| Soil fauna plays an important role in litter decomposition.However,we know little about the contribution of soil fauna to litter decomposition in different land uses.To investigate the community structures of soil fauna and the effects of soil fauna on leaf litter decomposition under different land use types in coastal areas of northern China,and to provide basic data for soil animal system research and ecosystem health assessment in this area,we studied the soil fauna under three different land uses(i.e.poplar-crop integrated system,poplar plantation,and cropland)from December 2013 to December 2014,in a coastal area of Northern Jiangsu Province.We applied chemical method(Naphthalene-remove all the soil fauna,Fosthiazate-expulsion of nematodes)and litter bags with three mesh sizes(5 mm,1 mm,and 0.01 mm,respectively)to control field experiment.Our study analyzed the community structures of soil fauna and the effects of soil fauna on leaf litter decomposition under different land uses and different treatments to quantify the contribution of various soil fauna to the decomposition of poplar leaf litter.(1)Acarina and Collembolan were the dominant genera in this area under different land uses,which constituted the body of the soil fauna community in a coastal area of Northern Jiangsu Province.The vertical distribution of the numbers and group components of soil fauna had obvious surface collection.The Simpson dominance index was highest in the cropland;the Shannon diversity index,Pielou evenness index were the highest in the poplar plantation;the Margalef abundance index were the highest in the poplar-crop integrated system.Soil fauna in the poplar-crop integrated system was characterized by the highest numbers of taxa and individuals,and highest Margalef’s diversity,which suggested that agro-forestry ecosystems may support a greater quantity,distribution of soil fauna than single-species agriculture or plantation forestry.The results revealed that when land-use changes may alter species composition and the structure of soil fauna assemblages,and moreover,human interventions may affect the diversity and evenness of soil fauna.(2)Acarina and Collembolan were the dominant genera in this area under different land uses and different treatments,which consistent with the comparison results.The individuals of soil fauna under litter bags were the highest which increased by 7.17%,the individuals of soil fauna under fosthiazate treatment was less than in control which reduced by 33.68%.The dominant genera and common groups of soil fauna were similar under different land uses and different treatments,but there were many differences between the proportions.Soil fauna in the poplar-crop integrated system was characterized by the highest numbers of taxa and individuals,and highest Margalef’s diversity under different treatments.(3)The primary mass remaining rates were CK < Fosthiazate treatment < Naphthaline treatment in the macro-mesh litterbags under different land uses and different treatments,which indicated soil fauna and Nematode play an important role in litter decomposition.The primary mass remaining rates were CK < Fosthiazate treatment < Naphthaline treatment in the meso-mesh litterbags under different land uses and different treatments,which indicated meso-and micro-fauna play an important role in litter decomposition.(4)The primary mass remaining rates were 0.01 mm(56.80 %)> 1 mm(46.43 %)> 5 mm(44.67 %),which indicated soil fauna and microbes > meso-and micro-fauna and microbes > only microbes.However soil fauna of different body sizes contribute variably to litter decomposition.The average contribution rate of meso-and micro-fauna to litter decomposition was 18.46 %,which was much higher than the contribution rate of macro-fauna to litter decomposition(3.31 %),which had extremely significant differences(P < 0.01).(5)The average contribution rate of soil fauna(Naphthalene treatments)to litter decomposition was 29.86 %,which had extremely significant differences(P < 0.01)under three different land uses.But the contribution rate of soil fauna was different in different stages of litter decomposition.(6)The average contribution rate of nematodes(Fosthiazate treatments)to litter decomposition was 4.39 %,which had no significant difference(P=0.868)under three different land uses,and no significant difference(P=0.053)under different stages of litter decomposition.But the average contribution rate of nematodes may be overvalued because of fosthiazate may impact on other the soil fauna and microbial activity. |
