| Soil fauna is the key to maintain the material circulation and energy flow in forest ecosystem.It is the indispensable important component in the soil food web and plays a special role in supporting and regulating ecosystem services.Due to the complexity and diversity of soil ecosystem in the restoration process,it is not clear how to utilize the appropriate interference pathway to promote the restoration of soil biodiversity.In view of this,this study is based on the investigation of the characteristics of soil faunal community in the secondary forest formed after 20 years being fallowed in Chinese fir(Cunninghamia lanceolate(Lamb.)Hook.)plantation(hereinafter referred to as“fallow blanks of clear-cutting Chinese fir plantation”),Chinese fir plantation and the evergreen broad-leaved forest at three different forest types in Huitong of Hunan Province.Two forest types of Chinese fir plantation and fallow blanks of clear-cutting Chinese fir plantation with obvious differences in the diversity of soil fauna community were selected as the research object.A full-factor experimental design method was used to simulate natural conditions,and three treatments were set up:Folsomia candida addition,litter control(addition/removal)and precipitation pattern change(uniform precipitation).After a year of field microscale control experiments,the effects of three regulation measures on forest soil fauna community,soil organic carbon and nutrient characteristics were systematically analyzed.The main research conclusions are as follows.1.Characteristics of soil faunal community of Chinese fir plantation,fallow blanks of clear-cutting Chinese fir plantation and secondary evergreen broad-leaved forest were investigated.Results showed that the composition of soil faunal community in the fallow blanks of clear-cutting Chinese fir plantation and secondary evergreen broad-leaved forest showed a higher similarity after 20 years being fallowed in Chinese fir plantation,among which the similarity Jaccard coefficient between the fallow blanks of clear-cutting Chinese fir plantation and secondary evergreen broad-leaved forest was 0.64,that Jaccard coefficient between the Chinese fir plantation and secondary evergreen broad-leaved forest was 0.58,and that Jaccard coefficient between the fallow blanks of clear-cutting Chinese fir plantations and secondary evergreen broad-leaved forest was 0.57.After fallow in clear-cutting forestland of Chinese fir plantation,Abundance of soil faunal community appeared significantly increase from 52 916.1 ind m-2 in Chinese fir plantation to 86 618.7 ind m-2 in the fallow blanks of clear-cutting Chinese fir plantation,that was close to 78298.4 ind m-2 in the evergreen broad-leaved forest.The Shannon diversity index increased by 25.71%from Chinese fir plantation to the fallow blanks of clear-cutting Chinese fir plantation,which reached 88.88%of the secondary evergreen broad-leaved forest.By comparing the abundance and diversity of soil fauna of the three forest types,it is obvious that the restoration rate of diversity of soil fauna is slower than that of abundance.Because the community composition,diversity and abundance characteristics of the abandoned land are closer to the secondary evergreen broad-leaved forest than the Chinese fir plantation forest,we believe that the fallow blanks of clear-cutting Chinese fir plantation promote the restoration of soil fauna.2.The paired t-test showed that the rapid increase of abundance of soil fauna community was promoted by Folsomia candida addition in two forest types.Soil organic carbon and nutrient contents did not change significantly except soil microbial biomass carbon content and microbial biomass quotient.Compared with Chinese fir plantation,the response to add Folsomia candida is more sensitive in fallow blanks of clear-cutting Chinese fir plantation.After litter addition,the abundance of soil faunal community in Chinese fir plantation increased obviously,but there was no significant change in fallow blanks of clear-cutting Chinese fir plantation.There was no significant change in diversity of soil faunal community in the two forest types.Soil organic carbon and nutrient content increased significantly.Compared with fallow blanks of clear-cutting Chinese fir plantation,the response to add litter is more sensitive in Chinese fir plantation.After litter removal,the abundance and diversity of soil faunal community in the two forest types significantly decreased.Except for the trend of soil microbial biomass carbon content and microbial quotient decreasing first and then increasing,soil organic carbon and nutrient content significantly decreased,indicating that the removal of litters accelerated the loss of soil organic carbon and nutrient.The abundance and diversity of soil fauna in the two forest types did not change significantly after precipitation pattern change.Except for the significant increase of soil microbial biomass carbon content and microbial quotitent,soil organic carbon and nutrient content decreased significantly,indicating that precipitation pattern change also promoted the loss of organic carbon and nutrient.3.Multi-factor analysis of variance showed that Folsomia candida addition,litter control and the interaction between them had significant effects on the abundance and diversity of soil animal community.Precipitation pattern change had no obvious effect on the abundance and diversity of soil faunal community,but the interaction between Folsomia candida addition and precipitation pattern change had a significant effect on the abundance and diversity of soil faunal community.Litter control and precipitation pattern change had significant effects on soil organic carbon and nutrient centent,but the interaction between Folsomia candida addition and precipitation pattern change and litter control had no significant effects on soil organic carbon and nutrient centent.In addition,according to the results of paired t-test and multi-factor analysis of variance,the significant impact of litters control on the diversity of soil faunal community was mainly reflected in the litter removal,while litter addition had no significant impact on the diversity of soil faunal community.4.Compared with the litter addition and precipitation pattern change,Folsomia candida addition has a drivinging actiont to improve the diversity and abundance of soil faunal community,stimulate the soil microbial activity and improving soil quality.It has better effect of restoration in fallow blanks of clear-cutting Chinese fir plantation,that is conducive to accelerate restoration process from fallow blanks of clear-cutting Chinese fir plantation to evergreen broad-leaved forest.So Folsomia candida addition can be treated as a soil ecosystem restoration and reconstruction of a control measure. |
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