The dominant plant litter plays a crucial role in carbon(C)and nutrients cycling as well as ecosystem functions maintenance on the Qinghai-Tibet Plateau(QTP).The impact of litter decomposition of dominant plants on ed...The dominant plant litter plays a crucial role in carbon(C)and nutrients cycling as well as ecosystem functions maintenance on the Qinghai-Tibet Plateau(QTP).The impact of litter decomposition of dominant plants on edaphic parameters and grassland productivity has been extensively studied,while its decomposition processes and relevant mechanisms in this area remain poorly understood.We conducted a three-year litter decomposition experiment in the Gansu Gannan Grassland Ecosystem National Observation and Research Station,an alpine meadow ecosystem on the QTP,to investigate changes in litter enzyme activities and bacterial and fungal communities,and clarify how these critical factors regulated the decomposition of dominant plant Elymus nutans(E.nutans)litter.The results showed that cellulose and hemicellulose,which accounted for 95%of the initial lignocellulose content,were the main components in E.nutans litter decomposition.The litter enzyme activities ofβ-1,4-glucosidase(BG),β-1,4-xylosidase(BX),andβ-D-cellobiosidase(CBH)decreased with decomposition while acid phosphatase,leucine aminopeptidase,and phenol oxidase increased with decomposition.We found that both litter bacterial and fungal communities changed significantly with decomposition.Furthermore,bacterial communities shifted from copiotrophic-dominated to oligotrophic-dominated in the late stage of litter decomposition.Partial least squares path model revealed that the decomposition of E.nutans litter was mainly driven by bacterial communities and their secreted enzymes.Bacteroidota and Proteobacteria were important producers of enzymes BG,BX,and CBH,and their relative abundances were tightly positively related to the content of cellulose and hemicellulose,indicating that Bacteroidota and Proteobacteria are the main bacterial taxa of the decomposition of E.nutans litter.In conclusion,this study demonstrates that bacterial communities are the main driving forces behind the decomposition of E.nutans litter,highlighting the vital roles of bacterial communities in affecting the ecosystem functions of the QTP by regulating dominant plant litter decomposition.展开更多
Litter decomposition is the fundamental process in nutrient cycling and soil carbon（C） sequestration in terrestrial ecosystems. The global-wide increase in nitrogen（N） inputs is expected to alter litter decomposit...Litter decomposition is the fundamental process in nutrient cycling and soil carbon（C） sequestration in terrestrial ecosystems. The global-wide increase in nitrogen（N） inputs is expected to alter litter decomposition and,ultimately, affect ecosystem C storage and nutrient status. Temperate grassland ecosystems in China are usually N-deficient and particularly sensitive to the changes in exogenous N additions. In this paper, we conducted a 1,200-day in situ experiment in a typical semi-arid temperate steppe in Inner Mongolia to investigate the litter decomposition as well as the dynamics of litter C and N concentrations under three N addition levels（low N with 50 kg N/（hm2？a）（LN）, medium N with 100 kg N/（hm2？a）（MN）, and high N with 200 kg N/（hm2？a）（HN）） and three N addition forms（ammonium-N-based with 100 kg N/（hm2？a） as ammonium sulfate（AS）, nitrate-N-based with 100 kg N/（hm2？a） as sodium nitrate（SN）, and mixed-N-based with 100 kg N/（hm2？a） as calcium ammonium nitrate（CAN）） compared to control with no N addition（CK）. The results indicated that the litter mass remaining in all N treatments exhibited a similar decomposition pattern： fast decomposition within the initial 120 days, followed by a relatively slow decomposition in the remaining observation period（120–1,200 days）. The decomposition pattern in each treatment was fitted well in two split-phase models, namely, a single exponential decay model in phase I（〈398 days） and a linear decay function in phase II（≥398 days）. The three N addition levels exerted insignificant effects on litter decomposition in the early stages（〈398 days, phase I; P〉0.05）. However, MN and HN treatments inhibited litter mass loss after 398 and 746 days, respectively（P〈0.05）. AS and SN treatments exerted similar effects on litter mass remaining during the entire decomposition period（P〉0.05）. The effects of these two N addition forms differed greatly from those of CAN after 746 and 1,053 days, respectively（P〈0.05）. During the decomposition period, N concentrations in the decomposing litter increased whereas C concentrations decreased, which also led to an exponential decrease in litter C：N ratios in all treatments. No significant effects were induced by N addition levels and forms on litter C and N concentrations（P〉0.05）. Our results indicated that exogenous N additions could exhibit neutral or inhibitory effects on litter decomposition, and the inhibitory effects of N additions on litter decomposition in the final decay stages are not caused by the changes in the chemical qualities of the litter, such as endogenous N and C concentrations. These results will provide an important data basis for the simulation and prediction of C cycle processes in future N-deposition scenarios.展开更多
We used a litterbag method to investigate litter decomposition and related soil degradative enzyme activities across four seasons in a broad-leaved forest and a coniferous forest on Zijin Mountain in sub-tropical Chin...We used a litterbag method to investigate litter decomposition and related soil degradative enzyme activities across four seasons in a broad-leaved forest and a coniferous forest on Zijin Mountain in sub-tropical China. Across four seasons, we quantified litter mass losses, soil pH values, and related soil degradative enzyme activities. Litter decomposition rates differed significantly by season. Litter decomposi- tion rates of broadleaf forest leaves were higher than for coniferous for- ests needles across four seasons, and maximal differences in litter de- composition rates between the two litter types were found in spring.展开更多
Microbial functional diversity and enzymatic activities are critical to maintaining material circulation during litter decomposition in forests.Thinning,an important and widely used silvicultural treatment,changes the...Microbial functional diversity and enzymatic activities are critical to maintaining material circulation during litter decomposition in forests.Thinning,an important and widely used silvicultural treatment,changes the microclimate and promotes forest renewal.However,how thinning affects microbial functional diversity and enzymatic activities during litter decomposition remains poorly understood.We conducted thinning treatments in a Chinese fir plantation in a subtropical region of China with four levels of tree stem removal（0,30,50,and 70%）,each with three replicates,and the effects of thinning on microbial functional diversity and enzymatic activities were studied 7 years after treatment by collecting litter samples four times over a 1-year period.Microbial functional diversity and enzymatic activities were analyzed using Biolog Ecoplates（Biolog Inc.,Hayward,CA,USA）based on the utilization of 31 carbon substrates.Total microbial abundance during litter decomposition was lower after the thinning treatments than without thinning.Microbial functional diversity did not differ significantly during litter decomposition,but the types of microbial carbon-source utilization did differ significantly with the thinning treatments.Microbial cellulase and invertase activities during litter decomposition were significantly higher under the thinning treatments due to changes in the litter carbon concentration and the ratios of carbon and lignin to nitrogen.The present study demonstrated the important influence of thinning on microbial activities during litter decomposition.Moderate-intensity thinning may maximize vegetation diversity and,in turn,increase the available substrate sources for microbial organisms in litter and promote nutrient cycling in forest ecosystems.展开更多
Litter decomposition is the key process in nutrient recycling and energy flow. The present study examined the impacts of soil fauna on decomposition rates and nutrient fluxes at three succession stages of wetland in t...Litter decomposition is the key process in nutrient recycling and energy flow. The present study examined the impacts of soil fauna on decomposition rates and nutrient fluxes at three succession stages of wetland in the Sanjiang Plain, China using different mesh litterbags. The results show that in each succession stage of wetland, soil fauna can obviously increase litter decomposition rates. The average contribution of whole soil fauna to litter mass loss was 35.35%. The more complex the soil fauna group, the more significant the role of soil fauna. The average loss of three types of litter in the 4mm mesh litterbags was 0.3-4. l times that in 0.058ram ones. The decomposition function of soil fauna to litter mass changed with the wetland succession. The average contribution of soil fauna to litter loss firstly decreased from 34.96% （Carex lasiocapa） to 32.94% （Carex rneyeriana）, then increased to 38.16% （Calamagrostics angustifolia）. The contributions of soil fauna to litter decomposition rates vary according to the litter substrata, soil fauna communities and seasons. Significant effects were respectively found in August and July on C. angustifolia and C. lasiocapa, while in June and August on C. meyeriana. Total carbon （TC）, total nitrogen （TN） and total phosphorus （TP） contents and the C/N and C/P ratios of decaying litter can be influenced by soil fauna. At different wetland succession stages, the effects of soil fauna on nutrient elements also differ greatly, which shows the significant difference of in- fluencing element types and degrees. Soil fauna communities strongly influenced the TC and TP concentrations of C. meyeriana litter, and TP content of C. lasiocapa. Our results indicate that soil fauna have important effects on litter decomposition and this influence will vary with the wetland succession and seasonal variation.展开更多
