Litter Mass Loss Research Articles

The Effects of Plant Secondary Metabolites from Coniferous Needle Leaf Litter on the Leaf Litter Decomposition of Betula albo-sinensis Burk

In this study, leaf litters of Betula albo-sinensis and 5 coniferous species were used as samples. The B. albo-sinensis leaf litter was buried in soil and termly treated with the water extracts of five types of coniferous leaf litter for a 6-month simulation decomposition experiment. The dynamics of mass loss and nutrients (C, N, P, and K) content of leaf litter and the soil enzymatic activities were measured to investigate the effects of plant secondary metabolites (PSM) from coniferous leaf litters on the decomposition processes of B. albo-sinensis leaf litter. The results indicated that the extracts of Pinus tabuliformis, Platycladus orientalis, P. armandii and Larix principis-rupprechtii leaf litters significantly inhibited the whole decomposition process and overall nutrients release of B. albo-sinensis leaf litter, while the extracts of Picea asperata leaf litter exhibited no significant influence. The general suppression of PSM on the soil sucrase, carboxymethyl cellulase and β-glucosidase activities might be the main reason leading to the inhibitory effects of the extracts of P. tabuliformis, P. orientalis, P. armandii and L. principis-rupprechtii leaf litter. The species causing inhibitory effects, especially L. principis-rupprechtii, was not recommended to be planted mixed with B. albo-sinensis, or their planting density should be lower in the mixed forests.

Patterns of Leaf Litter Decomposition as Related to Litter Traits in the Sudano-Guinea Savannahs of Ngaoundere, Cameroon

Litter decomposition processes are poorly studied in the savannahs. Leaf litter decomposition of the twenty-four contrasting plant species including trees, shrubs and grass species, was studied in the sudano-guinea savannahs of Ngaoundere, Cameroon. The litterbag technique was used to assess litter mass loss and single exponential model was adopted to estimate decay rate constants. Initial litter thickness varied from 0.02 to 1.11 mm, area from 4.27 to 245.89 mm2, sclerophyllous index from 0.01 to 1.75 mg.mm-2, density from 0.21 to 87.50 mg.mm-3, and specific mass area from 0.57 to 185.46 mm2.mg-1. Litter cellulose content varied from 3.79 to 11.84%; lignin from 2.84 to 8.12%, NDF from 21.35 to 80.41%, and total phenolic compounds from 0.47 to 17.76%. During the 52 weeks of the field experiment, mean dry mass remaining of litter samples was significantly between 8.05 and 75.22% of initial litter dry mass for C. papaya and C. regidus respectively. Litter decomposition rate constant (k) significantly ranged from 0.003 (C. regidus) to 0.121 %.week-1 (C. papaya). Litter mass remaining (LMR) was positively related to thickness (R2 = 0.605, P<0.01), Sclerophyllous index (R2 = 0.446, P<0.05), Specific mass area (R2 = 0.569, P<0.001), lignin (R2 = 0.631, P<0.01) and phenolic compounds (R2 = 0.618, P<0.001). The litter decomposition rate constant (k) was negatively related to thickness (R2 = 0.602, P<0.01, n=12), Sclerophyllous index (0.542; P<0.05), Specific mass area (0.419; P<0.05) and phenolic compounds (0.530; P<0.01). It can be concluded that litter decomposition is affected by plant species diversity, plant groups and physico-chemical traits of litters in the sudano-guinea savannahs of Ngaoundere, Cameroun. These preliminary results would contribute to understanding the mechanism of litter decomposition in general and in these savannahs in particular.

