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Trees allocate carbon below‐ground to fuel the functioning of roots and mycorrhizal fungi, which affect litter decomposition, but the direction and magnitude of this effect are variable. While tree mycorrhizal type is often suggested to mediate this above‐ground–below‐ground linkage, previous studies yield mixed results. In this study, we investigated how absorptive root traits, soil conditions and litter type influence the response of litter decomposition to altered below‐ground carbon allocation, both within and across mycorrhizal types. We girdled transport roots of seven subtropical tree species to eliminate carbon allocation to distal absorptive roots. We monitored leaf and root litter decomposition surrounding girdled and un‐girdled root branches. We found that girdling generally slowed leaf litter decomposition. However, the effect of girdling on root litter decomposition depended on soil moisture, stimulating decomposition in dry soil but suppressing it in moist soil. Absorptive root traits did not influence the girdling effect on either leaf or root litter decomposition. These findings suggest that disturbance in carbon allocation can impact litter decomposition, with the outcome largely contingent on litter type and soil moisture. Synthesis. Our findings highlight the importance of accounting for local soil variability in understanding the relationship between above‐ground and below‐ground carbon dynamics. This study underscores a critical need for comprehensive assessment of below‐ground ecosystem responses to above‐ground disturbances, as it is essential for accurately predicting future forest carbon and nutrient cycles. [ABSTRACT FROM AUTHOR]

The 'home‐field advantage (HFA)' for decomposition means that leaf litter decomposes faster on soils under the conspecific species (i.e. the home field) than on soils under different species (i.e. 'away'). Many previous studies have demonstrated the HFA, but the underlying mechanisms remain unclear. We conducted a reciprocal litter‐decomposition experiment using two species with different leaf traits: Abies mariesii, an evergreen conifer, and Fagus crenata, a deciduous broad‐leaved tree. Dominance of these species shifts along an elevation gradient with a transition zone where both species coexist. In mixed forests of the transition zone along the elevation gradient, we explored how the magnitude of HFA between these two species was influenced by temperature, soil properties, or leaf litter traits which could directly affect the decomposition rate. The magnitude of HFA observed between the two species varied widely from −3.89 to 28.3%. Our modeling showed that the magnitude of HFA increased with decreasing soil pH and leaf litter N, i.e. in more acidic soil and for less decomposable litter. Soil pH affected leaf litter decomposition in the home plots of each species, whereas leaf litter N did not. The magnitude of the HFA increased as the difference in soil pH between the F. crenata and A. mariesii plots at the same elevation became greater, but decreased as the difference in soil C became greater. Thus, the response of leaf litter decomposition to environmental changes might vary not only through direct effects of vegetation traits but also through indirect effects of the HFA. This highlights the importance of considering HFA for accurately predicting the response of local carbon and nutrient cycles to climate change, particularly in communities where a replacement of dominant species by others is expected due to climate change. [ABSTRACT FROM AUTHOR]

Litter decomposition has historically been attributed to soil microbial community at local scale, but which fundamental process directly contributes to carbon release from decomposing litter remains not fully understood. Here we used in situ microcosms to assess the temporal changes in soil microbial biomass, taxonomic composition, alpha and beta diversity, network complexity and carbon-degrading functional genes during litter decomposition of a subtropical dominant species (Castanopsis carlesii) in an older (45-years) and a younger (9-years) evergreen broadleaved forests. The soil phospholipid fatty acids, bacterial and fungal community composition, α-diversity indexes and network topological properties were not changed significantly after short-term litter input when litter was decomposed by approximately 70%. However, the absolute abundance of functional genes involved in the decomposition of starch, pectin, hemicellulose, cellulose, chitin and lignin were up-regulated, and these variations were associated with soil α-1.4-glucosidase, β-glucosidase and cellobiohydrolase activities in contributing to litter carbon release during decomposition. These results suggest that the upregulation of functional genes rather than microbial community composition and diversity controls local-scale litter decomposition by encoding and secreting enzymes in these subtropical forests. [ABSTRACT FROM AUTHOR]

Summary: The first step in carbon (C) turnover, where senesced plant biomass is converted through various pathways into compounds that are released to the atmosphere or incorporated into the soil, is termed litter decomposition. This review is focused on recent advances of how solar radiation can affect this important process in terrestrial ecosystems. We explore the photochemical degradation of plant litter and its consequences for biotic decomposition and C cycling. The ubiquitous presence of lignin in plant tissues poses an important challenge for enzymatic litter decomposition due to its biological recalcitrance, creating a substantial bottleneck for decomposer organisms. The recognition that lignin is also photolabile and can be rapidly altered by natural doses of sunlight to increase access to cell wall carbohydrates and even bolster the activity of cell wall degrading enzymes highlights a novel role for lignin in modulating rates of litter decomposition. Lignin represents a key functional connector between photochemistry and biochemistry with important consequences for our understanding of how sunlight exposure may affect litter decomposition in a wide range of terrestrial ecosystems. A mechanistic understanding of how sunlight controls litter decomposition and C turnover can help inform management and other decisions related to mitigating human impact on the planet. [ABSTRACT FROM AUTHOR]

[Objective] This study explored the effects of arbuscular mycorrhizal (AM) fungi on the growth and decomposition of dead leaves of Acer truncatum and determined the relationship between AM fungi and the growth status of Acer truncatum. [Method] The Acer truncatum seedlings were subjected to two treatments of arbuscular mycorrhizal fungi (AMF) and control without fungi (CK) . In the AMF treatment, Rhizophagus intraradices (Ri) was added to the sterilized substrate. In the CK treatment, sterilized Ri and fungicide filtration were added. At the same time, two decomposing boxes containing dead leaves of Acer truncatum were placed in two pots for both treatments. After 180 days of growth, growth index and nutrient contents of seedlings, as well as nutrient contents of dead leaves of Acer truncatum were determined. The decomposition amounts of dead leaves at different particle sizes and their remaining quantities were calculated. Redundancy analysis was conducted to examine the correlations between growth status, nutrient contents and decomposition rates of dead leaves. [Result] (1) Compared to CK, AMF treatment significantly enhanced fresh and dry masses and contents of total nitrogen, total phosphorus and total potassium roots and total phosphorus in leaves. There were no significant differences in plant height, ground diameter and leaf total nitrogen content. Total potassium content in leaves was significantly decreased. (2) Compared with CK, total decomposition capacity of dead leaves treated with AMF was significantly increased. The mass of dead leaves with size larger than 0. 15 mm was notably reduced while that of 0. 25 μm-0. 15 mm showed significant increases. (3) Compared to CK, AMF treatment enhanced the release of polyphenols and mitigated the accumulation of total nitrogen in withered leaves, while it had no significant impacts on tannin, cellulose, total phosphorus, total potassium and organic carbon. (4) The correlation analysis revealed that total nitrogen in dead leaves had a positive association with total potassium content in leaves and negative correlations with biomass and nutrient contents in roots and leaves. The accumulation coefficients of polyphenols in dead leaves exhibited inverse relationships. [Conclusion] The ino-culation of AM fungi enhanced the decomposition process of dead leaves, influenced the nutrient availability in dead leaves, and facilitated the growth and development of Acer truncatum. [ABSTRACT FROM AUTHOR]

