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The rewetting of long-term drained peatlands leads to the development of eutrophic shallow lakes, gradually inhabited by reed communities. These shallow lakes are characterized by significant nutrient and methane emissions. To comprehend the fate of organic compounds from decaying Phragmites australis litter in water and anaerobic soil layers, we conducted a 1.6-year decomposition experiment. The experiment employed bulk and lignin-derived phenol analysis, as well as Fourier-transform infrared spectroscopy. As anticipated, the highest level of decomposition was observed in the surface water body of the shallow lake, while the non-rooted degraded peat exhibited the lowest decay. The bulk mass loss of plant litter decreased with depth from 55 to 27% across the four decomposition environments. Analysis using infrared spectroscopy indicated that the decrease in mass loss was primarily driven by the breakdown of carbohydrates, which constitute a significant portion of plant litter. Interestingly, litter in the rooted degraded peat layer exhibited the highest degree of lignin decay. Furthermore, the study revealed a preferential loss of vanillin phenols and an accumulation of p-hydroxyl phenols. These findings suggest that the increased methane emissions in rewetted fens may be partially attributed to the demethoxylation of vanillin phenols and the subsequent formation of p-hydroxyl phenols. In conclusion, this study provides valuable insights into anaerobic lignin decomposition of plant litter and sheds light on potential mechanisms underlying elevated methane emissions in rewetted peatlands. Furthermore, the study's findings hold significant implications for both carbon cycling and sequestration within these ecosystems, thereby stimulating further research into the microbial community and its extended effects. [ABSTRACT FROM AUTHOR]

Fire-derived charcoal (charcoal) is a stable byproduct of forest fires, which accumulates in the litter layer and soils of boreal forests. Therefore, the decomposition of litter and roots as one of the key processes in the carbon cycle in the soils of northern forests proceeds almost everywhere in the presence of charcoal. To date, the data on the influence of charcoal on the organic material decomposition in boreal forests are extremely scarce and most of them do not consider the cold period, which lasts on the average half a year in this zone. The goal of this work is to determine the seasonal influence of charcoal on the decomposition of plant litter of different qualities (larch needles, birch leaves, grasses, and mixtures of these litter types) on the soil surface and the roots of the same types in the soil. A field litterbag experiment demonstrates that charcoal accelerates the decomposition of litter in a species-specific manner. Charcoal accelerates the mass loss of recalcitrant aboveground litter (needles) and all types of roots during the cold season. As for the warm season, charcoal accelerates the decomposition of only needles and has no effect on the roots. Thus, our study shows a greater influence of charcoal on the subsoil decomposition especially in the cold season. The seasonal influence of charcoal is demonstrated for the first time and should be taken into account as an important factor of humus formation and carbon dynamics in the soils of boreal forests. [ABSTRACT FROM AUTHOR]

The effect of mixing litter on decomposition has received considerable attention in terrestrial and aquatic (but rarely in both) ecosystems, with a striking lack of consensus in the obtained results. We studied the decomposition of a mixture of poplar and alder in three terrestrial: aquatic exposures to determine (1) if the effect of mixing litter on mass loss, associated decomposers (fungal biomass, sporulation rates, and richness), and detritivores (abundance, biomass, and richness of invertebrate shredders) differs between the stream (fully aquatic exposure) and when litter is exposed to a period of terrestrial exposure prior to immersion and (2) the effect of the mixture across exposure scenarios. The effect of the mixture was additive on mass loss and synergistic on decomposers and detritivores across exposure scenarios. Within scenarios, mass loss and decomposers showed synergistic effects only in the fully aquatic exposure, detritivores showed synergistic effects only when the period of terrestrial was shorter than the period of aquatic exposure, and when the period of terrestrial was equal to the period of aquatic exposure the effect of the mixture was additive on mass loss, decomposers, and detritivores. The species‐specific effects also differed among exposure scenarios. Alder affected poplar only when there was a period of terrestrial exposure, with increased sporulation rates and fungal richness in exposure 25:75, and increased mass loss in exposure 50:50. Poplar affected alder only under fully aquatic exposure, with increased mass loss. In conclusion, the synergistic effects of the mixture changed with a period of terrestrial exposure prior to immersion. These results provide a cross‐boundary perspective on the effect of mixing litter, showing a legacy effect of exposure to terrestrial decomposition on the fate of plant litter in aquatic ecosystems and highlighting the importance of also assessing the effect of mixing litter on the associated biota and not only on mass loss. [ABSTRACT FROM AUTHOR]

Climate change drives a northward shift of biomes in high‐latitude regions. This might have consequences on the decomposition of plant litter entering the soil, including its lignin component, which is one of the most abundant components of vascular plants. In order to elucidate the combined effect of climate and soil characteristics on the decomposition pattern of lignin, we investigated lignin contents and its degree of oxidative decomposition within soil profiles along a climosequence in western Siberia. Soil samples were collected from organic topsoil to mineral subsoil at six sites along a 1500‐km latitudinal transect, stretching from tundra, through taiga and forest steppe to typical steppe. The stage of lignin degradation, as mirrored by decreasing organic carbon‐normalized lignin contents and increasing oxidative alteration of the remnant lignin (acid‐to‐aldehyde ratios of vanillyl‐ and syringyl‐units [(Ac/Al)V and (Ac/Al)S]) within soil horizons, increased from tundra to forest steppe and then decreased to the steppe. Principal component analysis, involving also climatic conditions such as mean annual temperature and aridity index, showed that the different states of lignin degradation between horizons related well to the activity of phenoloxidases and peroxidases, enzymes involved in lignin depolymerization that are produced primarily by fungi and less importantly by bacteria. The low microbial lignin decomposition in the tundra was likely due to low temperature and high soil moisture, which do not favour the fungi. Increasing temperature and decreasing soil moisture, facilitating a higher abundance of fungi, led to increased fungal lignin decomposition towards the forest‐steppe biome, while drought and high pH might be responsible for the reduced lignin decomposition in the steppe. We infer that a shift of biomes to the north, driven by climate change, might promote lignin decomposition in the northern parts, whereas in the south a further retardation might be likely. [ABSTRACT FROM AUTHOR]

Background and aims: Dioecy may subject females and males to contrasting selective pressures, leading to differences in adaptive traits associated with resource allocation and ecophysiology across sex. Such differences may then exert carry-over effects on the surrounding ecosystem. However, effect of different sex combinations over ecosystem biogeochemical cycles, via organic matter decomposition, has not yet been addressed. Here, we used different combinations of female and male Populus cathayana to elucidate the carry-over effects of dioecy on organic matter decomposition. Methods: 900 saplings were grown in field plots in either single-sex or mixed-sex treatments. Soil organic matter decomposition rates were estimated using the teabag index, and measurements of soil microbial respiration in vitro, and characterization of the rhizosphere microbial community, were done. Results: Different sex combinations variedly influenced plant growth, assimilation rates, and soil processes under field conditions. showed highest shoot length, stem diameter, photosynthetic rates, soil microbial respiration rates, litter decomposition rate, the extent of litter stabilization, and soil microbial structure were highest under the FM treatment. Bacterial abundance and diversity were highest in FF plots, while the highest abundance and diversity of classified fungi occurred in MM plots. Our piecewise structural equation model analysis results further confirmed that sex was a significant driver of photosynthesis, shoot dry weight, specific root length, microbe abundance and diversity, soil nutrient status, soil respiration, and organic matter decomposition. Conclusion: Our results indicate that sex plays a significant role in soil biogeochemical processes and provides novel insights relevant to dioecious plantations and biogeochemical modeling. [ABSTRACT FROM AUTHOR]

Although microbial communities play an important role in explaining plant litter decomposition rates, whether and how litter chemistry may alter catabolic capacities of soil microbial communities remains poorly studied.During a 1‐year litter decomposition experiment of 12 herbaceous species with contrasting litter chemistry, we examined the effect of plant litter type (roots vs. leaves) and litter chemical traits on the resulting capacity of soil microbial communities to degrade a wide range of carbon substrates of variable complexity (MicroResp™ method).Litter chemistry impacted both the total catabolic activity as well as specific catabolic capacities of microbial communities. In the early stages of litter decomposition total catabolic activity was mainly influenced by the amount of C and N in litter leachates, and litter N, P and Mg, then, later, by lignin concentrations. Some specific catabolic capacities could also be related to litter initial chemistry. Overall, litter trait effects on soil microbial communities decreased over time and the relative importance of traits shifted during the decomposition process.Our results highlight that litter chemistry is a strong driver of catabolic capacities of microbial decomposers and, while its effect fades with time, it remains substantial throughout the litter decomposition process. These long‐lasting effects of litter chemistry suggest a persistent control on microbial catabolic capacities in ecosystems with recurrent litter production. Soil microbial catabolic activities were driven by broadly the same chemical traits across leaf and root litters.Synthesis. Such long‐lasting effects of litter chemistry on catabolic capacities of microbial communities may represent a substantial indirect driver of the decomposition process. Disentangling the relative importance of this overlooked effect of litter chemistry on decomposition represents the next challenge. We argue that such research line should open ground‐breaking perspectives for reconsidering our current understanding of the mechanistic links between litter traits and decomposition rate. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Background: Plants can directly affect litter decomposition by producing litter materials of different qualities. However, whether living plants have indirect effects on litter decomposition by affecting changes in forest microenvironments is presently unclear in plantation forests. Methods: We addressed this issue by studying the decomposition of the leaf litter and fine roots of Chinese fir [Cunninghamia lanceolata (Lamb.) Hook.], a timber species widely planted in China, in 113 non-neighboring quadrats of varying basal area of the dominant plant species (i.e., Chinese fir) and distinct basal areas and species richness of regenerated woody plants (i.e., species other than Chinese fir) in a subtropical Chinese fir forest. Results: Our results showed that fine roots decomposed significantly more rapidly than leaf litter possibly because fine roots were easier access to mineralized nutrients and microbes compared with leaf litter. Further analyses showed that leaf litter and fine root decomposition rates were significantly controlled by the plant community attributes. The decomposition of both leaf litter and fine roots was mainly controlled by woody species regenerated during stand development rather than by Chinese fir. Specifically, leaf litter and fine root decomposition rates decreased with increasing basal area of regenerated woody plants, possibly due to nutrient competition and/or reduced photodegradation. Conclusions: This study provides empirical evidence that woody species regenerated during stand development play a certain role in determining litter decomposition rates through plant-soil interactions in Chinese fir plantations. Regenerated woody plants should be considered in future studies on soil carbon and nutrient cycling in plantation forest. [ABSTRACT FROM AUTHOR]

