Litter Mass Loss Research Articles

Summer litter decomposition is moderated by scale‐dependent microenvironmental variation in tundra ecosystems

Tundra soils are one of the world's largest organic carbon stores, yet this carbon is vulnerable to accelerated decomposition as climate warming progresses. The landscape‐scale controls of litter decomposition are poorly understood in tundra ecosystems, which hinders our understanding of the global carbon cycle. We examined the extent to which the thermal sum of surface air temperature, soil moisture and permafrost thaw depth influenced litter mass loss and decomposition rates (k), and at which spatial thresholds an environmental variable becomes a reliable predictor of decomposition, using the Tea Bag Index protocol across a heterogeneous tundra landscape on Qikiqtaruk–Herschel Island, Yukon, Canada. We found greater green tea litter mass loss and faster decomposition rates (k) in wetter areas within the landscape, and to a lesser extent in areas with deeper permafrost active layer thickness and higher surface thermal sums. We also found higher decomposition rates (k) on north‐facing relative to south‐facing aspects at microsites that were wetter rather than warmer. Spatially heterogeneous belowground conditions (soil moisture and active layer depth) explained variation in decomposition metrics at local scales (< 50 m2) better than thermal sum. Surprisingly, there was no strong control of elevation or slope on litter decomposition. Our results reveal that there is considerable scale dependency in the environmental controls of tundra litter decomposition, with moisture playing a greater role than the thermal sum at < 50 m2 scales. Our findings highlight the importance and complexity of microenvironmental controls on litter decomposition in estimates of carbon cycling in a rapidly warming tundra biome.

Thinning promotes litter decomposition and nutrient release in poplar plantations via altering the microclimate and understory plant diversity

Thinning is widely employed in forest management to improve productivity, protect forest biodiversity and maintain ecosystem functions. Here a thinning experiment with four treatments (unthinned, CK; 30% tree removal from below, MB; 50% tree removal by interlaced thinning, HI; and 50% tree removal from below, HB ) was set up in the poplar plantation, while a followed decomposition experiment with four litter types was conducted under the poplar plantations of undergoing four thinning treatments using the litterbag technique. Thinning affected the microclimate, but only the heavy thinning (HI and HB) significantly enhanced photosynthetic photon flux density (PPFD) and soil moisture in the plantations during the growing season. Thinning promoted understory vegetation biomass and vegetation diversity via modifying the microclimate parameters. Pearson correlation analysis showed that PPFD and understory herbaceous biomass were significantly correlated to Shannon-Weiner diversity index. Both thinning intensity and litter type significantly affected the litter remaining mass over times. Overall, increasing thinning intensity and litter complexity enhanced decay rate, while reduced half live (t0.5) and t0.95 values. Correlation analysis showed that air relative humidity, soil temperature, air temperature and soil moisture significantly influenced the litter mass loss rates. Non-additive (synergistic) effects were observed when different litters were mixed, but the non-additive effect was most pronounced when more herbaceous species litter were mixed with poplar leaves and 50% thinning intensity was applied. Dynamics of nutrient release from different litter types were similar to those on the litter mass lose, depending on the litter quality and microclimatic conditions. Our results suggest that a thinning operation with 50% tree removal from below (HB) would maintain the structural and functional features of the poplar plantations at the similar sites.

Effects of Thinning on Litterfall Production and Leaf Litter Decomposition Rates of Karacabey Forested Wetlands, Bursa, Turkiye

The contribution of litterfall (dead leaves, twigs, etc., fallen to the ground) and forest floor (organic residues such as leaves, twigs, etc., in various stages of decomposition, on the top of the mineral soil) is fundamental in both forest ecosystem sustainability and soil greenhouse gases (GHG) exchange system with the atmosphere. A focus on forested wetlands is particularly important, as these systems account for a disproportionate amount of global carbon flux relative to their spatial coverage, and the decomposition of leaf litter is a major contributor. In this study, we aimed to investigate the effects of two different thinning treatments (low thinning-canopy closure 41-70% and intense thinning-canopy closure 10-40%) on litterfall, forest floor litter and leaf litter decomposition rates of alder (Alnus glutinosa) stands in Karacabey forested wetlands. The litterfall was monthly collected using open litterfall traps for 2 years from 2021 to 2022. The forest floor litter was also sampled 50 x 50 cm2 quadrates of 5 points in research plots of 20×20 m. The differences in leaf litter decomposition rates between the low and intense thinning stands were investigated using the litterbag method in the field for 18 months. The results indicated that the intense thinning significantly reduced the total litterfall production (7.24 ± 0.384 Mg ha-1) and the forest floor litter (2.78 ± 0.41 Mg ha-1) compared to the low thinning stand (10.8 ± 0.527 Mg ha-1 and (4.38 ± 0.82 Mg ha-1 respectively). Lower leaf litter decomposition rates were also seen in the intense thinning stands than in the lower thinning stands. At the end of the 18 months, the leaf litter mass loss was 83.6% in the intense thinning stands compared to the lower thinning stands (88.3%).