The importance of macro- and micro-nutrients over climate for leaf litter decomposition and nutrient release in Patagonian temperate forests

Temperate forests play an important role in the global carbon (C) cycle. Extensive research on litter decomposition in temperate forests in the Northern Hemisphere have greatly contributed to our conceptual framework of the controls of C cycling, where climate and litter lignin/N ratio have played a dominant role. However, there is a noteworthy lack of basic information on southern temperate forests, which have unique characteristics demonstrated by differences in ecosystem functioning and their response to human impact when compared to their northern counterparts. Patagonian forests are the most extensive temperate forests in South America and offer the opportunity to evaluate the importance of climate and litter traits in old growth forests with relatively little human impact. We compared litter decomposition of 10 dominant native tree species and of two non-native tree species (used as common substrates) in two native forests with varying precipitation and tree species composition: a Nothofagus mesic mixed forest (2200 mm MAP) and an Austrocedrus open dry forest (1350 mm MAP). In addition to rainfall, these forest types differed markedly in tree species composition and leaf litter traits that resulted in 1.5 times larger soil carbon and nitrogen pool in Austrocedrus open dry forest and 5 times higher soil inorganic nitrogen than in Nothofagus mesic forests. Nevertheless, decomposition of common litter substrates was similar between both forest types. In contrast, native tree species litter showed up to 10-fold differences in their decomposition rates in a common forest site. Litter mass loss and nitrogen dynamics were strongly associated with magnesium (Mg) and manganese (Mn) content of the litter, respectively. In contrast to dominant control of climate and litter lignin/N, our results demonstrate that native tree species traits may be more important than climate and its effects on plant-soil interactions in Patagonian forests. Our study also highlights the importance of macro- and micro-nutrients (Mg and Mn) in litter that are generally overlooked as determinants of litter decomposition in terrestrial ecosystems. These native Patagonian forests show distinctive controls of litter decomposition compared with other temperate forests of the world. They also highlight the importance of considering how management that affects tree species identity and composition may have far-reaching effects on ecosystem functioning that are currently not being considered.

Nutrient and Isotopic Dynamics of Litter Decomposition from Different Land Uses in Naturally Restoring Taihang Mountain, North China

Litter decomposition is a prominent pathway for nutrient availability and management in terrestrial ecosystems. An in-situ litter decomposition experiment was carried out for different land use types along an elevation gradient in the Taihang Mountain area restored after heavy forest degradation in the past. Four land use types, i.e., cropland, shrubland, grassland, and forest, selected randomly from a 300–700 m elevation were investigated for the experiment using the litter bag technique. Litter mass loss ranged from 26.9% (forest) to 44.3% (cropland) varying significantly among land use types. The initial litter quality, mainly N and C/N, had a significant effect on the litter loss rate. The interaction of elevation × land use types × time was significant (p < 0.001). Litter nutrient mobility (K > P ≈ N > C) of the decomposing litter was sporadic with substantial stoichiometric effects of C/N, N/P, and C/P. The residual litters were enriched in 15N and depleted in 13C as compared to the initial litter. Increment of N, P, and δ15N values in residual litter indicates that, even in the highly weathered substrate, plant litter plays a crucial role in conserving nutrients. This study is a strong baseline for monitoring the functioning of the Taihang Mountain ecosystem restored after the complete destruction in the early 1990s.

One plus one is greater than two: mixing litter types accelerates decomposition of low-quality alpine dwarf shrub litter

AimsLitter decomposition patterns, non-additive effects, and spectral data of abundant alpine leaf litters were assessed in litterbag experiments containing single species and mixtures. We tested if low-quality shrub litter decomposes faster in mixtures with high-quality litter and if predictions on decomposed litter using spectral data are feasible.MethodsChemical and physical traits and near-infrared reflectance (NIR) spectra of six alpine freshly fallen litter types were measured. A litterbag experiment (0.1 mm mesh size) with single and 2- and 3-species mixtures was conducted with three species from three functional groups (shrub, grass, forb). Decomposition rates, litter mass loss, non-additive effects, and NIR spectra were recorded after 6, 12, and 24 months.ResultsThe six freshly fallen litter types differed significantly in leaf litter traits and NIR spectra. Decomposition rates steadily slowed during the 24 months, with shrub litter having the lowest on all sampling dates. In litter mixtures, shrub and grass litter showed higher decomposition rates after 12 and 24 months compared with the single-species treatments.DiscussionThe accelerated decomposition in litter mixtures indicates stimulating interactions between low- and high-quality litter types, most probably mediated by their associated microbiomes. By using NIR spectra, we successfully predicted all initial litter traits, but only total carbon content along the entire decomposition period.