Invasive alien plants (IAPs) represent a major challenge to biodiversity and ecosystem functioning, especially those transformer species. Litter chemistry and decomposition rates are relevant factors to understand the invasion process due to its influence on nutrient cycling and ecosystem dynamics. Here, we present the results of a litterbag mesocosm comparing the decomposition dynamics of litter produced by two common IAPs (Acacia dealbata and Carports edulis) with similar amounts of native litter from invaded ecosystems (shrubland and coastal dunes invaded by A. dealbata and C. edulis, respectively), and how this different leaf litter origin further affects soil community function and the growth of seedlings of different native species. After 12 months of incubation, plant litter decayed at a rate of between 54 and 36% (C. edulis litter > dune litter and Shrub litter > A. dealbata litter) with slight changes in nutrient composition (C, N, C:N, and P content) at the end of the assay. Whereas the effect of the litterbag content (native vs. non-native plant litter) was rather limited, the incubation time significantly affected physico-chemical parameters. Thus, extracellular enzymatic activities (EAs, including acid and basic phosphatase, β-glucosidase, urease) varied depending on the litterbag content (native and non-native) for both decomposing species (A. dealbata or C. edulis). The correspondence analysis (CA) based on the community level physiological profile (CLPPs) showed a similar trend of data clustering regardless of the IAP considered. In both cases, different decomposition times were more relevant than litter origin to discriminate the soil functional activity. Finally, seedlings of different native species were grown in soils previously used for the litter incubation experiment. Here, seedlings of native species growing in soils from the mesocosm (previously covered with native or invasive litter) showed a species-dependent response. At the end of the assay, slight differences were found between the invasive and native plant litter. The results of the decomposition rates between litter of different origin, the effect of litter origin on soil nutrient content, on extracellular EAs, on the functional profile of soil communities, and also on the performance of native seedlings can be considered as limited. These results suggest that litter chemistry might not be as relevant as previously suggested—at least not relevant to explain ecosystem-level alterations—while highlighting the importance of assessing invasion thresholds rather than litter chemical composition. [ABSTRACT FROM AUTHOR]

Background Aims Methods Results Conclusions Liquid organic fertilizer (LOF) and root exudates contain easily decomposable carbon that can stimulate microbial growth. It is unknown what role the amount of organic matter (OM) in the growing media, and potential interactions between root presence and LOF, might play in enhancing the breakdown of OM.The aim was to better understand how the decomposition rate of plant litter is affected by added fertilizer, plant presence, and growing media OM content.A container experiment was conducted with and without tomato plants (Solanum lycopersicum L.; Heinz 5608 variety) present to evaluate the effect of three one‐time fertilizer additions (no fertilizer, LOF, and synthetic fertilizer) on litter decomposition rate. The equivalent amount of nitrogen (N), phosphorus (P), and potassium(K) was added in both fertilizer treatments. The experiment was conducted using two growing media, one containing high OM and one with negligible OM.The presence of tomato roots stimulated litter decomposition in high OM media, but not in low OM media. Adding LOF did not affect decomposition in either growing medium. Adding synthetic fertilizer led to a negative priming effect in low OM media when roots were present. The rate of decomposition was not affected by root traits.When ample OM was available, the presence of plant roots had a strong positive impact on litter decomposition. In both low and high OM media, a one‐time addition of fertilizer had minimal or negative effects on litter decomposition. We speculate that the continuous nature of root exudation leads to sustained changes in the microbial population (both community composition and size). Boosting root length growth via the one‐time addition of inorganic fertilizer when OM was negligible allowed the plant to outcompete decomposing microbes for N, possibly leading to selection for microbes that primarily feed on exudates, which resulted in retarded litter decomposition rates. In conclusion, as adding inorganic fertilizer stimulated plant and root growth more than adding the equivalent nutrients in LOF, particularly in growth media with a high OM content, it is better to add inorganic nutrients than LOF to stimulate OM breakdown when plants are present. [ABSTRACT FROM AUTHOR]

Litter decomposition is not fully explained by the general triangle of climate, litter quality and soil decomposers. Therefore, other theoretical frameworks, such as Home-Field Advantage (HFA), have emerged to explain the remaining variation of decomposition. HFA states that litter decomposes faster in their site of origin (home) than far from it (away). However, there are no consistent patterns of HFA and this can varies depending the ecosystem and plant species analyzed. One of the most variable ecosystems in terms of species biodiversity turnover, topography, and soil conditions are the Upper Andean Tropical Forests (UATF), but to date there is no study testing HFA in this ecosystem. Here, HFA was tested through a reciprocal litterbag translocation field experiment across different UATF. The experiment comprised 2520 litterbags placed in 14 20 x 20 m plots that belonged to four sites to analyze decomposition of 15 plant species for 18 months. Of these 15 species, seven were present at only one site. The mean decomposition was calculated for all 15 species to determine the relative decomposition at each site and the decomposition of the seven species at home and away sites was analyzed through two-way ANOVA (sites x species) and linear mixed models. I contrasted environmental charcteristics between sites including litter depth, slope, leaf area index, canopy openness, and microclimatic variables. The results showed that the pattern of decomposition was always the same, no matter the origin of the species and the decomposition period. Microclimate, litter depth, and slope varied between sites, yet these differences were not enough to influence affinity effects of decomposition, as relative decay rates were similar between home and away sites. Overall, no HFA was found in UATF possibly because: (i) strong environmental filters along montane forests homogenize decomposer communities; (ii) high diversity in litters drive decomposers with high ability to degrade different organic compounds; (iii) little adaptation of decomposers to recurrent litter as they respond mainly to changes in litter quality. These results imply that changes in species composition by current anthropogenic pressures could have profound impacts on carbon cycle and nutrient fluxes depending on the identity of species arriving in UATF. [ABSTRACT FROM AUTHOR]

A major challenge in ecology is to understand how different species interact to determine ecosystem function, particularly in communities with large numbers of co‐occurring species. We use a trait‐based model of microbial litter decomposition to quantify how different taxa impact ecosystem function. Furthermore, we build a novel framework that highlights the interplay between taxon traits and environmental conditions, focusing on their combined influence on community interactions and ecosystem function. Our results suggest that the ecosystem impact of a taxon is driven by its resource acquisition traits and the community functional capacity, but that physiological stress amplifies the impact of both positive and negative interactions. Furthermore, net positive impacts on ecosystem function can arise even as microbes have negative pairwise interactions with other taxa. As communities shift in response to global climate change, our findings reveal the potential to predict the biogeochemical functioning of communities from taxon traits and interactions. [ABSTRACT FROM AUTHOR]

Litter decomposition is a crucial biochemical process regulated by microbial activities in the forest ecosystem. However, the dynamic response of the fungal community during litter decomposition to vegetation changes is not well understood. Here, we investigated the litter decomposition rate, extracellular enzyme activities, fungal community, and nutrient cycling-related genes in leaf and twig litters over a three-year decomposition period in a pure Liquidamabar formosana forest and a mixed L. formosana/Pinus thunbergii forest. The result showed that during the three-year decomposition, twig litter in the mixed forest decomposed faster than that in the pure forest. In both leaf litter and twig litter, β-cellobiosidase and N-acetyl-glucosamidase exhibited higher activities in the mixed forest, whereas phosphatase, β-glucosidase, and β-xylosidase were higher in the pure forest. The fungal α-diversity were higher in both litters in the pure forest compared to the mixed forest, with leaf litter showing higher α-diversity than twig litter. Fungal species richness and α-diversity within leaf litter increased as decomposition progressed. Within leaf litter, Basidiomycota dominated in the mixed forest, while Ascomycota dominated in the pure forest. Funguild analysis revealed that Symbiotroph and ectomycorrhizal fungi were more abundant in the mixed forest compared to the pure forest. In the third-year decomposition, genes related to phosphorus cycling were most abundant in both forests, with the pure forest having a higher abundance of cex and gcd genes. Fungal community structure, predicted functional structure, and gene composition differed between the two forest types and between the two litter types. Notably, the fungal functional community structure during the first-year decomposition was distinct from that in the subsequent two years. These findings suggest that dominant tree species, litter quality, and decomposition time all significantly influence litter decomposition by attracting different fungal communities, thereby affecting the entire decomposition process. [ABSTRACT FROM AUTHOR]