The Response of Mesofauna to Nitrogen Deposition and Reduced Precipitation during Litter Decomposition

Soil mesofauna plays an important role in decomposing organic matter, recycling nutrients, and increasing nutrient availability. The effects of nitrogen (N) deposition and reduced precipitation on the litter-dwelling mesofaunal community and how this process affects litter decomposition remain poorly understood. Herein, a two-year simulated N deposition and throughfall reduction experiment was carried out in a natural evergreen broad-leaved subtropical forest to examine the effects of N deposition and reduced precipitation on soil mesofauna during litter decomposition. Four treatments were established: control (CK), N deposition (N), reduced precipitation (RP), and combined N deposition and reduced precipitation (N + RP). We collected and identified 19,782 individuals of mesofauna in litterbags during the whole experiment. Mites (Prostigmata, Mesostigmata, and Oribatida) and Collembola comprised almost 90% of the total number of individuals collected and dominated the soil mesofauna in our study. Our results revealed the negative effects of N deposition on the density of Oribatida mites and Collembola and the total density of soil mesofauna. Reduced precipitation significantly increased the density of Collembola and Oribatida mites and the total density of mesofauna and marginally significantly increased the density of Mesostigmata mites but decreased the diversity of mesofauna. The interaction effects of N deposition and reduced precipitation significantly affected the density of Prostigmata mites, Oribatida mites, Collembola, and the diversity of mesofauna. N deposition combined with reduced precipitation significantly inhibited litter decomposition, whereas no significant interaction effects were observed. Furthermore, correlation analysis indicated that litter mass loss was significantly positively correlated with the density of Prostigmata, Mesostigmata, and Oribatida, as well as the diversity of mesofauna. Overall, during the two-year decomposition process, our results suggest that N deposition and reduced precipitation interactively affected mesofaunal diversity and that N deposition adversely affected the mesofaunal community, while reduced precipitation increased the density of some groups but decreased mesofaunal diversity, consequently cascading on the decomposition of leaf litter.

Alder stands promote N-cycling but not leaf litter mass loss in Mediterranean streams flowing through pine plantations

During the last century, the abandonment of traditional dryland farming and pastures in the Mediterranean basin promoted the development of ambitious afforestation programs causing a drastic transformation of the landscape. Afforestation programs were usually accomplished without considering the potential ecological impacts on the recipient ecosystems. Forest streams rely on terrestrial organic detritus, so their functioning and conservation status can be altered by changes in riparian forest biodiversity and composition. However, the influences of conifer plantations in particular on stream functioning are still unclear, possibly because the presence of multiple species in plantations or the presence of other species in the riparian zones of streams may act as buffers of such effects. Here, by means of a field experiment, we assessed whether the presence of black alder in the riparian zone and/or as leaf litter within the stream may mitigate the impacts exerted by pine plantations on stream ecosystem functioning. We found (i) that streams were functionally similar but differed in water N concentrations; (ii) no differences in litter mas loss between riparian types, but higher total litter mass loss of those mixtures containing alder leaf litter; and (iii) higher N losses (or lower N gains) for all litter types in streams without riparian alder. These results demonstrate that microbial decomposers can use either stream water N or litter N, and that detritivores can feed simultaneously on resources of contrasting quality to balance their diet. Our study underscores the effect of even low-density riparian cover of alder promoting microbial nutrient cycling by moderate increases of water N concentrations. We suggest thinning of pine plantations combined with planting of native deciduous species as alder to alleviate the effects of pine plantations on Mediterranean streams.

Nitrogen rather than carbon released by litter decomposition mediates nutrient relationships in a multispecies forest plantation with hemiparasite

