| Litter decomposition is an important driver of ecosystem carbon and nutrient cycling.Revealing the mechanisms of the impact of disiversity on decomposition can help to predict the potential impact of biodiversity loss on this critical ecosystem process.Compared with the individual decomposition,the mixed decomposition of multi-species frequently appears non-additive effect,i.e.the combined decomposition rate of multiple species decomposition is greater or less than the sum of the decomposition rates of the constituent species.The universality of this non-additive effect and its formation mechanism is one of the most important issues in the field of decomposition.In this study,we chose the leaf litter of four dominant tree species in the evergreen broad-leaved forest in Jinyunshan,China,using the method of litterbags to carry out the field mixed decomposition experiments in 4 random blocks.Along the species richness of 1 species gradually increased to 4 species,a total of 15 species combinations were set up to explore the species richness,community-weighted mean trait of the effect on the remaining of mass and elements.The litter bags were designed in two apertures(25 ?m and 4 mm)to explore the effects of microorganisms and soil animals on the mixed decomposition.The main results are as follows:? After 461 days of field decomposition,the average mass remaining of litter in 15 different combinations ranged from 41.46%to 78.95%in small mesh litter bag(mainly microbial participation in decomposition).Also,the average remaining of carbon(C),nitrogen(N)and phosphorus(P)were 39.91%to 77.42%,65.44%to 120.95%and 59.04%to 128.21%,respectively.And the average mass remaining of litter in 15 different combinations ranged from 39.56%to 69.40%in large mesh litter bag(all decomposers participate in the decomposition).And the average remaining of C,N and P were 35.38%to 66.95%,59.47%to 116.39%and 48.01%to 147.18%,respectively.These results showed that with the participation of soil animals,the average remaining of mass,C and N were significantly reduced by 5.38%,5.57%and 5.38%,respectively,while P increased by 2.90%.?The mass and element remaining of mixed litters had no significant correlation with species richness and trait diversity,but were mainly affected by community-weighted mean trait.Herein,the water standard holding capacity negatively correlating with the remaining of mass and elements was the most important factor.Only a small number of significant non-additive effects were observed in the mass and C and P remaining of mixed decomposition of litters,but most of the N remaining in the litter bags with large mesh showed significant negative non-additive effects.Species richness had nothing to do with the mixing effect of mass and elements,while community-weighted mean trait value was significantly related to the mixing effect of the C and P elements,and the litter characteristics diversity only significantly affected the mixing effect of the N element.? The participation of soil animals significantly promoted the mixing effect strength of mass and C remaining.The significant effect of the species richness on different microbial groups disappeared under the action of animals.In addition,significant differences between predictable and average observations of the mass remaining of the mixed decomposition also disappeared due to the participation of the animals,but the significant difference between the predicted value and the observed value of the average C remaining of each combination was attributed to soil fauna.These results suggested that soil fauna has an important regulatory effect on the factors affecting the mixed litter decomposition. |
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