Root nitrogen (N) reallocation is a conservative N-use strategy involving root N remobilization for shoot growth, reproduction, and other metabolic processes, but a critical framework for how it varies among plants is missing. Community-level root N reallocation increases with richness of plant species and N-acquisition strategies because of complementarity in N uptake and storage. Root N reallocation is a conservative trait opposite to competitive root traits along the major axis of the fast–slow spectrum of the root economics space. Root N reallocation declines with more abundant soil microbial K -strategists, hyphosphere/rhizosphere microbial recruitment, and mycorrhizal colonization due to acceleration of N release from recalcitrant organic matter and facilitation of plant efficiency in N foraging. Root nitrogen (N) reallocation involves remobilization of root N-storage pools to support shoot growth. Representing a critical yet underexplored facet of plant function, we developed innovative frameworks to elucidate its connections with key ecosystem components. First, root N reallocation increases with plant species richness and N-acquisition strategies, driven by competitive stimulation of plant N demand and synergies in N uptake. Second, competitive root traits and mycorrhizal symbioses, which enhance N foraging and uptake, exhibit trade-offs with root N reallocation. Furthermore, root N reallocation is attenuated by N-supply attributes such as increasing litter quality, soil fungi-to-bacteria ratios, and microbial recruitment in the hyphosphere/rhizosphere. These frameworks provide new insights and research avenues for understanding the ecological roles of root N reallocation. [ABSTRACT FROM AUTHOR]

Forest litter can decompose faster at home sites than at guest sites (home-field advantage, HFA), yet few studies have focused on the response of the HFA of native plant decomposition to the presence of invasive plants. We loaded the dry leaves of native Neosinocalamus affinis (decomposition resistant) and Ficus virens (more easily decomposable) leaves into litterbags with and without invasive Alternanthera philoxeroides, and incubated these litterbags at N. affinis and F. virens sites at the edge of the forest. The results showed that positive HFA effects with litter mass loss were at least 1.32% faster at home sites than at guest sites. The addition of A. philoxeroides reduced the mean HFA of N. affinis litter and increased that of F. virens litter. The HFA index without A. philoxeroides was significantly higher than that with A. philoxeroides. Soil faunal abundance colonized at home sites was always higher than that colonized at guest sites. Compared with the F. virens site, the abundance of Collembola, Arachnida, Formicidae and Lepismatidae at the N. affinis site was significantly higher compared to the F. virens site, while the abundance of Isopoda, Oligochaeta, Nematoda and Dermaptera was significantly lower. Our results indicate that invasive plants may regulate HFA effects by promoting the decomposition of native plants and increasing fauna abundance. Particularly, soil fauna groups play a very important role in this process. Our findings help us to re-understand the role of invasive plants in material cycling and energy flow in the context of achieving carbon neutrality goals. [ABSTRACT FROM AUTHOR]

The dominant plant litter plays a crucial role in carbon (C) and nutrients cycling as well as ecosystem functions maintenance on the Qinghai-Tibet Plateau (QTP). The impact of litter decomposition of dominant plants on edaphic parameters and grassland productivity has been extensively studied, while its decomposition processes and relevant mechanisms in this area remain poorly understood. We conducted a three-year litter decomposition experiment in the Gansu Gannan Grassland Ecosystem National Observation and Research Station, an alpine meadow ecosystem on the QTP, to investigate changes in litter enzyme activities and bacterial and fungal communities, and clarify how these critical factors regulated the decomposition of dominant plant Elymus nutans (E. nutans) litter. The results showed that cellulose and hemicellulose, which accounted for 95% of the initial lignocellulose content, were the main components in E. nutans litter decomposition. The litter enzyme activities of β-1,4-glucosidase (BG), β-1,4-xylosidase (BX), and β-Dcellobiosidase (CBH) decreased with decomposition while acid phosphatase, leucine aminopeptidase, and phenol oxidase increased with decomposition. We found that both litter bacterial and fungal communities changed significantly with decomposition. Furthermore, bacterial communities shifted from copiotrophic-dominated to oligotrophic-dominated in the late stage of litter decomposition. Partial least squares path model revealed that the decomposition of E. nutans litter was mainly driven by bacterial communities and their secreted enzymes. Bacteroidota and Proteobacteria were important producers of enzymes BG, BX, and CBH, and their relative abundances were tightly positively related to the content of cellulose and hemicellulose, indicating that Bacteroidota and Proteobacteria are the main bacterial taxa of the decomposition of E. nutans litter. In conclusion, this study demonstrates that bacterial communities are the main driving forces behind the decomposition of E. nutans litter, highlighting the vital roles of bacterial communities in affecting the ecosystem functions of the QTP by regulating dominant plant litter decomposition. [ABSTRACT FROM AUTHOR]

Urbanization is a growing phenomenon affecting soils worldwide. Urban centers have been highlighted as hotspots for global change factors due to heightened anthropogenic activity. However, few studies have investigated the multifaceted impacts of global change factors (GCFs) acting in concert with urban soils. Thus, the objective of this study was to add GCFs in different combinations (0, 1, 2, 5, and 8 simultaneously) in three high-urbanity and three low-urbanity soils in Berlin and to evaluate their effects on soil parameters and functions. We hypothesized four potential outcomes of soil process responses to GCF exposure, Site-Specific Resistance, General Susceptibility, Low-Urbanity Resistance, and High-Urbanity Resistance. We provide evidence for the negative impacts of individual and multiple GCF application on litter decomposition, water repellency, and water-stable aggregates. Additionally, we highlight the General Susceptibility of litter decomposition to GCF exposure regardless of urbanity, as well as the Low-Urbanity Resistance of water repellency and High-Urbanity Resistance of water-stable aggregates under increased exposure to GCFs. This study expands on evidence of the growing threat of global change factors in urban settings and highlights some potential consequences regarding soil function. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Microplastics (MPs) as emerging contaminants have a global occurrence, including both terrestrial and marine ecosystems. Soil enzymes contribute to maintaining ecosystem multifunctionality, for example, nutrient cycling, organic material decomposition, and carbon and climate regulation. Our present review highlights the impacts of MPs on soil enzyme activities, influencing factors, and the underlying mechanisms. Increasing findings confirm that MPs can change the activities of a range of soil enzymes involved in the biogeochemical cycling of C and N. However, current results are highly controversial. The effects of MPs highly vary from significant to nonsignificant and are dependent on polymer type, biodegradability, dosage, size, shape, and aging degree of MPs, and exposure conditions. Compared to traditional MPs, biodegradable MPs generally show more pronounced effects. MPs can change soil enzyme activities via different pathways. On one hand, MPs can directly change soil enzyme structure, leading to alterations in enzyme activity. On the other hand, MPs can create unique habitats, provide carbon sources for specific functional microbes producing enzymes, and release plastic additives and pollutants disturbing the production of these enzymes. Furthermore, MPs can alter soil physicochemical and biological properties, the availability of substrates, plants and soil fauna, regulating soil enzymes and their functions. In conclusion, MPs can regulate soil enzyme activities and pose a profound impact on ecosystem multifunctionality. [ABSTRACT FROM AUTHOR]

The sandy Pinus sylvestris var. mongolica plantation which is the boundary part of the Three North Shelterbelt Project in Northeast China has been well protected and prohibited disturbance for more than 10 years and thus bring about lots of forest floor litter and then humus layer (complete decomposed aboveground litter and not mixed into surface soil) during this restoration process. While humus layer accumulation could change the interface between litter and soil, its effects on litter and soil, and especially the interaction among them, were still poorly understood. Hence, three different treatments that included remove all forest floor litter and humus, double forest floor litter and humus layer, and retain forest floor litter and humus original (no treatment) were conducted, and the physicochemistry properties and microbial communities were monitored. Results showed that the humus layer increased forest floor litter decomposition rate and its total carbon, total nitrogen, and total phosphorus significantly, while it changed soil pH and nutrients differently and slightly. The abundances of bacterial groups at different taxonomic levels increased while its diversity indexes decreased in litter when the humus layer existed; however, the fungi community both in litter and soil varied insignificantly. The humus layer not only increased remarkably the proportions of common OTUs between humus and litter, humus and soil compared to litter and soil both for fungi and bacteria but also decreased the differences of the number of fungal and bacterial taxa statistics between litter and soil. It implied that the humus layer could play an important role in the recovery process of degraded forest ecosystem. [ABSTRACT FROM AUTHOR]

