A Study On The Conservation Of Soil Fauna Diversity In The Black Soil Agroecosystem,Northeast China

The Northeast Black Soil Region is a region with a concentrated distribution of arable land resources in China,which is one of the three largest black soil belts in the world,with a land area of 1.03 million square kilometers.The arable land in the Northeast Black Soil Region accounts for 22.2%of the total arable land in the country,and the total annual food production accounts for about 20%of the country,which plays a pivotal role in agriculture.In recent years,a dramatic decline in soil biodiversity has occurred due to the destruction of the natural environment,with habitat fragmentation and agricultural intensification being the main factors contributing to this phenomenon.The decline in biodiversity has had a serious impact on the productivity of arable land and regional ecosystem services.Therefore,maintaining soil biodiversity and revealing the spatial distribution patterns of soil fauna is one of the key scientific issues in achieving sustainable use of black soil resources.At present studies on the spatial distribution patterns of soil fauna are mostly based on single-scale analyses,and it is difficult to accurately characterise the distribution of communities at different spatial scales research on the mechanisms of soil faunal diversity maintenance is progressing very slowly.At the same time the decline in farmland biodiversity is the result of a combination of natural and anthropogenic factors,of which irrational land use is one of the important factors in reducing soil fauna.Previous research bureaus have rarely analyzed the problem from the perspective of soil fauna,which is insufficient to fully reveal the seriousness of the problem in black soil areas.In response to the above problems,the establishment of a soil fauna ecological monitoring station and a unified monitoring and analysis of above-ground-subsurface as a means to reveal changes in soil fauna at different spatial scales and to formulate policies for the maintenance and conservation of soil fauna diversity can provide theoretical and data support for the ecological management of the black soils of Northeast China.In this research,long-term farmland in the black soil region of Northeast China was selected as the study area,and the spatial pattern distribution of soil fauna,diversity maintenance mechanisms and soil fauna conservation analysis were carried out at different spatial scales.The relationship between soil macrofaunal community distribution patterns and environmental factors at different latitudes is investigated through the Montel test,providing data support for the spatial distribution of soil faunal communities;the concept of assemblage communities is introduced into the soil faunal diversity maintenance mechanism,enabling the analysis of soil faunal communities at different spatial scales and identifying the mechanisms behind the patterns;through beta diversity decomposition,specific measures and recommendations are proposed for soil faunal reserves and key taxa.Finally,the study will link soil fauna living in different soil depths to provide policy recommendations and theoretical support for the ecological management of black soils.The main findings and conclusions of the study are as follows.(1)Spatial distribution characteristics of macrofauna in farmland at different latitudesInvestigating the horizontal and vertical structure of soil faunal communities at different latitudes is key to the maintenance and conservation of soil faunal diversity.In this study,experimental investigations were conducted at different latitudes in the black soil region of Northeast China to analyse the horizontal distribution and vertical structure of the macrofaunal communities and to reveal the distribution of macrofaunal communities in the black soil region of Northeast China.The study showed that the density,abundance and diversity index of macrofauna at different latitudes decreased with increasing soil depth.The density and abundance of macrofauna did not show a regular trend with increasing latitude.The community structure and diversity of macrofauna were influenced by latitude and soil temperature,and there were no significant differences in the community structure indices of macrofauna between different sites,suggesting that most taxa are adaptable to different latitudes in the wider environment of Northeast black soil farmland.(2)Mechanisms for maintaining ground-dwelling macro-arthropod diversity at different spatial scalesSpatial scale is an important influence on the spatial distribution of biodiversity,and understanding the mechanisms of biodiversity maintenance at different spatial scales has been the core of ecological research.In this study,we applied the assemblage community'theory to address the mechanisms of soil faunal diversity maintenance at different spatial scales,based on the distribution patterns of soil fauna in a long-term cultivated black soil farmland.The study shows that the species composition of the three areas varies at the regional scale,while at the local scale,the species composition of each sample plot is similar.The structure of assemblage communities at different spatial scales in agricultural landscapes was driven by three different sets of explanatory factors.Dispersal limitation and environmental screening have a dominant role at the regional scale;whereas interorganismal interactions are not a significant driver of above-ground macrofaunal assemblage communities at the local scale.We therefore propose a range of land management measures to enhance soil biodiversity in the region,for example,increased farmland biodiversity can be achieved by increasing the application of available nutrients and increasing land landscape heterogeneity.(3)Research on belowground sanctuaries for micro-arthropodsCompared to large mammals,soil animals are often overlooked because of their small size.However,soil animals are numerous and play an important function in the ecosystem in terms of material cycling and energy flow.In recent years,due to the decline in the quality of the black soil in the north-east,a sudden decline in soil biodiversity has occurred.It is therefore necessary to call for the establishment of soil fauna conservation stations to prevent the decline in soil fauna diversity.Based on the important role of beta diversity in ecology and conservation,we use beta diversity to select sites for soil faunal diversity conservation stations and to select taxa for conservation.In general,the higher the beta diversity,the more valuable it is for conservation.It was found that the beta diversity of soil fauna in the Black Soil Region reflected 42%of the variation in species composition between Bei'an,Hulan and Dhui,while the functional variation was as high as 89%.This indicates that there are significant differences in the functional composition of species in the three regions.Therefore,we should establish several different conservation stations in the Northeast Black Earth Region rather than larger protected areas on a regional scale.At the same time the main cause of changes in functional beta diversity is caused by high species conversion,so when carrying out soil biodiversity conservation,more attention should be paid to keystone species(species unique to each region,rather than species shared by the three regions),and less attention can be paid to species shared by the three regions as appropriate.This research makes targeted recommendations for soil biodiversity conservation in the black soil region of Northeast China,providing a scientific basis for the sustainable use of land resources in the black soil region.(4)Interaction between above-and below-ground ecosystemsThe soil fauna includes not only the large arthropods that inhabit the surface,but also some small and medium-sized soil animals that feed on debris and fungi.These soil organisms are vertically distributed at different depths in the soil.The surface soil fauna can obtain energy from photosynthesis of above-ground plants,while another part of the soil small and medium-sized soil fauna living underground decompose the plant litter,breaking down organic carbon into different states combined into the soil organic matter,forming an important cycle of the ecosystem.This above-ground-underground ecosystem interaction is of great value for the maintenance of biodiversity and conservation.The study have found that the abundance,diversity and composition of soil fauna are influenced by plant species,plant diversity and composition.We can therefore increase biodiversity in agricultural soils by creating ecological buffer zones through the planting of trees,shrubs or grasslands related to the reduction of soil erosion.At the same time,we should take proactive measures to promote the integration of different land use systems at the ecosystem level and to minimize the use of fertilizers,pesticides,herbicides and fungicides to ensure the sustainable use of biodiversity.