Litter decomposition in pure and mixed Quercus and Fagus stands as influenced by arthropods in Belgrad Forest, Turkey

Arthropod assemblages and decomposition rates were compared in the litter of pure and mixed Quercus (Quercus petraea L.) and Fagus (Fagus orientalis L.) stands. Litter was sampled on a monthly basis for 1 year and stored in litterbags of different mesh sizes. The experimental objective was to test the effect of mesh size on litter decomposition, decomposition rates of litter, and diversity of the invertebrate fauna between the two types of stands. Decomposition rates were measured by filling three fiber litterbags of different mesh sizes with pure Quercus litter (3 g) left in the pure Quercus stand, and litterbags with Fagus litter (3 g) were left in the pure Fagus stand. Mixed litter samples were prepared by mixing of equal amounts of each litter in the same litterbag and leaving them in the mixed stand. The residual mass of litter from the pure Quercus stand was significantly lower in fine- and coarse-mesh bags than in the medium-mesh bags in pure the Fagus stand. Carbon and nitrogen levels in the pure Quercus litter were significantly different among the mesh sizes at the end of the incubation period. Macroarthropods from 27 taxa were collected from pitfall traps every month. Their relative numbers differed significantly between the pure and mixed-stand litter samples. Litter-dwelling Isotomidae (Collembola) and Mesostigmata (Acarina), and soil-dwelling Mesostigmata were the most numerous in the mixed stand. It is significant that the abundance of macroarthropods contributed to the mass loss of litter in both the medium and coarse mesh sizes in the mixed stand, but did not significantly affect the mass of litter in the pure stands. In the mixed stand, there was a negative correlation between litter mass loss and total number of microarthropods in all mesh sizes. Mixed-stand litter decomposed more slowly than pure-stand litter.

Nitrogen, lignin, C/N as important regulators of gross nitrogen release and immobilization during litter decomposition in a temperate forest ecosystem

Litter decomposition plays an important role in nutrient cycling and ecosystem functions. Although litter quality has been considered as an important factor of decomposition rate, how litter quality regulates the gross nitrogen (N) fluxes (release and immobilization) remains unclear. Here, we conducted a field study of litter decomposition using 15N-labeled litter. We found that the temporal patterns of gross N release and immobilization were best described by the one-pool model y=100-a1∗e-k1∗x and y=a2∗(1-e-k2∗x), respectively, which could help us better predict the gross N fluxes during litter decomposition. We also found that litter with higher initial N or lower initial lignin concentration had higher gross N release rate, which is consistent with their effects on litter mass loss. Initial C/N ratio was the most important factor determining gross N immobilization rate. Gross N release was mainly regulated by N concentration during the initial stage (0–0.5 years) of decomposition dominated by leaching process, but was mainly regulated by lignin concentration during the second stage (0.5–2.25 years). Gross N immobilization was positively correlated with N concentration during the initial stage of decomposition, but was positively correlated with C/N ratio during the second stage. Furthermore, litter with higher gross N release rate contributed more to soil N pools and to N losses from the litter-soil system. Our study highlights the different controlling factors of N release and immobilization at different stages of litter decomposition and helps better estimation and management of forest N fluxes and productivity.

Warming alters fungal communities and litter chemistry with implications for soil carbon stocks

Rates of leaf litter decay are generally expected to accelerate with increasing temperature. However, chronic temperature elevation may cause changes in the quality of litter residues or in the composition of decomposer communities that result in unexpected decay responses. We performed a 23-month litter decomposition study at a long-term soil warming experiment to determine how soil warming affects litter decay rate, litter chemistry, extracellular enzyme activities, and fungal community composition. Experimental soil warming did not affect litter mass loss, but did result in a 23% increase in the relative abundance of lignin; a concomitant shift in enzyme activity wherein lignin-decomposing enzymes had higher activity in the heated treatment while cellulose-decomposing enzymes were suppressed; and a shift in the composition of the active fungal community. In particular, ectomycorrhizal fungi were three times more abundant in the heated treatment than the control, and shifts in fungal community composition were significantly correlated with the observed changes in extracellular enzyme activities. Our results suggest that warming altered the trajectory of decay resulting in litter residues enriched in lignin compounds and that were populated by a higher relative abundance of ectomycorrhizal fungi. These shifts may have altered the temperature sensitivity of litter decay by reducing the quality of litter residues and changing fungal community function.