Allelopathy is an underlying and controversial mechanism for detrimental environmental effects in the management of Eucalyptus plantations. However, little attention has been paid to the dynamics of allelochemicals and phytotoxicity in soil fauna during litter decomposition. To explore the relationship between the dynamics of phytotoxicity and allelochemicals, a decomposition experiment was conducted using 4-year-old and 8-year-old Eucalyptus grandis litter (0, 10, 20, 30, and 45 days). The acute toxicity of Eisenia fetida was assessed, and a chemical analysis of the eucalyptus leaves was performed. Biochemical markers, including total protein, acetylcholinesterase (AChE) activity, and oxidative stress levels (SOD and MDA) were measured. A comet assay was used to determine DNA damage in E. fetida cells. The results showed that after 20–30 days of decomposition, E. grandis litter exhibited stronger phytotoxic effects on E. fetida in terms of growth and biochemical levels. After 20 days of decomposition, the weight and total protein content of E. fetida first decreased and then increased over time. SOD activity increased after 20 days but decreased after 30 days of decomposition before increasing again. MDA content increased after 20 days, then decreased or was stable. AChE activity was inhibited after 30 days of decomposition and then increased or stabilized with further decomposition. Soluble allelochemicals, such as betaine, chlorogenic acid, and isoquercitrin, significantly decreased or disappeared during the initial decomposition stage, but pipecolic acid significantly increased, along with newly emerging phenolic fractions that were present. More allelochemicals were released from 8-year-old litter than from 4-year-old E. grandis litter, resulting in consistently more severe phytotoxic responses and DNA damage in E. fetida. Scientific management measures, such as the appropriate removal of leaf litter in the early stages of decomposition, might help support greater biodiversity in E. grandis plantations. [ABSTRACT FROM AUTHOR]

Alpine ecosystems are important terrestrial carbon (C) pools, and microbial decomposers play a key role in litter decomposition. Microbial metabolic limitations in these ecosystems, however, remain unclear. The objectives of this study aim to elucidate the characteristics of microbial nutrient limitation and their C use efficiency (CUE), and to evaluate their response to environmental factors. Five ecological indicators were utilized to assess and compare the degree of microbial elemental homeostasis and the nutrient limitations of the microbial communities among varying stages of litter decomposition (L, F, and H horizon) along an altitudinal gradient (2800, 3000, 3250, and 3500 m) under uniform vegetation (Abies fabri) on Gongga Mountain, eastern Tibetan Plateau. In this study, microorganisms in the litter reached a strictly homeostatic of C content exclusively during the middle stage of litter decomposition (F horizon). Based on the stoichiometry of soil enzymes, we observed that microbial N- and P-limitation increased during litter degradation, but that P-limitation was stronger than N-limitation at the late stages of degradation (H horizon). Furthermore, an increase in microbial CUE corresponded with a reduction in microbial C-limitation. Additionally, redundancy analysis (RDA) based on forward selection further showed that microbial biomass C (MBC) is closely associated with the enzyme activities and their ratios, and MBC was also an important factor in characterizing changes in microbial nutrient limitation and CUE. Our findings suggest that variations in MBC, rather than N- and P-related components, predominantly influence microbial metabolic processes during litter decomposition on Gongga Mountain, eastern Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: A large fraction of plant litter comprises recalcitrant aromatic compounds (lignin and other phenolics). Quantifying the fate of aromatic compounds is difficult, because oxidative degradation of aromatic carbon (C) is a costly but necessary endeavor for microorganisms, and we do not know when gains from the decomposition of aromatic C outweigh energetic costs.To evaluate these tradeoffs, we developed a litter decomposition model in which the aromatic C decomposition rate is optimized dynamically to maximize microbial growth for the given costs of maintaining ligninolytic activity. We tested model performance against > 200 litter decomposition datasets collected from published literature and assessed the effects of climate and litter chemistry on litter decomposition.The model predicted a time‐varying ligninolytic oxidation rate, which was used to calculate the lag time before the decomposition of aromatic C is initiated. Warmer conditions increased decomposition rates, shortened the lag time of aromatic C oxidation, and improved microbial C‐use efficiency by decreasing the costs of oxidation. Moreover, a higher initial content of aromatic C promoted an earlier start of aromatic C decomposition under any climate.With this contribution, we highlight the application of eco‐evolutionary approaches based on optimized microbial life strategies as an alternative parametrization scheme for litter decomposition models. See also the Commentary on this article by Shao & Sulman, 243: 825–827. [ABSTRACT FROM AUTHOR]

Background and aims: Knowledge regarding the interactive effects of soil invertebrates and microbes on litter decomposition is limited. We aimed to reveal the interaction between soil invertebrates and microbes, and the mechanism underlying the effects of them on litter decomposition. Methods: Foliar litter of German oak (Quercus acutissima Carruth.) and China cedar (Cryptomeria sinensis Miquel.) were enclosed in the nylon bags with two different mesh sizes and incubated on the floor in a rainy zone of western China, respectively. Then retrieved at four critical periods each year in two years. The mass loss, invertebrates, and microbial community in the litterbags were measured. Results: The invertebrate abundances in both litter species were higher in the first year than in the second year, and that in German oak litter was higher than that in China cedar litter at most periods. Meanwhile, German oak litter decomposed faster than China cedar litter, and significantly higher decomposition rates occurred in the micro and early rainy seasons. Furthermore, soil invertebrate exclusion made the decomposition rates of German oak and China cedar litter decrease by 14.45% and 26.45%, respectively. Additionally, the interactive effects between invertebrates and microbes on litter decomposition varied greatly with litter quality and critical periods. The interactive effects between soil invertebrates and microbial communities dominated litter mass loss in the first decomposition year, but the gram-positive bacteria became the dominant decomposers in the second decomposition year. Conclusion: These results provided a holistic decomposition view, highlighting how invertebrates and microbes act in synergy to degrade litter. [ABSTRACT FROM AUTHOR]

The decomposition of returned straw is increasing facing the negative impacts by metal nanoparticles (NPs), however, which may be modulated by soil fauna and this modulation effect is unclear. Here, the interactive effects of ZnO NPs with soil fauna on wheat straw decomposition were investigated in a potted rice cropping system. The results showed that ZnO NP below middle concentrations did not significantly influence straw decomposition, and mass loss was mainly driven by microfauna and microbes. High concentrations of ZnO NPs significantly impeded decomposition, mainly by reducing the complexity of fungal communities. This negative effect was ascribed to the promotion of Zn solubilization by bacterial taxa such as unclassified Acidobacteria, Bacteroidetes and Gemmatimonadetes. ZnO NPs had a greater impact on soil microorganisms than on fauna, reduced microbial activity, promoted the released straw nutrients entering into the soil by damaging nutrient transferring microorganisms and dominated the effects on soil stoichiometry. However, soil fauna significantly increased the activities of C- and N-releasing enzymes, decreased the activity of P-releasing enzymes, regardless of ZnO NP concentration, and promoted straw C decomposition. ZnO NPs altered soil microbial community composition, but these changes were modulated by soil fauna. Nonetheless, nutrient transport by fungi such as Ascomycota and Zygomycota and grazing by fauna were the predominant modulators on straw stoichiometry. The results of this study revealed that rational control of soil fauna will be helpful for promoting straw decomposition and efficient recycling of straw nutrients by crops under ZnO NP contamination.Article Highlights: High ZnO NP concentrations inhibit straw decomposition mainly by reducing diversity of fungal community. The negative effects of ZnO NPs are ascribed to Zn solubilization by bacterial taxa such as unclassified Acidobacteria, Bacteroidetes and Gemmatimonadetes. ZnO NPs have greater impact on soil microorganisms than on fauna, reduce microbial activity, promote the released nutrients into soil and dominate the effects on soil stoichiometry. Fungal transport (e.g., Ascomycota and Zygomycota) and fauna grazing are the predominant modulators on straw stoichiometry. [ABSTRACT FROM AUTHOR]