Soil organic matter (SOM) is comprised of a diverse array of reactive carbon molecules, including hydrophilic and hydrophobic compounds, that impact rates of SOM formation and persistence. Despite clear importance to ecosystem science, little is known about broad-scale controls on SOM diversity and variability in soil. Here, we show that microbial decomposition drives significant variability in the molecular richness and diversity of SOM between soil horizons and across a continental-scale gradient in climate and ecosystem type (arid shrubs, coniferous, deciduous, and mixed forests, grasslands, and tundra sedges). The molecular dissimilarity of SOM was strongly influenced by ecosystem type (hydrophilic compounds: 17%, P < 0.001; hydrophobic compounds: 10%P < 0.001) and soil horizon (hydrophilic compounds: 17%, P < 0.001; hydrophobic compounds: 21%, P < 0.001), as assessed using metabolomic analysis of hydrophilic and hydrophobic metabolites. While the proportion of shared molecular features was significantly higher in the litter layer than subsoil C horizons across ecosystems (12 times and 4 times higher for hydrophilic and hydrophobic compounds, respectively), the proportion of site-specific molecular features nearly doubled from the litter layer to the subsoil horizon, suggesting greater differentiation of compounds after microbial decomposition within each ecosystem. Together, these results suggest that microbial decomposition of plant litter leads to a decrease in SOM a-molecular diversity, yet an increase in β-molecular diversity across ecosystems. The degree of microbial degradation, determined by the position in the soil profile, exerts a greater control on SOM molecular diversity than environmental factors, such as soil texture, moisture, and ecosystem type. [ABSTRACT FROM AUTHOR]

We believe that correcting for leaching in (terrestrial) litterbags studies such as the Tea Bag Index will result in more uncertainties than it resolves. That is, although shorter durations of leaching experiments increase the likelihood that they only quantify primary leaching, they result in a higher probability of missing events that contribute to primary leaching. Future litter decomposition and leaching studies will improve by careful interpretation of solid experiments, by being transparent about definitions used and by explaining the way in which leaching corrections were applied (if any). [Extracted from the article]

Aims: Soil fauna is one of the major drivers of plant litter decomposition. This study aims to assess how soil fauna density and diversity may affect litter decomposition. Also, we assessed whether faunal communities inside the litterbags that are used to control the access of faunal groups or communities in ambient soils are better for predicting their effects on litter decomposition, given that soil fauna frequently move into and out of such litterbags. Methods: To answer this question, we synthesized 5336 observations extracted from 46 publications to assess the effects of soil fauna communities, their density and diversity on the rate of litter decomposition (k) and litter mass loss. Results: Results showed that (1) the presence of soil fauna significantly increased k by an average of 33.0% and that the effects were mainly controlled by initial litter concentrations of phosphorus and magnesium, (2) the density and diversity of soil fauna in litterbags significantly affected k and/or mass loss, but ambient communities had limited effects, and (3) the effects of soil fauna in litterbags on k were most significant during the early stages of decomposition (0 − 30% mass loss). Conclusions: Our study clearly showed that litterbag communities were better for predicting the effects of soil fauna on litter decomposition, and that their effects were most significant during the early stages of decomposition. These results improve our ability to estimate the contribution of soil fauna in liter decomposition and the associated carbon and nutrient cycling. [ABSTRACT FROM AUTHOR]

Plant litter decomposition figures importantly in the cycling of C and N pools in terrestrial ecosystems. We investigated how C and N fluxes changed during the decomposition of leguminous and non-leguminous leaf litters, and how these processes responded to different precipitation regimes. We used the dual-isotope tracing method to investigate differences in leaf and soil C and N, along with δ13C and δ15N, in the soil of the Loess Plateau in China. The δ15N and δ13C values were 3604‰ and 56‰ for Robinia pseudoacacia (Leguminosae) and 8115‰ and 452‰ for Populus tomentosa (Salicaceae) leaf litters. Through decomposition, δ13C decreased in all litters, and δ15N in the leguminous litter increased while it decreased in the non-leguminous litter. In the surface soil, the fraction of litter-derived N (14%) from the leguminous litter was significantly higher than that of the non-leguminous litter after 16 months. The C and N concentrations of both litters and soil always had a positive correlation during decomposition, and the responses of N to C changes in soil were reduced by the litter cover. Increased precipitation enhanced the litters' C and N correlation. The 600 mm precipitation treatment most benefited litter C's transformation to SOC, and drought conditions promoted the transformation of legume litter N to soil TN, but inhibited non-legume litter N. In the soil and both litters, C and N changes always had a positive correlation. After 16 months, the proportion of soil N from legumes was higher than that from non-legumes. Reduced precipitation could promote leguminous N in soil. Our results provide a scientific basis for accurately predicting the C and N cycles in terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

Understanding how genetic differences among soil microorganisms regulate spatial patterns in litter decay remains a persistent challenge in ecology. Despite fine root litter accounting for ~50% of total litter production in forest ecosystems, far less is known about the microbial decay of fine roots relative to aboveground litter. Here, we evaluated whether fine root decay occurred more rapidly where fungal communities have a greater genetic potential for litter decay. Additionally, we tested if linkages between decay and fungal genes can be adequately captured by delineating saprotrophic and ectomycorrhizal fungal functional groups based on whether they have genes encoding certain ligninolytic class II peroxidase enzymes, which oxidize lignin and polyphenolic compounds. To address these ideas, we used a litterbag study paired with fungal DNA barcoding to characterize fine root decay rates and fungal community composition at the landscape scale in northern temperate forests, and we estimated the genetic potential of fungal communities for litter decay using publicly available genomes. Fine root decay occurred more rapidly where fungal communities had a greater genetic potential for decay, especially of cellulose and hemicellulose. Fine root decay was positively correlated with ligninolytic saprotrophic fungi and negatively correlated with ECM fungi with ligninolytic peroxidases, likely because these saprotrophic and ectomycorrhizal functional groups had the highest and lowest genetic potentials for plant cell wall degradation, respectively. These fungal variables overwhelmed direct environmental controls, suggesting fungal community composition and genetic variation are primary controls over fine root decay in temperate forests at regional scales. [ABSTRACT FROM AUTHOR]

The decomposition of plant litter and animal dung is the key processes of nutrient cycling and has been studied in a wide range of grassland ecosystems. However, most studies focus on the separate processes of either plant litter or animal dung decomposition, while the interactions between these two processes, which occur in grazed grassland ecosystems, are rarely studied. We conducted an experiment in a semi-arid grassland in Central Inner Mongolia, to examine the mass loss rates and chemical composition changes of two plant litter species and three herbivore dung types separately or in combination over a 2-year period. Twenty litterbag treatments were used to represent 2 treatments of plant litter only, 6 treatments of herbivore dung only at two addition levels, and 12 treatments of litter and dung combinations. We found that horse dung had the biggest mass loss rate, followed by cattle dung and sheep dung, either separately or mixed with plant litter. Dung addition promoted the mass loss, nitrogen release and fiber fraction (hemicellulose, cellulose and lignin) loss of plant litter, and the promotion was strongest for cattle dung, weakest for sheep dung, and stronger at high dung addition levels and in the early stages. However, the effect of litter addition on dung decomposition, a negative effect, was significant only when the dung proportion was low in the litter and dung mixture (that is, in the treatment of 10 g litter + 6 g dung). Furthermore, a significant positive non-additive effect of mixing litter and dung on their total mass loss was detected for the mixture at a litter:dung ratio of 10:6, the ratio in the major grazing area of the grassland. Our findings suggest that mixture of herbivore dung with plant litter, as in actual grassland ecosystems, promotes litter decomposition, and the composition of the litter and dung in mixture, though it may inhibit dung decomposition, due to the changes in chemical stoichiometry of decomposing materials and biophysical microenvironment by the mixing. It is necessary to incorporate the non-additive effect of litter and dung mixture in modeling carbon and nutrient cycling of grassland ecosystems. [ABSTRACT FROM AUTHOR]