Effects of changed litter inputs on soil labile carbon and nitrogen pools in a eucalyptus-dominated forest of southeast Queensland, Australia

The quantity and quality of litter inputs to forest soils are likely to be changed as a result of the climate change and human disturbances. However, the effects of changed litter inputs on soil labile carbon (C) and nitrogen (N) pools still remain unclear. A 15-month in situ field experiment was conducted within both high and low litter quality site in a eucalyptus-dominated native forest of Queensland, Australia. Three rates of litter inputs were applied, including (i) no litter (NL); (ii) single litter (SL), representing the average condition of the surrounding forest floor; and (iii) double litter (DL). Water-extractable organic C (WEOC) and total N (WETN), hot water-extractable organic C (HWEOC) and total N (HWETN), microbial biomass C (MBC), and N (MBN) were analyzed in the 0–5-cm soil layer seasonally. Litter input rates had no significant effects on litter decomposition at both sites (P > 0.05). After 15-month of decomposition, mean litter mass loss was 46.3% and 31.2% at the HQ and LQ sites, respectively. Changed litter quantity had no significant effects on any of the soil labile C and N pools, regardless of litter quality. However, soil labile C and N pools significantly varied with sampling times, and the samples of different sampling times were clearly separated at both sites according to the redundancy analysis (RDA). WEOC peaked in summer, declined in autumn and winter, and increased again in spring, while the concentrations of HWEOC and MBC peaked in the winter period. The seasonal trends of MBN were opposite to the trends of WETN, which might be due to the temporal partitioning of N between plants and microbes. The findings indicated that soil labile C and N pools in the eucalyptus-dominated forest of subtropical Australia were resistant to a short-term change in aboveground litter inputs. Future research should expand on these findings by keeping observing over a longer time period and considering the influence of changed belowground litter inputs.

Epi-anecic rather than strict-anecic earthworms enhance soil enzymatic activities

Earthworms in interaction with soil microorganisms play a key role in litter decomposition. Moreover, as soil engineers, earthworms modify microbial communities and their enzymatic activities. Most studies focusing on earthworms and soil enzymatic activities compare distinct ecological categories of earthworms whereas their contributions and interactions within a given ecological category remain largely unknown. In this context, the aims of the present study were to determine and compare the contribution of (1) three strict-anecic earthworm species, (2) three epi-anecic earthworm species and (3) the pairwise interactions between these different species on Lolium perenne leaf litter decomposition and soil microbial activity. After 30 days of incubation, the surface litter mass loss and five soil enzymatic activities (FDAse, β-D-glucosidase, cellobiohydrolase, leucine amino-peptidase and acid phosphatase) were measured in both earthworm burrows and middens. In mono-specific assemblages, leaf litter mass loss and enzymatic activities were significantly higher in the presence of epi-anecic compared to strict-anecic species, whatever the species identity. These differences were higher for the β-D-glucosidase, leucine amino-peptidase and FDAse (+78%, +57% and +34%, respectively). Earthworm species interactions at both intra- and inter-ecological sub-categories did not enhance either leaf litter mass loss or enzymatic activities. Interestingly, FDAse activity was higher in earthworm burrows whereas acid phosphatase activity was higher in earthworm middens. These results indicate that the two anecic ecological sub-categories have different impacts on soil functioning and each of them regroups earthworm species with similar behaviour. This functional distinction highlights the key role of epi-anecic earthworms in fresh surface litter burial and decomposition, featuring their importance on nutrient cycling in soil and for microbial activities stimulation through resource availability.

Early exposure to UV radiation overshadowed by precipitation and litter quality as drivers of decomposition in the northern Chihuahuan Desert.

