Responses of Soil Fauna Structure and Leaf Litter Decomposition to Effective Microorganism Treatments in Da Hinggan Mountains,China

Microorganisms are nutritious resources for various soil fauna.Although soil fauna grazing affects microorganism composition and decomposition rate,the responses of soil fauna and leaf litter decomposition to added microorganism is little understood.In this study,in the coniferous and broad-leaved mixed forest of Tahe County in the northern Da Hinggan Mountains,China,three sampling sites(each has an area of 10 m2) were selected.The first two sites were sprinkled with 250 times(EM1) and 1000 times(EM2) diluted effective microorganism(EM) preparations evenly,and the third site was sprinkled with the same volume of water as a control site.The responses of soil fauna structure and leaf litter decomposition to EM treatment were conducted during three years.The results revealed that EM treatment resulted in significant increase of soil organic matter.The number of soil fauna in the EM1 and EM2 sites increased by 12.88% and 2.23% compared to the control site,and among them springtails and mites showed the highest increase.However,the groups of soil fauna in the EM1 and EM2 sites decreased by 6 and 9,respectively.And the changes in the diversity and evenness index were relatively complicated.EM treatment slowed the decomposition of broad-leaved litter,but accelerated the decomposition of coniferous litter.However,the decomposition rate of broad-leaved litter was still higher than that of coniferous litter.The results of this study suggested that the added microorganisms could help individual growth of soil fauna,and this method led to a change in the process of leaf litter decomposition.This paper did not analyze the activity of soil microorganisms,thus it is difficult to clearly explain the complex relationships among litter type,soil fauna and soil microorganisms.Further research on this subject is needed.

Leaf litter decomposition characteristics and controlling factors across two contrasting forest types

Plant leaf litter decomposition provides a source of energy and nutrients in forest ecosystems.In addition to traditional environmental factors,the degradation process of litter is also affected by plant functional traits and litter quality.However,at the community level,it is still unclear whether the relative importance of plant traits and litter quality on the litter decomposition rate is consistent.A year-long mixed leaf litter decomposition experiment in a similar environment was implemented by using the litterbag method in seven typical forest types in Dongling Mountain,Beijing,North China,including six monodominant communities dominated by Juglans mandshurica,Populus cathayana,Betula dahurica,Betula platyphylla,Pinus tabuliformis and Larix gmelinii var.principis-rupprechtii and one codominant community dominated by Fraxinus rhynchophylla,Quercus mongolica and Tilia mongolica.The results showed that there were considerable differences in the litter decomposition rate(k-rate)among the different forest types.The community weighted mean(CWM)traits of green leaves and litter quality explained 35.60%and 9.05%of the k-rate variations,respectively,and the interpretation rate of their interaction was 23.37%,indicating that the CWM traits and their interaction with litter quality are the main factors affecting the k-rate variations.In the recommended daily allowance,leaf nitrogen content,leaf dry matter content,leaf tannin content and specific leaf area were the main factors affecting the k-rate variations.Therefore,we suggest that future studies should focus on the effects of the CWM traits of green leaves on litter decomposition at the community level.

Decay stages and meteorological factors affect microbial community during leaf litter in situ decomposition

Litter microorganisms play a crucial role in the biological decomposition in forest ecosystems;however,the coupling effect of meteorological and substrate changes on it during the different stages of leaf decomposition in situ remains unclear.Hence,according to meteorological factors dynamics,a one-year field litter of Quercus wutaishanica in situ decomposition experiment was designed for four decay stages in a warm temperate forest.Microbial community composition was characterized using Illumina sequencing of fungal ITS and bacterial 16S genes.Bacterial(6.6)and fungal(3.6)Shannon indexes were the largest after 125 days’litter decomposition(October).The relative abundance of Acidobacteria after 342 days and Bacteroidetes after 125 days were 3 and 24 times higher than after 31 days,respectively.Some non-dominant species(bacteria:Firmicutes,Planctomycotes,and Verrucomicrobia;fungi:Chytridiomycota and Glomeromomycota)may be absent or present at different decomposition stages due to litter properties or meteorological factors.Chemoheterotrophy and aerobic-chemoheterotrophy were the dominant bacterial functional groups,and the dominant fungal functional groups were saprotrophs,pathotrophs,and symbiotrophs.Precipitation and relative humidity significantly affected bacteria.Temperature,sunlight intensity,and net radiation significantly affected fungi.Besides,among the relative contributions of changes in bacterial and fungal community structure,leaf litter properties alone explained the variation of 5.51%and 10.63%.Microbial diversity and decay stage directly affected the litter mass-loss rate,with meteorological factors(precipitation,relative humidity,air temperature,and sunlight intensity)being indirect.Our findings highlight the importance of microbial diversity for leaf litter decomposition and the influence of meteorological factors.