Ongoing global warming is expected to alter temperature-dependent processes. Nevertheless, how co-occurring local drivers will influence temperature sensitivity of plant litter decomposition in lotic ecosystems remains uncertain. Here, we examined the temperature sensitivity of microbial-mediated decomposition, microbial respiration, fungal biomass and leaf nutrients of two plant species varying in litter quality. We also assessed whether the type of microbial community and stream water characteristics influence such responses to temperature. We incubated alder (Alnus glutinosa) and eucalypt (Eucalyptus globulus) litter discs in three streams differing in autumn–winter water temperature (range 4.6–8.9 °C). Simultaneously, in laboratory microcosms, litter discs microbially conditioned in these streams were incubated at 5, 10 and 15 °C with water from the conditioning stream and with a water control from an additional stream. Both in the field and in the laboratory, higher temperatures enhanced litter decomposition rates, except for eucalypt in the field. Leaf quality modified the response of decomposition to temperature in the field, with eucalypt leaf litter showing a lower increase, whereas it did not in the laboratory. The origin of microbial community only affected the decomposition rates in the laboratory, but it did not modify the response to temperature. Water quality only defined the phosphorus content of the leaf litter or the fungal biomass, but it did not modify the response to temperature. Our results suggest that the acceleration in decomposition by global warming will be shaped by local factors, mainly by leaf litter quality, in headwater streams. [ABSTRACT FROM AUTHOR]

Phyllosphere microbes are essential in the mediation of plant–soil biogeochemical recycling during the decomposition of plant litter in wetland ecosystems. However, there are few studies into microbial community succession in phyllosphere microbial communities in wetlands, and their functional attributes across a full period of wetland plant litter decomposition remain unclear. Here, we collected leaf samples of Typha latifolia var. orientalis (C. Presl.) Rohrb., an emergent wetland plant, during various stages of decomposition (growing, standing, lodging, and submerging stages) to investigate fungal and bacterial assemblage succession in the phyllosphere. We then parsed these assemblages into specific fungal trophic modes and bacterial phenotypes. Over the litter decomposition period, both fungal and bacterial assemblages underwent distinct succession, with generally increasing alpha diversity, and the proportion of litter microbes originating from sediments increased with decomposition. Saprotrophic and pathotrophic fungi dominated the fungal assemblage in the early stages of decomposition, but their dominance was replaced by undefined fungi as decomposition progressed. Relative abundances of both pathotrophic fungi and potentially pathogenic bacteria increased from the growing to the standing stage, implying that there was a turning point in assemblage composition shortly after plant leaf death. Gram-positive and gram-negative bacteria had opposite trends in their relative abundances over successive decomposition stages. When plant litter entered the water, bacteria tolerant of oxidative stress gradually decreased in abundance, but anaerobic bacteria abundance increased. We also aimed to determine the relationships between predicted microbial functional traits and leaf litter physicochemical attributes. Lignin and N content were the predominant predictors of decomposer fungal trophic modes and bacterial phenotypes. These findings provide evidence that the complex litter decomposition seen in wetlands is accompanied by a dynamic cross-kingdom succession of phyllospheric microbial communities, coupled with distinct changes in the phenotypes of the microbes present. Insights into phyllospheric microbial functional traits have implications for better elucidating the plant litter cycle for wetland plants. [ABSTRACT FROM AUTHOR]

Photodegradation is an important mechanism that affects carbon and nutrient cycling; a significant amount of data has been reported previously. The present review includes the effect of a wider spectrum of solar radiation (sun light, UV, and visible light) on plant litter decay in terrestrial ecosystems. Although the positive effect of photodegradation on decomposition is most common, a substantial number of studies reports contrasting results. Litter from 148 plant species, from 41 families, have been used in photodegradation studies, representing functional groups of trees (33%), graminoids (30%), shrubs (23%), forbs (11%), and peat (1%). Although the majority of studies focused on mass loss, a growing number focuses on nutrient release. Positive effects on mass loss are most common across different climate regions and laboratory studies, whereas "positive" influence and "no effect" on nitrogen and lignin release are equally common in temperate and sub-tropical environments. This may potentially be due to other decomposition processes which increase in relevance with increasing moisture and can facilitate microbial activity, leaching, and fractioning by soil fauna. In addition to climate region, initial litter quality influences photodegradation. Field-based and laboratory experiments frequently obtain contrasting results, suggesting that the mechanisms controlling the responses are unclear and might be dependent on several interactions, and/or the differences in experimental approaches (such as UV filters), or coverage by particles. Future research should focus on interactions between different factors, and on conducting experiments that test specific relationships such as the potential interaction between photodegradation, soil moisture, microbial communities, soil fauna, and their effects on litter decomposition (both mass loss and nutrient release). Furthermore, the topic would benefit from international studies applying the same experimental approach, as has successfully been conducted in other fields. [ABSTRACT FROM AUTHOR]

The extramatrical mycelium of ectomycorrhizal fungi (EMF) is an important source of soil carbon and nitrogen. While the importance of recalcitrant compounds in the fungal cell wall has been explored earlier, the contribution of highly abundant but labile components, like glucans, and the role of their temporal dynamics during decomposition remains unknown. For the first time, we examined how the concentration of three main fungal cell wall components (chitin, melanin, glucans) in EMF necromass are related to necromass decomposition, over a period of 6 weeks. Although the initial concentrations of the three components were not good predictors of necromass loss, we found species–specific trends of chitin and glucans loss over time. The chitin concentration during decomposition was tightly linked to the weekly necromass degradation, with trends of chitin loss being dissimilar across fungal species. Chitin concentration was positively correlated with the mass loss in the first week, but in the remaining 5 weeks, it was found to be weakly negatively correlated with mass loss. The similarity in susceptibility to the decomposition of glucans and chitin likely compensates for the impacts of interspecific differences in their initial concentration, leading to overall similar decomposition patterns. Alternatively, other, non‐measured, components (e.g., glycoproteins, N content) may contribute to explaining similar decomposition patterns. Our results indicate that ectomycorrhizal necromass decomposition processes differ from those of plant litter decomposition with, unlike in plants, differences in initial concentrations of major structural carbohydrates (e.g., glucans) being unrelated to differences in decomposition rates. These findings indicate that the decomposition of fungal material cannot be inferred from assumptions based on data provided by studies of plant decomposition. Highlights: Necromass of different ectomycorrhizal species decomposes similarlyMain cell wall components show different decomposition patternsThe relationship between cell wall compounds and mass loss changes over timeMycorrhizal necromass decomposition differs substantially from that of plant litter. [ABSTRACT FROM AUTHOR]

The effect of soil moisture on plant litter decomposition is one of the major focuses of decomposition research. In this study, 150-day laboratory experiments were conducted with the simulated soil environment under different moisture levels. Three macrophytes, Phragmites australis, Miscanthus lutarioriparius, and Carex cinerascens, were selected. The dry biomass weight, and nutrient concentrations of plant samples were measured during the experiment, and a modified bi-exponential formula was used to investigate the effects of soil moisture on plant decomposition under non-submerged conditions. The litter decomposition process is considered as the simultaneous exponential decomposition of labile and refractory components. The relationship between the decomposition rates of the two components and soil moisture was found to be exponential. The results showed that the modified formula with moisture factor agreed well with the dry weight data (R2 > 0.97). The mass fractions of the labile component were 5.9%, 11.3%, and 6.7% for P. australis, M. lutarioriparius, and C. cinerascens, respectively. As moisture increased from 50 to 90%, the decomposition rate k1 of labile part increased from 0.05 to 0.12 day−1, and k2 of refractory part increased from about 0.0007 to 0.006 day−1. Higher quality plant (with high N content and low C content) decomposed faster. The effect of different moisture levels on the microbial community in the experiment was not significant. Furthermore, a longer humidification time in one cycle can promote the decomposition of both parts. The proposed bi-exponential formula of plant decomposition can be used to estimate vegetation decomposition in alternating wetting and drying surface waters. [ABSTRACT FROM AUTHOR]

