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Introduction: Epiphytic and endophytic fungi are primary decomposers of forest litter due to their complex species composition and metabolic functions. To clarify the community diversity of phyllospheric fungi and to explore nutrient loss and the role of fungal decomposition, we conducted a study on the decomposition of leaf litter during the 1-year decomposition of Larix gmelinii in the cold temperate zone. Methods: Fungal diversity data were characterized via Single Molecule Sequencing (based on the Sequel II Sequencing System) and statistical analyses in R. Results and discussion: Our findings revealed the presence of 11 known fungal phyla and 29 dominant genera in the larch litter of Greater Khingan. Among these, Basidiomycota and Leucosporidium were dominant in the epiphytic environment, while Ascomycota and Exutisphaerella dominated the endophytic environment. In the early periods of decomposition, phyllospheric fungi became the primary colonizers during litter decomposition by adjusting their life strategies to transition to saprophytic or pathogenic metabolic processes. During decomposition, significant differences in alpha diversity were observed between endophytes and epiphytes. Correlation analysis between these fungi and biological factors revealed a strong relationship between cellulose loss in leaves and the return of N, P, and K. This indicated that the combined biological effects of nutrients, aminosugars, and plant fibers strongly explained changes in community structure. Our results also revealed a significant clustering effect between fungi and biological factors, reflecting the important role of phyllospheric functional fungal communities in carbon fluctuations, cellulose decomposition, and the enrichment of P and K in leaf litter. In summary, this study offers insights into ecosystem processes and nutrient cycling within cold temperate forests, with potential applications for understanding global carbon dynamics. [ABSTRACT FROM AUTHOR]

Alders are nitrogen (N)-fixing riparian trees that promote leaf litter decomposition in streams through their high-nutrient leaf litter inputs. While alders are widespread across Europe, their populations are at risk due to infection by the oomycete Phytophthora ×alni, which causes alder dieback. Moreover, alder death opens a space for the establishment of an aggressive N-fixing invasive species, the black locust (Robinia pseudoacacia). Shifts from riparian vegetation containing healthy to infected alder and, eventually, alder loss and replacement with black locust may alter the key process of leaf litter decomposition and associated microbial decomposer assemblages. We examined this question in a microcosm experiment comparing three types of leaf litter mixtures: one representing an original riparian forest composed of healthy alder (Alnus lusitanica), ash (Fraxinus angustifolia), and poplar (Populus nigra); one with the same species composition where alder had been infected by P. ×alni; and one where alder had been replaced with black locust. The experiment lasted six weeks, and every two weeks, microbially driven decomposition, fungal biomass, reproduction, and assemblage structure were measured. Decomposition was highest in mixtures with infected alder and lowest in mixtures with black locust, reflecting differences in leaf nutrient concentrations. Mixtures with alder showed distinct fungal assemblages and higher sporulation rates than mixtures with black locust. Our results indicate that alder loss and its replacement with black locust may alter key stream ecosystem processes and assemblages, with important changes already occurring during alder infection. This highlights the importance of maintaining heathy riparian forests to preserve proper stream ecosystem functioning. [ABSTRACT FROM AUTHOR]

Leaf litter decomposition, a crucial component of the global carbon cycle, relies on the pivotal role played by microorganisms. However, despite their ecological importance, leaf-litter-decomposing microorganism taxonomic and functional diversity needs additional study. This study explores the taxonomic composition, dynamics, and functional role of microbial communities that decompose leaf litter of forest-forming tree species in two ecologically unique regions of Europe. Twenty-nine microbial metagenomes isolated from the leaf litter of eight forest-forming species of woody plants were investigated by Illumina technology using read- and assembly-based approaches of sequences analysis. The taxonomic structure of the microbial community varies depending on the stage of litter decomposition; however, the community's core is formed by Pseudomonas, Sphingomonas, Stenotrophomonas, and Pedobacter genera of Bacteria and by Aureobasidium, Penicillium, Venturia genera of Fungi. A comparative analysis of the taxonomic structure and composition of the microbial communities revealed that in both regions, seasonal changes in structure take place; however, there is no clear pattern in its dynamics. Functional gene analysis of MAGs revealed numerous metabolic profiles associated with leaf litter degradation. This highlights the diverse metabolic capabilities of microbial communities and their implications for ecosystem processes, including the production of volatile organic compounds (VOCs) during organic matter decomposition. This study provides important advances in understanding of ecosystem processes and the carbon cycle, underscoring the need to unravel the intricacies of microbial communities within these contexts. [ABSTRACT FROM AUTHOR]

Fertilizer application plays a crucial role in the decomposition of white poplar leaf litter and cycling of nutrients within forest ecosystems. The impact of various fertilizer additions on white poplar leaf litter and nutrient cycling is poorly understood. In this study, seven treatments were conducted at the following levels: Control (CK), no adding mineral fertilizers, N fertilization (+N), N and P fertilization (+NP), N, P, K fertilization (+NPK), P, K (+PK), manure fertilizer (+MF), and bird fertilizers (+BF) in a white poplar plantation in Qadis district, and used the litterbag techniques to measure litter mass remaining. The main objectives of our study were: (1) to explore the response of white poplar leaf litter decomposition to various fertilizers and accelerate the decomposition process; (2) to examine the relationship between C, N, and P concentration and their stoichiometric characteristic in leaf litter and soil. In this investigation, our results showed that white poplar leaf litter was significantly affected by fertilizers, and the decomposition process was greatly accelerated with + MF, +NPK, and + BF. The decay rate constant k (year −1) shows the decomposition rate of white poplar leaf litter as follows: +MF > +NPK > +BF > +PK > +NP > +N > CK (0.56, 0.53, 0.52, 0.51,0.51,0.5, and 0.46). Soil nutrients N, P and K increased significantly during the decomposition time with + MF, +NPK, and + BF, respectively, while C:N, C:P, and N:P ratios were highest in the white poplar leaf litter, and lowest in soil, we observed significant association between nutrients concentrations in soil and white poplar leaf and their stoichiometric. This current study concluded that adding + MF, +NPK and + BF fertilizers might be the preferred management option as they provided potentially beneficial changes in leaf litter decomposition and increased nutrient concentration. The data obtained will be a valuable reference for fertilization management strategies in forest ecosystems.

