Effects Of Species Richness And Functional Diversity On Decomposition Characteristics Of Mixed Litter In Stipa Grandis Community

Stipa grandis steppe is a kind of bunchgrass steppe unique to the eastern part of the Eurasian steppe region.It is the most representative grassland type in the typical steppe region of the Mongolian plateau.This study took 6 main plant species of S.grandis steppe as the research object,and aims to clarify the influence of the species richness and functional diversity of the mixed litter on the decomposition characteristics of mixed litter decomposition through establishing the leaf and root litter decomposition experiment of a single and mixed species,and determining the index of functional diversity based on the functional traits of single species.The research results have important guiding significance for predicting the true decomposition state and geochemical process of litter in the S.grandis steppe.The main results are as follows:1.During the decomposition of litter of single species,the mass residue rate of the leaf and root litter decreased with the increase of decomposition time,whichdecreased rapidly in the early stage and slowly in the later stage.The decomposition rate of leaf and root litter increased gradually with the prolongation of decomposition time,and then decreased gradually after reaching the peak value.In the decomposition process of leaf and root litter of each species,Convolvulus ammannii and Anemarrhena asphodeloides were of the fastest decomposition rate,and Cleistogenes squarrosa showed the slowest one.2.Among the 42 mixed litter combinations,36 groups of mixed litter produced non-additive effect,among which,the synergistic effect reached 33 groups,the antagonistic effect had 3 groups,and the other 6 groups produced additive effect.The additive effect in root mixed litter combination reached 27 groups,while 15 groups produced non-additive effect and mainly concentrated in different combinations of three plants,including 9 groups of synergetic cultivation and 6 groups of antagonism.The effect of non-additive effect of litter mixture on leaf was more obvious than that of root system.3.The increase in the number of plant species had a certain effect on the decomposition of leaf litter,and the decomposition rate of leaf litter increased as compared with that of single species,but the effect of plant species richness on the decomposition rate of root litter was not significant.4.The decomposition rate of leaf and root litter showed(positive or negative)correlation with the community weighted mean and functional dispersion of some morphological and chemical traits.The functional diversity of morphology and chemical traits of leaf and root litter had a close effect on the decomposition rate ofleaf and root litter.In addition,the mixed decomposition effect of leaf litter was correlated with the community weighted mean of leaf morphology and chemical traits,but there was no significant correlation between mixed decomposition effect of leaf litter and functional dispersion of each trait.There was no significant correlation between the functional diversity of root morphology and chemical traits and the mixed decomposition effect of litter.