A field experiment was carried out in plant litter decomposition at three sites of the Balaton System (Balaton — Kis Balaton wetland — Zala Mouth) differing in their environment type during winter 2019/2020. The largest freshwater shallow lake in Central Europe (Carpathian Basin) is the Balaton, with a surface area of about 600 km2 and an average depth of 3.25 m. Right around the lake, a nutrient filtering system, the Kis-Balaton wetland, is functioning to avoid water deterioration and eutrophication. The aim of the study was to investigate crop-weather relations in two sample species, the widely distributed native P. australis and the allied S. canadensis incubated beneath the water using leaf-bag technique to characterise plant organ decomposition. Based on our results, the most consistent meteorological variable regarding decomposition process was global radiation (r = − 0.62* to − 0.91**; r: correlation coefficient; * and ** mean that correlations are significant at the 0.05 and 0.01 levels), in each treatment. In modelling the decomposition process, out of eight meteorological variables, only the daily mean air temperatures and humidity were excluded from regression equations. On dominatingly windy days, with the increase in water temperature of the Zala Mouth, the sensitivity of the decomposition of S. canadensis litter tended to decrease as compared to P. australis. The remaining litter masses were in a Kis-Balaton > Balaton > Zala order, contrasting the water temperature gradient that decreased from the Zala to the Kis-Balaton wetland under wind-dominated conditions. Considering all sampling places in three aquatic ecosystems, there was a 2.2 and a 2.7% daily mean detritus mass loss in P. australis and S. canadensis, respectively. We concluded that the invasive S. canadensis litter decomposed more quickly than those of native P. australis, irrespective to sampling site. Increase in winter water temperature significantly promoted the litter decomposition of both plant species. The originality of the study is that it quantifies the litter decomposition for an Eastern European wetland, during wintertime. [ABSTRACT FROM AUTHOR]

Coevolution has driven speciation and evolutionary novelty in functional traits across the Tree of Life. Classic coevolutionary syndromes such as plant–pollinator, plant–herbivore, and host–parasite have focused strongly on the fitness consequences during the lifetime of the interacting partners. Less is known about the consequences of coevolved traits for ecosystem-level processes, in particular their 'afterlife' legacies for litter decomposition, nutrient cycling, and the functional ecology of decomposers. We review the mechanisms by which traits resulting from coevolution between plants and their consumers, microbial symbionts, or humans, and between microbial decomposers and invertebrates, drive plant litter decomposition pathways and rates. This supports the idea that much of current global variation in the decomposition of plant material is a legacy of coevolution. Plant litter decomposition adds a different process and ecological context to the coevolution literature, which has thus far focused on the ecology of symbionts during their lifetimes. This context integrates the literature on how arms races between plants and their consumers (herbivores, pathogens) or mutualists (nitrogen-fixing bacteria, mycorrhizal fungi) drive the quality of plant tissue, with an important legacy for litter decomposability. We know little about recent coevolutionary decomposition legacies involving plant domestication by humans via farming, plant breeding, and modified landscapes with feedback to evolution of human brain, digestion, and dentition. How myriad coevolutionary links between invertebrates and microbial decomposers affect global carbon cycling needs further investigation. Overall, plant decomposition rates are largely the legacy of wide-ranging coevolutionary relationships. [ABSTRACT FROM AUTHOR]

Simple Summary: Global warming could affect Collembola and related decomposition processes within soil ecosystems in permafrost wetlands. Open top chambers (OTCs) were used to simulate climate warming in a cold temperate monsoon climate zone in the Great Hing'an Mountains of Northeast China. Collembola were captured using an aspirator after five years of simulated warming. We found that warming treatment increased the species richness and abundance of Collembola in most of the different seasons, except in May. Species composition differed significantly in the control and warming treatment in May and September. The Collembola species composition in permafrost wetlands was mainly determined by air humidity, indicating different responses of Collembola species to the indirect effect of warming on water availability. It is indicated that warming was the primary factor positively affecting the abundance of Collembola. An increase of Collembola abundance and community alteration to warming could have profound cascading effects on the microbes and plants they feed on in permafrost wetlands. The consideration of environmental factors has long been crucial to developing theories about the spatial variability of species diversity. However, the effects of global warming on Collembola, in permafrost wetlands, are largely unknown. Understanding how Collembola are affected by climate warming is important as they directly affect the community assembly and decomposition processes of plant litter within soil ecosystems. A peatland area in a cold temperate monsoon climate zone in the Great Hing'an Mountains of Northeast China was selected as the study area. Collembola were captured using an aspirator after five years of simulated warming using open top chambers (OTCs). Sampling in different growth seasons showed different characteristics in the control (CK) and warming (OTCs) treatment. Further, the results showed that (1) warming treatment increased the species richness and abundance of Collembola in the different seasons, except in May, (2) warming increased Collembola abundance in permafrost wetlands, and the warming effect was more significant during the cold season (about eight times in April), (3) species composition differed significantly in the control and warming treatment in May and September, and (4) the Collembola species composition in permafrost wetlands was mainly determined by air humidity, indicating different responses of Collembola species to the indirect effect of warming on water availability. We found that warming was the primary factor positively affecting the abundance of Collembola. An increase of Collembola abundance and community alteration to warming could have profound cascading effects on the microbes and plants they feed on in permafrost wetlands. [ABSTRACT FROM AUTHOR]

Predicting and mitigating changes in soil carbon (C) stocks under global change requires a coherent understanding of the factors regulating soil organic matter (SOM) formation and persistence, including knowledge of the direct sources of SOM (plants vs. microbes). In recent years, conceptual models of SOM formation have emphasized the primacy of microbial‐derived organic matter inputs, proposing that microbial physiological traits (e.g., growth efficiency) are dominant controls on SOM quantity. However, recent quantitative studies have challenged this view, suggesting that plants make larger direct contributions to SOM than is currently recognized by this paradigm. In this review, we attempt to reconcile these perspectives by highlighting that variation across estimates of plant‐ versus microbial‐derived SOM may arise in part from methodological limitations. We show that all major methods used to estimate plant versus microbial contributions to SOM have substantial shortcomings, highlighting the uncertainty in our current quantitative estimates. We demonstrate that there is significant overlap in the chemical signatures of compounds produced by microbes, plant roots, and through the extracellular decomposition of plant litter, which introduces uncertainty into the use of common biomarkers for parsing plant‐ and microbial‐derived SOM, especially in the mineral‐associated organic matter (MAOM) fraction. Although the studies that we review have contributed to a deeper understanding of microbial contributions to SOM, limitations with current methods constrain quantitative estimates. In light of recent advances, we suggest that now is a critical time to re‐evaluate long‐standing methods, clearly define their limitations, and develop a strategic plan for improving the quantification of plant‐ and microbial‐derived SOM. From our synthesis, we outline key questions and challenges for future research on the mechanisms of SOM formation and stabilization from plant and microbial pathways. [ABSTRACT FROM AUTHOR]

Simple Summary: The addition of plant leaf litter to soils represents a critical component of the global carbon (C) and nitrogen (N) cycles. Tropical cyclones known at typhoons in the western Pacific islands transfer an enormous amount of green leaf litter from the forest canopy to the soil. We have shown on the island of Guam that this green litter releases carbon and nitrogen extremely rapidly compared with senesced leaf litter. Moreover, species such as Guam's native cycad Cycas micronesica produce slowly decomposing litter, while other species such as Guam's native angiosperm Morinda citrifolia produce rapidly decomposing litter. Soil priming is an important process in the global C cycle, and occurs when pre-existing organic matter releases more C as a result of new organic C additions. The green litter generated soil priming that was almost double that of the senesced litter. The release of N from the green litter into forms that are available to plants required only 14 d for the M. citrifolia litter but required more than 90 d for the C. micronesica litter. Scientists predict more frequent intense typhoons in the future, and we have shown one of the ecosystem-level processes that these typhoons will change. Plant leaf litter decomposition is directly influenced by the identity of the source plants and the leaf age. Defoliation of forests by tropical cyclones (TC) transfers copious amounts of high-quality green leaf litter to soils. We used a soil amendment approach with the incubated buried bag method to compare carbon (C) and nitrogen (N) mineralization dynamics of green and senesced leaf litter from cycad Cycas micronesica and angiosperm Morinda citrifolia trees on the island of Guam. Soil priming increased the decomposition of pre-existing organic C, and were greater for green leaf litter additions than senesced leaf litter additions. Available N content increased by day 14 and remained elevated for the entire 117-d incubation for soils amended with green M. citrifolia litter. In contrast, available N content increased above those in control soils by day 90 and above those in soils amended with senesced litter by day 117 for green C. micronesica litter. The net N mineralization rate was higher than control soils by 120% for the senesced litter treatments and 420% for the green litter treatments. The results reveal a complex but predictable interplay between TC defoliation and litter quality as defined by tree identity. We have illuminated one means by which increased frequency of intense TCs due to climate change may alter the global C and N cycles. [ABSTRACT FROM AUTHOR]

Decomposition of plant litter is a fundamental ecological process, integral to soil formation, soil organic matter chemistry, and biogeochemical cycling. However, much of our understanding of decay dynamics focuses on rates of litter mass loss and therefore carbon dynamics, with relatively less exploration of the chemical nature of litter decomposition during which the degradation of litter structural and metabolic compounds into fragments are either metabolized or ultimately incorporated into soil humus. Our understanding of the patterns of changes in litter chemistry throughout decomposition is incomplete, as few studies have measured chemical content beyond initial litter chemistry and throughout decay, and particularly not chemistry beyond carbon and nitrogen. The existing literature also reports idiosyncratic instances of litter chemical convergence and divergence. We used archived litter decomposition samples and data from across the U.S. Long-Term Ecological Research Network to investigate the trajectory of a comprehensive array of litter chemistry, including nutrient, structural, and metabolic parameters, across a wide variety of plant functional types and ecosystems, throughout the first 70% of mass loss. Our results do not yield a universally common pattern of litter chemical trajectories across all functional types and regions, and very limited evidence of convergence or divergence in chemistry over time, mostly within the nutrient elements. We provide details about the behavior of individual chemical parameters to functional type and region over decay. Changes in plant communities driven by global change may alter nutrient cycling and SOM formation through persistence or divergence on litter chemistry inputs. [ABSTRACT FROM AUTHOR]