Microorganisms are vital in leaf litter decomposition and contribute significantly to global nutrient cycling. However, there is a need for improved understanding of the taxonomic and functional diversity of litter-associated bacteria. The Knyszyn Forest comprises a unique ecosystem providing diverse microhabitats for microorganisms in central Europe, similar to the southwestern taiga in many respects. This study presents the results of high-throughput sequencing performed for Betula pendula, B. pubescens, and Carpinus betulus litter-associated microbial communities from northern Poland. Microbial assemblage composition and structure at different stages of litter decomposition revealed the domination of phyllosphere-associated taxa of Sphingomonas and Pseudomonas in bacterial communities in the early stages. Meanwhile, at the later stages of decomposition, the representation of soil-associated bacterial communities, such as Pedobacter, was higher. This study identifies key bacteria (Pedobacter, Mucilaginibacter, and Luteibacter) as pivotal in nutrient cycling through cellulose and hemicellulose decomposition, dominating later decomposition phases. Taxonomic analysis based on functional markers associated with nitrogen metabolism highlights the pivotal role of specific Pseudomonadota (Proteobacteria) taxa in driving nitrogen cycling dynamics during litter decomposition. Most of these taxa were unclassified at the genus level, particularly in the later stages of litter decomposition, and are crucial in mediating nitrogen transformation processes, underscoring their significance in ecosystem nutrient cycling. [ABSTRACT FROM AUTHOR]

IntroductionEpiphytic and endophytic fungi are primary decomposers of forest litter due to their complex species composition and metabolic functions. To clarify the community diversity of phyllospheric fungi and to explore nutrient loss and the role of fungal decomposition, we conducted a study on the decomposition of leaf litter during the 1-year decomposition of Larix gmelinii in the cold temperate zone.MethodsFungal diversity data were characterized via Single Molecule Sequencing (based on the Sequel II Sequencing System) and statistical analyses in R.Results and discussionOur findings revealed the presence of 11 known fungal phyla and 29 dominant genera in the larch litter of Greater Khingan. Among these, Basidiomycota and Leucosporidium were dominant in the epiphytic environment, while Ascomycota and Exutisphaerella dominated the endophytic environment. In the early periods of decomposition, phyllospheric fungi became the primary colonizers during litter decomposition by adjusting their life strategies to transition to saprophytic or pathogenic metabolic processes. During decomposition, significant differences in alpha diversity were observed between endophytes and epiphytes. Correlation analysis between these fungi and biological factors revealed a strong relationship between cellulose loss in leaves and the return of N, P, and K. This indicated that the combined biological effects of nutrients, aminosugars, and plant fibers strongly explained changes in community structure. Our results also revealed a significant clustering effect between fungi and biological factors, reflecting the important role of phyllospheric functional fungal communities in carbon fluctuations, cellulose decomposition, and the enrichment of P and K in leaf litter. In summary, this study offers insights into ecosystem processes and nutrient cycling within cold temperate forests, with potential applications for understanding global carbon dynamics.

Leaf litter decomposition, a crucial component of the global carbon cycle, relies on the pivotal role played by microorganisms. However, despite their ecological importance, leaf-litter-decomposing microorganism taxonomic and functional diversity needs additional study. This study explores the taxonomic composition, dynamics, and functional role of microbial communities that decompose leaf litter of forest-forming tree species in two ecologically unique regions of Europe. Twenty-nine microbial metagenomes isolated from the leaf litter of eight forest-forming species of woody plants were investigated by Illumina technology using read- and assembly-based approaches of sequences analysis. The taxonomic structure of the microbial community varies depending on the stage of litter decomposition; however, the community’s core is formed by Pseudomonas, Sphingomonas, Stenotrophomonas, and Pedobacter genera of Bacteria and by Aureobasidium, Penicillium, Venturia genera of Fungi. A comparative analysis of the taxonomic structure and composition of the microbial communities revealed that in both regions, seasonal changes in structure take place; however, there is no clear pattern in its dynamics. Functional gene analysis of MAGs revealed numerous metabolic profiles associated with leaf litter degradation. This highlights the diverse metabolic capabilities of microbial communities and their implications for ecosystem processes, including the production of volatile organic compounds (VOCs) during organic matter decomposition. This study provides important advances in understanding of ecosystem processes and the carbon cycle, underscoring the need to unravel the intricacies of microbial communities within these contexts.

Leaf litter constitutes a major fraction in total litter production in mangrove forests. Its contribution to NPP of mangrove forests and carbon sequestration is less studied. These aspects were investigated for Kunhimangalam mangrove forest in Kerala, India. We quantified the leaf litter production and estimated the decomposition rates of leaf litter from Aegiceras corniculatum, Avicennia officinalis, Excoecaria agallocha and Rhizophora mucronata. These four species together constituted 92.49% of abundance in Kunhimangalam. The average annual leaf litter production was 8.83 ± 0.95 t ha−1yr−1, 78% of the total litter produced. Leaf litter production was negatively correlated with soil pH (R2 = 0.531) and rainfall (R2 = 0.561). Temperature, salinity and humidity did not show any remarkable influence. The rate of decomposition varied significantly among these species (F = 2497.79, p < 0.01) but as for the mixed leaf litter category (a mixture of leaves from the above four species in equal weight), the rate of decomposition was the highest. The pattern of leaf litter decomposition observed in mixed, R. mucronata and E. agallocha categories best fitted to the exponential decay model indicating an initial phase of faster decomposition followed by a terminal slow phase. The leaf litter of A. corniculatum and A. officinalis categories fitted best to the linear regression model showing a steady pace throughout the period of decomposition. Leaf litter of these four species together contributed 3.56 ± 0.01 t C ha−1 y−1 to NPP. Higher production of leaf litter in Kunhimangalam showed higher potential for carbon sequestration. However, only less than 1% (0.62%) of the leaf litter was decomposed when macrobenthos were excluded from the system. The destiny of the rest 99% appeared critical as this determined the capacity of Kunhimangalam mangrove forest to act as a source or sink for carbon. [ABSTRACT FROM AUTHOR]

The associations of arbuscular mycorrhizal (AM) or ectomycorrhiza (EcM) fungi with plants have sequentially evolved and significantly contributed to enhancing plant nutrition. Nonetheless, how evolutionary and ecological forces drive nutrient acquisition strategies of AM and EcM woody plants remains poorly understood. Our global analysis of woody species revealed that, over divergence time, AM woody plants evolved faster nitrogen mineralization rates without changes in nitrogen resorption. However, EcM woody plants exhibited an increase in nitrogen mineralization but a decrease in nitrogen resorption, indicating a shift towards a more inorganic nutrient economy. Despite this alteration, when evaluating present‐day woody species, AM woody plants still display faster nitrogen mineralization and lower nitrogen resorption than EcM woody plants. This inorganic nutrient economy allows AM woody plants to thrive in warm environments with a faster litter decomposition rate. Our findings indicate that the global pattern of nutrient acquisition strategies in mycorrhizal plants is shaped by the interplay between phylogeny and climate. [ABSTRACT FROM AUTHOR]