Dryland ecosystems cover nearly 45% of the Earth’s land area and account for large proportions of terrestrial net primary production and carbon pools. However, predicting rates of plant litter decomposition in these vast ecosystems has proven challenging due to their distinctly dry and often hot climate regimes, and potentially unique physical drivers of decomposition. In this study, we elucidated the role of photopriming, i.e. exposure of standing dead leaf litter to solar radiation prior to litter drop that would chemically change litter and enhance biotic decay of fallen litter. We exposed litter substrates to three different UV radiation treatments simulating three-months of UV radiation exposure in southern New Mexico: no light, UVA+UVB+Visible, and UVA+Visible. There were three litter types: mesquite leaflets (Prosopis glandulosa, litter with high nitrogen (N) concentration), filter paper (pure cellulose), and basswood (Tilia spp, high lignin concentration). We deployed the photoprimed litter in the field within a large scale precipitation manipulation experiment: ∼50% precipitation reduction, ∼150% precipitation addition, and ambient control. Our results revealed the importance of litter substrate, particularly N content, for overall decomposition in drylands, as neither filter paper nor basswood exhibited measurable mass loss over the course of the year-long study, while high N-containing mesquite litter exhibited potential mass loss. We saw no effect of photopriming on subsequent microbial decay. We did observe a precipitation effect on mesquite where the rate of decay was more rapid in ambient and precipitation addition treatments than in the drought treatment. Overall, we found that precipitation and N played a critical role in litter mass loss. In contrast, photopriming had no detected effects on mass loss over the course of our year-long study. These results underpin the importance of biotic-driven decomposition, even in the presence of photopriming, for understanding litter decomposition and biogeochemical cycles in drylands.

Decomposition of Spartina alterniflora and concomitant metal release dynamics in a tidal environment

The decomposition of salt marsh plants is affected by the variation of physiochemical factors caused by the change of tide level. In the present study, plant tissues of Spartina alterniflora from controlled metal exposure experiments were subjected to a field decomposition trial at different tidal levels in a tidal flat of Chongming Island, Shanghai. The contents of the metals and Pb stable isotope ratios of the plant litter and the adjacent sediment were followed. The mass loss rate of the root and leaf litters of S. alterniflora decreased with the increase of burial time. Leaf had the highest decomposition rate (0.009 day−1 to 0.020 day−1) compared to that of the roots (0.004 day−1 to 0.005 day−1) and stems (0.002 day−1 to 0.006 day−1). Leaf had the highest decomposition rate possibly due to the significantly lower C/N ratio (16.0–44.6) compared to that of the roots (32.8–88.9) and stems (43.7–120.9). The mass loss rate of the roots and leaves of S. alterniflora was higher in the high tidal marsh than that in the low tidal marsh, especially at the late stages of decomposition. The concentrations of metals in leaf litter of S. alterniflora increased, whereas the pools of metals in most of the plant litters decreased significantly with the increasing of the decomposition time. The ratios of 207Pb/206Pb and 208Pb/206Pb in the root litters decreased significantly in the first 290 days of decomposition and then increased significantly at Day 350, while the Pb isotope ratios in adjacent sediment showed no significant changes. Fast mass loss of plant litters induced the significant decrease in metals' pools at early stages of decomposition, and release of the plant tissue Pb was greatly inhibited due to the slowed mass loss at the late stages of decomposition.

Pond-bottom decomposition of leaf litters canopied by free-floating vegetation.

In wetland ecosystems, vegetation can float freely on water surface, forming dense canopy which may play important ecological roles. This is especially true in many urban wetlands in which fluidity is low and nutrient level is high. So far, effects of free-floating vegetation on abiotic and biotic factors of wetlands have been known, while little on wetland ecosystem functions such as litter decomposition. To examine whether the canopy of free-floating vegetation on water surface will influence litter decomposition in wetlands or not, we conducted a 50-day in situ decomposition experiment in a subtropical urban pond wetland, in which litter bags of nine combinations of three mesh sizes and three litter species were put on the bottoms of total 22 ponds which were half with and half without free-floating vegetation canopy on the water surface. The ponds with and without the canopy had different water physicochemical properties. Overall, the canopy, the species identity, and the mesh size significantly decelerated mass loss and carbon loss of leaf litters while slightly on nitrogen loss. Effects of the canopy on leaf litter decomposition also showed species- and mesh size-dependent. Our results suggest that free-floating vegetation on water surface can alter water environmental factors and consequently change ecosystem functioning in wetlands.

