Influences Of Vegetation Restoration On Soil Arthropods In Degraded Red Soil

Soil arthropods are important components of forest ecosystems,and they play a particularly significant role in the process of nutrient cycling and energy flowing.From the view of ecosystem,it is the fact that the changes of plant affect the soil arthropods.Soil arthropods alter the availability of nutrients for plant as well as structure and function of plant directly or indirectly,by their effect on the process of decomposition,and their moving ability.The interactions between soil fauna and plant has been one of the hottest topics in soil faunal ecology abroad,however,few has been mentioned in China.Soil arthropods was studied quarterly in degraded red soil,including 5 restored plantatins, i.e.a bare land(Ⅰ),a xeric mesophilous herbosa(Ⅱ),a sparse coniferous woodland(Ⅲ),a coniferous woodland(Ⅳ),a coniferous-broadleaf mixed woodland(Ⅴ) and an evergreen broadleaf forest(Ⅵ)(ⅠandⅥwere used as CK).Soil fauna,including macroarthropods and microarthropods was sampled in the above vegetations from the autumn of 2005 to the summer of 2006.Soil macroarthropods were taken in the litter,0-10cm and 10-20cm,while, soil microarthropods were taken in the litter,0-5cm and 5-10cm.In the meantime,nutrients contents in the soil and species diversity of vegetation at different restored plantations were studied too.Based on a comprehensive knowledge of the soil fauna in the degraded red soil, the effects of vegetation restored on the soil fauna were analyzed.And the relevance between plant and soil macroarthropods as well as the relevance between soil property and soil microarthropods was also studied.It will contribute to,a deep understanding of the effects of vegetation restoration on soil biodiversity and it is theoretically of great significance to further exploration of internal dynamics of soil degradation.The main findings are as follows:1.Soil macroarthropods in the degraded red soil were abundant,a total of 107 families was observed,falling into 21 orders.The dominant group was Tetramorium,accounting for 10.24%of the total;the common groups were Scarabaeidae larvae,Asilidae larvae and Formica and others,altogether making up 63.61%of the total.The main groups of microarthropods were Acarina and Collembolan,A/C value was as high as 7.6.A total of 53 families of Acarina was observed,fairing into 4 suborders(17 Prostigmata,8 Mesostigmata,27 Oribatida and 1 Astigmata),dominant families were Nanhermanniidae and Haplozetidae;common families were Ascidae,Stigmaeidae,Tarsonemidae and others.A total of 23 genus of collembolan was observed,falling into 2 suborder and 7 families,respectively,dominant genus were Folsomia,Folsomina,Sminthurinus, Onychiurus;common genus were Entomobrya,Tullbergia,Folsomides.2.Both the numbers of groups and individuals in the litter were much richer than in 0-10cm and 10-20cm.both the number of soil macroarthropods and individuals varied widely in four seasons.The number of soil macroarthropods was highest in summer (112),the second highest in spring(92) and lowest in autumn and winter(82). Individuals was highest in summer,accounting for 33.42%of the annual total,lowest in autumn,accounting for 17.42%of the annual total The dominant groups changed along with seasons.Tetramorium and Crematogaster were dominant groups in spring, Tetramorium was the only dominant group in summer.By density-groups index(DG), the seasonal fluctuations of diversity of soil macroarthropods can be represented as: summer＞spring＞autumn＞winter,however,the seasonal fluctuations of diversity of soil microarthropods can be represented as:summer＜spring＜autumn＜winter.3.With the restoration of vegetations,both the number of groups and individuals have increased,which tended to fluctuate in the different restored vegetations.In the hierarchy of order,the dominant groups changed in the different vegetations,excepting for Hymenoptera,which was dominant group in all of these vegetations.However,in the hierarchy of family or genus,dominant groups in different vegetations were different.4.Both the number of groups and individuals were highest inⅥ,they were second highest, inⅡ,ⅢandⅤ,and they were lowest inⅠ.By density-groups index(DG),the diversity of soil macroarthropods in different restored vegetations can be represented as. follows:Ⅵ＞Ⅴ＞Ⅲ＞Ⅱ＞Ⅳ＞Ⅰ.5.Based on Jaccard index and Bray-Curtis index,Soil macroarthropods in