Study On Decomposition Of 15 Common Plant Litter In Tibetan Alpine Meadow

Litter decomposition affects a series of ecological process,for example,the dynamic of soil C,nutrient cycling,soil organism community,seeding establishment and colonization,and is a vital part of ecological system,which has an important ecological significance.Researches on decomposition mainly focus on some aspects such as effects of abiotic factors(such as,irradiance,fertilization)and species diversity(richness and evenness)on litter decomposition(mass loss ratio,N and P dynamic),and non-additive and additive effects of litter mixture on decomposition in a Tibet Alpine Meadow.There are few studies about the influence of litter initial chemical traits and chemical stoichiometric ratio on decomposition.So we conducted a one-year leaf litter decomposition experiment in a Tibet Alpine Meadow,mainly to solve the following three problems: 1,which initial chemical traits and stoichiometric ratio can predict the single litter decomposition rate 2,test”the mass ratio hypothesis” 3,what is relationship between litter interaction and functional dispersion in mixture litter.We used the litter bag method and selectes 15 dominant species and common species in this region,including Elymus nutans,Kobresia capillifolia,Ligularia virgaurea,Thermopsis lanceolata,Carex kansuensis,Saussurea hieracioides,Saussurea pachyneura,Anaphalis lactea,Anemone trullifolia,Scutellaria scordifolia,Artemisia sieversiana,Anemone rivularis,Saussurea nigrescens,Aster alpinus,Gentiana straminea.The experiment was divided into two parts: the first part was single litter decomposition using 15 litter species,the second part was decomposition of litter mixtures,which were consisted of two species,three species and four species,repectively,using Elymus nutans,Kobresia capillifolia,Ligularia virgaurea and Thermopsis lanceolata.Each treatment contained five replicates and this experiment lasted for one year.Main results:(1)There were no significant relationships between the initial contents of N,P,C,lignin,C/N of leaf litter and decomposition rates.Leaf litter initial hemicellulose content,cellulose content and lignin/N had a significant relationships with decomposition rates,and explained 47.3% and 43.9%,27.2% of the variation respectively.The combination of cellulose and lignin/N explained 64.8% of the variation of litter decomposition rates.(2)Litter mixing effects on decomposition existed in the mixed litters,with the positive and negative directions.At average levels,our results supported ”the mass ratio hypothesis”.(3)Based on cellulose,FDis were negatively correlated with the actual values of interaction in mixture litters,but had no relations with absolute values.In summary,we had drawn the following conclusions: the initial hemicellulose,cellulose content and lignin/N value of leaf litter can predict the rate of litter decomposition in Tibetan alpine meadow;Our experiment on average of all mixture support " mass ratio hypothesis ",therefore it can used to predict decomposition of litter mixtures;In mixture litter,the degree of functional dispersion of the components could affect the interaction of litter.