Land-use intensity drives productivity and ecosystem functions in grassland. The effects of long-term land-use intensification on plant functional community composition and its direct and indirect linkages to processes of nutrient cycling are largely unknown. We manipulated mowing frequency and nitrogen inputs in an experiment in temperate grassland over ten years. We assessed changes in species composition and calculated functional diversity (FDis) and community weighted mean (CWM) traits of specific leaf area (SLA), leaf dry matter content (LDMC) and leaf and root nitrogen of the plant community, using species-specific trait values derived from databases. We assessed above- and belowground decomposition and soil respiration. Plant diversity strongly decreased with increasing land-use intensity. CWM leaf nitrogen and SLA decreased, while CWM LDMC increased with land-use intensification, which could be linked to an increased proportion of graminoid species. Belowground processes were largely unaffected by land-use intensity. Land use affected aboveground litter composition directly and indirectly via community composition. Mowing frequency, and not a land-use index combining mowing frequency and fertilization, explained most of the variation in litter decomposition. Our results show that land-use intensification not only reduces plant diversity, but that these changes also affect nutrient dynamics. [ABSTRACT FROM AUTHOR]

We studied the dynamics of stable carbon (δ13C) and nitrogen (δ15N) isotopes in litter from Norway spruce (NSL) (Picea abies) and Scots pine (SPL) (Pinus silvestris) during in situ decomposition over a period of more than 4 years. Relative to initial values, δ13CNSL showed a weak enrichment (0.33‰), whereas δ13CSPL was depleted (−0.74‰) at the end of decomposition. Both litter types experienced a depletion in δ15N during decomposition; δ15NNSL decreased by −1.74‰ and δ15NSPL decreased by −1.99‰. The effect of the selective preservation of acid-unhydrolyzable residue (AUR) in lowering δ13C of the residual litter was evident only in SPL. In the NSL, only in the initial stage did C/N have a large effect on the δ13C values. In the later stages, there was a non-linear decrease in δ13CNSL with a simultaneous increase in AUR concentrations, but the effect size was large, suggesting the role of lignin in driving δ13C of residues in later stages. Depletion in 15N in the residual litters concomitant with the increase in N concentration suggests bacterial transformation of the litter over fungal components. A consistent decline in δ15N values further implies that bacterial dominance prompted this by immobilizing nitrate depleted in 15N in the residual litter. [ABSTRACT FROM AUTHOR]

Headwater streams are reliant on riparian tree leaf litterfall to fuel brown food webs. Terrestrial agents like herbivores and contaminants can alter plant growth, litter production, litter quality, and the timing of litterfall into streams, influencing aspects of the brown food web. At Mount St. Helens (USA), early successional streams are developing willow (Salix sitchensis) riparian zones. The willows are attacked by stem-boring herbivores, altering litter quality and the timing of litterfall. Within a established experimental plots, willows (male and female plants) were protected from herbivores using insecticides and provided with experimental additions of nitrogen. This enabled us to test the interacting influences of herbivores, nitrogen deposition, and willow sex on leaf litter quality, aquatic litter decomposition, and microbial and invertebrate detritivores. We found weak litter quality effects (higher N and lower C:N) for the herbivore treatment, but no effect of nitrogen deposition. Although litter decomposition rates were not strongly affected by litter treatments, detritivore communities were altered by all treatments. Nitrogen deposition resulted in decreased bacterial richness and decreased fungal diversity in-stream. Aquatic macroinvertebrate communities were influenced by the interacting effects of herbivory and nitrogen addition, with abundances highest in herbivore litter with the greatest N addition. Shredders showed the highest abundance in male, herbivore-attacked litter. The establishment of riparian willows along early successional streams and their interacting effects with herbivores and nitrogen deposition may be influencing detritivore community assembly at Mount St. Helens. More broadly, global changes like increased wet and dry N deposition and expanded ranges of key herbivores might influence tree litter decomposition in many ecosystems. [ABSTRACT FROM AUTHOR]

Litter's chemical complexity influences carbon (C) cycling during its decomposition. However, the chemical and microbial mechanisms underlying the divergence or convergence of chemical complexity under UV radiation remain poorly understood. Here, we conducted a 397-day field experiment using 13C cross-polarization magic-angle spinning nuclear magnetic resonance (13C-CPMAS NMR) to investigate the interactions among the initial chemistry, microbial communities, and UV radiation during decomposition. Our study found that the initial concentrations of O-substituted aromatic C, di-O-alkyl C, and O-alkyl C in Deschampsia caespitosa were higher than those in Kobresia tibetica. Litter's chemical composition exhibited divergent patterns based on the initial chemistry, UV radiation, and decay time. Specifically, D. caespitosa consistently displayed higher concentrations of di-O-alkyl C and O-alkyl C compared to K. tibetica, regardless of the UV exposure and decay time. Additionally, litter's chemical complexity was positively correlated with changes in the extracellular enzyme activities, particularly those involved in lignin, cellulose, and hemicellulose degradation, which accounted for 9%, 20%, and 4% of the variation in litter's chemical complexity, respectively. These findings highlighted the role of distinct microbial communities in decomposing different C components through catabolism, leading to chemical divergence in litter. During the early decomposition stages, oligotrophic Planctomycetes and Acidobacteria metabolized O-alkyl C and di-O-alkyl C under UV-blocking conditions. In contrast, copiotrophic Actinobacteria and Chytridiomycota utilized these components under UV radiation exposure, reflecting their ability to thrive under UV stress conditions due to their rapid growth strategies in environments rich in labile C. Our study revealed that the inherent differences in the initial O-alkyl C and di-O-alkyl C contributed to the chemical divergence, while UV radiation further influenced this divergence by shifting the microbial community composition from oligotrophic to copiotrophic species. Thus, differences in the initial litter chemistry, microbial community, and UV radiation affected the quantity and quality of plant-derived C during decomposition. [ABSTRACT FROM AUTHOR]

The differences inmass loss of leaf litter are primarily thought to be driven by microbial activity, especially by fungi. However, the existence of such differences across large spatial scales has not been well explored in field studies and the underlying mechanisms of difference are still unclear, especially for the role of different fungal guilds in driving different mass losses. We conducted a 1-year decomposition study within each of four coastalwetlands inChina to test the difference inmass loss across a large spatial scale (ranging from 26° N to 41° N in latitude). In each wetland, six sites including three composed of P. australis and three composed of another dominant plant species typically in coastal ecosystems were selected. We used P. australis leaf litter as the standard decomposition material, placing it into litter bags with mesh sizes 1mm and 4 mm, respectively. Final litter mass loss was examined approximately after 3, 9 and 12months. The differentmass loss was quantified using additionalmass loss at P. australis sites compared to that at another species sites. We found that themass loss of leaf litter of P. australis showed a clear difference across multiple coastal wetlands only at later stages of decomposition, which was independent of mesofauna (mesh size) contribution to decomposition. Furthermore, the observed difference in mass loss was primarily attributed to the dissimilarities in initial soil fungal community, particularly the symbiotrophic fungi, rather than the soil bacterial community. Our results provide empirical evidence of a large-scale difference in mass loss in litter decomposition and have linked the observed difference to different soil fungal guilds. These results indicate that symbiotrophic fungi might play a direct or indirect role in driving difference inmass loss, which contributes to a better understanding and invites in-depth further investigation on the underlying microbe-driven mechanisms of the difference. [ABSTRACT FROM AUTHOR]