different restored vegetations can be clustered as follows:ⅠandⅥwas isolated respectively,all others were classed into one group,which showed the response of soil macroarthropods to these different restored plantations in degraded red soil.The result showed that the soil macroarthropods in the bare land was essentially distinct from those in the forested land,and the soil macroarthropods in the natural forest markedly different from those in the other forested land.In the 4 different restored plantations(Ⅴ,Ⅲ,ⅡandⅣ),there were no remarkable changes in the soil macroarthropod communities.6.The characteristics of soil mite community structure was analyzed by using individual density,number of taxon,diversity,DG index,abundance,and evenness as well as MGP analysis and MI index.The highest density was observed inⅥandⅢ,the lowest density was observed inⅠandⅣ.The same pattern was observed by using other indices.MGPⅠanalysis indicated the soil oribatida communities of all these ecosystems match the M Pattern,however,MGPⅡanalysis identified different patterns for them,ie,MP pattern forⅠ,P pattern forⅡ,O pattern forⅥ,M pattern for others. No difference was observed by MI index among these different restored plantations. These 6 communities were classed into 3 groups by using DCA analysis,ie,ⅠandⅥwas isolated respectively,all others were classed into one group,which showed the response of soil mite to these different restored plantations in degraded red soil.7.The characteristics of soil collembolan community were analyzed by using individual density,number of taxon,diversity,abundance as well as evenness index.The lowest species richness was found in the bare land and highest was found in the evergreen broadleaved forest,difference amongⅡ,Ⅲ,Ⅳ,Ⅴwas not significant.The same pattern was observed by using other indices.The Bray-Curtis between the 5 restored plantations and the evergreen broadleaf forest were high,reaching its maximum(0.99) whenⅠandⅥwere compared.This survey indicated that planting is beneficial to restoration of collembolan community in degraded red soil,although these degraded ecosystems were still in the early stages of the restoration.8.Soil macroarthropods and plant diversity were studied under different restored plantations in degraded red soil,and CCA was used to explore the distributional relationship between soil macroarthropods and plant diversity.The genus(or sites)-enviroument biplots of CCA were automatically mapped using CANOCO 4.5, and the relationships between the distribution of the species and communities with the plant diversity were clearly revealed on these biplots.The results also showed that shannon diversity of tree was the most important factor influencing the distribution of soil macroarthropods,Simpson index of herbage was major factor affecting soil macroarthropods.Common genus of evergreen broadleaf forest such as Paratrechina, Macrotermes,closely linked to high shannon diversity of herbage and high richness of tree.Common genus of xere-mesophilous herbosa such as Pericapritermes, Formica,closely linked to low Shannon diversity of shrubbery and high cover of herbage.Ubiquitous genus such as Polyrhachis,Blattella Caudel,closely linked to low Shannon diversity of tree and high Shannon diversity of herbage.CCA can be a useful tool to understand the distribution of soil macroarthropods in degraded red soil.9.The relationship between soil microarthropods and soil properties was analysed by canonical correlation analysis based on 4 groups of soil microarthropos and 9 indexes of soil properties in the paper,which respectively include Prostigmata,Mesostigmata, Oribatida,Collembola and soil organic matter,pH,moisture content,total nitrogen, available kalium Urease,Sucrase,AP,Protease aimed to find major soil factor variables affecting soil microarthropods in different restored plantations in degraded red soil.The results indicated that CoUembola,Prostigmata were affected firstly by the contents of Sucrase,total nitrogen and moisture content in soil,and Mesostigmata,Oribatida were affected by the contents of organic matters and total nitrogen in soil,while other factors had not much relation with that pattern of distribution.It was found that 13.75%and 32.71%of the variance of soil microarthropods in degraded red soil was respectively explained by the first and the second canonical variable of soil factor variable,the rest was not interpreted yet.