Hemiparasitic plants influence community composition by altering nutrient cycling. Although hemiparasites can deplete a host's nutrients via parasitism, their potentially positive effects on nutrient return to multispecies communities remain unclear. We used 13C/15N-enriched leaf litter of the hemiparasite sandalwood (Santalum album, Sa) and two N2-fixing hosts of acacia (Acacia confusa, Ac) and rosewood (Dalbergia odorifera, Do), either as a single-species or mixed-species litter, to elucidate nutrient return by litter decomposition in an acacia-rosewood-sandalwood mixed plantation. We determined litter decomposition rates, litter C and N release, and the resorption of C and N from seven litter types (Ac, Do, Sa, AcDo, AcSa, DoSa, and AcDoSa) at 90, 180, 270, and 360 days. We found that non-additive mixing effects were common during the decomposition of mixed litter and depended on litter type and decomposition timing. After rapidly increasing for around 180 days, both the decomposition rate and release of C and N from litter decomposition declined, but the resorption of litter-released N by the target tree species increased. There was a 90-day lag time between the release and resorption of litter N. Sandalwood litter consistently stimulated the litter mass loss of its mixed litter. Rosewood had the highest release rate of litter 13C or 15N from litter decomposition, but resorbed more litter 15N into its leaves than other tree species. In contrast, acacia had a lower decomposition rate and a higher 15N resorption in its roots. Initial litter quality was closely correlated with the release of litter 15N. Neither the release nor resorption of litter 13C significantly differed among sandalwood, rosewood, and acacia. Our study demonstrates that the fate of litter N, rather than litter C, mediates nutrient relationships in mixed sandalwood plantations and thus provides important silvicultural implications for planting sandalwood with other host species.

Dead bamboo culms promote litter mass, carbon and nitrogen loss, but do not modulate the effect of soil fauna on litter decomposition

Bamboos contribute significantly to carbon cycling in many (sub)tropical and temperate forests. In East Asia, unmanaged Moso bamboo stands accumulate large amounts of dead culms. However, very little is known about the indirect effects of dead culms on biogeochemical cycling through changes in soil conditions and decomposer communities. We evaluated the interactive effects of dead culms and soil fauna on litter decomposition in an unmanaged Moso bamboo stand. We placed leaf litter beneath the dead culms and on the forest floor (control) and used litterbags with different mesh sizes (1 mm and 42 μm) to control the access of soil mesofauna to the litter. We hypothesized that dead culms and soil fauna synergistically accelerate litter decomposition mainly because dead culms influence soil conditions and alter the litter fauna assemblage. We found that litter decomposing under the dead culms had greater litter mass, carbon and nitrogen loss, and microbial respiration rates than the control. The presence of soil mesofauna decreased litter mass, carbon and nitrogen loss but had no effect on the microbial respiration rate. Soil moisture was consistently higher under the dead culms, but their effect on soil temperature was dependent on the season. The litter decomposing below the dead culms had relatively higher mesofauna abundance and order richness. However, the contribution of the mesofauna to litter mass and nutrient loss was not modulated by the dead culms, suggesting that soil fauna had essentially the same effect on litter decomposition irrespective of the presence of dead culms. We showed that dead bamboo culms influence litter nutrient dynamics and promote habitat heterogeneity for soil microarthropods. Our results further highlight the ecological role played by dead culms and have implications for Moso bamboo management. The removal of dead culms from the forest floor could have substantial impact on the soil biota and ecosystem processes in managed stands.

Vine leaf decomposition: Feeding preferences and effects of physico-chemical traits of litter on life-history traits of the woodlice Armadillidium vulgare Latreille, 1804

Litter decomposition is a key ecosystem process which is dependent on the litter characteristics and diversity, the decomposer community and activity, and the environmental conditions. We assessed vine leaf decomposition by Armadillidium vulgare (Latreille, 1804), a terrestrial isopod widely distributed and naturally present in vineyards. We compared the decomposition of three grape varieties (Chardonnay, Pinot Noir and Sauvignon) with regular laboratory food (Tilia tomentosa (Moench, 1785)) for seven consecutive weeks. Seven traits were measured on the four litters tested in order to define their importance concerning (i) litter mass loss by the action of microorganisms and isopods (ii) the trophic traits (consumption and assimilation) and (iii) life-history traits (survival and growth) of A. vulgare. Thus, the chemical and physical traits (C/N ratio, tannin and fiber content, thickness) known to influence litter palatability and digestibility for decomposers were determined by standardized methods. In addition, the copper frequently used in viticulture as a fungicide which is potentially responsible for toxic effects on decomposers was measured by ICP-OES after litter mineralization in nitric acid. Our results showed a higher percentage of decomposability by microorganisms in litter with low cellulose content and C/N ratio. Higher isopod consumption and assimilation was found in the litters which is the poorest in tannin, lignin and copper contents. Variation of consumption according to litter was on average 1.5 to 2.7 lower for grape varieties compared to T. tomentosa litter. Assimilation was significantly lower with Pinot Noir than the other litters. To conclude, after seven weeks of experimentation, this study showed that if the growth and survival of woodlice were not affected by inter-varietal differences in vine leaf quality, their role in the decomposition process may be strongly modulated and reduced, especially after consumption of grape variety litters rich in copper, lignin and tannin.