Background and aims: Home-field advantage (HFA) in litter decomposition occurs widely in terrestrial ecosystems, but it remains unknown that how leaf, absorptive and transport roots differ in their HFA. Here we conducted a 635-day litter transplant (leaves, absorptive roots, and transport roots) decomposition experiment, using three tree species (Cyclobalanopsis multinervis, Fagus lucida, Cryptomeria japonica), in a subtropical forest to explore their differences in HFA effects. Results: The mass loss of leaves was higher than that of absorptive and transport roots. The mass loss of fine roots differed among species. Leaves were more prone to exhibit significant HFA compared to absorptive and transport roots, and absorptive roots were more prone to exhibit significant HFA compared to transport roots. The HFA effect was not explained by the initial chemical characteristics of litter except C concentration. Conclusions: These findings suggest that HFA effect can occur in labile and recalcitrant litters and are generally not regulated by the initial chemical characteristics. Absorptive and transport roots exhibit different HFA patterns, highlighting the need to identify the effects of HFA on root decomposition by functional classification rather than diameter class to gain a better understanding of fine root decomposition. [ABSTRACT FROM AUTHOR]

Plant species affect key ecosystem processes like nutrient cycling and overall ecosystem productivity through their litter. The outcome of litter effects is largely determined by its decomposability, which directly effects soil properties. If litter remains standing or unshed (i.e. marcescent), its final decomposability can be increased by photodegradation of recalcitrant structures (like lignin). If the litter is immediately shed, its decomposability largely depends on its original nutrient content. Moreover, plant species may affect soil also through other, more direct effects. It is however unknown whether marcescent and immediately shed litters affect soil, and by that plants, differently, whether direct effects of plants on soil interact with those of marcescent and shed litters, and whether these interactions are consistent under different soil conditions.We set up a pot experiment, where we tested the effects of originally marcescent and shed litters (both added on the soil surface of the pots) on three grassland species (Bromus erectus, Filipendula vulgaris and Plantago media) in contrasting soils from long‐term stable ancient grassland and grassland restored on arable land 20 years before. We also tested how litter types and plant species affect soil chemical properties and microbial community (characterised by PLFA markers).Marcescent litter contained a lower amount of nutrients, but still increased plant biomass more than shed litter, although only for F. vulgaris (likely due to mobilisation of soil nutrients).The effect of litter on soil chemical properties and microbial community was low. These were largely affected by the plant species growing in the pot. The effect of these species on the microbial community was stronger in the undisturbed soil of ancient grasslands, while plant species affected mainly chemical properties in disturbed soil of restored grasslands. B. erectus slowed down the decomposition of both litter types in restored grassland soil.The effect of marcescent litter on living plants was significant but species‐specific and depended on soil conditions. Marcescence seems to have a stronger effect on plants in disturbed soil, which indicates its importance for recovery of the ecosystem after disturbance. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Recent studies have highlighted the crucial role of abiotic processes, such as photodegradation and microclimatic fluctuation, in accelerating dryland litter decomposition. In grasslands, substantial amounts of dead plant material persist upright above the soil surface after senescence, experiencing distinct microclimatic conditions compared to surface litter. However, our understanding of how ultraviolet (UV) exposure and microclimatic conditions influence their decomposition is limited. To address this knowledge gap, we conducted a field experiment manipulating UV radiation for both soil surface litter and standing litter and monitored their microclimatic conditions in a semi‐arid grassland. Our findings indicate that UV exposure enhanced the decomposition of soil surface litter by alleviating the constraint of lignin on litter decomposition, while having no significant influence on standing litter. Although the mean levels of thermal‐hydric conditions were lower, more intense fluctuation of temperature and air humidity was detected in standing litter. These higher‐level microclimatic fluctuations facilitated the release of dissolved organic carbon, potentially increasing the availability of labile substrates to microbes. Meanwhile, standing litter released more photo‐sensitive phenols, leading to decreased sensitivity to UV exposure. Consequently, while UV exposure initially increased standing litter decomposition during the early stage, its influence eventually diminished. These findings underscore the critical yet differing roles of microclimatic conditions and UV exposure in the decomposition of standing and surface litter. Relying solely on knowledges derived from surface litter decomposition and microclimate conditions may not accurately capture the patterns of grassland litter degradation. Plain Language Summary: The limited precipitation in drylands is widely believed to restrict litter decomposition. However, the observed litter decomposition rates in these regions often exceed model predictions based on climatic conditions. In arid and semi‐arid steppes, the sparse vegetation cover results in intense ultraviolet (UV) radiation reaching soil surface, thereby triggering photodegradation of the recalcitrant compounds in litter. Additionally, substantial dead plant materials persist standing for months to years, and undergoes more intense warm‐cold and wet‐dry cycles. However, there have been limited studies assessing the intricate interplay between UV radiation and microclimate fluctuations on litter decomposition in drylands. In this study, we found that UV radiation facilitated the degradation of recalcitrant compounds and enhanced litter degradability of soil surface litter. More intense temperature and humidity fluctuations increased the concentration of dissolved organic carbon in standing litter. This increase could provide more labile substrate to decomposers, consequently accelerating litter decomposition. Moreover, microclimatic fluctuation enhances the loss of photo‐sensitive compounds in litter, reducing litter's sensitivity to UV exposure. Our study highlighted the significant role played by the interaction between climatic conditions and UV radiation in driving litter decomposition in water‐limited steppes, contributing to a better understanding of carbon turnover in dryland ecosystem. Key Points: The degradation of soil surface litter was mainly driven by warmer and wetter microclimate and ultraviolet (UV) exposureGreater microclimatic fluctuation in standing litter enhanced the release of dissolved labile carbon, thereby accelerating its decompositionGreater microclimatic fluctuation increased the loss of photo‐sensitive compound and weakened sensitivity of standing litter to UV radiation [ABSTRACT FROM AUTHOR]

Nutrient recycling is a fundamental process for the functioning of tropical forests; however, anthropogenic activities such as mining could affect this process in tropical ecosystems. Given that little is known about the effects of mining on nutrient recycling in tropical forests, the objective was set to evaluate the influence of mining on nutrient cycling in tropical rainforests of the Colombian Pacific. Additionally, the hypothesis that nutrient cycling could be lower in post-mining areas was evaluated. To evaluate the effect of mining on nutrient cycling, permanent plots were established in mature and post-mining forests. In both forests, soil acidity, aluminum (Al), organic matter (OM), total nitrogen (N), available phosphorus (P), magnesium (Mg), potassium (K), calcium (Ca), and effective cation exchange capacity (ECEC) were considered. Likewise, the litter production, decomposition, and accumulation on the ground were determined; additionally, nutrient content and nutrient use efficiency (NUE) were determined. It was observed that mining influenced the nutrient contents of the soil in a different way. It was evident that total N and soil OM were similar in both forests, while the contents of P, K, Ca, Mg, Al, and ECEC available were higher in post-mining. The litterfall production and litter mass accumulation on the ground were greater in post-mining, while litter decomposition was greater in mature forests. In mature forests, there was higher foliar content of N, Ca, and B and, in addition, higher NUE of Ca. However, in post-mining, there was higher leaf content of K, Mg, P, Fe, Cu, Mn, and Zn and, in addition, greater NUE of N, P and K. In conclusion, an increase in post-mining nutrient cycling was noted as a strategy for nutrient conservation, and recovery of the functioning and maintenance of productivity in degraded Pacific ecosystems. Consequently, it is expected that in the future, if mining continues in the region, productivity and nutrient recycling will be altered. [ABSTRACT FROM AUTHOR]