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

Heterotrophic microbial decomposers colonize submerged leaf litter in close spatial proximity to periphytic algae that exude labile organic carbon during photosynthesis. These exudates are conjectured to affect microbial decomposers' abundance, resulting in a stimulated (positive priming) or reduced (negative priming) leaf litter decomposition. Yet, the occurrence, direction, and intensity of priming associated with leaf material of differing recalcitrance remains poorly tested. To assess priming, we submerged leaf litter of differing recalcitrance (Alnus glutinosa [alder; less recalcitrant] and Fagus sylvatica [beech; more recalcitrant]) in microcosms and quantified bacterial, fungal, and diatom abundance as well as leaf litter decomposition over 30 days in absence and presence of light. Diatoms did not affect beech decomposition but reduced alder decomposition by 20% and alder-associated fungal abundance by 40% in the treatments including all microbial groups and light, thus showing negative priming. These results suggest that alder-associated heterotrophs acquired energy from diatom exudates rather than from leaf litter. Moreover, it is suggested that these heterotrophs have channeled energy to alternative (reproductive) pathways that may modify energy and nutrient availability for the remaining food web and result in carbon pools protected from decomposition in light-exposed stream sections. [ABSTRACT FROM AUTHOR]

The frequency of flow intermittency and drying events in Alpine rivers is expected to increase due to climate change. These events can have significant consequences for stream ecological communities, though the effects of reduced flow conditions on microbial communities of decomposing allochthonous leaf material require additional research. In this study, we investigated the bacterial and fungal communities associated with the decomposition of two common species of leaf litter, chestnut (Castanea sativa), and oak (Quercus robur). A sampling of experimentally placed leaf bags occurred over six collection dates (up to 126 days after placement) at seven stream sites in the Western Italian Alps with historically different flow conditions. Leaf-associated bacterial and fungal communities were identified using amplicon-based, high-throughput sequencing. Chestnut and oak leaf material harbored distinct bacterial and fungal communities, with a number of taxonomic groups differing in abundance, though bacterial community structure converged later in decomposition. Historical flow conditions (intermittent vs perennial rivers) and observed conditions (normal flow, low flow, ongoing drying event) had weaker effects on bacterial and fungal communities compared to leaf type and collection date (i.e., length of decomposition). Our findings highlight the importance of leaf characteristics (e.g., C:N ratios, recalcitrance) to the in-stream conditioning of leaf litter and a need for additional investigations of drying events in Alpine streams. This study provides new information on the microbial role in leaf litter decomposition with expected flow changes associated with a global change scenario. [ABSTRACT FROM AUTHOR]

Many degraded ecosystems have altered nutrient dynamics due to invaders' possessing a suite of traits that allow them to both outcompete native species and alter the environment. In ecosystems where invasive species have increased nutrient turnover rates, it can be difficult to reduce nutrient availability. This study examined whether a functional trait‐based restoration approach involving the planting of species with conservative nutrient‐use traits could slow rates of nutrient cycling and consequently reduce rates of invasion. We examined a functional trait restoration initiative in a heavily invaded lowland wet forest site in Hilo, Hawaiʻi. Native and introduced species were chosen to create four experimental hybrid forest communities, in comparison to the invaded forest, with a factorial design in which communities varied in rates of carbon turnover (slow or moderate [SLOW, MOD]), and in the relationship of species in trait space (redundant or complementary [RED, COMP]). After the first 5 years, we evaluated community‐level outcomes related to nutrient cycling: carbon (C), nitrogen (N), and phosphorus (P) via litterfall, litter decomposition, and outplant productivity and rates of invasion. We found that (1) regardless of treatment, the experimental communities had low rates of nutrient cycling through litterfall relative to the invaded reference forest, (2) the MOD communities had greater nutrient release via litterfall than the SLOW communities, (3) introduced species had greater nutrient release than native species in the two MOD experimental communities, and (4) within treatments, there was a positive relationship between nutrient levels and outplant basal area, but outplant basal area was negatively associated with rates of invasion. The negative relationships among basal area and weed invasion, particularly for the two COMP treatments, suggest species existing in different parts of trait space may help confer some degree of invasion resistance. The diversification of trait space was facilitated by the use of introduced species, a new concept in Hawaiian forest management. Although challenges remain in endeavors to restore this heavily degraded ecosystem, this study provides evidence that functional trait‐based restoration approaches using carefully crafted hybrid communities can reduce rates of nutrient cycling and invasion in order to reach management goals. [ABSTRACT FROM AUTHOR]

Midwestern forests are currently impacted by two prominent invaders, the emerald ash borer (EAB; Agrilus planipennis) and Amur honeysuckle (AHS; Lonicera maackii). The loss of ash (Fraxinus spp.) trees due to EAB invasion can further facilitate AHS invasion, driving changes in the composition of forest leaf litter to reflect a greater portion of labile, more easily decomposed litter. To evaluate the extent to which these changes alter ecosystem function, we conducted litter bag and culture-based decomposition experiments using leaf litter from sugar maple (Acer saccharum), oak (Quercus spp.), black ash (Fraxinus nigra), green ash (Fraxinus pennsylvanica), spicebush (Lindera benzoin) and AHS. To further understand the mechanism driving differences in decay rates, we inoculated six species of decomposing fungi separately onto both single species and multispecies (half AHS and half native species) leaf litter and measured decomposition rate, fungal growth and enzymatic activity in laboratory-based cultures. AHS leaf litter decomposed faster, had increased fungal growth, and had higher activity for carbon degrading enzymes compared to native species leaf litter. Furthermore, multispecies mixtures followed the same patterns as AHS, suggesting that the addition of AHS to leaf litter to native litter will accelerate ecosystem functions related to carbon breakdown. Consequently, forests that experience the invasion of AHS and EAB induced loss of ash are likely to have faster rates of decomposition, potentially resulting in an influx of available nutrients. [ABSTRACT FROM AUTHOR]

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

Large-scale dam removals provide opportunities to restore river function in the long-term and are massive disturbances to riverine ecosystems in the short-term. The removal of two dams on the Elwha River (WA, USA) between 2011 and 2014 was the largest dam removal project to be completed by that time and has since resulted in major changes to channel dynamics, river substrates, in-stream communities, and the size and shape of the river delta. To assess ecosystem function across the restored Elwha watershed, we compared leaf litter decomposition at twenty sites: 1) four tributary sites not influenced by restoration activities; 2) four river sites downstream of the upper dam (Glines Canyon Dam); 3) four river sites within the footprint of the former Aldwell Reservoir upstream of the lower dam (Elwha Dam); 4) four river sites downstream of the lower dam; and 5) four lentic sites in the newly developing Elwha delta. Three major findings emerged: 1) decomposition rates differed among sections of the Elwha watershed, with slowest decomposition rates at the delta sites and fastest decomposition rates just downstream of the upper dam; 2) aquatic macroinvertebrate communities establishing in leaf litterbags differed significantly among sections of the Elwha watershed; and 3) aquatic fungal communities growing on leaf litter differed significantly among sections. Aquatic macroinvertebrate and fungal diversity were sensitive to differences in canopy cover, water chemistry, and river bottom sediments across sites, with a stronger relationship to elevation for aquatic macroinvertebrates. As the Elwha River undergoes recovery following the massive sediment flows associated with dam removal, we expect to see changes in leaf litter processing dynamics and shifts in litter-dependent decomposer communities (both fungal and invertebrate) involved in this key ecosystem process.

