| The process of forest litter humification is an important link of material circulation and energy flow in terrestrial ecosystem.Humus has an important effect on improving soil physical and chemical properties and enhancing soil fertility.Soil fauna plays an important role in the process of litter humiliation,but it has been related personnel is not clear.Therefore,this study used litterbag method(excluding soil animals)to select representative vegetation typical leaf litter in the Minjiang River Basin typical ecosystems to carry out research.The typical litter species were Ajania nubigena and Carex atrofuscain in alpine meadow,Salix salturaria and Sabina paraqplesia in alpine forest,Abies faxoniana and Betula albo-sinensis in subalpine forest,Quercus baronii and Cupresus chengiana in montane forest ecotone,Campylotropisia.Delavayi and Cupressus.Chengiana in dry valley,Cryptomeria fortune and Quercus acutissima in north subtropical evergreen broad-leaved forest,Pinus massoniana and Chnnamomum longepaniculatum in central subtropical evergreen broad-leaved forest.In order to better understand the role of soil fauna on the litter humification process,and provide some theoretical basis for the soil carbon fixation mechanism in the Minjiang River Basin.The effects of soil fauna on ?log K and E4/E6 values,humus carbon composition and humification degree and humification rate of forest litter were studied from November 2013 to October 2016 in various ecosystems.During the culture period,soil fauna had a significant effect on the value of ?log K in the ecosystems of alpine forest,dry valley,mountain forest ecotone,northern subtropical evergreen broad-leaved forest and central subtropical evergreen broad-leaved forest.And there is no significant effect on the value of ?log K to other ecosystems.The soil fauna had a significant effect on E4/E6 values of litter in seven ecosystems.Soil fauna had a certain influence on the process of litter humification at different critical period ecosystems.With the increase of culture time,the more stable the structure of the humus,the simpler the molecular structure.Soil fauna had a significant effect on the litter humus carbon content in seven ecosystems.During the study period,soil fauna promoted the humus carbon content of the leaves of the A.nubigena,C.atrofusca,S.paraqplesia,C.chengiana(MFE),C.Delavayi,Q.acutissima and P.massoniana and inhibited the leaves of the S.salturaria,B.albo-sinensis,A.faxoniana,C.Delavayi,C.fortune and C.longepaniculatum.After one year of cultivation(the sample is more complete),the humus carbon content in each ecosystem is:north subtropical evergreen broad-leaved forest>alpine meadow>subalpine forest>dry valley>montaneforest ecotone>alpine forest>central subtropical evergreen broad-leaved forest.After two year of cultivation,the humus carbon content in each ecosystem is:north subtropical evergreen broad-leaved forest>central subtropical evergreen broad-leaved forest>alpine forest>montaneforest ecotone>subalpine forest>dry valley.The soil fauna had no significant effect on the content of humic acid carbon in the dry valley ecosystem,but had significant effects on other ecosystems.During the study period,soil fauna had inhibitory effect on the content of humic acid carbon in the litter of C.chengiana(MFE),and promoted the content of humic acid carbon of other leaves.Soil fauna had a significant effect on the content of fulvic acid carbon in the subalpine forest,dry valley and central subtropical evergreen broad-leaved forest,but had no significant effect on other ecosystems.During the study period,soil fauna promoted the fulvic acid carbon content of the leaves of the A.nubigena,C.atrofusca,C.chengiana(MFE),C.Delavayi,C.hengiana(DV)and C.fortuneand inhibited the leaves of the C.atrofusca,S.salturaria,S.paraqplesia,B.albo-sinensis,A.faxoniana,Q.baronii,C.fortune and P.massoniana.Soil fauna had significant effects on accumulation of humus carbon in various ecosystems.During the study period,soil fauna promoted the accumulation of humus carbon in the leaves of A nubigena,C.atrofusca,C.Delavayi,C.Cherngiana and Q.acutissima,butinhibited the leaves of S.salturaria,S.paraqplesia,B.albo-sinensis,A.faxoniana,Q.baronii,C.chengiana,C.fortune,C.longepaniculatum and P.massoniana.There was no significant effect of soil fauna on the net ccumulation of humus carbon of leaf litter in each ecosystem.The net accumulation of humus carbon in the leaves is mainly due to the trend of enrichment-degradation-enrichment-degradation-enrichment.During the whole study period,each species showed a high degree of humification.After one year of culture,the leaf litter of each species was shown as:Campylotropis delavayi(19.99-10.14%)>Cryptomeria.Fortune(9.82-7.56%)>Pinus massoniana(7.48-3.61%)>Ajania nubigena(7.02-3.3%)>Quercus acutissima(6.63-0.42%)>Abies faxoniana(6.59-2.5%)>Cupressus chengiana(MFE,5.69-1.68%)>Cupressus chengiana(DV,5.47-5.11%)>Betula albo-sinensis(5.21-4.26%)>Chnnamomum longepaniculatum(2.9-1.78%)>Quercus baronii(2.83-2.45%)>Salix salturaria(2.72-2.49%)>Sabina paraqplesia(2.26-1.16%).Soil fauna had significant effects on the humification degree and humification rate of litter in alpine forests and dry valleys.During the study period,the soil fauna promoted the humification degree of the leaves of A.nubigena,S.paraqplesia,C.chengiana(MFE),C.Delavayi,Q.acutissima and P.massoniana,and inhibited the yield of S.salturaria,S.paraqplesia,B,albo-sinensis,Q.baronii,C.chengiana(DV),C.fortune and C.longepaniculatum.During the incubation period,the soil fauna promoted the humification rate of the leaves of A.nubigena,A,faxoniana,C.chengiana(MFE),Q.acutissima and P.massoniana,and inhibited the yield ofS.salturaria,S.paraqplesia,B.albo-sinensis,Q.baronii,C.Delavayi,C.Chengiana(DV),C.fortune,C.longepaniculatum.The humification degree and humification rate of litter in each ecosystem basically reached the maximum in October of the first year.The hunification degree and humification rate are mainly manifested:The first year of the non-growing season is positive,the beginning of growth season at the first year is a negative effect,the end of the growth season at the first year is positive season,the second year of the non-growing season and the end of the growth season is negative,the second year of growth and the third year are positive effects.In summary,in the typical ecological system of the Minjiang River Basin,soil fauna have different degrees of significant on the humus process,humus carbon content,fulvic acid carbon content,humus carbon accumulation,humic carbon net accumulation,humification degree and humification Rates.The process of humiliation of litter decreased not with the increase of altitude,but also affected by the quality of litter,the climatic conditions,the vegetation type and the microenvironment.In the same ecosystem,the soil fauna had significant effect on humus carbon content,fulvic acid carbon content,humification degree and net accumulation of humus carbon in different species.These provide a theoretical basis for understanding the humicification process and soil organic carbon fixation in the typical ecosystem of Minjiang River Basin. |
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