Plant litter decomposition is a key process in the biogeochemical cycles of terrestrial ecosystems. The main goal of this work is to determine the impact of current climate change on the decomposition process of the litter of Palo Laziale Wood (Rome, Italy), one of the last remnants of the Tyrrhenian lowland forest. A time-dependent simulation of leaf litter decay was previously performed on a dynamic semi-empirical model based on Olson's model (1963). It was also assumed that microbial activity depended on optimal temperature and moisture conditions simulated by Climatic Decomposition Index (CDI). The comparison between the observed and simulated leaf litter biomass reduction over time (t = −0.127, p = 0.901) highlighted the adequacy of CDI in reproducing biomass trends under limiting climatic conditions (high temperature and low precipitation). However, the decomposition model used here was not able to simulate the reduction of recalcitrant compounds (lignin) in strongly limiting conditions of water availability in the Palo Laziale Wood. These climatic conditions were attributable to climate change, which made the year 2020 representative of future years increasingly characterized by limiting climatic conditions. Therefore, it is necessary to carefully calibrate the CDI in order to consider the current and future changes in temperature and water availability in the Mediterranean area, and to, therefore, perform a better model-based foreseeing for leaf litter decomposition. [ABSTRACT FROM AUTHOR]

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 (0–5 cm 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. [ABSTRACT FROM AUTHOR]

Purpose: In long-term global change experiments, while cumulative treatment effects on soil and plant responses can emerge over time, comparisons between short and long-term responses can potentially be confounded with interannual variability in the environment. We added new nitrogen addition and warming plots to a pre-existing nitrogen and warming field experiment in a grass-dominated field to compare the short-term (1–2 year; new plots) versus long-term (14–15 year; old plots) treatment effects on soil microbial activity and plant litter decomposition, while controlling for the effects of interannual environmental variability. Methods: We assessed microbial activity by assaying the potential activities of five soil extracellular enzymes: three hydrolase enzymes (N-acetyl-glucosaminidase, phosphatase and β-glucosidase) and two oxidase enzymes (phenol oxidase and peroxidase). We measured mass loss from litter bags to assess the decomposition of grass and forb litter. Results: Warming interacted with plot age, with increased hydrolase activity in spring in response to warming only occurring in the long-term plots; increases in peroxidase activity with nitrogen addition in spring occurred for all plots. By summer, there were no significant interactions between the treatments and plot age for enzyme activity. Decreased decomposition with warming, observed for forb litter, only occurred in the long-term plots, but increased decomposition with nitrogen addition, observed for grass litter, occurred in both the long-term and short-term plots. Conclusions: Our results confirm an intensification of treatment effects on enzyme activity and litter decomposition over time for warming, but no interactions with plot age for nitrogen addition. [ABSTRACT FROM AUTHOR]

Purpose: Winter snow cover is a key control over soil biogeochemical cycles in cold biomes but has decreased with climate warming, particularly in high-latitude and high-altitude areas. Previous studies have found a decline in carbon (C) release from decomposing litter without snow cover, yet partitioning what C fractions respond to snow removal remains not fully understood. Methods: Here we incubated fir and birch litter in microcosms over two years of decomposition in an alpine forest to assess the release of various C fractions with and without snow cover using 13C nuclear magnetic resonance (NMR). Results: We found that 51% and 61% of total organic C was lost from fir and birch litter, respectively, after two years of decomposition, and 59% and 60% of this C was decomposed during winter. More C was lost from both fir and birch litter under snow cover, and the decomposition rate of birch litter C was decreased by 50% after snow removal. However, only O-alkyl C (particularly carbohydrate C) release was reduced with snow removal, and the release of other C fractions (i.e., alkyl C, aromatic C and carbonyl C) did not change significantly after removing snow cover. Delayed O-alkyl C release from fir and birch litter was in accordance with the declines in soil dissolved organic C and microbial respiration rate under removed snow plots, but this delay induced by snow removal did not carry over to the following growing season. Conclusion: We conclude that a reduction in winter snow cover regulates early decomposition of plant litter by controlling the rapid release of more labile C fractions (i.e., carbohydrates) in seasonally snow-covered ecosystems. [ABSTRACT FROM AUTHOR]

To assess how the presence of an invasive plant and different-sized decomposers affect plant litter decomposition under different seasonal conditions, we allocated leaves of native Ficus virens Aiton into four different mesh sizes (0.025, 0.042, 0.5 and 5 mm) with and without invasive Alternanthera philoxeroides (Mart.) Griseb. We incubated them for 65 days in an eutrophic lake in summer and winter respectively. The average decomposition rate was significantly higher in summer than in winter, and was significantly higher in mixtures than in F. virens monocultures in both seasons. The presence of A. philoxeroides in the mixture significantly increased invertebrate density and microbial respiration rates in summer but not in winter. Furthermore, contribution of invertebrates to decomposition was higher in the early stage of decomposition and lower in the late stage in summer, yet that of microbes was relatively constant in winter. Contribution of microinvertebrates increased in summer but that of meio-, macroinvertebrates increased in winter. Our findings indicate that the presence of an invasive plant altered litter decomposition, which may depend on seasonal variations, invertebrate density and decomposition stages. [ABSTRACT FROM AUTHOR]

(1) Background: Plant litter decomposition and its effect on soil nutrients are important parts of the ecosystem material cycle, and understanding these processes is key for species selection and allocation, to promote the effective use of litter in ecological tea gardens. (2) Methods: In situ decomposition was used in this study Changes in decomposition rate, element release, and soil properties during the decomposition of the mixed plant residues were measured. (3) Results: The decomposition rate (k) of the CCG (Camellia sinensis + Cinnamomum glanduliferum) mixed plant residue was significantly higher than that of the CS (Camellia sinensis) residue. The decomposition of the CCG, CPM (C. sinensis + Pinus massoniana), and CBL (C. sinensis + Betula luminifera) mixed plant residues showed an additive effect, whereas that of the CCL residue showed an antagonistic effect. The CBL mixed plant residue promoted the release of N; the decomposition of the CCG, CPM, CCL (C. sinensis + Cunninghamia lanceolata), and CBL residues promoted the release of TC (total carbon); and the decomposition of the CCG residue promoted the release of cellulose. After 428 d of decomposition, the four mixed plant residues had improved the soil nutrient contents to some extent. CCG and CBL residue decomposition resulted in greater improvements in soil nutrients. (4) Conclusions: The application of the mixture of material obtained by pruning C. glanduliferum, B. luminifera, and C. sinensis in an ecological tea garden accelerated the decomposition and nutrient release rates, increased soil nutrient contents, shortened the decomposition turnover period of plant residues, and accelerated the nutrient cycle of plant residues in the ecological tea garden. [ABSTRACT FROM AUTHOR]

Application of organic soil amendments is commonplace in horticulture to improve soil fertility. Whether this practice can also augment the soil carbon (C) pool has been of increasing interest in recent years. We used a controlled field experiment that has received annual applications of six different horticultural soil amendments for seven consecutive years. Each amendment was examined in terms of its contribution to bulk C and the distribution of C between theoretical pools, as defined by physical fractionation. Physical fractionation was combined with 13C nuclear magnetic resonance spectroscopy with cross-polarization and magic angle spinning (CPMAS NMR) analysis. Results indicated that the difference in total C concentration between treatments resulted from an increase in unprotected, free, particulate organic matter (fOM), rather than an increase in soil organic matter being occluded in aggregates or in organo-mineral complexes, and that C persisted in the fOM fraction as a result of accumulation in the alkyl C region. Unlike fresh litter or plant residues, organic amendments have undergone decomposition during the composting process (or during formation in the case of peat), in the absence of mineral soil components. This ex situ decomposition (and possible stabilization through acquired recalcitrance) could reduce the opportunity to become physically or chemically protected through association with the soil mineral phase following addition to soil. Carbon:Nitrogen (C:N) of amendment material likely influenced the rate of amendment decomposition. In addition, C:N determines the decomposition of plant litter inputs, as determined by the tea bag index. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) play an important role on litter decomposition, which is the keyways for nutrients returning to natural ecosystems. Although having no known saprotrophic abilities like ectomycorizal and ericoid fungi, AMF can affect litter decomposition by releasing low molecular compounds such as sugar, amino acids and organic acids through extraradical mycorrhizal hyphae, or deposit dead hypha fragments as nutrient (e.g., carbon) input and to stimulate microbial decomposers, i.e., priming effect. Besides, interactions of AMF with saprotrophic microorganisms through ways such as niche competition, synergistic cooperation, specific microorganisms recruitment and by soil nutrient removal that can influence litter decomposition. Under different microenvironments, AMF display various nutrient acquisition strategies, which also affects this process. The magnitude and direction of AMF effects on litter decomposition depend on plant communities, litter quality, soil and litter nutrient dynamics, soil physical and chemical properties (mainly, physical structure, temperature, humidity, pH and nutrient content). The exacerbation of global changes (drought, chemical fertilization and soil acidification) is exerting pervasive impacts on ecosystem processes and functions mediated by AMF. In this review, we explore the current state of knowledge about the impacts of AMF on litter decomposition from microenvironment perspective. The summary of the potential influence of various microsite abiotic and biotic factors on this process in order to provide theoretical reference for comprehensive analysis of ecosystem functions of AMF is made. [ABSTRACT FROM AUTHOR]