Earthworms increase forest litter mass loss irrespective of deposited compounds - A field manipulation experiment in subtropical forests.

Earthworms modulate carbon and nitrogen cycling in terrestrial ecosystems, but their effect may be compromised by the deposition of pollutants from industrial emissions. However, studies investigating how deposited compounds affect the role of earthworms in carbon cycling such as litter decomposition are lacking, although the interactions of earthworms and deposited compounds are important for understanding the impact of pollutants on ecosystems and the potential of earthworms in bioremediation. We performed a 365-day in situ litterbag decomposition experiment in a deciduous (Quercus variabilis) and coniferous (Pinus massoniana) forest in southeast China. We manipulated nitrogen (N), sodium (Na), and polycyclic aromatic hydrocarbons (PAHs) as model compounds during litter decomposition with and without earthworms (Eisenia fetida). After one year, N, Na, and PAH all slowed down litter mass loss, with the effects of Na being the strongest. By contrast, E. fetida generally increased litter mass loss, and the positive effects were uniformly maintained irrespective of the type of compounds added. However, the pathways to how earthworms increased litter mass loss varied among the compounds added and the two forests studied. As indicated by structural equation modeling, earthworms mitigated the negative effects of deposited compounds by directly increasing litter mass loss and indirectly increasing soil pH and microbial biomass. Overall, the results indicate that the acceleration of litter mass loss by earthworms is little affected by deposited compounds, and that earthworms have the potential to mitigate negative impacts of pollutants on litter decomposition and ecosystem processes.

N and P combined addition accelerates the release of litter C, N, and most metal nutrients in a N-rich subtropical forest

Imbalanced nitrogen (N) and phosphorus (P) depositions are profoundly shifting terrestrial ecosystem biogeochemical processes. However, how P addition and its interaction with N addition influence the release of litter carbon (C), N, P, and especially metal nutrients in subtropical forests remains unclear. Herein, a two-year field litterbag experiment was conducted in a natural subtropical evergreen broadleaved forest of southwestern China using a factorial design with three levels of N addition (0, 10, and 20 g N m−2 y−1) and P addition (0, 5, 15 g P m−2 y−1). During two years of decomposition, N- and P-only addition treatments decreased the accumulated mass loss and release rates of litter C, N, P, K, Na, and Mn (p < 0.05); N and P coaddition treatments increased the accumulated mass loss and release rates of litter C, N, K, Na, Mn, and Cu (p < 0.05) and decreased the accumulated release rates of litter P and Mg (p < 0.05); the C/P and N/P ratios of the residual litter increased under the N-only addition treatments (p < 0.05) and decreased under the P-only addition and N and P coaddition treatments (p < 0.05). Overall, the results suggest that combined N and P supply can increase biological activities and thus accelerate the release of litter C, N, and most metal nutrients, as expected within the framework of ecological stoichiometry and growth rate hypothesis. Our study also highlights that the effect of N addition on litter C and nutrients release depends on P availability.

Direction of Alliaria petiolata (garlic mustard) leachate's effect on early litter mass loss is dependent upon saprotrophic community composition

Differences between fungal and bacterial decomposition trajectories can be related to differences in sensitivity to nutrient input and to plant secondary metabolites. The invasive plant Alliaria petiolata (Beib. Cavara and Grande; garlic mustard) produces unique secondary metabolites (glucosinolates) capable of altering the functioning of root-associated communities. However, few studies explore whether these compounds can alter litter decomposition— a route for ecosystem-level impacts of garlic mustard invasion. This preliminary study investigated the potential for aqueous garlic mustard leachate to alter mass loss from tea litterbags in artificially fungal-dominant compared to intact soils (fungal and bacterial components) in laboratory microcosm incubations. Garlic mustard and native Acer saccharum (Marsh.; sugar maple) leachates stimulated fungal decomposition indistinguishably. In intact soils, garlic mustard suppressed mass loss relative to a water control and native leachate, though this later effect was only marginally significant. These results suggest the energetic benefit of labile carbon in garlic mustard leachate may exceed any negative effect of glucosinolates for fungal decomposers, but that bacteria were more sensitive to leachate toxicity and the inhibitory effects of high nutrient input. Overall, our results imply the direction of garlic mustard's effect on decomposition may depend on saprotrophic community composition and therefore the consequences for litter decay in garlic mustard invaded soils may be context-dependent.

Maize/peanut intercropping has greater synergistic effects and home-field advantages than maize/soybean on straw decomposition.