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 mi...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.展开更多
Forests and grasslands in arid and semi-arid regions receive high-intensity ultraviolet（UV） radiation year-round. However, how the UV radiation affects the litter decomposition on the forest floor remains unclear. H...Forests and grasslands in arid and semi-arid regions receive high-intensity ultraviolet（UV） radiation year-round. However, how the UV radiation affects the litter decomposition on the forest floor remains unclear. Here, we conducted a field-based experiment in 2011 in the southeastern Horqin Sandy Land, Northeast China, to investigate the effects of UV radiation, litter layer thickness, and their interaction on the mass loss and chemical properties of decomposing litter from Xiaozhuan poplar（Populus × xiaozhuanica） and Mongolian pine（Pinus sylvestris var. mongolica） plantation trees. We found that UV radiation accelerated the decomposition rates of both the Xiaozhuan poplar litter and Mongolian pine litter. For both species, the thick-layered litter had a lower mass loss than the thin-layered litter. The interaction between UV radiation and litter layer thickness significantly affected the litter mass loss of both tree species. However, the effects of UV radiation on the chemical properties of decomposing litter differed between the two species, which may be attributed to the contrasting initial leaf litter chemical properties and morphology. UV radiation mostly had positive effects on the lignin concentration and lignin/N ratio of Xiaozhuan poplar litter, while it had negative effects on the N concentration of Mongolian pine litter. Moreover, litter layer thickness and its interaction with UV radiation showed mostly positive effects on the N concentration and lignin/N ratio of Xiaozhuan poplar litter and the ratios of C/N and lignin/N of Mongolian pine litter, and mostly negative effects on the C/N ratio of Xiaozhuan poplar litter and the N concentration of Mongolian pine litter. Together, these results reveal the important roles played by UV radiation and litter layer thickness in the process of litter decomposition in this semi-arid region, and highlight how changes in the litter layer thickness can exert strong influences on the photodegradation of litter in tree plantations.展开更多
Nitrogen(N)addition has profound impacts on litter-mediated nutrient cycling.Numerous studies have reported different effects of N addition on litter decomposition,exhibiting positive,negative,or neutral effects.Previ...Nitrogen(N)addition has profound impacts on litter-mediated nutrient cycling.Numerous studies have reported different effects of N addition on litter decomposition,exhibiting positive,negative,or neutral effects.Previous meta-analysis of litter decomposition under N addition was mainly based on a small number of samples to allow comparisons among ecosystem types.This study presents the results of a meta-analysis incorporating data from 53 published studies(including 617 observations)across forests,grasslands,wetlands,and croplands in China,to investigate how environmental and experimental factors impact the effects of N addition on litter decomposition.Averaged across all of the studies,N addition significantly slows litter decomposition by 7.02%.Considering ecosystem types,N addition significantly accelerates litter decomposition by 3.70%and 11.22%in grasslands and wetlands,respectively,clearly inhibits litter decomposition by 14.53%in forests,and has no significant effects on litter decomposition in croplands.Regarding the accelerated litter decomposition rate in grasslands due to N addition,litter decomposition rate increases slightly with increasing rates of N addition.However,N addition slows litter decomposition in forests,but litter decomposition is at a significantly increasing rate with increasing amounts of N addition.The responses of litter decomposition to N addition are also influenced by the forms of N addition,experiential duration of N addition,humidity index,litter quality,and soil pH.In summary,N addition alters litter decomposition rate,but the direction and magnitude of the response are affected by the forms of N addition,the rate of N addition,ambient N deposition,experimental duration,and climate factors.Our study highlights the contrasting effects of N addition on litter decomposition in forests and grasslands.This finding could be used in biogeochemical models to better evaluate ecosystem carbon cycling under increasing N deposition due to the differential responses of litter decomposition to N addition rates and ecosystem types.展开更多
The decomposition of plant litter is a key process of litter decomposition to global climate warming in plateau in the flows of energy and nutrients in ecosystems. However, the response wetlands remains largely unknow...The decomposition of plant litter is a key process of litter decomposition to global climate warming in plateau in the flows of energy and nutrients in ecosystems. However, the response wetlands remains largely unknown. In this study, we conducted a one-year litter decomposition experiment along an elevation gradient from 1891 m to 3260 m on the Yurman Plateau of Southwest China, using different litter types to determine the influences of climate change, litter quality and microenvironment on the decomposition rate. The results showed that the average decomposition rate （K） increased from 0.608 to 1.152, and the temperature sensitivity of litter mass losses was approximately 4.98%/℃ along the declining elevation gradient. Based on a correlation analysis, N concentrations and C ： N ratios in the litter were the best predictors of the decomposition rate, with significantly positive and negative correlations, respectively. Additionally, the cumulative effects of decomposition were clearly observed in the mixtures of Scirpus tabernaemontani and Zizania caduciflora. Moreover, the litter decomposition rate in the water was higher than that in the sediment, especially in high-elevation areas where the microenvironment was significantly affected by temperature. These results suggest that future climate warming will have significant impacts on plateau wetlands, which have important fimctions in biogeochemical cycling in cold highland ecosystems.展开更多
Litter decomposition is an important component of the nutrient recycling process and is highly sensitive to climate change.However,the impacts of warming and increased precipitation on litter decomposition have not be...Litter decomposition is an important component of the nutrient recycling process and is highly sensitive to climate change.However,the impacts of warming and increased precipitation on litter decomposition have not been well studied,especially in the alpine grassland of Tianshan Mountains.We conducted a manipulative warming and increased precipitation experiment combined with different grassland types to examine the impact of litter quality and climate change on the litter decomposition rate based on three dominant species(Astragalus mongholicus,Potentilla anserina,and Festuca ovina)in Tianshan Mountains from 2019 to 2021.The results of this study indicated there were significant differences in litter quality,specific leaf area,and leaf dry matter content.In addition,litter quality exerted significant effects on litter decomposition,and the litter decomposition rate varied in different grassland types.Increased precipitation significantly accelerated the litter decomposition of P.anserina;however,it had no significant effect on the litter decomposition of A.mongholicus and F.ovina.However,warming consistently decreased the litter decomposition rate,with the strongest impact on the litter decomposition of F.ovina.There was a significant interaction between increased precipitation and litter type,but there was no significant interaction between warming and litter type.These results indicated that warming and increased precipitation significantly influenced litter decomposition;however,the strength was dependent on litter quality.In addition,soil water content played a crucial role in regulating litter decomposition in different grassland types.Moreover,we found that the litter decomposition rate exhibited a hump-shaped or linear response to the increase of soil water content.Our study emphasizes that ongoing climate change significantly altered litter decomposition in the alpine grassland,which is of great significance for understanding the nutrient supply and turnover of litter.展开更多
