| Returning farmland into forest or grassland is a major ecological project in China.In order to understand the response of the communities of soil ciliates under ecological restoration to the soil environmental changes and in order to provide reference for evaluation of its ecological benefit.The community of soil ciliates in Yuzhong County,Gansu Province after twenty years of converting cultivated lands into forestlands was studied by usingnon-flooded Petridish method,observation in vivo and directing-culture counting method from March of 2016 to February of 2017.Four converted forestlands are mixed multiple-species ecological forest,mixed multiple-species economic forest,monoculture economic forest and monoculture ecological 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,contents of soil total nitrogen,total phosphorus,total potassium and organic matterin different plots were also measured.? Analysis of plant community composition exhibited that a total of 44 species belonging to 2 phyla,2 classes,21 orders,24 families and 35 genera.(1)Arborous plants 8 species,being 18.6% of total number;Gymeospermae 2 species and Dicotyledoneae 6 species.(2)Suffruticosa plants 3 species,being 6.81% of total number.(3)Herbaceous plants 33 species,being 75% of total number,Dicotyledoneae26 species was dominant groups,occupied 60.47%;Gramineae and Compositae each of them were 6 species,belong to dominant groups,occupied 27.9%.It was also foundthat theplant species diversity of mixed forestisfar higher than economic forest.The results of this study were consistent with the actual field investigation of vegetation growth.? Test results of physic-chemical factors showed that content of soil moisture,soil porosity,organic matter and total nitrogen in restoration soils were significantly higher thanthat incropland(P<0.05),butthe plots A and D is higher than B and C.Soil p H inrestoration soils was decreased slightly compared to the cropland.Content of total phosphorus of cropland in fertilizer seasons were significantly higher than that in restoration soils(P<0.05).The content of total potassium has no significant differencein various sampling plots(P>0.05).Cluster analysis of soil physic-chemicalfactorsin various sampling plots indicated that the soil environmental conditionsin restoration plotsis different to croplandplots.? Analysis of soil ciliates community composition showed that 131 ciliates identified in 5 collection plots belonging to10 classes,21 orders,38 families,55 genera.Distribution of ciliates in various collection plots indicated that 120 species distributed in plot A,which had the most species,then 101 species distributed in plot D,94 species distributed in plot C,66 species distributed in plot B,CK plot 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.Cluster analysis of species distribution in various sampling plots indicated that the distribution of soil ciliates in restoration soils is different to cropland.? 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 CAP 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.The results of Pearson analysis showed that the species number of ciliates was significantly positively correlated with the organic matter and porosity of total nitrogen content. |
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