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]

The ecological impact of nitrogen (N) deposition has gained significance since the advent of the industrial revolution. Although numerous studies have examined the impact of N deposition on soil organic carbon (SOC), certain arid and barren rocky mountainous regions, which experience more pronounced N limitations, have been overlooked. This study was conducted in the Yimeng Mountains, examining eight treatments created by four N addition levels (0 kg N ha−1 yr−1, 50 kg N ha−1 yr−1, 100 kg N ha−1 yr−1 and 200 kg N ha−1 yr−1) and two tree species (Quercus acutissima Carruth. and Pinus thunbergii Parl.). The research revealed variations in the effect of N addition on leaf litter decomposition and SOC density (SOCD) between different tree species. Notably, N addition stimulated the decomposition of leaf litter from Quercus acutissima Carruth. However, the decomposition of Pinus thunbergii Parl. leaf litter was enhanced at N addition levels below 100 kg N ha−1 yr−1, while it was hindered at levels exceeding 100 kg N ha−1 yr−1. In the Quercus acutissima Carruth. forest, the N addition levels of 50 kg N ha−1 yr−1, 100 kg N ha−1 yr−1 and 200 kg N ha−1 yr−1 resulted in decreases in SOCD by 10.57%, 22.22% and 13.66%, respectively, compared to 0 kg N ha−1 yr−1. In the Pinus thunbergii Parl. forest, the N addition levels of 50 kg N ha−1 yr−1, 100 kg N hm−2 ha−1 and 200 kg N ha−1 yr−1 led to increases in SOCD by 49.53%, 43.36% and 60.87%, respectively, compared to 0 kg N ha−1 yr−1. Overall, N addition decreases the SOCD of Quercus acutissima Carruth., but it increases the SOCD of Pinus thunbergii Parl., attributed to the alteration in soil enzyme stoichiometry and nutrient cycling by N addition. This study fills a theoretical gap concerning leaf litter decomposition and SOC sequestration in arid and barren rocky mountainous regions under global climate change. [ABSTRACT FROM AUTHOR]

Aims: Increasing global nitrogen (N) and phosphorus (P) deposition may affect the response mechanism of litter decomposition. We aimed to explore the responses of nutrient release and enzyme activities to exogenous N and P inputs. Methods: We conducted a two‑year field litterbag experiment in larch (Larix principis-rupprechtii) plantation at the Saihanba Forest Farm in Hebei Province, China. Four treatments, i.e., N addition (+ N), P addition (+ P), N and P addition (N + P), and control (CK) were designed and examined the overall effect of the fertilization treatments on the remaining mass, nutrients, and enzymatic activity. Results: In contrast to CK, the + N, + P, and N + P treatments significantly reduced the remaining leaf litter mass by 36.33%, 35.21%, and 38.50% at the end of the experiment, respectively. During the decomposition of leaf litter, + N had a significant effect on carbon (C) release and no significant effect on N and P release. + P promoted C release and significantly reduced the N remaining but increased the P remaining. Invertase activity decreased sharply in the early stage of decomposition. However, the activities of catalase, urease, and acid phosphatase declined in the middle stage in each treatment. The effect of + N on enzyme activities was not significant, while + P significantly increased urease activity. Conclusion: The results reveal that continuous N and P deposition could promote the litter decomposition rate, while altered the nutrient release pattern in larch plantation. [ABSTRACT FROM AUTHOR]

Aims: Rising atmospheric CO2 concentrations and nitrogen (N) deposition alter litter decomposition processes that control soil carbon (C) and nutrient cycles. However, few studies have explored such impacts on litter decomposition and micronutrient and macronutrient (C, N, phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)) release in a heavy-metal-contaminated environment. Methods: We performed an open-top chamber experiment to explore the effects of 15-month elevated CO2 and N addition on leaf litter decomposition rate and nutrient release of Cinnamomum camphora (non-N-fixing species) and Acacia auriculiformis (N-fixing species) during litter decomposition in cadmium (Cd)-contaminated environment. Results: We found that Cd addition consistently reduced leaf litter nutrient (C, N, P, K, Ca, and Mg) loss, while these negative effects were offset by elevated CO2 (average 10.6%) and N addition (average 23.9%). The mitigative effects of elevated CO2 and N addition together (β = −0.78) far exceeded the effects of each (β = −0.15 for elevated CO2 and β = −0.42 for N addition) separately. Such mitigative effects were related to higher litter quality (the increased N, P and Ca in the initial litter), and higher soil microbial activities (higher ligninase and cellulase activities). Additionally, these mitigative effects on leaf litter nutrient release were greater in C. camphora litter than in A. auriculiformis litter, due to its higher C:N and cellulose: N ratios. Conclusions: Our results suggest that N addition and elevated CO2 concentration may diminish the negative effects of Cd addition on leaf litter decomposition and increase nutrient cycle, especially in non-N fixing trees under the global change. [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]

Aims: Litter decomposition is a fundamental process in the carbon cycle in subtropical forests. Accurate evaluation of leaf litter decomposition rate is critical for understanding global carbon budgets. The effect of initial soil environmental factors (i.e., temperature and water content) on litter decomposition rates warrant detailed study. Methods: Six groups of decomposition experiments starting in different months (January, March, May, July, September, and November) were conducted to simulate different initial soil environmental factors in a subtropical forest in southwest China. The annual litter mass loss was then calculated using the decomposition rate obtained from initial month treatments and local litterfall input data. Results: Annual litter decomposition rates showed significant differences among treatments starting in the dry and rainy seasons, characterized by low and high initial soil temperatures and water contents. The average soil temperature and water content in the first 10–15 days significantly affected the annual litter decomposition rate. Compared with the accumulation algorithm, the calculated annual litter mass loss based on the decomposition rate obtained from the experimental group starting in May (at the transition of the dry and rainy seasons) was almost the same. However, it was overestimated by 18.2% in the experimental groups starting in the rainy season (July, September) and underestimated by 15.0% in the dry season (January, March). Conclusions: Our findings suggested that a random arrangement of litter decomposition experiments may lead to inaccurate estimates of litter mass loss in areas with obvious seasonal changes. [ABSTRACT FROM AUTHOR]