During the past two centuries, global changes (i.e., enhanced nitrogen deposition) have exerted profound effects on ecological processes of steppe ecosystems. We used litterbag method and mixed litters of three differ...During the past two centuries, global changes (i.e., enhanced nitrogen deposition) have exerted profound effects on ecological processes of steppe ecosystems. We used litterbag method and mixed litters of three different plant species tissues (Stipa baicalensis: Sb, Leymus chinensis: Lc and Artemisia frigid: Af), endemic to Stipa baicalensis Steppe, and measured the mass loss of mixtures over 417 days under the N addition treatment. We studied the effect of N addition (N0: no N addition;N15: 1.5 g N/m<sup>2</sup>·a;N30: 3.0 g N/m<sup>2</sup>·a;N50: 5.0 g N/m<sup>2</sup>·a;N100: 10.0 g N/m<sup>2</sup>·a;N150: 15.0 g N/m<sup>2</sup>·a) on the rate of mixed litter decomposition and nutrient dynamics change. The decomposition constant (k) of leaf mixtures was higher than that of root mixtures. The k values of leaf mixed combinations were 0.880 (Sb + Lc), 1.231 (Lc + Af), 1.027 (Sb + Lc + Af), respectively. The k value of stem was 0.806 (Lc + Af) and the root mixed combinations were 0.665 (Sb + Lc), 0.979 (Lc + Af) and 1.164 (Sb + Lc + Af), respectively. The results indicated that N addition had significantly effect on the mixed litter decomposition and nutrient releasing. The rate of plant tissues litter decomposition had different response to N addition. In the context of N addition, litter decomposition rate and nutrient dynamics were changed by synthetic effect of decaying time, specie types and N addition dose. Our findings suggested that prairie plants may adapt to environmental change by adjusting litter quality, thus retaining the stability of the steppe ecosystem.展开更多
Soil fauna decompose litter, whereas land use changes may significantly alter the composition and structure of soil fauna assemblages. However, little is known of the effects of land-use on the contribution of soil fa...Soil fauna decompose litter, whereas land use changes may significantly alter the composition and structure of soil fauna assemblages. However, little is known of the effects of land-use on the contribution of soil fauna to litter decomposition. We studied the impacts of soil fauna on the decomposition of litter from poplar trees under three different land uses （i.e. poplar-crop integrated system, poplar plantation, and cropland）, from December 2013 to December 2014, in a coastal area of Northern Jiangsu Province. We collected litter samples in litterbags with three mesh sizes （5, 1 and 0. 01 mm, respectively） to quantify the contribution of various soil fauna to the decomposition of poplar leaf litter. Litter decomposition rates differed significantly by land use and were highest in the cropland, intermediate in the poplar-crop integrated system, and lowest in the poplar plantation. Soil fauna in the poplar-crop integrated system was characterized by the highest numbers of taxa and individuals, and highest Margalef＇s diversity, which suggested that agro-forestry ecosystems may support a greater quantity, distribution, and biodiversity of soil fauna than can single-species agriculture or plantation forestry. The individuals and groups of soil fauna in the macro-mesh litterbags were higher than in the meso-mesh litterbags underthe same land use types. The average contribution rate of meso- and micro-fauna to litter decomposition was 18.46%, which was higher than the contribution rate of macro-fauna （3.31%）. The percentage of remaining litter mass was inversely related to the density of the soil fauna （P 〈 0.05） in poplar plantations; however, was unrelated in the poplar-crop integrated system and cropland. This may have been the result of anthropogenic interference in poplar-crop integrated systems and croplands. Our study suggested that when land-use change alters vegetation types, it can affect species composition and the structure of soil fauna assemblages, which, in turn, affects litter decomposition.展开更多
Based on the introduction of concept of forest litter, changes in the amount of forest litter with climate zone, elevation, forest type and age of stand were analyzed, and then the decomposition of forest litter was d...Based on the introduction of concept of forest litter, changes in the amount of forest litter with climate zone, elevation, forest type and age of stand were analyzed, and then the decomposition of forest litter was discussed.展开更多
Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) monoculture plantations account for 17.4% of the total plantation area in China. The decomposition of Chinese fir litter plays a fundamental role in maintaining nutr...Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) monoculture plantations account for 17.4% of the total plantation area in China. The decomposition of Chinese fir litter plays a fundamental role in maintaining nutrient cycling and soil fertility in these plantations. Here, we conducted a continental synthesis based on 64 studies to estimate the mass loss and release rates of carbon (C) and nutrients (including nitrogen (N), phosphorous (P), potassium (K), calcium (Ca) and magnesium (Mg)) during the first year of Chinese fir litter decomposition. The average mass loss rates of needle, twig, root and cone litter were 0.503, 0.319, 0.551 and 0.372 year^(-1), respectively. The decomposition rates of C and cellulose for needle litter were 0.649 and 0.801 year^(-1), respectively, while those of K, Ca and Mg were 2.27, 0.852 and 0.551 year^(-1), respectively. Decomposition rates were strongly influenced by mean annual temperature, soil N concentration and the initial C/N ratio of the litter. Climate warming and elevated ultraviolet-B radiation accelerated mass loss of Chinese fir litter, while increased N deposition and acid rain reduced it. However, elevated N deposition facilitated nutrient release from decomposing Chinese fir litter. These results provided a comprehensive assessment of Chinese fir litter decomposition, which is crucial for understanding soil biogeochemical cycles and improving soil fertility in Chinese fir plantations under global change scenarios.展开更多
Cover cropping is a diversifying agricultural practice that can improve soil structure and function by altering the underground litter diversity and soil microbial communities.Here,we tested how a wheat cover crop alt...Cover cropping is a diversifying agricultural practice that can improve soil structure and function by altering the underground litter diversity and soil microbial communities.Here,we tested how a wheat cover crop alters the decomposition of cucumber root litter.A three-year greenhouse litterbag decomposition experiment showed that a wheat cover crop accelerates the decomposition of cucumber root litter.A microcosm litterbag experiment further showed that wheat litter and the soil microbial community could improve cucumber root litter decomposition.Moreover,the wheat cover crop altered the abundances and diversities of soil bacterial and fungal communities,and enriched several putative keystone operational taxonomic units(OTUs),such as Bacillus sp.OTU1837 and Mortierella sp.OTU1236,that were positively related to the mass loss of cucumber root litter.The representative bacterial and fungal strains B186 and M3 were isolated and cultured.In vitro decomposition tests demonstrated that both B186 and M3 had cucumber root litter decomposition activity and a stronger effect was found when they were co-incubated.Overall,a wheat cover crop accelerated cucumber root litter decomposition by altering the soil microbial communities,particularly by stimulating certain putative keystone taxa,which provides a theoretical basis for using cover crops to promote sustainable agricultural development.展开更多