Fungal community succession on decomposing leaf litter across five phylogenetically related tree species in a subtropical forest

Fungi are an essential component of the ecosystem.They play an integral role in the decomposition of leaf litter and return nutrients to the ecosystem through nutrient cycling.They are considered as the“key players”in leaf litter decomposition,because of their ability to produce a wide range of extracellular enzymes.Time-related changes of fungal communities during leaf litter decomposition have been relatively well-investigated.However,it has not been established how the tree species,tree phylogeny,and leaf litter chemistry influence fungal communities during decomposition.Using direct observations and a culturing approach,this study compiles fungi found in freshly collected leaf litter from five phylogenetically related,native tree species in Taiwan:Celtis formosana(CF),Ficus ampelas(FA),Ficus septica(FS),Macaranga tanarius(MT),and Morus australis(MA).We investigated(i)the effects of tree species(including tree phylogeny)and leaf litter chemistry on fungal community succession,and(ii)specific patterns of fungal succession(including diversity and taxonomic community assembly)on decomposing leaf litter across the selected tree species.We hypothesized that host species and leaf litter chemistry significantly affect fungal community succession.A total of 1325 leaves(CF:275,FA:275,FS:275,MT:275 and MA:225)were collected and 236 fungal taxa were recorded(CF:48,FA:46,FS:64,MT:42 and MA:36).Tree species relationships had variable associations on the fungal communities,as even closely related tree species had strongly differing communities during decomposition.A high number of species were unique to a single tree species and may indicate‘host-specificity’to a particular leaf litter.The overlap of microfungal species in pair wise comparisons of tree species was low(7–16%),and only 1–2%of microfungal species were observed in leaves of all tree species.The percentage of occurrences of fungal communities using Hierarchical Cluster Analyses(HCA)showed that there were at least four succession stages in each tree species during decomposition.Fungal diversity increased at the beginning of each tree species leaf decay,reached peaks,and declined at the final stages.Overall,our findings demonstrate that tree species and leaf litter chemistry are important variables in determining fungal diversity and community composition in leaf litter.Referring to the establishment of fungal discoveries from this experimental design,two new families,two new genera,40 new species and 56 new host records were reported.This study provides a host-fungus database for future studies on these hosts and increases the knowledge of fungal diversity in leaf litter.

Microcosm study on fate and dynamics of mangrove tannins during leaf litter leaching

Background Mangrove tannins can participate in wetland biogeochemical cycling.However,their fate and dynamics during leaf litter leaching have yet to be elucidated in coastal aquatic environments.Methods By using a simulated microcosm experiment,changes in leaf litter mass and tannin compounds,including total phenolics(TP),extractable condensed tannins(ECT),and bound condensed tannins(BCT),were examined in the litters and leachates of four common mangrove species:Kandelia obovata(Ko),Aegiceras corniculatum(Ac),Sonneratia apetala(Sa),and Avicennia marina(Am).Results Leaching caused a notable decline in litter mass,TP,and ECT in the leaf litter of Ko,Ac,Sa,and Am,while BCT increased significantly in Ko and Ac.Loss in foliar TP was higher than in leaf litter mass,and loss in foliar ECT was higher than in TP of Ko and Ac,but Sa showed the opposite result.The temporal changes of TP and ECT concentrations in leachates followed a similar trend,with an initial increase followed by a decrease.ECT dynamics in Ko and Ac leachates correlated with their TP concentrations,while in Sa leachate,the peak ECT occurred 72 h later than its TP peak.The leachate ECT concentrations were highest in Ac,followed by Ko,and significantly lower in Sa.The peak TP and ECT proportions in leachates accounted for 9.2-23.9%and 7.7-9.4%of the total decreases in foliar TP and ECT,respectively.Conclusion During the leaching process,tannins’fate was species-specific,while the dynamics were almost similar.