Leaf litter decomposition in solution is an important part of the carbon cycle. When leaf litter is deposited in water, the decomposition process takes place, releasing carbon dioxide into the atmosphere. In Hungary, the goldenrod and bulrush are spreading over increasing areas along lakes and rivers, including the shores of Lake Balaton. The primary role of the Kis-Balaton wetland is to retain inorganic nutrients, thereby improving the water quality of Lake Balaton. As the water movement in this area is not very intensive and the water retention time is long, carbon dioxide emissions of parts of decomposing plants can be higher in this area. We set up a microcosm experiment in a climate chamber to determine the carbon dioxide emissions from the decomposition of goldenrod and bulrush leaves and stems in winter when information about the process is limited. Due to short investigation time, the difference in the impact of temperatures on decomposition of the studied plants was restricted to leaves only. In the study, significant difference was obtained for the plant species and the plant parts. The carbon dioxide increments ranged from 46.7 (p<0.001) to 54.5% (p<0.001) in every plant treatment related to control one. Changes in water temperature are reflected in carbon dioxide release with a minor time delay. The results showed that the decomposition of plant parts in water during winter contributes to the increase of carbon dioxide emissions from shallow water bodies, such as the Kis-Balaton wetland. [ABSTRACT FROM AUTHOR]

Bacteria and fungi drive decomposition, a fundamental process in the carbon cycle, yet the importance of microbial community composition for decomposition remains elusive. Here, we used an 18-month reciprocal transplant experiment along a climate gradient in Southern California to disentangle the effects of the microbial community versus the environment on decomposition. Specifically, we tested whether the decomposition response to climate change depends on the microbial community. We inoculated microbial decomposers from each site onto a common, irradiated leaf litter within "microbial cages" that prevent microbial exchange with the environment. We characterized fungal and bacterial composition and abundance over time and investigated the functional consequences through litter mass loss and chemistry. After 12 months, microbial communities altered both decomposition rate and litter chemistry. Further, the functional measurements depended on an interaction between the community and its climate in a manner not predicted by current theory. Moreover, microbial ecologists have traditionally considered fungi to be the primary agents of decomposition and for bacteria to play a minor role. Our results indicate that not only does climate change and transplantation have differential legacy effects among bacteria and fungi, but also that bacterial communities might be less functionally redundant than fungi with regards to decomposition. Thus, it may be time to reevaluate both the role of microbial community composition in its decomposition response to climate and the relative roles of bacterial and fungal communities in decomposition.

Plant litter decomposition plays an important role in carbon and nutrient cycling in terrestrial ecosystems. The influence of abiotic factors on the decomposition of plants in humid ecosystems is higher due to the favorable moisture conditions and the abundance of decomposer microorganisms. However, in arid and semi-arid ecosystems, plant litter decomposition is influenced by both abiotic and biotic factors, depending on sparse plant cover, high soil temperature, and low rainfall. The effects of environmental factors on leaf litter decomposition in arid and semi-arid Mongolian steppes are unclear. A field experiment was carried out in meadow steppe, typical steppe, and desert steppes of Mongolia to investigate the effect of environmental factors such as light-expose, shade, and climate conditions on three species of Stipa (Stipa baicalensis, Stipa grandis, Stipa gobica) representing different litter qualities over a two year of incubation (6, 12, 18 and 24 months). The results of the study revealed that the leaf litter decomposition rate differed among the three species, in which Stipa gobica had a relatively high leaf litter decomposition rate. Also, the rate of leaf decomposition of Stipa gobica was directly and indirectly correlated with leaf traits, while it was positively correlated to climatic conditions (r=0.55). However, for Stipa baicalensis, was negatively correlated to leaf traits (r=-0.56 – -0.63) and on the contrary, Stipa grandis was strongly positively correlated to leaf traits (r=0.68-0.89). Seasonality has an effect on the leaf litter decomposition, with the highest decomposition rate occurring from April to October, while the decomposition rate was very low from November to March. [ABSTRACT FROM AUTHOR]

Leaf litter decomposition is one of the main ecological material cycle processes in waterfront areas. In this microcosm experiment, the rate of decomposition of the most frequently occurring dominant waterside plants were examined in the summer months of 2022 in a class "A" evaporation pan, using litterbag technique. The study provides information about the decomposition dynamics of willow (Salix sp.), poplar (Populus sp.), reed (Phragmites australis) and different leaf litter mixture combinations. Dry mass, exponential decay coefficient and the chemical parameters of the water (pH, conductivity, NH4+, PO43-, SO42-) were determined during the 84 days long experimental period. The weight loss curves showed negative exponential pattern in every case. On average, the different samples lost ~ 57% of their initial dry mass during the experimental period. The largest mass loss was measured in case of poplar (67.2%), while reed leaves had the smallest mass loss (47.25%). Based on the results, it cannot be proven, that mixed leaf litter accelerates the rate of decomposition. [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]

Agricultural pesticides are known to significantly impact the non-target aquatic communities and key ecosystem processes of stream ecosystems such as litter decomposition. The unresolved questions are remaining of how such stressors interact to alter ecosystem structure and function, and how impacted ecosystems are able to maintain their ecological balance. Hence, this paper discusses the effects of the insecticide Profenofos and herbicide MCPA on Ficus racemosa and Panicum maximum litter breakdown in 40 days of indoor microcosm systems. Litter breakdown rates were analysed in microcosms treated with pesticide concentrations of 0.010, 0.025, 0.100, 0.250, 1.000 mg/L and in control tanks with no pesticides. The results of the study indicated a significant alteration of litter breakdown rate of MCPA-treated tanks compared to the control tanks in terms of reduction percentage of dry weight, remaining organic matter content, microbial community sporulation, and remaining nutrient content (p < 0.05). The herbicide MCPA accelerated the structural impairment of leaf material by destructing the leaf material. No significant differences were observed between Profenofos-treated leaf packs and control leaf packs (p < 0.05). Aquatic hyphomycetes have degraded the applied Profenofos by consuming the nutrients from the litter. These alterations were modulated by the litter quality and microbial colonizations on leaf materials. The findings of the study emphasize the effects of pesticides on the structure and functional properties of lower levels organisms in the ecological food chain and the importance of considering indirect effects of pesticides in ecological processes. [ABSTRACT FROM AUTHOR]

