Effects Of Species Composition On Litter Production Of Typical Forests In Mid-subtropical

Forest is one of important terrestrial ecosystems,of which the subtropical forest in China is a endemic vegetation type across the world,with a surprising high species richness.As such,it is important to investigate the maintenance of diversity and its implications for ecosystem functioning in the subtropical forests in China.Litter input is a critical ecological process,involving in the biogeochemical cycle of terrestrial ecosystems,and linking the aboveground autotrophic process to the underground heterotrophic process.It plays an indispensable role in regulating the functions of the subtropical forest ecosystem.However,we know little about of how tree species identity,diversity,community composition and their combinations affect litter input in the subtropical forest.Aiming to resolve this question,a field experiment was conducted in Xingang Mountain,one of the platform of biodiversity and ecosystem function of subtropical forests in Southeast China(BEF-China),where the litter inputs in two sites(site A and site B)were collected and measured in the plots with six different tree species richnesses(i.e.,1 species,2 species,4 species,8 species,16 species and 24 species).Based on the study,we would provide theoretical and practical basis for the operation and management of forest ecosystem.The main results are as follows:(1)The annual total amount of litters was 3.321 Mg·ha^-1,among which leaf litters,debris flower and fruit litters,and branch litters accounted for 80.51%,7.06%,and 3.57%,respectively.(2)The total amount of litter and leaf litters in the plots with mixed species were significantly higher than that in the monoculture plot,and the amount of these litters increased with the increase of tree species richness.Branch litters and flower and fruit litters reached the maximum in 24 species and16 species mixed plots,respectively.Obviously,tree species richness has a positive effect on litter production.In general,the annual litter amount of most evergreen and deciduous tree species in the mixed planting plots was higher than that in the monoculture plot.(3)There was significant interactive effects between tree species richness and sampling time on litter inputs.Meanwhile,the dynamics of total litter and each component of litter in either of the two sites showed a bimodal curve.The dynamics of total and leaf litter changed in a similar way,with the two peaks appearing from April to June and from October to December,respectively.The two peaks of branch litter appeared in April and July,respectively,while the peaks of flower and fruit litter appeared from June to July and from October to December,respectively.Furthermore,the dynamics of litter inputs in most deciduous trees showed a unimodal pattern,while those in evergreen species displayed as bimodal pattern.Moreover,the peak value of litter inputs in different tree species varied with species richness,and was lower in single species plot than in mixed species plot.