The decomposition of plant litter mass is responsible for substantial carbon fluxes and remains a key process regulating nutrient cycling in natural and managed ecosystems. Litter decomposition has been addressed in agricultural monoculture systems, but not in intercropping systems, which produce species-diverse litter mass mixtures. The aim here is to quantify how straw type, the soil environment and their combined effects may influence straw decomposition in widely practiced maize/legume intercropping systems. Three decomposition experiments were conducted over 341 days within a long-term intercropping field experiment which included two nitrogen (N) addition levels (i.e. no-N and N-addition) and five cropping systems (maize, soybean and peanut monocultures and maize/soybean and maize/peanut intercropping). Experiment I was used to quantify litter quality effects on decomposition; five types of straw (maize, soybean, peanut, maize-soybean and maize-peanut) from two N treatments decomposed in the same maize plot. Experiment II addressed soil environment effects on root decomposition; soybean straw decomposed in different plots (five cropping systems and two N levels). Experiment III addressed 'home' decomposition effects whereby litter mass (straw) was remained to decompose in the plot of origin. The contribution of litter and soil effects to the home-field advantages was compared between experiment III ('home' plot) and I-II ('away' plot). Straw type affected litter mass loss in the same soil environment (experiment I) and the mass loss values of maize, soybean, peanut, maize-soybean, and maize-peanut straw were 59, 77, 87, 76, and 78%, respectively. Straw type also affected decomposition in the 'home' plot environment (experiment III), with mass loss values of maize, soybean, peanut, maize-soybean and maize-peanut straw of 66, 74, 80, 72, and 76%, respectively. Cropping system did not affect the mass loss of soybean straw (experiment II). Nitrogen-addition significantly increased straw mass loss in experiment III. Decomposition of maize-peanut straw mixtures was enhanced more by 'home-field advantage' effects than that of maize-soybean straw mixtures. There was a synergistic mixing effect of maize-peanut and maize-soybean straw mixture decomposition in both 'home' (experiment III) and 'away' plots (experiment I). Maize-peanut showed greater synergistic effects than maize-soybean in straw mixture decomposition in their 'home' plot (experiment III). These findings are discussed in terms of their important implications for the management of species-diverse straw in food-production intercropping systems.

No home‐field advantage in litter decomposition from the desert to temperate forest

Abstract Litter decomposition rates are determined by the interplay of climate, decomposer organisms and litter quality. It has been suggested that the decomposer community may be locally adapted to litter quality, providing a home‐field advantage (HFA) resulting in accelerated decomposition of local compared to non‐local litter, after accounting for decomposition differences due to litter quality and the functional capacity of microorganisms. Although widely tested in forests, this hypothesis remains controversial and lacks support of its generality across climates. We therefore tested the HFA hypothesis for litter decomposition in four contrasting ecosystems along an extensive climatic gradient in Chile, using a translocation experiment involving litter from 20 species. In addition to comparing mass loss, we adopted a novel way to disentangle decomposer effects from climate effects, based on loss rates of elements that are actively released from the litter by decomposers during its breakdown versus elements that are simply leached by precipitation. We used the ratios of nitrogen and potassium losses (N/K loss) and phosphorus and potassium losses (P/K loss) to unravel the relative role of microbial breakdown (N and P loss) versus physical leaching (K loss) along the climate gradient. Thus, at each site, we tested whether litter mass loss, N/K loss and P/K loss presented an additional loss due to a HFA for local compared to non‐local litter. Across a wide range of environments and litter types, our findings unequivocally contradicted the HFA hypothesis. We observed no significantly positive HFA along the gradient; however, litter quality and the general ability of the decomposer community influenced litter decomposition much more strongly than origin or location of the litter. Our study questions the applicability of the HFA for litter decomposition and calls for more studies that include a large range of climatic conditions to understand the context‐dependency of HFA. Read the free Plain Language Summary for this article on the Journal blog.

Experimental Warming of Typically Acidic and Nutrient-Poor Boreal Soils Does Not Affect Leaf-Litter Decomposition of Temperate Deciduous Tree Species