Acute resource pulses can have dramatic legacies for organismal growth, but the legacy effects of resource pulses on broader aspects of community structure and ecosystem processes are less understood. Mass emergence of periodical cicadas (Magicicada spp.) provides an excellent opportunity to shed light on the influence of resource pulses on community and ecosystem dynamics: the adults emerge every 13 or 17 years in vast numbers over much of eastern North America, with a smaller but still significant number becoming incorporated into forest food webs. To study the potential effects of such arthropod resource pulse on primary production and belowground food webs, we added adult cicada bodies to the soil surface surrounding sycamore trees and assessed soil carbon and nitrogen concentrations, plant‐available nutrients, abundance and community composition of soil fauna occupying various trophic levels, decomposition rate of plant litter after 50 and 100 days, and tree performance for 4 years. Contrary to previous studies, we did not find significant cicada effects on tree performance despite observing higher plant‐available nutrient levels on cicada addition plots. Cicada addition did change the community composition of soil nematodes and increased the abundance of bacterial‐ and fungal‐feeding nematodes, while plant feeders, omnivores, and predators were not influenced. Altogether, acute resource pulses from decomposing cicadas propagated belowground to soil microbial‐feeding invertebrates and stimulated nutrient mineralization in the soil, but these effects did not transfer up to affect tree performance. We conclude that, despite their influence on soil food web and processes they carry out, even massive resource pulses from arthropods do not necessarily translate to NPP, supporting the view that ephemeral nutrient pulses can be attenuated relatively quickly despite being relatively large in magnitude. [ABSTRACT FROM AUTHOR]

Plant litter decomposition is a complex, long-term process. The decomposition of litterfall is a major process influencing nutrient balance in forest soil. The soil microbiome is exceptionally diverse and is an essential regulator of litter decomposition. However, the microbiome composition and the interaction with litterfall and soil remain poorly understood. In this study, we examined the bacterial and fungal community composition of Lithocarpus across soil samples from different sampling seasons. Our results displayed that the microbiome assembly along the soil layer is influenced predominantly by the soil layer rather than by the sampling season. We identified that the soil layer strongly affected network complexity and that bacterial and fungal microbiomes displayed different patterns in different soil layers. Furthermore, source tracking and community composition analysis indicated that there are significantly different between soil and litter. Moreover, our results demonstrate that few dominant taxa (2% and 4% of bacterial and fungal phylotypes) dominated in the different soil layers. Hydnodontaceae was identified as the most important biomarker taxa for humic fragmented litter fungal microbiome and Nigrospora and Archaeorhizomycetaceae for organic soil and the organic mineral soil layer, and the phylum of Acidobacteria for the bacteria microbiome. Our work provides comprehensive evidence of significant microbiome differences between soil layers and has important implications for further studying soil microbiome ecosystem functions. [ABSTRACT FROM AUTHOR]

Summary: Plant litter decomposition is a key process for carbon (C) turnover in terrestrial ecosystems. Sunlight has been shown to cause and accelerate C release in semiarid ecosystems, yet the dose–response relationships for these effects have not been evaluated.We conducted a two‐phase experiment where plant litter of three species was subjected to a broad range of cumulative solar radiation (CSR) exposures under field conditions. We then evaluated the relationships between CSR exposure and abiotic mass loss, litter quality and the subsequent biotic decomposition and microbial activity in litter.Dose–response relationships demonstrated that CSR exposure was modestly correlated with abiotic mass loss but highly significantly correlated with lignin degradation, saccharification, microbial activity and biotic decay of plant litter across all species. Moreover, a comparison of these dose–response relationships suggested that small reductions in litter lignin due to exposure to sunlight may have large consequences for biotic decay.These results provide strong support for a model that postulates a critical role for lignin photodegradation in the mechanism of photofacilitation and demonstrate that, under natural field conditions, biotic degradation of plant litter is linearly related with the dose of solar radiation received by the material before coming into contact with decomposer microorganisms. [ABSTRACT FROM AUTHOR]

Wetland emergent plants are important carriers for maintaining the functions of wetland ecosystems, and the decomposition process is a necessary part of the material energy cycle. In order to fully understand the decomposition characteristics of wetland litter, we selected nine dominant wetland emergent plants in Dianchi lakeside and collected the leaf litter samples in four stages from living to death, including vigorous growth season, standing dead stage, lodging stage, and submerged stage. We measured the leaf litter decomposition rate and sixteen physical and chemical indexes during the 3.5 a period. We analyzed the dynamic changes of decomposition rate and physical and chemical indicators, as well as their correlation, and we calculated the contribution of species and decomposition stages to the variation of each indicators. The results were as follows:(1)Decomposition rates(k value)ranged from 0.43 a-1 to 1.41 a-1, among which Zizania latifolia decomposed the fastest(k=1.41 a-1), Thalia dealbata decomposed the slowest(k=0.43 a-1).(2)Specific leaf area, puncture strength and dry matter amount showed a trend of “continuous increase” “continuous decrease” and “first increase and then decrease”, respectively. Nutrient element indexes mainly presented “release-enrichment”“enrichment-release” and “net release” modes. Among the key carbon-related indexes, lignin showed the trend in “enrichment-release”“enrichment-release-enrichment” and “enrichment”, respectively. Cellulose and hemicellulose showed “accumulation-release” changes.(3)Leaf litter decomposition rate had the highest correlation with initial physical indexes(i.e., specific leaf area, puncture strength, amount of dry matter)and initial carbon-related indexes(i.e., cellulose, hemicellulose).(4)Dynamic changes of thirteen indexes during the incubation period were mainly dominated by the decomposition stage, and three indexes were dominated by species. Among them, specific leaf area, puncture strength, amount of dry matter, carbon, potassium, calcium, sulfur, iron and other indexes have consistency in the decomposition dynamics of different emergent plants. Therefore, it can be used as key indexes for emergent plant litter decomposition. This study indicates that the decomposition rates of different plants are different, and physical and carbon-related compound indicators are the main factors regulating the decomposition rate, the decomposition law of wetland emergent plants is revealed to provide crucial theoretical reference for further predicting litter decomposition of wetland emergent plants. [ABSTRACT FROM AUTHOR]

Plant litter decomposition in terrestrial ecosystems involves the physical and chemical breakdown of organic matter. Development of databases is a promising tool for achieving a predictive understanding of organic matter degradation at regional and global scales. In this paper, we present aridec, a comprehensive open database containing litter mass loss data from aridlands across the world. We describe in detail the structure of the database and discuss general patterns in the data. Then, we explore what are the most appropriate model structures to integrate with data on litter decomposition from the database by conducting a collinearity analysis. The database includes 184 entries from aridlands across the world, representing a wide range of climates. For the majority of the data gathered in aridec, it is possible to fit models of litter decomposition that consider initial organic matter as a homogenous reservoir (one pool models), as well as models with two distinct types of organic compounds that decompose at different speeds (two pool models). Moreover, these two carbon pools can either decompose without interaction (parallel models) or with matter transfer from a labile pool to a slowly decomposing pool after transformation (series models). Although most entries in the database can be used to fit these models, we suggest that potential users of this database test identifiability for each individual case as well as the number of degrees of freedom. Other model applications that are not discussed in this publication might also be suitable for use with this database. Lastly, we give some recommendations for future decomposition studies to be potentially added to this database. The extent of the information included in aridec in addition to its open-science approach makes it a great platform for future collaborative efforts in the field of aridland biogeochemistry. The aridec version 1.0.2 is archived and publicly available at 10.5281/zenodo.6600345 (Sarquis et al., 2022), and the database is managed under a version-controlled system and centrally stored in GitHub (https://github.com/AgustinSarquis/aridec , last access: 31 May 2022). [ABSTRACT FROM AUTHOR]

To evaluate how increased anthropogenic nutrient inputs alter carbon cycling in grasslands, we conducted a litter decomposition study across 20 temperate grasslands on three continents within the Nutrient Network, a globally distributed nutrient enrichment experimentWe determined the effects of addition of experimental nitrogen (N), phosphorus (P) and potassium plus micronutrient (Kμ) on decomposition of a common tree leaf litter in a long‐term study (maximum of 7 years; exact deployment period varied across sites). The use of higher order decomposition models allowed us to distinguish between the effects of nutrients on early‐ versus late‐stage decomposition.Across continents, the addition of N (but not other nutrients) accelerated early‐stage decomposition and slowed late‐stage decomposition, increasing the slowly decomposing fraction by 28% and the overall litter mean residence time by 58%.Synthesis. Using a novel, long‐term cross‐site experiment, we found widespread evidence that N enhances the early stages of above‐ground plant litter decomposition across diverse and widespread temperate grassland sites but slows late‐stage decomposition. These findings were corroborated by fitting the data to multiple decomposition models and have implications for N effects on soil organic matter formation. For example, following N enrichment, increased microbial processing of litter substrates early in decomposition could promote the production and transfer of low molecular weight compounds to soils and potentially enhance the stabilization of mineral‐associated organic matter. By contrast, by slowing late‐stage decomposition, N enrichment could promote particulate organic matter (POM) accumulation. Such hypotheses deserve further testing. [ABSTRACT FROM AUTHOR]