Background The forest floor humus layer is an important carbon pool and serves as a key interface that influences forest soil carbon and nutrient cycling,especially in temperate and boreal forests.Over the past decade...Background The forest floor humus layer is an important carbon pool and serves as a key interface that influences forest soil carbon and nutrient cycling,especially in temperate and boreal forests.Over the past decades,China has implemented numerous forestry ecological programs,leading to an increasing quantity of forest floor litter and the formation of humus layers,which has altered the interface between aboveground litter and surface soil.Our previous study revealed that these alterations affect the litter decomposition rate;however,it is still unclear how the litter decomposition process changes,how nutrients are released or imported and the extent to which these changes depend on the humus layer.Results In this study,we used a 535-day in situ litterbag experiment to monitor the litter decomposition process and nutrient variations under forest floor humus layer removal in a Pinus sylvestris var.mongolica plantation in Northeast China.The results revealed that the litter decomposed quickly when a forest floor humus layer was present,with the decomposition rate constant(k value)increasing from 0.122 to 0.328.Accordingly,during decomposition,the litter C,N and P concentrations increased,whereas their contents varied only slightly(with the exception of the litter P content,which decreased significantly)compared with those in the treatment where the humus layer was removed.However,both the litter C and N contents decreased,whereas the litter P content increased significantly compared with the initial litter content.Moreover,the litter C:N,C:P and N:P ratios decreased significantly during decomposition.In addition,the microbial community diversity of the litter showed no significant change,whereas the relative abundances of several major fungal and bacterial taxa at the phylum and genus levels varied significantly.Furthermore,redundancy analysis revealed effective relationships among the k values,chemical traits and microbial communities,and the least squares method suggested that the C,P and C:P ratios of the litter were significantly correlated with the litter decomposition rate.Conclusions These results enhance our understanding of the role of the humus layer in forest soil-plant carbon and nutrient cycling and should be considered in carbon cycle models in the future.展开更多
Background The prevalence of understory removal and anthropogenic nitrogen(N)deposition has significantly altered the ecological processes of forest ecosystems at both regional and global scales.However,it remains a p...Background The prevalence of understory removal and anthropogenic nitrogen(N)deposition has significantly altered the ecological processes of forest ecosystems at both regional and global scales.However,it remains a pressing challenge to understand how N deposition and understory removal affect leaf nutrient dynamics,nutrient resorption,litter decomposition,and their linkages for better managing forest ecosystems under nutrient imbalances induced by N enrichment.To address this research gap,a field manipulation experiment was carried out in a subtropical Cunninghamia lanceolata plantation with four treatments including:control(CK),canopy N addition(CN),understory removal(UR),and canopy N addition plus understory removal(CN×UR).Green and senesced leaf N and phosphorus(P)concentrations,N and P resorption efficiencies,litter decomposition,and their correlations were measured.Results The results revealed that the average N concentrations of green early and late leaves in UR were increased by 6.61 and 18.89%compared to CK.UR had the highest whereas CN had the lowest P concentrations in green leaves across the two sampling seasons.Following this,UR,leaf type,season,and their interactions significantly affected leaf N,P,and N:P(P<0.05).The highest leaf N resorption(32.68%)and P resorption efficiencies(63.96%)were recorded in UR.Litter decomposition was significantly retarded in UR(P<0.01)relative to CN.The regression analysis demonstrated that leaf nutrient status was significantly interconnected with leaf nutrient resorption efficiencies.In addition,leaf nutrient dynamics were strongly correlated with litter nutrients,indicating that both were coupled.Conclusion These findings can deepen our knowledge of biogeochemical cycling and reveal contrasting nutrientacquisition strategies on N and P limitation in response to UR and CN.Considering the P limitation,it is important to note that P was resorbed more efficiently,illustrating a remarkable nutrient preservation approach for nutrientlimitations.Resorption may be a crucial mechanism for keeping nutrients in these forests,so better understory management practices are required to prevent reliance on external nutrient pools.Overall,this study sheds meaningful insights into the ability of forest adaptation in response to global climatic change.展开更多
Climate warming has intensified the global hydrological cycle,amplifying the differences in precipitation and soil moisture between arid and humid areas.Such a change under regional drought may alter nitrogen(N)and ph...Climate warming has intensified the global hydrological cycle,amplifying the differences in precipitation and soil moisture between arid and humid areas.Such a change under regional drought may alter nitrogen(N)and phosphorus(P)releases during litter decomposition in terrestrial ecosystems,but how these biogeochemical processes respond to drought differently between arid and humid areas remains unclear.Here,we compiled 259 and 138 paired observations(with and without drought conditions)to assess the global variations in the drought effects on N and P releases during litter decomposition between arid(aridity index<0.5)and humid(aridity index>0.5)areas.Litter N release increased under drought in both arid(0.35%)and humid(3.62%)areas,and P release decreased by 7.32%in arid areas but increased by 2.22%in humid areas under drought.These changes in N and P releases from decomposing litter were positively correlated with drought duration in arid areas,dependent on microclimate,edaphic factors,and litter quality.Our findings highlight the contrasting effects of drought on litter N and P releases between arid and humid ecosystems,and this differential influence will greatly improve our capability to evaluate and forecast nutrient cycling during litter decomposition under different precipitation patterns.展开更多
Aims We aim to construct a comprehensive global database of litter decomposition rate(k value)estimated by surface floor litterbags,and investigate the direct and indirect effects of impact factors such as geographic ...Aims We aim to construct a comprehensive global database of litter decomposition rate(k value)estimated by surface floor litterbags,and investigate the direct and indirect effects of impact factors such as geographic factors(latitude and altitude),climatic factors(mean annual tempePlrature,MAT;mean annual precipitation,MAP)and litter quality factors(the contents of N,P,K,Ca,Mg and C:N ratio,lignin:N ratio)on litter decomposition.Methods We compiled a large data set of litter decomposition rates(k values)from 110 research sites and conducted simple,multiple regression and path analyses to explore the relationship between the k values and impact factors at the global scale.Important findings The k values tended to decrease with latitude(LAT)and lignin content(LIGN)of litter but increased with temperature,precipitation and nutrient concentrations at the large spatial scale.Single factor such as climate,litter quality and geographic variable could not explain litter decomposition rates well.However,the combination of total nutrient(TN)elements and C:N accounted for 70.2%of the variation in the litter decomposition rates.The combination of LAT,MAT,C:N and TN accounted for 87.54%of the variation in the litter decomposition rates.These results indicate that litter quality is the most important direct regulator of litter decomposition at the global scale.This data synthesis revealed significant relationships between litter decomposition rates and the combination of climatic factor(MAT)and litter quality(C:N,TN).The global-scale empirical relationships developed here are useful for a better understanding and modeling of the effects of litter quality and climatic factors on litter decomposition rates.展开更多
Dynamical patterns of mineral elements during decomposition processes were investigated for seven common canopy species in a subtropical evergreen broad-leaved forest by means of litterbag technique over 2 years. The ...Dynamical patterns of mineral elements during decomposition processes were investigated for seven common canopy species in a subtropical evergreen broad-leaved forest by means of litterbag technique over 2 years. The species studied are representative for the vegetation in the study area and differed significantly in chemical qualities of their litter. No significant relationships were found between decomposition rate （percentage dry mass remaining and decomposition constant k） and initial element cuncentrations.However, there were significant correlations betweeu the percentage of dry mass remaining and the mineral element concentrations in the remaining litter for most cases. The rank of the element mobility in decomposition process was as follows： Na = K 〉 Mg ≥ Ca 〉 N ≥ Mn ≥ Zn ≥ P 〉 Cu 〉〉 Al 〉〉 Fe. Concentrations of K and Na decreased in all species as decomposition proceeded. Calcium and Mg also decreased in concentrntion but with a temporal increase in the initial phase of decomposition, while the concentrations of other elements （Zn, Cu, AL and Fei increased for all species with exception of Mn which revealed a different pattern in different species. In most species, microelements （Cu, Al, and Fe） significantly increased in absolute amounts at the end of the litterbag incubation, which could be ascribed to a lange extent to the mechanism of abiotic fixation to humic substances rather than biological immobilization.展开更多
基金funded by the National Natural Science Foundation of China(31870435)the European Union's Marie Sklodowska-Curie Action Postdoctoral Fellowship(101061660)the China Scholarship Council(202106180060).