Abstract Forest degradation succession often leads to changes in forest ecosystem functioning. Exactly how the decomposition of leaf litter is affected in a disturbed forest remains unknown. Therefore, in our study, we selected a primary Korean pine forest (PK) and a secondary broad‐leaved forest (SF) affected by clear‐cutting degradation, both in Northeast China. The aim was to explore the response to changes in the leaf litter decomposition converting PK to SF. The mixed litters of PK and SF were decomposed in situ (1 year). The proportion of remaining litter mass, main chemistry, and soil biotic and abiotic factors were assessed during decomposition, and then, we made an in‐depth analysis of the changes in the leaf litter decomposition. According to our results, leaf litter decomposition rate was significantly higher in the PK than that in the SF. Overall, the remaining percent mass of leaf litter's main chemical quality in SF was higher than in PK, indicating that leaf litter chemical turnover in PK was relatively faster. PK had a significantly higher amount of total phospholipid fatty acids (PLFAs) than SF during decomposition. Based on multivariate regression trees, the forest type influenced the soil habitat factors related to leaf litter decomposition more than decomposition time. Structural equation modeling revealed that litter N was strongly and positively affecting litter decomposition, and the changes in actinomycetes PLFA biomass played a more important role among all the functional groups. Selected soil abiotic factors were indirectly driving litter decomposition through coupling with actinomycetes. This study provides evidence for the complex interactions between leaf litter substrate and soil physical–chemical properties in affecting litter decomposition via soil microorganisms.

Polystyrene nanoparticles (PS NPs) released from plastic products have been demonstrated to pose a threat to leaf litter decomposition in streams. Given the multitrophic systems of species interactions, the effects of PS NPs through different exposure routes on ecosystem functioning remain unclear. Especially dietary exposure, a frequently overlooked pathway leading to toxicity, deserves more attention. A microcosm experiment was conducted in this study to assess the effects of waterborne and dietary exposure to PS NPs on the litter-based food chain involving leaves, microbial decomposers, and detritivores (river snails). Compared to waterborne contamination, dietary contamination resulted in lower microbial enzyme activities and a significantly higher decrease in the lipid content of leaves. For river snails, their antioxidant activity was significantly increased by 20.21%–69.93%, and their leaf consumption rate was significantly reduced by 16.60% through the dietary route due to the lower lipid content of leaves. Besides, the significantly decreased nutritional quality of river snails would negatively influence their palatability to predators. The findings of this study indicate that dietary exposure to PS NPs significantly impacts microbial and detritivore activities, thus affecting their functions in the detritus food chain as well as nutrient cycling. [Display omitted] • Impacts of PS NPs on detrital food chain were dependent on exposure routes. • A less lipid in leaves was due to reduced microbial activity by contaminated leaves. • Detritivores had severer oxidative stress and lower consumption by dietary exposure. • Dietary exposure to PS NPs led to the lowest quality of detritivore for its predator. [ABSTRACT FROM AUTHOR]

Human impacts, particularly nutrient pollution and land‐use change, have caused significant declines in the quality and quantity of freshwater resources. Most global assessments have concentrated on species diversity and composition, but effects on the multifunctionality of streams and rivers remain unclear. Here, we analyse the most comprehensive compilation of stream ecosystem functions to date to provide an overview of the responses of nutrient uptake, leaf litter decomposition, ecosystem productivity, and food web complexity to six globally pervasive human stressors. We show that human stressors inhibited ecosystem functioning for most stressor‐function pairs. Nitrate uptake efficiency was most affected and was inhibited by 347% due to agriculture. However, concomitant negative and positive effects were common even within a given stressor‐function pair. Some part of this variability in effect direction could be explained by the structural heterogeneity of the landscape and latitudinal position of the streams. Ranking human stressors by their absolute effects on ecosystem multifunctionality revealed significant effects for all studied stressors, with wastewater effluents (194%), agriculture (148%), and urban land use (137%) having the strongest effects. Our results demonstrate that we are at risk of losing the functional backbone of streams and rivers if human stressors persist in contemporary intensity, and that freshwaters are losing critical ecosystem services that humans rely on. We advocate for more studies on the effects of multiple stressors on ecosystem multifunctionality to improve the functional understanding of human impacts. Finally, freshwater management must shift its focus toward an ecological function‐based approach and needs to develop strategies for maintaining or restoring ecosystem functioning of streams and rivers. [ABSTRACT FROM AUTHOR]

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

The differences between aquatic and terrestrial habitats could change microbial community composition and regulate litter decomposition in a subtropical forest, but the linkage remains uncertain. Using microbial phospholipid fatty acids (PLFAs), the litter decomposition associated with microbial organisms was monitored to characterize the differences of microbial communities in the forest floor, headwater stream, and intermittent stream. Habitat type did not significantly affect the concentrations of total PLFA. However, microbial community composition (fungi, G+ bacteria, and eukaryote) was significantly affected by the microenvironment among habitats. Compared with which in headwater stream, more individual PLFAs were identified in the natural forest floor and the intermittent stream during the whole decomposition period. The differences in individual PLFA concentrations were reflected in the forest floor and aquatic system in the early stage of litter decomposition, but they mainly reflected in the headwater stream and the intermittent stream in the later stage of litter decomposition. We linked the relationships between microbial community and litter decomposition and found that communities of decomposers drive differences in litter decomposition rate among habitats. Intriguingly, the microbial community showed the greatest correlation with the decomposition rate of litter in streams. These findings could contribute to the understanding of habitats difference on the microbial community during litter decomposition. [ABSTRACT FROM AUTHOR]

Stream functioning is affected by allochthonous and autochthonous energy sources, organic matter decomposition and the structure and composition of the aquatic community. The presence of non-native tree species in the riparian zone may affect stream functioning. Thus, we quantified the allochthonous organic matter input to streams from native tree species and Hovenia dulcis, a non-native species, over a year, and we evaluated litter colonization and decomposition by aquatic invertebrates. The input of native organic matter was greater in Winter and Spring. On the other hand, the input of H. dulcis was higher in Autumn. The annual contribution of native organic matter was twofold greater than that of H. dulcis and was correlated with rainfall. H. dulcis leaf litter had decomposition rates that were three- to fourfold greater than those of native leaf litter. The invertebrate abundance and richness, and functional feeding groups did not vary between native and non-native leaf litter. We conclude that the presence of H. dulcis in the riparian zone changed the input patterns of allochthonous organic matter into streams. Furthermore, H. dulcis litter broke down faster than that of native species and did not directly affect the associated invertebrate community. However, the dominance of this species in riparian zones causes homogenisation of environment, resulting in changes in the composition of other biological communities (e.g., fungi and fish). [ABSTRACT FROM AUTHOR]