Trends of major, minor and rare earth elements in decomposing litter in a cool temperate ecosystem, South Korea

The decomposition dynamics of 34 different elements in four different litter types (foliar and woody litter) from Pinus densiflora (Korean red pine) and Castanea crenata (Korean chestnut) was investigated in a cool temperate ecosystem using the litterbag method. Two contrasting trends were observed in the dynamics of elements with accumulated mass loss of litter and carbon. Leaf litter of Korean chestnut, which was richer in elements, showed a general decrease in concentrations of elements with accumulated mass loss of litter and carbon on a dry mass basis during decomposition in the field. Other litter types, with initially lower concentrations of elements, exhibited an increase in concentration on a dry mass basis during field incubation. Highest relative increase in the concentration was noticed for the minor elements, and for the woody litters. Concentrations of major and minor elements increased by factors ranging from 1.07 for antimony (Sb) to 853.7 for vanadium (V). Rare earth elements (REE) concentrations increased by factors ranging from 1.04 for scandium (Sc) to 83.5 for thorium (Th). Our results suggest that litter type plays an important role for nutrient dynamics. Results from principal component analysis for major, minor, and rare earth elements showed grouping of elements and high correlation among them (P < 0.05), which suggests a common source. At both sites, element concentrations were high in the soil, especially for REE. This suggests that increase in element concentrations during field incubation probably was due to transfer of elements from soil to the overlying decomposing litter.

Additive effects of experimental climate change and land use on faunal contribution to litter decomposition

Litter decomposition is a key process determining the cycling of nutrients in ecosystems. Soil fauna plays an essential role in this process, e.g., by fragmenting and burrowing surface litter material, and thereby enhancing microbial decomposition. However, soil fauna-mediated decomposition might be influenced by interacting factors of environmental changes. Here we used a large-scale global change field experiment to test potential interacting effects between land-use type (croplands and grasslands differing in management intensity) and projected climate change on litter decomposition rates over a period of two years. For that, climate and land-use treatments were orthogonally crossed: (1) two climate scenarios: ambient vs. future; and (2) five land-use regimes: conventional farming, organic farming, intensively used meadow, extensively used meadow, and extensively used pasture. Litterbags with two mesh sizes (5 mm and 0.02 mm) were used to differentiate contributions of microbes and fauna to the mass loss of standardized crop residues. Soil fauna accounted for more than 68% of surface litter mass loss. Future climate treatment decreased decomposition rates as a result of reduced precipitation and elevated temperature during summer months. Litter decomposition and the contribution of soil fauna to it were significantly higher in croplands than in grasslands, but did not differ due to management intensity within these land-use types. In grasslands, faunal contribution to decomposition decreased under future climate. There were no interacting effects between climate change and land use on decomposition rates. These findings indicate that predicted changes in precipitation patterns and temperature will consistently decelerate litter decomposition across land-used types via both microbial and faunal effects.

Soil fauna effect on Dryas octopetala litter decomposition in an Alpine tundra of the Changbai Mountains, China

Soil fauna are critical for litter decomposition via physical fragmentation, chemical digestion, and changing activity of microorganisms, yet a few studies have been performed regarding the effects of soil fauna on alpine tundra litter decomposition. To better understand the effects of soil fauna on alpine tundra litter decomposition, we set up a litterbag experiment to determine the characteristics of the Dryas octopetala decomposition, and the diversity of the soil fauna in the litterbags, as well as the influence of the soil fauna on the decomposition in the tundra of the Changbai Mountains over a 36-month period. We found that the decomposition rate of the coarse mesh (2 mm) litterbags was faster than that of the fine mesh (0.01 mm) litterbags. The percentage of the mass lass of litter in the coarse mesh litterbags (2 mm) was 47.60%, while that in the fine mesh (0.01 mm) litterbags was 34.11% at the end of the experimental period (36th month of decomposition), and the contribution of soil fauna to the litter decomposition was confirmed to be 30.50%. The characteristics of litter decomposition exhibited some seasonal and annual differences. In addition, the diversity of the soil fauna in the litterbags was different during each of the years of the experiment. However, there were no significant differences observed during the same year. The effect of soil fauna on the litter decomposition was not obvious at the beginning of the experiment, and soil fauna contribution had a significant negative relationship with mass loss of litter. Our results provide experimental evidence that soil fauna can promote the decomposition of Dryas octopetala litter, but soil fauna contribution decreased with litter decomposition in the alpine tundra ecosystem.

