotes muscorum,Histriculus similis and Oxytricha fallax were dominant. In the sampling site A2,Colpoda edaphoni,Colpoda inflata,Drepanomonas revoluta,Cohnilemebus fusiformis and Oxytricha fallax were dominant. In the sampling site B1,Colpoda edaphoni,Colpoda inflata,Colpoda colpidiopsi,Colpoda patella,Drepanomonas obtusa, Cohnilemebus fusiformis, Euplotes muscorum, Histriculus similis and Oxytricha fallax were dominant.(6) The correlation analysis showed species number had an obvious positive correlation with water content(p<0.05),while had a significant positive correlation with available potassium,total nitrogen and organic matter(p<0.01). The density of soil ciliate had an obvious positive correlation with available potassium and water content(p<0.05). The density of soil ciliate was mostly influenced by total nitrogen and organic matter,it had a significant positive correlation with total nitrogen and organic matter(p<0.01). The species diversity index and evenness index had an obvious positive correlation with available potassium(p<0.05), had a significant positive correlation with total nitrogen and organic matter phosphorus(p<0.01), while had an obvious negative correlation with available phosphorus(p<0.05) and the species diversity index had an obvious negative correlation with available nitrogen(p<0.05);The dominance index had an obvious positive correlation with available phosphorus(p<0.05), had an obvious negative correlation with available potassium(p<0.05), while had a significant negative correlation with organic matter and total nitrogen(p<0.01).(7) The results of redundancy analysis suggested that soil ciliates community in forestlands were great different from the control sampling sites. the content of organic matter of each sampling site was: A1 > B1> A2> B0> A0. the content of total nitrogen of each sampling site was: B1>A1 > A2> B0> A0.(8)The correlation analysis showed that the ciliate community parameters(species diversity index, dominance and evenness) is related to the plant community parameters(species diversity index, richness, dominance and evenness).While the species number and density of ciliates is related to the species number,density and coverage of plant.After the conversion of cropland to forest and grassland ecological restoration,soil environment was improved obviously, soil ciliate community composition tends to be complicated, dominant species of soil ciliates gradually increased and from r-selected species to K-selected species.Community characteristic parameters of soil ciliate was related to organic matter and total nitrogen.To sum up, returning farmland to forest ecological recovery had a significant impact on the soil ciliate community,the changes of the parameters of soil ciliate community can make a positive response to ecological restoration.