文摘The dominant plant litter plays a crucial role in carbon(C)and nutrients cycling as well as ecosystem functions maintenance on the Qinghai-Tibet Plateau(QTP).The impact of litter decomposition of dominant plants on edaphic parameters and grassland productivity has been extensively studied,while its decomposition processes and relevant mechanisms in this area remain poorly understood.We conducted a three-year litter decomposition experiment in the Gansu Gannan Grassland Ecosystem National Observation and Research Station,an alpine meadow ecosystem on the QTP,to investigate changes in litter enzyme activities and bacterial and fungal communities,and clarify how these critical factors regulated the decomposition of dominant plant Elymus nutans(E.nutans)litter.The results showed that cellulose and hemicellulose,which accounted for 95%of the initial lignocellulose content,were the main components in E.nutans litter decomposition.The litter enzyme activities ofβ-1,4-glucosidase(BG),β-1,4-xylosidase(BX),andβ-D-cellobiosidase(CBH)decreased with decomposition while acid phosphatase,leucine aminopeptidase,and phenol oxidase increased with decomposition.We found that both litter bacterial and fungal communities changed significantly with decomposition.Furthermore,bacterial communities shifted from copiotrophic-dominated to oligotrophic-dominated in the late stage of litter decomposition.Partial least squares path model revealed that the decomposition of E.nutans litter was mainly driven by bacterial communities and their secreted enzymes.Bacteroidota and Proteobacteria were important producers of enzymes BG,BX,and CBH,and their relative abundances were tightly positively related to the content of cellulose and hemicellulose,indicating that Bacteroidota and Proteobacteria are the main bacterial taxa of the decomposition of E.nutans litter.In conclusion,this study demonstrates that bacterial communities are the main driving forces behind the decomposition of E.nutans litter,highlighting the vital roles of bacterial communities in affecting the ecosystem functions of the QTP by regulating dominant plant litter decomposition.
基金funded by the National Natural Science Foundation of China (41073061, 41203054, 40730105, 40973057)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-EW-302)
文摘Litter decomposition is the fundamental process in nutrient cycling and soil carbon（C） sequestration in terrestrial ecosystems. The global-wide increase in nitrogen（N） inputs is expected to alter litter decomposition and,ultimately, affect ecosystem C storage and nutrient status. Temperate grassland ecosystems in China are usually N-deficient and particularly sensitive to the changes in exogenous N additions. In this paper, we conducted a 1,200-day in situ experiment in a typical semi-arid temperate steppe in Inner Mongolia to investigate the litter decomposition as well as the dynamics of litter C and N concentrations under three N addition levels（low N with 50 kg N/（hm2？a）（LN）, medium N with 100 kg N/（hm2？a）（MN）, and high N with 200 kg N/（hm2？a）（HN）） and three N addition forms（ammonium-N-based with 100 kg N/（hm2？a） as ammonium sulfate（AS）, nitrate-N-based with 100 kg N/（hm2？a） as sodium nitrate（SN）, and mixed-N-based with 100 kg N/（hm2？a） as calcium ammonium nitrate（CAN）） compared to control with no N addition（CK）. The results indicated that the litter mass remaining in all N treatments exhibited a similar decomposition pattern： fast decomposition within the initial 120 days, followed by a relatively slow decomposition in the remaining observation period（120–1,200 days）. The decomposition pattern in each treatment was fitted well in two split-phase models, namely, a single exponential decay model in phase I（〈398 days） and a linear decay function in phase II（≥398 days）. The three N addition levels exerted insignificant effects on litter decomposition in the early stages（〈398 days, phase I; P〉0.05）. However, MN and HN treatments inhibited litter mass loss after 398 and 746 days, respectively（P〈0.05）. AS and SN treatments exerted similar effects on litter mass remaining during the entire decomposition period（P〉0.05）. The effects of these two N addition forms differed greatly from those of CAN after 746 and 1,053 days, respectively（P〈0.05）. During the decomposition period, N concentrations in the decomposing litter increased whereas C concentrations decreased, which also led to an exponential decrease in litter C：N ratios in all treatments. No significant effects were induced by N addition levels and forms on litter C and N concentrations（P〉0.05）. Our results indicated that exogenous N additions could exhibit neutral or inhibitory effects on litter decomposition, and the inhibitory effects of N additions on litter decomposition in the final decay stages are not caused by the changes in the chemical qualities of the litter, such as endogenous N and C concentrations. These results will provide an important data basis for the simulation and prediction of C cycle processes in future N-deposition scenarios.
基金supported by the National Natural Science Foundation of China(30870419,40971151)Strategic Priority Research Program Climate Change:Carbon Budget and Related Issues of the Chinese Academy of Sciences(XDA05050204)
文摘We used a litterbag method to investigate litter decomposition and related soil degradative enzyme activities across four seasons in a broad-leaved forest and a coniferous forest on Zijin Mountain in sub-tropical China. Across four seasons, we quantified litter mass losses, soil pH values, and related soil degradative enzyme activities. Litter decomposition rates differed significantly by season. Litter decomposi- tion rates of broadleaf forest leaves were higher than for coniferous for- ests needles across four seasons, and maximal differences in litter de- composition rates between the two litter types were found in spring.
基金financed by a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Research Innovation Program for College Graduates of Jiangsu Province,China(KYLX16_0832)
文摘Microbial functional diversity and enzymatic activities are critical to maintaining material circulation during litter decomposition in forests.Thinning,an important and widely used silvicultural treatment,changes the microclimate and promotes forest renewal.However,how thinning affects microbial functional diversity and enzymatic activities during litter decomposition remains poorly understood.We conducted thinning treatments in a Chinese fir plantation in a subtropical region of China with four levels of tree stem removal（0,30,50,and 70%）,each with three replicates,and the effects of thinning on microbial functional diversity and enzymatic activities were studied 7 years after treatment by collecting litter samples four times over a 1-year period.Microbial functional diversity and enzymatic activities were analyzed using Biolog Ecoplates（Biolog Inc.,Hayward,CA,USA）based on the utilization of 31 carbon substrates.Total microbial abundance during litter decomposition was lower after the thinning treatments than without thinning.Microbial functional diversity did not differ significantly during litter decomposition,but the types of microbial carbon-source utilization did differ significantly with the thinning treatments.Microbial cellulase and invertase activities during litter decomposition were significantly higher under the thinning treatments due to changes in the litter carbon concentration and the ratios of carbon and lignin to nitrogen.The present study demonstrated the important influence of thinning on microbial activities during litter decomposition.Moderate-intensity thinning may maximize vegetation diversity and,in turn,increase the available substrate sources for microbial organisms in litter and promote nutrient cycling in forest ecosystems.