Climate change is accelerating sea‐level rise and saltwater intrusion in coastal regions world‐wide and interacting with large‐scale changes in species composition in coastal wetlands. Quantifying macrophyte litter breakdown along freshwater‐to‐marine coastal gradients is needed to predict how carbon stores will respond to shifts in both macrophyte communities and water chemistry under changing environmental conditions.To test the interactive drivers of changing species identity and water chemistry, we performed a reciprocal transplant of four macrophyte litter species in seven sites along freshwater‐to‐marine gradients in the Florida Coastal Everglades. We measured surface water chemistry (dissolved organic carbon, total nitrogen and total phosphorus), litter chemistry (% nitrogen, % phosphorus, change in N:P molar ratio, % cellulose and % lignin as proxies for recalcitrance) and litter breakdown rates (k/degree‐day).Direct effects of salinity and surface water nutrients were the strongest drivers of k, but unexpectedly, litter chemistry did not correlate with litter k. However, salinity strongly correlated with changes in litter chemistry, whereby litter incubated in brackish and marine wetlands was more labile and gained more phosphorus compared with litter in freshwater marshes. Our results suggest that litter k in coastal wetlands is explained by species‐specific interactions among water and litter chemistries. Water nutrient availability was an important predictor of breakdown rates across species, but breakdown rates were only explained by the carbon recalcitrance of litter in the species with the slowest breakdown (Cladium jamaicense), indicating the importance of carbon structure, and species identity on breakdown rates.Synthesis. In oligotrophic ecosystems, nutrients are often the primary driver of organic matter breakdown. However, we found that variation in macrophyte breakdown rates in oligotrophic coastal wetlands was also explained by salinity and associated seawater chemistry, emphasising the need to understand how saltwater intrusion will alter organic matter processing in wetlands. Our results suggest that marine subsidies associated with sea‐level rise have the potential to accelerate leaf litter breakdown. The increase in breakdown rates could either be buffered or increase further as sea‐level rise also shifts macrophyte community composition to more or less recalcitrant species. [ABSTRACT FROM AUTHOR]

Aims: Although litter decomposition is closely linked to soil biochemical processes, the non-additive effects of litter mixing on soil C:N:P stoichiometry and the factors that regulate it have been rarely studied. Methods: In this study, an in situ foliar litter decomposition experiment examined the effects of mixtures of the foliar litter of Eucalyptus urophylla × grandis with five native tree species (Acacia crassicarpa, Castanopsis hystrix, Michelia macclurei, Magnolia sumatrana and Mytilaria laosensis) in subtropical China. We investigated the decomposition and element release dynamics of single and mixed foliar litters, their non-additive effects on soil C:N:P stoichiometry, and the potential factors regulating this non-additive effect. Results: Our results show that foliar litter mixing promoted mass loss and element release, with less mass remaining for one mixture. The magnitude of the non-additive effects of decomposing mixed foliar litter on mass remaining, element release, and soil C:N:P stoichiometry varied by litter type. Specifically, antagonistic effects were common for mass remaining (accounting for 10.0% of all cases), the release of N (16.7%) and N:P (10.0%) of mixed foliar litter, and soil C:N (13.3%). Synergistic effects were common for the release of C (23.3%), P (10.0%), C:N (23.3%), C:P (26.7%) of mixed foliar litter, and C (20.0%), N (16.7%), P (16.7%), C:P (13.3%), N:P (10.0%) of soil. Mixing the foliar litter of Eucalyptus with some species had significant synergistic effects on soil N and N:P, whereas mixing it with other species had significant antagonistic effects on soil C:P and N:P. Conclusions: Overall, foliar litter mixtures affected soil C:N:P stoichiometry in non-additive ways, and the magnitude and direction of these effects were jointly regulated by edaphic factors, initial litter chemical traits, and the presence of an invasive species, Eucalyptus. [ABSTRACT FROM AUTHOR]

The initial concentration of litter nutrient not only affects the following decomposition process but also determines the quantities of nutrients returned to the soil. The aim of this study is to assess the global patterns and driving factors of three macronutrients, namely potassium (K), calcium (Ca) and magnesium (Mg), in freshly fallen litter.By synthesizing 5861 data points extracted from 584 publications, we quantitatively evaluated the concentrations of litter K, Ca and Mg in different litter types, life forms, taxonomic divisions and mycorrhizal associations. Also, using the machine learning method, we predicted their global patterns in forests, grasslands and shrublands.We found that (1) mean K, Ca and Mg concentrations ranged from 2.63 to 6.23, 1.05 to 11.50 and 0.20 to 2.74 g/kg, respectively, across different litter types; (2) the initial nutrients of the litter were significantly affected by plant functional types (e.g. life form, taxonomic division and mycorrhizal association), climate (e.g. isothermality, mean diurnal range, annual evapotranspiration and precipitation seasonality) and soil properties (e.g. pH, exchangeable Ca concentration and water content), with a higher litter K concentration of herbaceous plants, higher K, Ca and Mg concentrations from angiosperms and higher K and Mg concentrations from plants associated with arbuscular mycorrhiza (AM) fungi; and (3) the predicted leaf litter K, Ca and Mg concentrations were lower in high‐latitude regions compared with those in low‐ and/or mid‐latitude regions.Our study provides a globally comprehensive analysis on the patterns and driving factors of three important macronutrients in freshly fallen litter, contributing to a better understanding of their role in the decomposition process of litter, as well as the associated biogeochemical cycles under the future climate change scenario. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The decomposition of allochthonous dead organic matter is a key process for the metabolism and functioning of stream and spring ecosystems. The litter breakdown process is influenced by several abiotic and biotic factors. Among abiotic parameters, the role of current velocity and physical abrasion was poorly investigated. Field studies gave contrasting results, mainly because of the covariation and the interaction of current velocity with other biotic/abiotic variables. For these reasons, we assessed leaf‐litter breakdown and the structure of crenic assemblages in two nearby reaches (erosional vs. depositional) of a physicochemically stable rheocrene spring. The two zones investigated were characterized by similar environmental conditions, but water current velocity was about four times greater in the erosional reach. We found substantial differences in the structure and functional organization of crenic assemblages. Overall taxa richness and density were higher in the depositional reach, while diversity and abundance of Ephemeroptera, Plecoptera and Trichoptera were taller in the erosional zone. Shredders were more abundant in the erosional zone, and scrapers were more represented in the slow current sector of the spring. We also demonstrated that water flow may promote a faster decomposition of leaf detritus in the spring erosional reach mainly through indirect effects: higher richness and abundance of shredder detritivores. Our results indicate that water current velocity may have a key role in affecting both spring assemblage composition and ecosystem processes. [ABSTRACT FROM AUTHOR]

Invasive plants have been shown to alter ecosystem functions. However, there is limited information available on the effect of the invasive species litter input on native litter decomposition and home-field advantage (HFA, increased decomposition at a home environment compared to a guest environment). To investigate this, we conducted a field experiment using leaves of native Trapa natans and Typha orientalis with and without invasive species Alternanthera philoxeroides and then incubated them at T. natans and T. orientalis habitats in a eutrophic lake for 50 days. In control and treatment, the decomposition and N release rate of T. natans were significantly higher than that in T. orientalis species litter at two habitats, indicating no HFA occurrence. A. philoxeroides litter input promoted the decomposition and N decay rate of T. orientalis, not T. natans. The mean decomposition rate of T. orientalis in control and treatment were 0.0138 and 0.0342 day−1; for T. natans, it was 0.0703 and 0.0754 day−1, respectively. The mean N decay rate of T. orientalis in control and treatment were 0.0235 and 0.0468 day−1; for T. natans, it was 0.0511 and 0.0544 day−1, respectively. Invasive species presence increased microbial respiration rate of T. orientalis, but not for T. natans species litter in two habitats. These results suggested that A. philoxeroides litter input accelerated low quality litter decomposition though increased microbial activity. However, it did not influence the HFA performance, which may be closely related to the lake eutrophication. [ABSTRACT FROM AUTHOR]