Abstract Fungi that bind leaf litter into mats and produce white‐rot via degradation of lignin and other aromatic compounds influence forest nutrient cycling and soil fertility. Extent of white‐rot litter mats formed by basidiomycete fungi in Puerto Rico decreased in response to disturbances—a simulated hurricane treatment executed by canopy trimming and debris addition in 2014, a drought in 2015, a treefall, and two hurricanes 10 days apart in September 2017. Percent fungal litter mat cover ranged from 0.4% after Hurricanes Irma and Maria to a high of 53% in forest with undisturbed canopy prior to the 2017 hurricanes, with means mostly between 10% and 45% of fungal litter mat cover in undisturbed forest. Drought decreased litter mat cover in both treatments, except in one control plot dominated by a drought‐resistant fungus, Marasmius crinis‐equi. Percent fungal litter mat cover sharply declined after hurricanes, a treefall, and a simulated hurricane treatment. Solar radiation was significantly inversely correlated with relative humidity (RH) and percent litter mat cover within each of the four climatic seasons. Solar radiation was also directly correlated with prior month litterfall, while RH was moderately correlated with throughfall, rain, and litter wetness. However, rainfall was inversely correlated with litter mat cover, possibly due to erosion or saturation during high rainfall events. Canopy opening reduced leaf fall and litter mat cover but these variables were not correlated except in winter. The main factor inhibiting basidiomycete fungi that bind leaf litter into mats was likely lower litter moisture associated with drought and increased solar radiation from canopy opening but secondary compounds in green litterfall may have contributed. Although higher litterfall likely increases fungal mat cover under closed canopy, changes in environmental factors apparently had a stronger inhibitory effect following canopy disturbances. Drought tolerance of some basidiomycete fungal litter mat species provided some resilience to drought.

Fungi that bind leaf litter into mats and produce white‐rot via degradation of lignin and other aromatic compounds influence forest nutrient cycling and soil fertility. Extent of white‐rot litter mats formed by basidiomycete fungi in Puerto Rico decreased in response to disturbances—a simulated hurricane treatment executed by canopy trimming and debris addition in 2014, a drought in 2015, a treefall, and two hurricanes 10 days apart in September 2017. Percent fungal litter mat cover ranged from 0.4% after Hurricanes Irma and Maria to a high of 53% in forest with undisturbed canopy prior to the 2017 hurricanes, with means mostly between 10% and 45% of fungal litter mat cover in undisturbed forest. Drought decreased litter mat cover in both treatments, except in one control plot dominated by a drought‐resistant fungus, Marasmius crinis‐equi. Percent fungal litter mat cover sharply declined after hurricanes, a treefall, and a simulated hurricane treatment. Solar radiation was significantly inversely correlated with relative humidity (RH) and percent litter mat cover within each of the four climatic seasons. Solar radiation was also directly correlated with prior month litterfall, while RH was moderately correlated with throughfall, rain, and litter wetness. However, rainfall was inversely correlated with litter mat cover, possibly due to erosion or saturation during high rainfall events. Canopy opening reduced leaf fall and litter mat cover but these variables were not correlated except in winter. The main factor inhibiting basidiomycete fungi that bind leaf litter into mats was likely lower litter moisture associated with drought and increased solar radiation from canopy opening but secondary compounds in green litterfall may have contributed. Although higher litterfall likely increases fungal mat cover under closed canopy, changes in environmental factors apparently had a stronger inhibitory effect following canopy disturbances. Drought tolerance of some basidiomycete fungal litter mat species provided some resilience to drought. [ABSTRACT FROM AUTHOR]

To investigate the effect of invasive Alternanthera philoxeroides mats on native leaf litter decomposition, we allocated two native leaf species of contrasting recalcitrance (Neosinocalamus affinis and Ficus virens) in litterbags with four different mesh sizes (0.025, 0.042, 0.5, and 5 mm) and the bags were either incubated under floating A. philoxeroides mats (Vegetated site) or under floating plastic foam boards without A. philoxeroides mats (Unvegetated site) for 65 days in Jianhu Lake, China, in July 2020. The average decomposition rates increased with pore size of litterbags. The interaction intensity of the site effect in leaf mass loss was negative in 0.025 mesh and positive in other meshes, while no significance existed between two native species in the same mesh sizes and sites. The contribution of microbes to decomposition was more than 50% in both sites. The contribution in the vegetation site was as follows: microbes > microinvertebrates > meioinvertebrates > macroinvertebrates, compared with microbes > macroinvertebrates > meioinvertebrates > microinvertebrates in the unvegetated site. The results suggest that A. philoxeroides mats can promote the decomposition of native leaf litter, and that the roles of micro-, meio-, and macroinvertebrates in decomposition are important but underestimated. [ABSTRACT FROM AUTHOR]

Streams draining through agricultural catchments are subjected to multiple stressors including pollution with nutrients and pesticides. Pesticides, in interaction with other agricultural stressors, can impact microbial diversity and key ecosystem processes underlying the delivery of ecosystem services from streams. The understanding of how such stressors interact to alter ecosystem structure and function and how responses of biota reflect their longer-term disturbance history remains limited. Effects of the fungicide chlorothalonil on litter breakdown rates of riparian tree leaves of Ficus racemosa and sedge Panicum maximum were assessed in 40-day indoor microcosm systems. Litter breakdown rates were analysed in microcosms treated with chlorothalonil concentrations of 0.01, 0.025, 0.10, 0.25 and 1.0 mg/L and in control tanks without pesticides using the ANCOVA test. The results of the study indicated a significant reduction (P < 0.05) of litter breakdown rate in chlorothalonil-treated tanks compared to the control tanks in terms of reduction percentage of dry weight and organic matter, microbial community sporulation and nutrient content. These alterations were modulated by the litter quality and microbial colonisations on leaf materials. Findings of the study emphasise the importance of considering indirect effects of pesticides on ecological processes. Stressing the need for deeper insight into how multiple stressors can affect the functioning of aquatic ecosystems and associated services. [ABSTRACT FROM AUTHOR]