基金Under the auspices of State Key Development Program for Basic Research of China (No. 2009CB421103)KeyProgram of National Natural Science Foundation of China (No. 40830535/D0101)Knowledge Innovation Programs of ChineseAcademy of Sciences (No. KZCX2-YW-BR-16, KSCX2-YW-N-46-06)
文摘Litter decomposition is the key process in nutrient recycling and energy flow. The present study examined the impacts of soil fauna on decomposition rates and nutrient fluxes at three succession stages of wetland in the Sanjiang Plain, China using different mesh litterbags. The results show that in each succession stage of wetland, soil fauna can obviously increase litter decomposition rates. The average contribution of whole soil fauna to litter mass loss was 35.35%. The more complex the soil fauna group, the more significant the role of soil fauna. The average loss of three types of litter in the 4mm mesh litterbags was 0.3-4. l times that in 0.058ram ones. The decomposition function of soil fauna to litter mass changed with the wetland succession. The average contribution of soil fauna to litter loss firstly decreased from 34.96% （Carex lasiocapa） to 32.94% （Carex rneyeriana）, then increased to 38.16% （Calamagrostics angustifolia）. The contributions of soil fauna to litter decomposition rates vary according to the litter substrata, soil fauna communities and seasons. Significant effects were respectively found in August and July on C. angustifolia and C. lasiocapa, while in June and August on C. meyeriana. Total carbon （TC）, total nitrogen （TN） and total phosphorus （TP） contents and the C/N and C/P ratios of decaying litter can be influenced by soil fauna. At different wetland succession stages, the effects of soil fauna on nutrient elements also differ greatly, which shows the significant difference of in- fluencing element types and degrees. Soil fauna communities strongly influenced the TC and TP concentrations of C. meyeriana litter, and TP content of C. lasiocapa. Our results indicate that soil fauna have important effects on litter decomposition and this influence will vary with the wetland succession and seasonal variation.
基金Under the auspices of National Natural Science Foundation of China(No.41071033,41101049)China Postdoctoral Science Foundation(No.2012M511361)
文摘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.
基金supported by the National Natural Science Foundation of China (31270668,41373038)the National Basic Research Program of China (2012CB416902)the China Postdoctoral Science Foundation (2016M601342)
文摘Forests and grasslands in arid and semi-arid regions receive high-intensity ultraviolet（UV） radiation year-round. However, how the UV radiation affects the litter decomposition on the forest floor remains unclear. Here, we conducted a field-based experiment in 2011 in the southeastern Horqin Sandy Land, Northeast China, to investigate the effects of UV radiation, litter layer thickness, and their interaction on the mass loss and chemical properties of decomposing litter from Xiaozhuan poplar（Populus × xiaozhuanica） and Mongolian pine（Pinus sylvestris var. mongolica） plantation trees. We found that UV radiation accelerated the decomposition rates of both the Xiaozhuan poplar litter and Mongolian pine litter. For both species, the thick-layered litter had a lower mass loss than the thin-layered litter. The interaction between UV radiation and litter layer thickness significantly affected the litter mass loss of both tree species. However, the effects of UV radiation on the chemical properties of decomposing litter differed between the two species, which may be attributed to the contrasting initial leaf litter chemical properties and morphology. UV radiation mostly had positive effects on the lignin concentration and lignin/N ratio of Xiaozhuan poplar litter, while it had negative effects on the N concentration of Mongolian pine litter. Moreover, litter layer thickness and its interaction with UV radiation showed mostly positive effects on the N concentration and lignin/N ratio of Xiaozhuan poplar litter and the ratios of C/N and lignin/N of Mongolian pine litter, and mostly negative effects on the C/N ratio of Xiaozhuan poplar litter and the N concentration of Mongolian pine litter. Together, these results reveal the important roles played by UV radiation and litter layer thickness in the process of litter decomposition in this semi-arid region, and highlight how changes in the litter layer thickness can exert strong influences on the photodegradation of litter in tree plantations.
基金This study was financially supported by the K.C.Wong Education Foundation,Strategic Priority Research Program of Chinese Academy of Sciences(XDA20050103)the"Light of West China"Program of the Chinese Academy of Sciences(Han W.X.).
文摘Nitrogen(N)addition has profound impacts on litter-mediated nutrient cycling.Numerous studies have reported different effects of N addition on litter decomposition,exhibiting positive,negative,or neutral effects.Previous meta-analysis of litter decomposition under N addition was mainly based on a small number of samples to allow comparisons among ecosystem types.This study presents the results of a meta-analysis incorporating data from 53 published studies(including 617 observations)across forests,grasslands,wetlands,and croplands in China,to investigate how environmental and experimental factors impact the effects of N addition on litter decomposition.Averaged across all of the studies,N addition significantly slows litter decomposition by 7.02%.Considering ecosystem types,N addition significantly accelerates litter decomposition by 3.70%and 11.22%in grasslands and wetlands,respectively,clearly inhibits litter decomposition by 14.53%in forests,and has no significant effects on litter decomposition in croplands.Regarding the accelerated litter decomposition rate in grasslands due to N addition,litter decomposition rate increases slightly with increasing rates of N addition.However,N addition slows litter decomposition in forests,but litter decomposition is at a significantly increasing rate with increasing amounts of N addition.The responses of litter decomposition to N addition are also influenced by the forms of N addition,experiential duration of N addition,humidity index,litter quality,and soil pH.In summary,N addition alters litter decomposition rate,but the direction and magnitude of the response are affected by the forms of N addition,the rate of N addition,ambient N deposition,experimental duration,and climate factors.Our study highlights the contrasting effects of N addition on litter decomposition in forests and grasslands.This finding could be used in biogeochemical models to better evaluate ecosystem carbon cycling under increasing N deposition due to the differential responses of litter decomposition to N addition rates and ecosystem types.
基金Under the auspices of Special Projects of National Key Basic Research Program of China(No.2012CB426509)National Natural Science Foundation of China(No.40971285,31370497,31500409)Yunnan Innovation Talents of Science and Technology Plan of China(No.2012HC007)
文摘The decomposition of plant litter is a key process of litter decomposition to global climate warming in plateau in the flows of energy and nutrients in ecosystems. However, the response wetlands remains largely unknown. In this study, we conducted a one-year litter decomposition experiment along an elevation gradient from 1891 m to 3260 m on the Yurman Plateau of Southwest China, using different litter types to determine the influences of climate change, litter quality and microenvironment on the decomposition rate. The results showed that the average decomposition rate （K） increased from 0.608 to 1.152, and the temperature sensitivity of litter mass losses was approximately 4.98%/℃ along the declining elevation gradient. Based on a correlation analysis, N concentrations and C ： N ratios in the litter were the best predictors of the decomposition rate, with significantly positive and negative correlations, respectively. Additionally, the cumulative effects of decomposition were clearly observed in the mixtures of Scirpus tabernaemontani and Zizania caduciflora. Moreover, the litter decomposition rate in the water was higher than that in the sediment, especially in high-elevation areas where the microenvironment was significantly affected by temperature. These results suggest that future climate warming will have significant impacts on plateau wetlands, which have important fimctions in biogeochemical cycling in cold highland ecosystems.
基金This study was financially supported by the National Natural Science Foundation of China(32101345).
文摘Litter decomposition is an important component of the nutrient recycling process and is highly sensitive to climate change.However,the impacts of warming and increased precipitation on litter decomposition have not been well studied,especially in the alpine grassland of Tianshan Mountains.We conducted a manipulative warming and increased precipitation experiment combined with different grassland types to examine the impact of litter quality and climate change on the litter decomposition rate based on three dominant species(Astragalus mongholicus,Potentilla anserina,and Festuca ovina)in Tianshan Mountains from 2019 to 2021.The results of this study indicated there were significant differences in litter quality,specific leaf area,and leaf dry matter content.In addition,litter quality exerted significant effects on litter decomposition,and the litter decomposition rate varied in different grassland types.Increased precipitation significantly accelerated the litter decomposition of P.anserina;however,it had no significant effect on the litter decomposition of A.mongholicus and F.ovina.However,warming consistently decreased the litter decomposition rate,with the strongest impact on the litter decomposition of F.ovina.There was a significant interaction between increased precipitation and litter type,but there was no significant interaction between warming and litter type.These results indicated that warming and increased precipitation significantly influenced litter decomposition;however,the strength was dependent on litter quality.In addition,soil water content played a crucial role in regulating litter decomposition in different grassland types.Moreover,we found that the litter decomposition rate exhibited a hump-shaped or linear response to the increase of soil water content.Our study emphasizes that ongoing climate change significantly altered litter decomposition in the alpine grassland,which is of great significance for understanding the nutrient supply and turnover of litter.