Forests worldwide are experiencing fragmentation, with especially important consequences for ecosystems bordering urbanized areas. Urban forests are exposed to local warming due to the urban heat island which affects their biodiversity and ecosystem functioning. A key ecosystem function affecting carbon and nutrient cycling in forests is litter decomposition, a process driven by the local microclimate. Thus, our aim was to clarify the impact of the urban heat island on litter decomposition in urban forests. We studied soil microclimate and litter decomposition in six urban forests across Europe and along local gradients from the urban forest edge to the interior. To quantify decomposition independent from local forest composition and litter quality, we used standardized green tea and rooibos tea litterbags. We determined the role of the soil microclimate and other environmental drivers for litter decomposition. Secondly, we assessed effects of edge proximity and landscape context on the soil microclimate. Soil characteristics were only driving green tea and not rooibos tea decomposition. On the contrary, higher soil temperatures resulted in faster rates of litter decomposition for both green and rooibos tea and were related to the proximity to the forest edge and the proportion of built-up area in the landscape. Via structural equation modelling we detected cascading effects of the urban heat island on litter decomposition. Such changes in litter decomposition have the potential to alter the soil food web, nutrient cycling and carbon drawdown in urban forests, and could result in significant interactions between urbanisation and ongoing climate change. [ABSTRACT FROM AUTHOR]

Litter decomposition is significantly influenced by soil fauna, litter quality, and climate. Effects of soil fauna on litter decomposition are largely dependent on the size classes of the fauna. However, the understanding of how different soil fauna groups affect litter decomposition remains elusive. In this study, we conducted a global meta-analysis of experiments using litterbags with varying mesh sizes to quantify the contributions of mesofauna and macrofauna to litter decomposition by calculating log response ratios. Additionally, we quantitatively assessed how climatic conditions and litter quality influence the effect of these two faunal size classes on litter decomposition. Our findings demonstrated that mesofauna and macrofauna increased litter decomposition by an average of 12.25% and 22.14%, respectively. Furthermore, the relative increase in litter decomposition induced by mesofauna and macrofauna exhibited a significant statistical difference on a global scale. Specifically, in dry and temperate climatics, the effect of soil macrofauna on litter decomposition was significantly greater than that of mesofauna. Climatic conditions, particularly temperature and precipitation, were the primary factors influencing litter decomposition by both mesofauna and macrofauna. In contrast, litter quality significantly influenced decomposition only by macrofauna in dry and tropical climatic conditions. Our findings underscore that the relative increase in litter decomposition rates to mesofauna and macrofauna differed significantly on a global scale and that the climate and litter quality differentially regulate litter decomposition across faunal size classes.

Litter decomposition is expected to be positively associated with precipitation despite evidence that decomposers of varying sizes have different moisture dependencies. We hypothesized that higher tolerance of macro-decomposers to aridity may counterbalance the effect of smaller decomposers, leading to similar decomposition rates across climatic gradients. We tested this hypothesis by placing plant litter baskets of different mesh sizes in seven sites along a sharp precipitation gradient, and by characterizing the macro-decomposer assemblages using pitfall trapping. We found that decomposers responded differently to precipitation levels based on their size. Microbial decomposition increased with precipitation in the winter while macro-decomposition peaked in arid sites during the summer. This led to similar overall decomposition rates across the gradient except in hyper-arid sites. Macro-decomposer richness, abundance, and biomass peaked in arid environments. Our findings highlight the importance of macro-decomposition in arid-lands, possibly resolving the dryland decomposition conundrum, and emphasizing the need to contemplate decomposer size when investigating zoogeochemical processes.

Soil fauna, key indicators of grassland ecosystem health, face significant threats from the vast amounts of chemical pollutants released by human activities. These organisms are crucial for fundamental processes such as litter decomposition and carbon cycling. However, the response of soil animal communities and their functional dynamics to environmental chemical stress remains poorly understood. To investigate this, we conducted a naphthalene addition and litterbag experiment in the Bashang Grassland, located on the southern Inner Mongolia Plateau, to analyze its effects on soil fauna and litter decomposition. The investigated soil fauna groups included Arachnida (Arachnids), Insecta (Insects), Collembola (Springtails), Enoplea (enopleans), and Chromadorea (chromadoreans). The litter composition included Leymus chinensis, Stipa krylovii, Artemisia, Saussurea amara, and Artemisia giraldii. The findings indicated that a high diversity of soil fauna enhanced the decomposition of litter and the release of organic carbon from the litter. While the addition of naphthalene decreased both the abundance of soil fauna and the rate of litter decomposition, it specifically increased the relative proportion of Collembola (Springtails). Microfauna and mesofauna (0.1–2.0 mm) contributed more to the loss of litter mass and the release of organic carbon from the litter than macrofauna (2.0–4.0 mm). The effects of diverse soil fauna on litter decomposition and soil organic carbon accumulation were diminished by naphthalene exposure. This study further reveals the relationship between composite soil fauna diversity, litter decomposition, and soil organic carbon under chemical stress, highlighting the threat of environmental pollution to ecosystem health. It also enriches our understanding of the complexity of grassland ecosystems, especially in response mechanisms under chemical pollution stress.

Abstract Background The prevalence of understory removal and anthropogenic nitrogen (N) deposition has significantly altered the ecological processes of forest ecosystems at both regional and global scales. However, it remains a pressing challenge to understand how N deposition and understory removal affect leaf nutrient dynamics, nutrient resorption, litter decomposition, and their linkages for better managing forest ecosystems under nutrient imbalances induced by N enrichment. To address this research gap, a field manipulation experiment was carried out in a subtropical Cunninghamia lanceolata plantation with four treatments including: control (CK), canopy N addition (CN), understory removal (UR), and canopy N addition plus understory removal (CN × UR). Green and senesced leaf N and phosphorus (P) concentrations, N and P resorption efficiencies, litter decomposition, and their correlations were measured. Results The results revealed that the average N concentrations of green early and late leaves in UR were increased by 6.61 and 18.89% compared to CK. UR had the highest whereas CN had the lowest P concentrations in green leaves across the two sampling seasons. Following this, UR, leaf type, season, and their interactions significantly affected leaf N, P, and N:P (P

Agricultural practices that promote the formation of soil organic matter (SOM) are considered important climate change mitigation strategies by increasing resilience to climate shocks and promoting soil carbon sequestration. Efforts to increase root production and depth distribution through planting deep rooted crops and selective crop breeding have been identified as a promising strategy to achieve these goals. However, we lack a complete understanding of how the decomposition of roots in the deep soil (e.g., below 30 cm), contributes to SOM formation and stabilization. Here using unique soil-biomass microcosms in the field to trace 13C enriched root litter to a depth of 90 cm, we show that as decomposition dynamics change with depth, so do the SOM formation pathways. At our study site, root residues decomposed faster in the top 0–30 cm, achieving 97 % mass loss by 13 months of incubation compared to 77 % and 81 % in the 30–60 and 60–90 cm depths, respectively. Litter derived carbon (LDC) was preferentially recovered as stable mineral associated organic matter (MAOM), primarily within aggregates, with 67 % more in the 0–30 cm than in the 60–90 cm depth. At depth, root residues decomposed slower and accumulated as the less stable particulate organic matter (POM) within macroaggregates with 145 % more LDC recovered in light POM in the 60–90 cm depth than the 0–30 cm depth. We found that bulk SOM measurements were too coarse to elucidate the likely fate of newly incorporated litter in the soil, but our detailed fractionation demonstrated the relative contribution of new root inputs to functionally different SOM pools, MAOM and POM, and allowed us to interpret the role of microaggregates in these dynamics in new detail, particularly microaggregates within macroaggregates (i.e., occluded microaggregates). Our results highlight the importance of balancing the trade-off between MAOM and POM formation when considering strategies to enhance both carbon sequestration and soil health in agroecosystems. If POM is critical for aggregate formation and microaggregates play an important role in MAOM formation, efforts to increase soil carbon sequestration need to focus on both fractions and on supporting overall soil structure.