有机碳质量对黄河三角洲芦苇凋落物分解及其温度敏感性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 有机碳质量对黄河三角洲芦苇凋落物分解及其温度敏感性的影响 DOI: 10.5846/stxb201808261828 作者: 作者单位: 聊城大学环境与规划学院,聊城大学环境与规划学院,聊城大学环境与规划学院,聊城大学环境与规划学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41501099）；聊城大学基金（318051430）；聊城大学实验技术研究项目（26322170123）；山东省本科高校教学改革研究项目（M2018X052） Effect of organic carbon quality on the litter decomposition and temperature sensitivity of Phragmites australi in the Yellow River Delta, China Author: Affiliation: College of Environment,Liaocheng University,College of Environment,Liaocheng University,College of Environment,Liaocheng University,College of Environment,Liaocheng University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:凋落物分解速率及其温度敏感性Q10能够影响凋落物对土壤的碳归还及其对全球变暖的响应。然而，凋落物有机碳质量对凋落物分解及其温度敏感性的影响研究仍不充分。以黄河三角洲芦苇（Phragmites australi）为例，通过凋落物袋法、室内模拟实验及固态13C核磁共振技术，研究有机碳质量对凋落物分解及其温度敏感性的影响，探讨预测凋落物分解及其温度敏感性的指标。结果表明：（1）随着凋落物分解，易分解碳组分（烷氧碳、双烷氧碳）相对含量逐渐降低，而难分解碳组分（芳香碳）相对含量显著增加，疏水碳/亲水碳、芳香碳/烷氧碳比值逐渐增大，凋落物有机碳更加稳定，凋落物呼吸速率及失重率呈下降趋势。（2）凋落物失重主要受烷基碳、烷氧碳相对含量及C/N的影响，凋落物CO2累积释放量主要受烷氧碳及双烷氧碳相对含量的影响。羰基碳相对含量可以用来解释Q10的变异。因此，相对于生态化学计量比，烷基碳、烷氧碳、双烷氧碳、羰基碳相对含量是预测凋落物分解及其温度敏感性的敏感性指标。 Abstract:The decomposition rate of litter and its temperature sensitivity Q10 could affect the return of organic carbon to the soil, and in turn, its response to global warming. However, exactly how the quality of organic carbon affects litter decomposition and its temperature sensitivity is still relatively unknown. In this study, field and laboratory incubation experiments were conducted to investigate how the quality of organic carbon affects litter decomposition and its temperature sensitivity. The leaf litter of reed (Phragmites australi) was collected in the Yellow River Delta, China, and the quality of organic carbon was assessed through solid-state 13C nuclear magnetic resonance spectroscopy (13C NMR). The results showed that (1) the relative abundance of O-alkyl and di-O-alkyl C was reduced, and the relative abundance of aromatic C was increased following litter decomposition. The ratios of hydrophobic to hydrophilic C and aromatic to O-alkyl C were also increased at the last stage of litter decomposition. These results indicate that the stability of organic carbon was enhanced during litter decomposition. The respiration and mass loss rate of litter also decreased during litter decomposition, and (2) the mass loss of litter was mainly controlled by the relative abundance of alkyl and O-alkyl C and C/N, whereas the cumulative CO2 production of litter was mainly controlled by the relative abundance of O-alkyl and di-O-alkyl C. Furthermore, the Q10 value of CO2 production was affected by the relative abundance of carboxyl C. In general, the relative abundance of alkyl, O-alkyl, di-O-alkyl, and carboxyl C are more effective in predicting litter decomposition and its temperature sensitivity compared to litter stoichiometry. 参考文献 相似文献 引证文献