Microbial life in soil is fueled by dissolved organic matter (DOM) that leaches from the litter layer. It is well known that decomposer communities adapt to the available litter source, but it remains unclear if they functionally compete or synergistically address different litter types. Therefore, we decomposed beech, oak, pine and grass litter from two geologically distinct sites in a lab-scale decomposition experiment. We performed a correlative network analysis on the results of direct infusion HR-MS DOM analysis and cross-validated functional predictions from 16S rRNA gene amplicon sequencing and with DOM and metaproteomic analyses. Here we show that many functions are redundantly distributed within decomposer communities and that their relative expression is rapidly optimized to address litter-specific properties. However, community changes are likely forced by antagonistic mechanisms as we identified several natural antibiotics in DOM. As a consequence, the decomposer community is specializing towards the litter source and the state of decomposition (community divergence) but showing similar litter metabolomes (metabolome convergence). Our multi-omics-based results highlight that DOM not only fuels microbial life, but it additionally holds meta-metabolomic information on the functioning of ecosystems. [ABSTRACT FROM AUTHOR]

Over longer periods of time, aboveground herbivores may stimulate plant compensatory growth to some extent, which can itself promote further herbivory and increase the return of plant litter, in the form of debris or herbivore feces, to the soil. Herbivory, plant evolution, secondary metabolites, soil community, species interactions, biotic interactions, leaf herbivory, plant-soil feedback, root exudates Keywords: biotic interactions; herbivory; leaf herbivory; plant evolution; plant-soil feedback; root exudates; secondary metabolites; soil community; species interactions EN biotic interactions herbivory leaf herbivory plant evolution plant-soil feedback root exudates secondary metabolites soil community species interactions 672 675 4 06/01/22 20220501 NES 220501 "We were men once, though we've become trees." The second has focused on the mechanisms of such interactions and, more specifically, how plant physiological changes, such as plant defence strategies or the production of particular primary and secondary metabolites, mediate above- and belowground interactions between herbivores and higher trophic level organisms (Soler et al., 2005). [Extracted from the article]

Litter decomposition plays a key role in nutrient cycling across ecosystems. The presence of Epichloë endophytes in grass plants affects litter decomposition. The overall effects of leaf litter containing Epichloë endophytes on the chemical and biological properties in non‐rhizosphere soils have not previously been examined. The current study is aimed to understand the effect of direct incorporation of leaf litter from Epichloë endophyte‐infected perennial ryegrass (Lolium perenne) on soil chemical characteristics, and fungal and bacterial biodiversity. Firstly, fresh leaf litter of the endophyte Epichloë festucae var. lolii‐infected (E+) and endophyte‐free (E−) L. perenne were incorporated into the soil, and then samples were collected from E+ and E− litter incorporated soil at T0, T1, T2 and T3 (0, 120, 240 and 360 days) for chemical and sequencing analyses. The Epichloë‐containing leaf litter incorporation changed the soil microbial environment by enhancing the soil organic carbon (SOC), total nitrogen (TN), total phosphorus, NH4+–N and NO3−–N contents, and acidifying soil pH. The endophyte had stronger effects on soil bacteria than soil fungi when the litter was determined with and without the endophyte. Litter containing the Epichloë endophyte significantly increased the absolute abundance of the 16S rRNA gene and relative abundances of the Actinobacteria, Nitrospirae and Gemmatimonadetes, while significantly decreasing the relative abundances of the Planctomycetes and Rokubacteria and the diversity in soil bacteria community. There was no significant effect of endophyte‐containing leaf litter incorporation on the absolute abundance and diversity of the soil fungal community except the increment in the relative abundance of Rozellomycota. Soil pH and the SOC‐to‐TN ratio (C:N) were the main factors influencing the soil bacterial community, and the presence of E. festucae var. lolii was directly and positively related to the soil bacterial diversity. The current study established that Epichloë endophyte‐infection altered the abundance and diversity of the soil bacterial community by affecting leaf litter quality and increasing soil chemical properties after litter incorporation. Highlights: Soil microbial habitat was changed by leaf litter with Epichloë endophyte incorporation.Litter containing endophytes increased the absolute abundance of the 16S rRNA gene.Epichloë endophytes altered the diversity of bacteria during litter incorporation.The response of soil bacteria to a litter containing endophytes was greater than that of soil fungi. [ABSTRACT FROM AUTHOR]

Atmospheric nitrogen (N) deposition has altered biogeochemical cycles and ecosystem functioning. As a key process involved in carbon and nutrient cycles in terrestrial ecosystems, litter decomposition is sensitive to external N inputs. However, it remains unclear how the interactions of ultraviolet (UV) radiation, soil biodiversity (bacteria, fungi and invertebrates) and conventional drivers (e.g. litter chemistry and microbial activities) regulate the responses of litter decomposition to continuous N inputs.Based on a multilevel N addition experimental platform, we conducted a 2‐year litter decomposition experiment to examine the relative importance of N‐induced changes in biotic and abiotic factors in mediating changes in the decomposition rates of four litter types (three representative species and their mixture) along an experimental N gradient in a Tibetan alpine steppe.Our results showed that litter decomposition rates exhibited a consistent decrease in response to N enrichment among all species and their mixture. The slowed decomposition rates with increasing N addition were associated with N‐induced reductions in UV radiation and soil bacterial diversity. An additional UV radiation manipulative experiment further confirmed that photodegradation had strong effects on plant litter decomposition at our study site.These results demonstrated that N‐induced declines in UV radiation and soil bacterial diversity inhibited litter decomposition, challenging the traditional view that changes in litter chemistry and microbial activities determine the responses of litter decomposition to external N inputs. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Fungal endophytes have been extensively found in most terrestrial plants. This type of plant–microorganism symbiosis generates many benefits for plant growth by promoting nutrient availability, uptake, and resistance to environmental disease or stress. Recent studies have reported that fungal endophytes have a potential impact on plant litter decomposition, but the mechanisms behind its effect are not well understood. We proposed a hypothesis that the impacts of fungal endophytes on litter decomposition are not only due to a shift in the symbiont-induced litter quality but a shift in soil microenvironment. To test this hypothesis, we set-up a field trial by planting three locally dominant grass species (wild barley, drunken horse grass, and perennial ryegrass) with Epichloë endophyte-infected (E+) and -free (E−) status, respectively. The aboveground litter and bulk soil from each plant species were collected. The litter quality and the soil biotic and abiotic parameters were analyzed to identify their changes across E+ and E− status and plant species. While Epichloë endophyte status mainly caused a significant shift in soil microenvironment, plant species had a dominant effect on litter quality. Available nitrogen (N) and phosphorus (P) as well as soil organic carbon and microbial biomass in most soils with planting E+ plants increased by 17.19%, 14.28%, 23.82%, and 11.54%, respectively, in comparison to soils with planting E− plants. Our results confirm that fungal endophytes have more of an influence on the soil microenvironment than the aboveground litter quality, providing a partial explanation of the home-field advantage of litter decomposition. [ABSTRACT FROM AUTHOR]

Plant litter decomposition in terrestrial ecosystems involves the physical and chemical breakdown of organic matter. Development of databases is a promising tool for achieving a predictive understanding of organic matter degradation at regional and global scales. In this paper we present aridec: a comprehensive open database con-taining litter-mass loss data from aridlands across the world. We describe in detail the structure of the database and discuss general patterns in the data. Then, we explore what are the most appropriate model structures to inte-grate with data on litter decomposition from the database by conducting a collinearity analysis. The database includes 184 entries from aridlands across the world, representing a wide range of climates. For the majority of the data gathered in aridec it is possible to fit models of litter decomposition that consider initial organic matter as a homogenous reservoir (one pool models), as well as models with two distinct types of organic compounds that decompose at different speeds (two pool models). Moreover, these two carbon pools can either decompose without interaction (parallel models), or with matter transfer from a labile pool to a slow-decomposing pool after transformation (series models). Although most entries in the database can be used to fit these models, we suggest potential users of this database to test identifiability for each individual case as well as the number of degrees of freedom. Other model applications that were not discussed in this publication might also be suitable for use with this database. Lastly, we give some recommendations for future decomposition studies to be potentially added to this database. The extent of the information included in aridec in addition to its open-science approach makes it a great platform for future collaborative efforts in the field of aridland biogeochemistry. The aridec version 1.0.1 is archived and publicly available at https://doi.org/10.5281/zenodo.6025969 (Sarquis et al., 2022), and the database is managed under a version-controlled system and centrally stored in GitHub (https://github.com/AgustinSarquis/aridec, last access: 9 February 2022). [ABSTRACT FROM AUTHOR]