Ongoing rapid climatic changes are expected to modify the structure, composition, and functioning of forest ecosystems. Studying the influence of such changes on biogeochemical processes is thus crucial for a fuller understanding of forest response to climate change. In a temperate forest of Quebec, Canada, we emulated climate change by warming the acidic, nutrient-poor, and dry soils of two mixedwoods by 3 to 4 °C using heating cables. Leaf-litter mass loss of the local red maple, sugar maple, large-tooth aspen, and American beech were monitored to assess the ability of these tree species to condition boreal soils in the context of their northward migration under climate change. We hypothesized that decomposition rates of all leaf-litter types would be decreased equally by warming due to a drying effect of the soil and its surface, which is detrimental to microbial biomass and activity. Our results suggest differences in decomposition rates between tree species as follows: sugar maple &gt; red maple ≥ American beech = large-tooth aspen. There was no indication of a slower turnover in these marginal soils compared to other studies conducted on typical hardwood soils. Moreover, no difference in litter mass loss was detected between treatments, likely due to a drying effect of the soil warming treatment. Results imply that climate change has a marginal influence on leaf-litter dynamics of temperate tree species on soils that are typical of the boreal forest. However, some variables that could play an important role on litter decomposition in the context of climate change were not measured (e.g., plant phenology, understory composition and density, microbes) and thus, uncertainties remain. The soil drying effect by warming also needs to be further documented and modeled. The study year was characterized by significant periods of water stress but was not considered an exceptional year in that regard. It would be relevant to test for leaf-litter dynamics during dry and wet summers and verify again our initial hypothesis of decreased leaf-litter decomposition rates due to soil warming/drying.

干旱与半干旱区灌丛微生境中红砂枯落物分解特征及中小型节肢动物的作用

PDF HTML阅读 XML下载 导出引用 引用提醒 干旱与半干旱区灌丛微生境中红砂枯落物分解特征及中小型节肢动物的作用 DOI: 10.5846/stxb202111193261 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 宁夏自然科学基金项目（2021AAC03047，2020AAC02014）；宁夏重点研发计划项目（2021BEG03007）；国家自然科学基金项目（41867005） The decomposition process of Reaumuria soongorica litter and the role of microarthropods in shrub microhabitats in arid and semi-arid regions Author: Affiliation: 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:在干旱区（内蒙古乌拉特后旗）和半干旱区（宁夏盐池）荒漠草原区，选择柠条灌丛内外微生境为研究样地，以红砂枯落物为研究对象，利用2种规格网孔分解袋（30目和250目网孔），探索中小型节肢动物在红砂枯落物分解过程中的作用规律，研究灌丛微生境中红砂枯落物质量损失变化特征及节肢动物群落的贡献。结果表明：（1）在干旱与半干旱区，红砂枯落物分解常数K均表现为灌丛内外微生境间无显著差异，且有无节肢动物参与对K的影响均较小。（2）分解至12个月时，无节肢动物参与的情况下，干旱与半干旱区红砂枯落物残留率均表现为裸地显著低于灌丛；但有节肢动物参与时，枯落物残留率则表现为灌丛内外微生境间无显著差异。分解至44个月时，无节肢动物参与的情况下，仅在干旱区枯落物残留率表现为裸地显著高于灌丛；而有节肢动物参与时，干旱与半干旱区枯落物残留率均表现为灌丛内外微生境间无显著差异。（3）节肢动物对红砂枯落物质量损失的贡献率呈现单峰值现象，且在分解至24个月时达到峰值。枯落物分解至12个月时，仅半干旱区节肢动物对红砂枯落物分解的贡献率表现为裸地显著低于灌丛；分解至44个月时，仅干旱区节肢动物对红砂枯落物分解的贡献率表现为裸地显著高于灌丛。（4）在半干旱区，节肢动物对红砂枯落物质量损失的贡献率与节肢动物类群数、土壤砂粒含量、土壤全碳和含水量密切相关；而在干旱区，节肢动物对红砂枯落物质量损失的贡献率与土壤pH值、土壤砂粒、土壤碳氮比d （C/N）和黏粉粒含量密切相关。综合表明，干旱和半干旱区灌丛微生境红砂枯落物分解特征受到节肢动物分解作用的影响较小；但在某些分解阶段，灌丛内外微生境中红砂枯落物质量损失的差异性受到节肢动物分解作用的显著影响，节肢动物的分解作用表现为弱（12个月）-强（24个月）-弱（44个月）的作用规律，而且受到气候区调节的灌丛微生境限制。 Abstract:In desertified grasslands of the arid Urad Rear Banner of the Inner Mongolia and the semi-arid Yanchi of Ningxia, the Caragana korshinskii shrub microhabitats beneath shrub canopies and in the open spaces were setup as study sites. The litter of Reaumuria soongorica was used as the research object. Two sizes of mesh (30-mesh, and 250-mesh) for litter bags were used to explore the role of soil microarthropods on litter decomposition of Reaumuria soongorica. The objective of present study was to probe into the mass loss of the litter and the contribution of soil microarthropod community in the shrub microhabitats. The results showed that:(1) there was no significant difference in decomposition constant K of litter between shrub canopy and open spaces; the presence or absence of microarthropods had little effect on K. (2) At decomposition stage of 12 months, there was significantly lower mass remaining rate of the litter in open spaces than beneath shrub canopy without the presence of microarthropods, but there was no significant difference between shrub canopy and open spaces in the case of microarthropods presence. At decomposition stage of 44 months, the mass remaining rate of litter was significantly higher in open spaces than beneath shrub canopy only in arid regions without the participation of microarthropods; however, there was no significant difference between both shrub microhabitats with microarthropod presence in both arid and semi-arid regions. (3) The contribution rate of microarthropods to the mass loss of litter showed a unimodal type during decomposition process, with a single peak at 24 months. At decomposition stage of 12 months, there was significantly lower contribution rate of microarthropods to the decomposition of litter in open spaces than beneath shrub canopy only in semi-arid region. At decomposition stage of 44 months, the contribution rate of microarthropods to the decomposition of litter was significantly higher in open spaces than beneath shrub canopy only in arid region. (4) In the semi-arid region, the contribution rate of microarthropods to litter mass loss was closely correlated to the group richness of microarthropod, soil sand content, soil total carbon, and water content. In the arid region, however, the contribution rate of microarthropods to the mass loss of litter was closely correlated to soil pH, soil sand, soil C/N, and clay and silt content. In conclusion, the overall litter decomposition in shrub microhabitats in arid and semi-arid regions was little affected by the role of microarthropods. However, at certain decomposition stages, the difference in mass loss of the litter between shrub microhabitats was affected remarkably by the role of microarthropods. There was a law of weak (12 months)-strong (24 months)-weak (44 months) role of microarthropods on litter decomposition that was regulated by the climatic factors. 参考文献 相似文献 引证文献

