| Soil mites are not only important contributors to soil ecosystem processes,but also connectors of material circulation and energy flow in both aboveground and underground ecosystems.They can monitor soil environmental quality and promote soil ecological balance.Therefore,the community structure characteristics of soil mites can be used as indicators of soil environmental change in ecosystems.Studying the community structure of mites in different crop soil environments in the Shibing Karst World Natural Heritage buffer zone will be of great significance for the ecological protection and sustainable development of the buffer zone.At the same time,it will also play a good role in filtering the core area of the heritage site,forming a "buffer zone ecological protection barrier".In December 2021(winter)and July 2022(summer),using soil mites as research objects,the differences in the number of families,genera,individual numbers,diversity,similarity,ecological groups of oribatid mites,and ecological groups of predatory gamasid mites in corn fields(CF),pear tree lands(PL),flue-cured tobacco fields(TF),grape fields(GF),and plum garden(PG)were analyzed,the relationship between the community structure of soil mites and different environmental factors in the study area was also discussed.The main conclusions are as follows:(1)A total of 10885 soil mites were captured in different crop environments,belonging to 3 orders,81 families and 154 genera.Oribatid mites are the main component of soil mites in the study area.Among them,1752 soil mites belonging to 21 families,41 genera of Mesostigmata,375 soil mites belonging to 6 families,7 genera of Trombidiforms,and 8758 soil mites belonging to 54 families,106 genera of Sarcoptiforms.Mesostigmata,Trombidiforms and Sarcopptiformes account for 25.93%,26.62%,16.10%,7.40%,4.55%,3.44% and 66.67%,68.83% and 80.46%of the total families,genera and individuals,respectively.A total of 1679 soil mites belonging to 108 genera and 62 families were captured in the corn fields;A total of 2585 soil mites belonging to 111 genera,66 families were captured in the pear tree lands;A total of 1563 soil mites belonging to 105 genera and 62 families were captured in the flue-cured tobacco fields;A total of 1505 soil mites belonging to 83 genera and 56 families were captured in the grape fields;A total of 3553 soil mites belonging to94 genera and 60 families were captured in plum garden.In the horizontal structure,there were significant differences in the number of families,genera,individual number and individual density of soil mites among different habitats(P<0.05).(2)In terms of time distribution,the number of families,genera,individual number and individual density of mites in the soil of the five crop environments in the study area are generally higher in winter than in summer;In terms of spatial distribution,soil mites of different crops in the study area showed surface aggregation characteristics,which was more obvious in winter than in summer;The dominant genera are distributed differently in different crops.Tectocephaus,Scheloribates,Lohmannia and Oppiella are the absolute dominant genera in the study area,and Trichogalumna,Acarus and Scutovertex can be used as biological indicators of crop soil environment in the study area.Lohmannia,Tectocephaus and Scheloribates are widely distributed in the study area,indicating that the soil ecological conditions of different crops in the study area are generally good,and the soil ecological environment of plum garden is the best.(3)There are certain differences in various parameters of soil mite community diversity,with significant seasonal changes.In a word,the diversity index and richness index of soil mites community of the five crops are as follows: pear tree lands >plum gardens>corn fields>flue-cured tobacco fields> grape fields.At the same time,the change trend of diversity index and evenness index of soil mites in the five habitats is similar,the change trend of dominance index and richness index is similar,but the change trend of the former two is opposite to the latter two;The diversity index and richness index of soil mites community in summer were higher than that in winter;The result of chord diagram shows that different crop environments in the buffer zone have different correlation strength with the composition of soil mites and the distribution of individual numbers.In general,the diversity index and richness index of pear tree lands and plum garden are higher,indicating that the number of soil mites and individuals is more abundant and the community stability is stronger.(4)The Jaccard similarity index of soil mite communities is generally medium.The similarity index of soil mites under the five crop environments in summer is between 0.41 and 0.64,indicating that they are in the range of medium dissimilarity and medium similarity;The similarity index of soil mites under five crop environments in winter is between 0.49 and 0.60,representing that the habitats are also in the range of medium dissimilarity and medium similarity;However,the similarity coefficient and two-way cluster analysis in summer and winter showed that the similarity index of soil mites in the five crop environments ranged from0.54 to 0.65,all of which were moderately similar,of which the highest degree of similarity was in the corn fields and the flue-cured tobacco fields,and the lower degree of similarity was in the pear tree lands and the grape fields,the flue-cured tobacco fields and the grape fields,and the plum garden and the corn fields.(5)The ecological groups of soil oribatid mites in different habitats are mainly O type.Combined with the percentage of MGP-I group genera and MGP-II individuals,O type is dominant in corn fields,O type in pear tree lands,O type and MP type in flue-cured tobacco fields,MP type in grape fields and O type in plum garden;Based on the analysis of the ecological groups of oribatid mites in summer,winter and summer+winter,the soil environment in the study area is maintained well and stable.The ecological groups of soil predatory gamasid mites in the five crop environments in the study area are basically of r-selection type,which indicates that the human activities in the study area have great interference;The MI index of winter,summer+winter is higher than that of summer,and that of plum garden and pear tree lands is higher than that of other three crop types;It is noteworthy that the MI index of plum garden is generally K-selection type,which is related to rich vegetation and more humus in plum garden,and the soil environment is relatively stable.(6)There are differences in the content of soil physical and chemical factors in different crop environments.TN,TP,TK,AK,SOM,NWC and BD are the main environmental factors affecting the parameters of soil mite community structure.The content of TN,TP,TK,AK and SOM in pear tree lands and plum garden is better than that in corn fields,flue-cured tobacco fields and grape fields,which shows that the planting of pear and plum is more beneficial to improve the nutrient supply of soil and improve soil quality.The correlation analysis showed that the family number,individual number and individual density of soil mites were positively correlated with TP,AK and SOM,respectively;The results of RDA further show that TN,TP,TK,AK and SOM are important explanatory variables of environmental factors;The dominant group in the study area,Scheloribates is greatly affected by AK,Oppiella is the most affected by TK,and Tectocephaus is greatly affected by SOM,TN,TP,p H and NWC.Based on the above research results,it can be seen that different crop environments in the Shibing Karst World Natural Heritage Buffer Zone are rich in soil mite resources.This study reveals the structure of soil mite communities in the buffer zone of the heritage site,providing basic data and theoretical significance for the ecological protection of different crop environments in the buffer zone.It is hoped that in the later stage,other crop types in the study area will be combined with more environmental factors,coupled with the characteristics of soil mites community and the internal mechanism of environmental factors,and the soil mites in the study area will be monitored for a long time,and the indicative role and functional groups of soil mites will be deeply explored,in order to provide more complete and scientific basic data and theoretical data for the ecological and environmental protection of the buffer zone. |
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