Aims: Grass fungal endophyte symbioses are widespread in the Qinghai-Tibetan Plateau grasslands. The symbioses with fungal endophytes would likely have an important role in affecting ecosystem functioning (e.g., carbon and nutrients cycling, and primary productivity) It is necessary to understand the role of fungal endophytes in the litter decomposition as well as the nutrient transition of ecosystem in which endophyte host species are abundant. Methods: Taking Festuca sinensis, Stipa purpurea and Achnatherum inebrians as study objects, litterbag method was used to compare the litter decomposition of these species with / without endophyte (E+ and E-). The changes in litter weight, total nitrogen, lignin and cellulose contents and their residual rate during the decomposition process were estimated in this study. The microbial biomass carbon and nitrogen of soil under litters were also compared. Results: The litter from E+ F. sinensis and S. purpurea decomposed more quickly along with the cellulose compared with E-. The contents and residual rates of nitrogen and lignin in the F. sinensis and S. purpurea litters had no apparent trend of change. The microbial biomass nitrogen of soil under the E+ F. sinensis and S. purpurea litters was higher than that of the E- litters. Alternatively, the rates of decomposition and degradation of lignin were lower in the E+ A. inebrians litter than those of the E- litter. The endophyte decreased the microbial biomass carbon of soil under A. inebrians litter. Conclusions: Endophytes will affect litter decomposition of host plants. Different grass-endophyte symbioses had different decomposition rates. Our results will enhance the knowledge of the role of endophytes in ecological progress of grassland. [ABSTRACT FROM AUTHOR]

• We provide a method on how to accurately simulate the autogenic process of peatland. • Peatland autogenic processes caused the fen-bog transition and Sphagnum colonization. • Temperature promoted plant growth more than plant litter decomposition in the fen phase. • A positive relationship between carbon accumulation and temperature in the bog phase. Peatland carbon accumulation plays a vital role in the global carbon pool and climate change dynamics. However, understanding how peatland carbon accumulation responds to climate change is challenging due to the influence of autogenic processes on carbon dynamics. In this study, we investigate the temporal variations of the Non-autogenic Carbon Accumulation Rate (NCAR) over approximately 1500 years in a peatland located in the Amur River Basin. To remove the effects of autogenic processes, we use conceptual models of peat development and employ plant macrofossils to identify vegetation changes, particularly the fen-bog phase transition. We apply different exponential decay models to capture autogenic processes in the fen and bog phases of the peatland. Subsequently, we analyze the sensitivity of peatland carbon accumulation to temperature and hydroclimate changes in the fen and bog phases, respectively. Our findings show that in the fen phase, higher temperature increases plant litter decomposition more than the plant net primary productivity (NPP) when water content is high, leading to lower NCAR. However, as temperature rises and water content is no longer a limiting factor, plant NPP surpasses plant litter decomposition, resulting in high NCAR. In the bog phase, we find no significant correlation between NCAR and precipitation but observe a positive relationship between NCAR and temperature. These results enhance our understanding of the connections between temperature, moisture, and peatland carbon accumulation by considering the influence of autogenic processes. [ABSTRACT FROM AUTHOR]

Reed belts acting as basic nutrient filters are important parts of lake buffer riparian zones. However, little is known about their impacts on nutrient release and bacterial community during plant litter decomposition. In this study, a field experiment was conducted in west-lake Taihu to monitor the changes in nutrients, bacterial enzymatic activities, and bacterial community in plant debris during Hydrilla verticillata (H. verticillata) decomposition in open water (HvC) and reed belts (HvL) area for 126 days. We found that there was lower temperature but higher nutrient concentrations in overlying water in HvL than HvC. Partial least squares path modeling revealed that environmental parameters in overlying water had important impacts on bacterial activities and nutrient release (such as alkaline phosphatase, cellulase, and soluble sugar) and therefore affected dissolved organic matter components in plant debris. According to Illumina sequencing, 46,003 OTUs from 10 dominant phyla were obtained and Shannon index was higher in HvL than HvC at the same sampling time. Neutral community model explained 49% of bacterial community variance and immigration rate by the estimate of dispersal in HvC (Nm: 27,154) and HvL (Nm: 25,765), respectively. Null model showed stochastic factors governed the bacterial community assembly in HvC (66.67%) and HvL (87.28%). TP and pH were key factors affecting the bacterial community structure at the phylum level. More hubs and complex interactions among bacteria were observed in HvL than HvC. Function analysis showed bacterial community had important role in carbon, organic phosphorus, and nitrogen removal but phosphorus-starvation was detected in debris of H. verticillata. This study provides useful information for understanding the changes in nutrients and bacterial community in litter during H. verticillata decomposition and highlights the role of reed belts on retained plant litter to protect lake from pollution. [Display omitted] • Reed belts have important role in nutrient retention and removal in Lake Taihu. • Sucrase and cellulase activity increased in plant debris in reed belts. • A lower temperature was observed due to shadow effects of reed belts. • Bacterial community assembly of debris was different in open water from reed belts. • Organic-P-mineralization and P-starvation paths dominated the phosphorus cycle. [ABSTRACT FROM AUTHOR]

• We conducted a comparative analysis of soil phosphorus fractions changes under unstable landforms. The aim was to clarify the differences between study area and Walker and Syers (1976) model. • Variation partitioning analysis (VPA) was employed to discern the impact of environmental factors (climate, microbes, and soil) on soil phosphorus fraction within unstable landforms. • Structural equation models (SEMs) were employed to investigate the cycling of soil phosphorus and the availability of bioavailable phosphorus within unstable landforms. Landslides significant influence on bedrock weathering, pedogenesis, and ecological succession, thereby playing a pivotal role in driving biogeochemical cycles. Landslide chronosequences have traditionally served as invaluable study systems for investigating vegetation succession and exploring soil development and nutrient dynamics. In this study, we analyzed soil phosphorus fractions across a 22,000-year landslide chronosequence. Our investigation examined the impact of environmental factors on these fractions and elucidated the supply of bioavailable phosphorus. Our findings revealed a decline in the concentration of all phosphorus fractions with soil age. Notably, even at an age exceeding 22,000 years, primary mineral phosphorus constituted 23 % of the total phosphorus pool at the later stages of soil development, while organic phosphorus accounted for a mere 7 %. This discrepancy can be attributed to frequent landslides replenishing phosphorus stocks. These findings indicate that the Walker and Syers model may not adequately anticipate alterations in soil phosphorus fractions under geologically unstable landscapes. Environmental factors had limited impact on primary mineral phosphorus concentrations. Yet, they significantly influenced occluded and nonoccluded phosphorus. Changes in organic phosphorus concentrations cannot be fully explained by the examined environmental factors, as organic phosphorus in the soil primarily originates from plant litter decomposition. The sources of bioavailable phosphorus in the investigated region were elucidated using structural equation modeling. The bioavailable phosphorus in the study area is mainly derived from nonoccluded phosphorus rather than organic phosphorus. This observation can be attributed to the distinct landform conditions, which sustain elevated levels of primary mineral phosphorus during soil development. Consequently, the continuous availability of nonoccluded phosphorus ensures a reliable supply of bioavailable phosphorus. In conclusion, the landslide chronosequence serves as a vital example of long-term ecosystem development under unstable landforms. Its refinement of the Walker and Syers model under unstable landscapes. [ABSTRACT FROM AUTHOR]

Background: Changes in the fungal community in the litter decomposition by invasive plants can negatively impact nutrient cycling in natural ecosystems. One still does not know the dimension of this hypothesis, but apparently, it is not despicable. This study evaluated the assemblage composition of fungi during litter decomposition in areas of Atlantic Forest invaded or not invaded by Tradescantia zebrina using Illumina MiSeq and metabarcoding analysis. Results: The invaded sample showed significantly higher richness and a difference in the species dominance than the invaded litter. Ascomycota was the first most abundant phylum in both areas. Even so, the dissimilarity between areas can be evidenced. The fungal from Basidiomycota were very representative in the non-invaded areas (ranged from an abundance of 43.29% in the non-invaded to 2.35% in the invaded sample). The genus Lepiota can indicate the primary functional group related to biomass degradation and showed the might difference about the invaded areas due to its essential reduction by the invader. In the invaded sample, there was a total absence of the endophyte-undefined saprotroph guild. Also, some genera not taxonomically characterized were eliminated in the invaded sample, revealing that the fungal biodiversity of areas has not yet been thoroughly characterized. Conclusions: Hence, makes impossible the real interpretation of the invasive plant impact, showing the importance of continuing research on fungal biodiversity. It is important to emphasize that the replacement of the native species by T. zebrina may be responsible for the elimination of fungal groups that have not yet been identified. [ABSTRACT FROM AUTHOR]

Thus, soil organic C storage is linked to N availability and can result in N immobilization in SOM with feedbacks to plant productivity. In-N-Out: A hierarchical framework to understand and predict soil carbon storage and nitrogen recycling Conversely, when N is available in excess of plant and microbial demand, the C and N cycles decouple, and N is lost from the system. We further hypothesize that C input-limited systems have N in excess of demand, resulting in decoupling of the N and C cycles, and the opening of N cycle to losses from the soil. [Extracted from the article]