Effect Of Litter Diversity And Evenness On Decomposition In Baijianghe Peatland Of Changbai Mountains,China

Peatlands make a large carbon(C)pool but their carbon sink is susceptible and labile to fluctuations in land-use and climate especially moisture conditions.Litter decomposition is effected by degradation in addition to litter quality and diversity components that’s why in peatlands litter decomposition is slow.Mixed litter decomposition studies had well documented the effects of species richness and composition,whereas the effect of evenness(relative abundance)along with pristine and drained peatland got less importance.In this study,we explored the effect of diversity and evenness(relative abundance)on decomposition at two microsites of peatland as a pristine and drained by using a litter bag technique.Four species including two bryophytes(nonvascular)species as Sphagnum flexuosum,Sphagnum magellanicum and two vascular species Potentilla fruticosa(dwarf shrub)and Carex lasiocarpa(sedge)were chosen as mono litter and 6 compositions with 3 ratios of relative abundance: M1(50%:50%),M2(30%:70%)and M3(70%:30%).Annually,mono litter results showed that mass loss(%)of vascular species(P.fruticosa and C.lasiocarpa)was significantly higher than the non-vascular species(S.flexuosum and S.magellanicum)on pristine and drained peatland.In nutrients study,vascular species(P.fruticosa and C.lasiocarpa)showed greater C and N contents in pristine and drained peatlands than non-vascular species(S.flexuosum and S.magellanicum)therefore C/N contents were lower in vascular species than non-vascular species.By using the General Linear Model(GLM),we found that diversity and evenness produce non-additive effects of litter mixing on mass loss but the direction for all the compositions was antagonistic which means that mass loss was not accelerated by litter mixing on both sites however evenness does not play a significant role in mass loss within each specific composition separately.In nutrients study,litter mixing produces non-additive effects on C content but in the case of N content(%)and C/N ratio,we found additive effects of litter mixing.After the completion of experiment,the results suggested that diversity and changes in the evenness produced an obvious effect on mass loss and nutrients but the direction of these effects were not up to our expectations which eventually means that we cannot predict litter mixture performance(mass loss % and nutrient contents %)from mono litter decomposition in a short period experiment.Moreover,diversity effects on mass loss were less visible in the drained peatland as a comparison to the pristine peatland.We recommend more exploration on how litter mixing effects litter decomposition in peatland by varying richness,composition and evenness of species on a long term basis and how these diversity factors influence ecological processes.