Changes in the nitrogen isotopic composition during the transformation of peat-forming plant litter at dried and post-pyrogenic sites of oligotrophic bogs

The aim of the study. Assessment of changes in the nitrogen isotopic composition (δ15N) during the decomposition of the main peat-forming plants’ litter in peat of oligotrophic bog ecosystems in the southern taiga subzone of West Siberia. Location and time of the study. The studies were carried out in 2019–2021 in two oligotrophic bogs: “Bakcharskoye” (field station “Vasyuganye” (IMCES SB RAS)) and “Iksinskoye”, which are the north-eastern spurs of the Great Vasyugan mire and located in the Bakcharsky district of the Tomsk region, Russia. Methods. The decomposition rate of peat-forming plants’ litter was determined by the method of partially isolated samples, which is widely used to study the transformation of plant material and peat. The nitrogen isotopic composition in the original and decomposed samples of the plant material was determined by isotope ratio mass spectrometry using a DELTA V Advantage mass spectrometer combined with a Flash 2000 elemental analyzer (EA-IRMS). Results. A three-year study of the decomposition of peat-forming plants (Sphagnum fuscum, Chamaedaphne calyculata, Eriophorum vaginatum and a Mixed sample) in four ecosystems (natural - VASnat, drained - VASdry, post-pyrogenic - Iksa1 and Iksa2) showed that melioration and fire influenced the litter decomposition rate, increasing the latter in the drained bog and slowing down Sph. fuscum and Mixed sample decomposition by 1.5–9.0% at the site with pyrogenic effects. During the plant litter transformation carbon and nitrogen were released as 24–62% and 21–46%, respectively. In all studied samples, except for Sph. fuscum, a relationship was revealed between the plant litter mass loss and changes in the nitrogen isotopic composition. Conclusions. The effect of peat fires is manifested by a decrease in the plant residue decomposition rate. The dynamics of changes in the isotopic composition during the transformation of the studied plant residues depended on the plant species, but does not depend on decomposition duration (1, 2, 3 years) and sample location. Key words: transformation of plant residues; nitrogen isotopes; biogeochemical cycle; pyrogenic peatlands; drained peatlands; West Siberia.

Regulation of initial soil environmental factors on litter decomposition rate affects the estimation accuracy of litter mass loss in a subtropical forest

Regulation of initial soil environmental factors on litter decomposition rate affects the estimation accuracy of litter mass loss in a subtropical forest

Mixed-litter effects of fresh leaf semi-decomposed litter and fine root on soil enzyme activity and microbial community in an evergreen broadleaf karst forest in southwest China.