文摘During the past two centuries, global changes (i.e., enhanced nitrogen deposition) have exerted profound effects on ecological processes of steppe ecosystems. We used litterbag method and mixed litters of three different plant species tissues (Stipa baicalensis: Sb, Leymus chinensis: Lc and Artemisia frigid: Af), endemic to Stipa baicalensis Steppe, and measured the mass loss of mixtures over 417 days under the N addition treatment. We studied the effect of N addition (N0: no N addition;N15: 1.5 g N/m<sup>2</sup>·a;N30: 3.0 g N/m<sup>2</sup>·a;N50: 5.0 g N/m<sup>2</sup>·a;N100: 10.0 g N/m<sup>2</sup>·a;N150: 15.0 g N/m<sup>2</sup>·a) on the rate of mixed litter decomposition and nutrient dynamics change. The decomposition constant (k) of leaf mixtures was higher than that of root mixtures. The k values of leaf mixed combinations were 0.880 (Sb + Lc), 1.231 (Lc + Af), 1.027 (Sb + Lc + Af), respectively. The k value of stem was 0.806 (Lc + Af) and the root mixed combinations were 0.665 (Sb + Lc), 0.979 (Lc + Af) and 1.164 (Sb + Lc + Af), respectively. The results indicated that N addition had significantly effect on the mixed litter decomposition and nutrient releasing. The rate of plant tissues litter decomposition had different response to N addition. In the context of N addition, litter decomposition rate and nutrient dynamics were changed by synthetic effect of decaying time, specie types and N addition dose. Our findings suggested that prairie plants may adapt to environmental change by adjusting litter quality, thus retaining the stability of the steppe ecosystem.
基金supported by the National Basic Research Program of China(973 Program,2012CB416904)partially supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Soil fauna decompose litter, whereas land use changes may significantly alter the composition and structure of soil fauna assemblages. However, little is known of the effects of land-use on the contribution of soil fauna to litter decomposition. We studied the impacts of soil fauna on the decomposition of litter from poplar trees under three different land uses （i.e. poplar-crop integrated system, poplar plantation, and cropland）, from December 2013 to December 2014, in a coastal area of Northern Jiangsu Province. We collected litter samples in litterbags with three mesh sizes （5, 1 and 0. 01 mm, respectively） to quantify the contribution of various soil fauna to the decomposition of poplar leaf litter. Litter decomposition rates differed significantly by land use and were highest in the cropland, intermediate in the poplar-crop integrated system, and lowest in the poplar plantation. Soil fauna in the poplar-crop integrated system was characterized by the highest numbers of taxa and individuals, and highest Margalef＇s diversity, which suggested that agro-forestry ecosystems may support a greater quantity, distribution, and biodiversity of soil fauna than can single-species agriculture or plantation forestry. The individuals and groups of soil fauna in the macro-mesh litterbags were higher than in the meso-mesh litterbags underthe same land use types. The average contribution rate of meso- and micro-fauna to litter decomposition was 18.46%, which was higher than the contribution rate of macro-fauna （3.31%）. The percentage of remaining litter mass was inversely related to the density of the soil fauna （P 〈 0.05） in poplar plantations; however, was unrelated in the poplar-crop integrated system and cropland. This may have been the result of anthropogenic interference in poplar-crop integrated systems and croplands. Our study suggested that when land-use change alters vegetation types, it can affect species composition and the structure of soil fauna assemblages, which, in turn, affects litter decomposition.
基金Supported by the National Key Technology R&D Program(2013BAC04B01)Research and Demonstration of Restoration Technology of Typical Degraded Ecosystems in Tibet Plateau
文摘Based on the introduction of concept of forest litter, changes in the amount of forest litter with climate zone, elevation, forest type and age of stand were analyzed, and then the decomposition of forest litter was discussed.
基金supported by the National Key Research and Development Program of China (2023YFF1305500)National Natural Science Foundation of China (32022056)。
文摘Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) monoculture plantations account for 17.4% of the total plantation area in China. The decomposition of Chinese fir litter plays a fundamental role in maintaining nutrient cycling and soil fertility in these plantations. Here, we conducted a continental synthesis based on 64 studies to estimate the mass loss and release rates of carbon (C) and nutrients (including nitrogen (N), phosphorous (P), potassium (K), calcium (Ca) and magnesium (Mg)) during the first year of Chinese fir litter decomposition. The average mass loss rates of needle, twig, root and cone litter were 0.503, 0.319, 0.551 and 0.372 year^(-1), respectively. The decomposition rates of C and cellulose for needle litter were 0.649 and 0.801 year^(-1), respectively, while those of K, Ca and Mg were 2.27, 0.852 and 0.551 year^(-1), respectively. Decomposition rates were strongly influenced by mean annual temperature, soil N concentration and the initial C/N ratio of the litter. Climate warming and elevated ultraviolet-B radiation accelerated mass loss of Chinese fir litter, while increased N deposition and acid rain reduced it. However, elevated N deposition facilitated nutrient release from decomposing Chinese fir litter. These results provided a comprehensive assessment of Chinese fir litter decomposition, which is crucial for understanding soil biogeochemical cycles and improving soil fertility in Chinese fir plantations under global change scenarios.
基金supported by the National Natural Science Foundation of China(32072655 and 32272792)。
文摘Cover cropping is a diversifying agricultural practice that can improve soil structure and function by altering the underground litter diversity and soil microbial communities.Here,we tested how a wheat cover crop alters the decomposition of cucumber root litter.A three-year greenhouse litterbag decomposition experiment showed that a wheat cover crop accelerates the decomposition of cucumber root litter.A microcosm litterbag experiment further showed that wheat litter and the soil microbial community could improve cucumber root litter decomposition.Moreover,the wheat cover crop altered the abundances and diversities of soil bacterial and fungal communities,and enriched several putative keystone operational taxonomic units(OTUs),such as Bacillus sp.OTU1837 and Mortierella sp.OTU1236,that were positively related to the mass loss of cucumber root litter.The representative bacterial and fungal strains B186 and M3 were isolated and cultured.In vitro decomposition tests demonstrated that both B186 and M3 had cucumber root litter decomposition activity and a stronger effect was found when they were co-incubated.Overall,a wheat cover crop accelerated cucumber root litter decomposition by altering the soil microbial communities,particularly by stimulating certain putative keystone taxa,which provides a theoretical basis for using cover crops to promote sustainable agricultural development.