Litter decomposition influences the nutrient cycle and the availability of soil nutrient resources in rubber plantation ecosystem. This study aimed to analyze effects of different factors such as soil layer depths, root accessibility and soil fertility levels on dynamic decomposition of leaf litter in rubber plantations, as well as physico-chemical properties and microbiological parameters of the soil. We performed decomposition experiments to analyze the effect of these factors on leaf litter decomposition in a rubber plantation in Danzhou, South China. The results showed that the rubber leaf litter decomposition activity increased with the depth of the soil layer. The fertility level of soil affected the decomposition process, with higher soil fertility level restraining litter decomposition. The litter decomposition was affected by the root accessibility, but the roots turned out to not be decisive factors in the decomposition process. The microorganism abundance differed seasonally in the above-ground and underground soil layers during the rubber leaf litter decomposition. The number of actinomycetes, bacteria and fungi changed most dramatically between March and May. The fastest rate of rubber leaf litter decomposition also occurred during this period. The microorganisms played a key role in the rubber litter decomposition underground. Enzymes sucrase, urease, polyphenol oxidase and cellulase contributed in regulating the decomposition of rubber leaf litter. These results may provide further insight into the potential of using leaf litter resources in tropical plantations. This study also provides valuable information about the decomposition mechanism of leaf litter as part of the nutrient cycle. [ABSTRACT FROM AUTHOR]

Forest degradation succession often leads to changes in forest ecosystem functioning. Exactly how the decomposition of leaf litter is affected in a disturbed forest remains unknown. Therefore, in our study, we selected a primary Korean pine forest (PK) and a secondary broad‐leaved forest (SF) affected by clear‐cutting degradation, both in Northeast China. The aim was to explore the response to changes in the leaf litter decomposition converting PK to SF. The mixed litters of PK and SF were decomposed in situ (1 year). The proportion of remaining litter mass, main chemistry, and soil biotic and abiotic factors were assessed during decomposition, and then, we made an in‐depth analysis of the changes in the leaf litter decomposition. According to our results, leaf litter decomposition rate was significantly higher in the PK than that in the SF. Overall, the remaining percent mass of leaf litter's main chemical quality in SF was higher than in PK, indicating that leaf litter chemical turnover in PK was relatively faster. PK had a significantly higher amount of total phospholipid fatty acids (PLFAs) than SF during decomposition. Based on multivariate regression trees, the forest type influenced the soil habitat factors related to leaf litter decomposition more than decomposition time. Structural equation modeling revealed that litter N was strongly and positively affecting litter decomposition, and the changes in actinomycetes PLFA biomass played a more important role among all the functional groups. Selected soil abiotic factors were indirectly driving litter decomposition through coupling with actinomycetes. This study provides evidence for the complex interactions between leaf litter substrate and soil physical–chemical properties in affecting litter decomposition via soil microorganisms. [ABSTRACT FROM AUTHOR]

Fungi play a critical role in the degradation of organic matter. Because different combinations of fungi result in different rates of decomposition, determining how climate change will affect microbial composition and function is fundamental to predicting future environments. Fungal response to global change is patterned by genetic relatedness, resulting in communities with comparatively low phylogenetic diversity (PD). This may have important implications for the functional capacity of disturbed communities if lineages sensitive to disturbance also contain unique traits important for litter decomposition. Here we tested the relationship between PD and decomposition rates. Leaf litter fungi were isolated from the field and deployed in microcosms as mock communities along a gradient of initial PD, while species richness was held constant. Replicate communities were subject to nitrogen fertilization comparable to anthropogenic deposition levels. Carbon mineralization rates were measured over the course of 66 days. We found that nitrogen fertilization increased cumulative respiration by 24.8%, and that differences in respiration between fertilized and ambient communities diminished over the course of the experiment. Initial PD failed to predict respiration rates or their change in response to nitrogen fertilization, and there was no correlation between community similarity and respiration rates. Last, we detected no phylogenetic signal in the contributions of individual isolates to respiration rates. Our results suggest that the degree to which PD predicts ecosystem function will depend on environmental context.

Abstract Allochthonous (e.g., riparian) plant litter is among the organic matter resources that are important for wetland ecosystems. A compact canopy of free‐floating vegetation on the water surface may allow for riparian litter to remain on it for a period of time before sinking to the bottom. Thus, we hypothesized that canopy of free‐floating vegetation may slow decomposition processes in wetlands. To test the hypothesis that the retention of riparian leaf litter on the free‐floating vegetation in wetlands affects their subsequent decomposition on the bottom of wetlands, a 50‐day in situ decomposition experiment was performed in a wetland pond in subtropical China, in which litter bags of single species with fine (0.5 mm) or coarse (2.0 mm) mesh sizes were placed on free‐floating vegetation (dominated by Eichhornia crassipes, Lemna minor, and Salvinia molesta) for 25 days and then moved to the pond bottom for another 25 days or remained on the pond bottom for 50 days. The leaf litter was collected from three riparian species, that is, Cinnamomum camphora, Diospyros kaki, and Phyllostachys propinqua. The retention of riparian leaf litter on free‐floating vegetation had significant negative effect on the carbon loss, marginal negative effects on the mass loss, and no effect on the nitrogen loss from leaf litter, partially supporting the hypothesis. Similarly, the mass and carbon losses from leaf litter decomposing on the pond bottom for the first 25 days of the experiment were greater than those from the litter decomposing on free‐floating vegetation. Our results highlight that in wetlands, free‐floating vegetation could play a vital role in litter decomposition, which is linked to the regulation of nutrient cycling in ecosystems.

Investigation was carried out on leaf litter decomposition and nutrient content of three agroforestry species—Annona muricata L., Senna siamea (Lam.) and Cola nitida (Vent.) using litterbag technique. Oven-dry leaf litters of each species were put in 432 litterbags of 23 g each. These were divided into two sets with one placed on the soil surface (SSP) and another, soil incorporated (SIP). Initial nutrient content (INC), decay constant, half- and full-lives (weeks) were determined. Decomposition rates, nutrient release patterns (NRP) and litter quality were measured fortnightly for 24 weeks after litter placement (WALP). Data collected were subjected to descriptive statistics and ANOVA at α0.05. The INC was significantly different among the species. N concentration decreased from C. nitida A. muricataS. siamea. P was significantly higher in S. siamea (0.38%) than C. nitida (0.22%) and A. muricata (0.32%). Decay constant was highest (0.005) in C. nitida under SIP. Highest half-life (49.5 weeks) and full-life (178.57 weeks) were recorded in S. siamea and C. nitida; and S. siamea and C. nitida under SSP. After 24 weeks, C. nitida had the highest decomposition rate, 5.97 ± 0.0 under SIP. NRP showed that A. muricata and S. siamea had the highest P (0.17%) and cellulose (28.2%) at 24 WALP under SIP. Lignin concentration at 24 WALP was highest in S. siamea (4.35%) and least in C. nitida (0.43%). Decomposition trend and nutrient release pattern from the leaf litters of selected agroforestry species indicated the potential of these leaf litters to offer nutrients on a sustainable basis in an agroforestry system. [ABSTRACT FROM AUTHOR]