Litter decomposition is the main process that affects nutrient cycling and carbon budgets in mixed forests. However, knowledge of the response of the soil microbial processes to the mixed-litter decomposition of fresh leaf, semi-decomposed leaf and fine root is limited. Thus, a laboratory microcosm experiment was performed to explore the mixed-litter effects of fresh leaf, semi-decomposed leaf and fine root on the soil enzyme activity and microbial community in an evergreen broadleaf karst forest in Southwest China. Fresh leaf litter, semi-decomposed litter and fine root in the Parakmeria nitida and Dayaoshania cotinifolia forests, which are unique protective species and dominant species in the evergreen broadleaf forest, were decomposed alone and in all possible combinations, respectively. Our results showed that the mass loss of fresh leaf litter in three mixed-litter treatment was significantly higher than that in two mixed-litter treatment in the P. nitida and D. cotinifolia forests. Mass loss of fine root in the single litter treatment was significantly lower in the P. nitida forest and higher in the D. cotinifolia forest compared to that in the other litter treatments. There were insignificant differences in the activities of β-glucosidase (BG) and leucine aminopeptidase (LAP) between control and mixed-litter treatment in the P. nitida forest and between control and single litter treatment in the D. cotinifolia forest. The N-acetyl-β-D-glucosaminidase (NAG) activity was significantly increased by the single litter decomposition of fresh leaf and fine root and three mixed-litter decomposition in the P. nitida and D. cotinifolia forests. The activity of acid phospomonoesterase (AP) in the decomposition of fresh leaf litter was lower in the P. nitida forest and higher in the D. cotinifolia forest compared to that in control. The most dominant soil bacteria were Proteobacteria in the P. nitida forest and were Actinobacteria and Proteobacteria in the D. cotinifolia forest. Shannon, Chao1, ACE and PD indexes in the mixed-litter decomposition of fresh leaf and semi-decomposition litter were higher than that in control in P. nitida forest. There were insignificant differences in observed species and indexes of Chao1, ACE and PD between litter treatments in the D. cotinifolia forest. Richness of mixed-litter significantly affected mass loss, soil enzyme activity and microbial diversity in the P. nitida forest. Litter N concentration and the presence of fresh leaf litter were significantly correlated with the mass loss and soil enzyme activity in the P. nitida and D. cotinifolia forests. These results indicated that the presence of fresh leaf litter showed a non-negligible influence on mixed-litter decomposition and soil enzyme activity, which might be partly explained by litter initial quality in the P. nitida and D. cotinifolia forests.

The response of litter decomposition to extreme drought modified by plant species, plant part, and soil depth in a temperate grassland.

Plant litter decomposition is a key ecosystem process in carbon and nutrient cycling, and is heavily affected by changing climate. While the direct effects of drought on decomposition are widely studied, in order to better predict the overall drought effect, indirect effects associated with various drought-induced changes in ecosystems should also be quantified. We studied the effect of an extreme (5-month) experimental drought on decomposition, and if this effect varies with two dominant perennial grasses, plant parts (leaves vs. roots), and soil depths (0-5cm vs. 10-15 cm) in a semi-arid temperate grassland. After 12 months, the average litter mass loss was 43.5% in the control plots, while only 25.7% in the drought plots. Overall, mass loss was greater for leaves (44.3%) compared to roots (24.9%), and for Festuca vaginata (38.6%) compared to Stipa borysthenica (30.5%). This variation was consistent with the observed differences in nitrogen and lignin content between plant parts and species. Mass loss was greater for deep soil (42.8%) than for shallow soil (26.4%). Collectively, these differences in decomposition between the two species, plant parts, and soil depths were similar in magnitude to direct drought effect. Drought induces multiple changes in ecosystems, and our results highlight that these changes may in turn modify decomposition. We conclude that for a reliable estimate of decomposition rates in an altered climate, not only direct but also indirect climatic effects should be considered, such as those arising from changing species dominance, root-to-shoot ratio, and rooting depth.

Tropical stream microcosms of isolated fungal species suggest nutrient enrichment does not accelerate decomposition but might inhibit fungal biomass production.

Terrestrial leaf litter is an essential energy source in forest streams and in many tropical streams, including Cerrado, litter undergoes biological decomposition mainly by fungi. However, there is a limited understanding of the contribution of isolated fungal species to in-stream litter decomposition in the tropics. Here we set a full factorial microcosms experiment using four fungal species (Aquanectria penicillioides, Lunulospora curvula, Pestalotiopsis submerses, and Pestalotiopsis sp.) incubated in isolation, two litter types (rapid and slow decomposing litter) and two nutrient levels (natural and enriched), all characteristics of Cerrado streams, to elucidate the role of isolated fungal species on litter decomposition. We found that all fungal species promoted litter mass loss but with contributions that varied from 1% to 8% of the initial mass. The fungal species decomposed 1.5 times more the slow decomposing litter and water nutrient enrichment had no effect on their contribution to mass loss. In contrast, fungal biomass was reduced by nutrient enrichment and was different among fungal species. We showed fungal contribution to decomposition depends on fungal identity and litter type, but not on water nutrients. These findings suggest that the identity of fungal species and litter types may have more important repercussions to in-stream decomposition than moderate nutrient enrichment in the tropics.