基金supported by the National Key Research and Development Program of China(2024YFD150140302)the Natural Science Foundation of China(Nos.32271843,41888101 and 41871027)the project of forestry science and technology innovation platform(No.LLC20245)
文摘Background The forest floor humus layer is an important carbon pool and serves as a key interface that influences forest soil carbon and nutrient cycling,especially in temperate and boreal forests.Over the past decades,China has implemented numerous forestry ecological programs,leading to an increasing quantity of forest floor litter and the formation of humus layers,which has altered the interface between aboveground litter and surface soil.Our previous study revealed that these alterations affect the litter decomposition rate;however,it is still unclear how the litter decomposition process changes,how nutrients are released or imported and the extent to which these changes depend on the humus layer.Results In this study,we used a 535-day in situ litterbag experiment to monitor the litter decomposition process and nutrient variations under forest floor humus layer removal in a Pinus sylvestris var.mongolica plantation in Northeast China.The results revealed that the litter decomposed quickly when a forest floor humus layer was present,with the decomposition rate constant(k value)increasing from 0.122 to 0.328.Accordingly,during decomposition,the litter C,N and P concentrations increased,whereas their contents varied only slightly(with the exception of the litter P content,which decreased significantly)compared with those in the treatment where the humus layer was removed.However,both the litter C and N contents decreased,whereas the litter P content increased significantly compared with the initial litter content.Moreover,the litter C:N,C:P and N:P ratios decreased significantly during decomposition.In addition,the microbial community diversity of the litter showed no significant change,whereas the relative abundances of several major fungal and bacterial taxa at the phylum and genus levels varied significantly.Furthermore,redundancy analysis revealed effective relationships among the k values,chemical traits and microbial communities,and the least squares method suggested that the C,P and C:P ratios of the litter were significantly correlated with the litter decomposition rate.Conclusions These results enhance our understanding of the role of the humus layer in forest soil-plant carbon and nutrient cycling and should be considered in carbon cycle models in the future.
基金funded by National Natural Science Foundation of China(Nos.32371733,31570444 and 32201368)the Xingdian Scholar Fund of Yunnan Provincethe Double Top University Fund of Yunnan University
文摘Background The prevalence of understory removal and anthropogenic nitrogen(N)deposition has significantly altered the ecological processes of forest ecosystems at both regional and global scales.However,it remains a pressing challenge to understand how N deposition and understory removal affect leaf nutrient dynamics,nutrient resorption,litter decomposition,and their linkages for better managing forest ecosystems under nutrient imbalances induced by N enrichment.To address this research gap,a field manipulation experiment was carried out in a subtropical Cunninghamia lanceolata plantation with four treatments including:control(CK),canopy N addition(CN),understory removal(UR),and canopy N addition plus understory removal(CN×UR).Green and senesced leaf N and phosphorus(P)concentrations,N and P resorption efficiencies,litter decomposition,and their correlations were measured.Results The results revealed that the average N concentrations of green early and late leaves in UR were increased by 6.61 and 18.89%compared to CK.UR had the highest whereas CN had the lowest P concentrations in green leaves across the two sampling seasons.Following this,UR,leaf type,season,and their interactions significantly affected leaf N,P,and N:P(P<0.05).The highest leaf N resorption(32.68%)and P resorption efficiencies(63.96%)were recorded in UR.Litter decomposition was significantly retarded in UR(P<0.01)relative to CN.The regression analysis demonstrated that leaf nutrient status was significantly interconnected with leaf nutrient resorption efficiencies.In addition,leaf nutrient dynamics were strongly correlated with litter nutrients,indicating that both were coupled.Conclusion These findings can deepen our knowledge of biogeochemical cycling and reveal contrasting nutrientacquisition strategies on N and P limitation in response to UR and CN.Considering the P limitation,it is important to note that P was resorbed more efficiently,illustrating a remarkable nutrient preservation approach for nutrientlimitations.Resorption may be a crucial mechanism for keeping nutrients in these forests,so better understory management practices are required to prevent reliance on external nutrient pools.Overall,this study sheds meaningful insights into the ability of forest adaptation in response to global climatic change.
基金financially supported by the National Key R&D Program of China(No.2023YFF1305500)the National Natural Science Foundation of China(Nos.32022056,32101509,and 32171641)。
文摘Climate warming has intensified the global hydrological cycle,amplifying the differences in precipitation and soil moisture between arid and humid areas.Such a change under regional drought may alter nitrogen(N)and phosphorus(P)releases during litter decomposition in terrestrial ecosystems,but how these biogeochemical processes respond to drought differently between arid and humid areas remains unclear.Here,we compiled 259 and 138 paired observations(with and without drought conditions)to assess the global variations in the drought effects on N and P releases during litter decomposition between arid(aridity index<0.5)and humid(aridity index>0.5)areas.Litter N release increased under drought in both arid(0.35%)and humid(3.62%)areas,and P release decreased by 7.32%in arid areas but increased by 2.22%in humid areas under drought.These changes in N and P releases from decomposing litter were positively correlated with drought duration in arid areas,dependent on microclimate,edaphic factors,and litter quality.Our findings highlight the contrasting effects of drought on litter N and P releases between arid and humid ecosystems,and this differential influence will greatly improve our capability to evaluate and forecast nutrient cycling during litter decomposition under different precipitation patterns.
基金supported by the Chinese Ecosystem Research Net(CERN)NSFC(30570350,40730102,30725006)+1 种基金by the Office of Science(BER),U.S.Department of Energy,Grant No.DE-FG03-99ER62800through the South Central Regional Center of the National Institute for Global Environmental Change under Cooperative Agreement No.DE-FC03-90ER61010.
文摘Aims We aim to construct a comprehensive global database of litter decomposition rate(k value)estimated by surface floor litterbags,and investigate the direct and indirect effects of impact factors such as geographic factors(latitude and altitude),climatic factors(mean annual tempePlrature,MAT;mean annual precipitation,MAP)and litter quality factors(the contents of N,P,K,Ca,Mg and C:N ratio,lignin:N ratio)on litter decomposition.Methods We compiled a large data set of litter decomposition rates(k values)from 110 research sites and conducted simple,multiple regression and path analyses to explore the relationship between the k values and impact factors at the global scale.Important findings The k values tended to decrease with latitude(LAT)and lignin content(LIGN)of litter but increased with temperature,precipitation and nutrient concentrations at the large spatial scale.Single factor such as climate,litter quality and geographic variable could not explain litter decomposition rates well.However,the combination of total nutrient(TN)elements and C:N accounted for 70.2%of the variation in the litter decomposition rates.The combination of LAT,MAT,C:N and TN accounted for 87.54%of the variation in the litter decomposition rates.These results indicate that litter quality is the most important direct regulator of litter decomposition at the global scale.This data synthesis revealed significant relationships between litter decomposition rates and the combination of climatic factor(MAT)and litter quality(C:N,TN).The global-scale empirical relationships developed here are useful for a better understanding and modeling of the effects of litter quality and climatic factors on litter decomposition rates.
文摘Dynamical patterns of mineral elements during decomposition processes were investigated for seven common canopy species in a subtropical evergreen broad-leaved forest by means of litterbag technique over 2 years. The species studied are representative for the vegetation in the study area and differed significantly in chemical qualities of their litter. No significant relationships were found between decomposition rate （percentage dry mass remaining and decomposition constant k） and initial element cuncentrations.However, there were significant correlations betweeu the percentage of dry mass remaining and the mineral element concentrations in the remaining litter for most cases. The rank of the element mobility in decomposition process was as follows： Na = K 〉 Mg ≥ Ca 〉 N ≥ Mn ≥ Zn ≥ P 〉 Cu 〉〉 Al 〉〉 Fe. Concentrations of K and Na decreased in all species as decomposition proceeded. Calcium and Mg also decreased in concentrntion but with a temporal increase in the initial phase of decomposition, while the concentrations of other elements （Zn, Cu, AL and Fei increased for all species with exception of Mn which revealed a different pattern in different species. In most species, microelements （Cu, Al, and Fe） significantly increased in absolute amounts at the end of the litterbag incubation, which could be ascribed to a lange extent to the mechanism of abiotic fixation to humic substances rather than biological immobilization.