Yak Dung Deposition Affects Litter Mixing Effects on Mass Loss in Tibetan Alpine Grassland

Plant litter and livestock excreta are two important ways of carbon and nutrient input to soil in grassland grazing systems. Grazing livestock often deposit dung on plant litter, which may affect litter decomposition through a changing microenvironment. We assessed effects of yak dung on litter mixing effects on litter decomposition in a Tibetan alpine grassland. Six common species were selected, including low-quality litter species Kobresia capillifolia, Elymus nutans, and Ligularia virgaurea and high-quality litter species Anemone rivularis, Saussurea nigrescens, and Thermopsis lanceolata. Litter bags containing each species alone and all two-species combinations were allowed to decompose with and without experimental dung addition in the field. Mass loss of the leaf litter was measured after 6 and 12 mo. High-quality litter species had significantly greater mass loss than low-quality litter species. Dung significantly accelerated litter mass loss after both 6 and 12 mo for low-quality litter species, but only after 12 mo for high-quality litter species. Litter mixtures containing both high- and low-quality species showed positive nonadditive effects (NAEs) on mass loss after 6 mo but additive effects after 12 mo. Dung increased the strength of NAEs after 6 mo and shifted litter mixing effects from positive to negative NAEs after 12 mo. Our results support previous findings that litter mixing could produce NAEs on litter decomposition and that these NAEs could change with incubation time. Most importantly, we show that dung can modify NAEs, demonstrating that litter mixing effects are dependent on the microenvironment. Our findings also demonstrate that yak dung can influence soil processes by varying both single-species litter decomposition rates and litter interactions within mixtures. Furthermore, the results suggest yak dung is closely related to material and nutrient cycling, so we believe dung should remain and not be substantially removed from this grazing ecosystem.

The effects of nitrogen deposition and invasion on litter fuel quality and decomposition in a Stipa pulchra grassland

Fuel loads from invasive annual grasses different from natives can alter the fire regime to one that positively feedbacks to their establishment, known as the grass-fire cycle. Nitrogen (N) deposition can exacerbate the grass-fire cycle by favoring non-native annual grasses and increase their biomass production, generating greater fuel loads. Less studied is how N enrichment can affect the chemical quality of litter as it pertains to the decomposition or accumulation of fuel. Here, we primarily tested how N addition affected the quality and mass loss of litter produced by the native perennial grass, Stipa pulchra, and the non-native annual grass, Bromus hordeaceus. We found that B. hordeaceus litter was significantly lower in quality and decomposed to a lesser extent than S. pulchra litter, even with N addition, which increased litter quality and mass loss overall. In addition, we show that B. hordeaceus sustained dead biomass with lower moisture content for a greater portion of the experimental year. Therefore, we conclude that B. hordeaceus invasion promotes fire by generating litter that decomposes more slowly, leaving a greater source of dry fuel for a longer period of time.

Litter decomposition: effects of temperature driven by soil moisture and vegetation type

We examined the importance of litter quality and microclimate on early-stage litter mass loss, analysed the importance of interactions among environmental factors in determining key decomposition parameters and compared the variation in decomposition rates in vegetation types and sites with similar climate. Following the Tea-Bag Index approach, 464 tea-bags were incubated in the soil in 79 sites, distributed across Italy, which included six vegetation types and a broad range of microclimatic conditions. Litter type exerted a stronger control on mass loss compared to climatic factors. The effects of soil moisture were not the same for high and lower quality litter. In addition, the effects of temperature on the decomposition rate depended on soil moisture. The stabilization factor was strongly temperature-dependent, but the influence of temperature differed among vegetation types: those dominated by small-size plants showed a strong decrease in the potential amount of plant material entering into the soil stock under warmer temperatures. The lowest variation in decomposition rate was found in sites characterised by low temperatures, and, among the vegetation types, in alpine snowbeds. The role of litter quality and of the interactions among environmental conditions can potentially determine significant shifts in the expected patterns of ecosystem carbon fluxes.