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Litter decomposition is a fundamental ecosystem process controlling the biogeochemical cycling of energy and nutrients. Using a 360-day lab incubation experiment to control for environmental factors, we tested how litter quality (low C/N deciduous vs. high C/N coniferous litter) governed the assembly and taxonomic composition of bacterial communities and rates of litter decomposition. Overall, litter mass loss was significantly faster in soils amended with deciduous (DL) rather than coniferous (CL) litter. Communities degrading DL were also more taxonomically diverse and exhibited stochastic assembly throughout the experiment. By contrast, alpha-diversity rapidly declined in communities exposed to CL. Strong environmental selection and competitive biological interactions induced by molecularly complex, nutrient poor CL were reflected in a transition from stochastic to deterministic assembly after 180 days. Constraining how the diversity and assembly of microbial populations modulates core ecosystem processes, such as litter decomposition, will become increasingly important under novel climate conditions, and as policymakers and land managers emphasize soil carbon sequestration as a key natural climate solution. [ABSTRACT FROM AUTHOR]

Plant litter is not only the major component of terrestrial ecosystem net productivity, the decomposition of which is also an important process for the returns of elements, including sodium (Na) and aluminum (Al), which can be beneficial or toxic for plant growth. However, to date, the global characteristics and driving factors of Na and Al concentrations in freshly fallen litter still remain elusive. Here, we evaluated the concentrations and drivers of litter Na and Al with 491 observations extracted from 116 publications across the globe. Results showed that (1) the average concentrations of Na in leaf, branch, root, stem, bark, and reproductive tissue (flowers and fruits) litter were 0.989, 0.891, 1.820, 0.500, 1.390, and 0.500 g/kg, respectively, and the concentrations of Al in leaf, branch, and root were 0.424, 0.200 and 1.540 g/kg, respectively. (2) mycorrhizal association significantly affected litter Na and Al concentration. The highest concentration of Na was found in litter from trees associated with both arbuscular mycorrhizal fungi (AM) and ectomycorrhizal fungi (ECM), followed by litter from trees with AM and ECM. Lifeform, taxonomic, and leaf form had significant impacts on the concentration of Na and Al in plant litter of different tissues. (3) leaf litter Na concentration was mainly driven by mycorrhizal association, leaf form and soil phosphorus concentration, while leaf litter Al concentration was mainly controlled by mycorrhizal association, leaf form, and precipitation in the wettest month. Overall, our study clearly assessed the global patterns and influencing factors of litter Na and Al concentrations, which may help us to better understand their roles in the associated biogeochemical cycles in forest ecosystem. [ABSTRACT FROM AUTHOR]

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

Litters of leaves and roots of different qualities occur naturally above‐ and below‐ground, respectively, where they decompose in contrasting abiotic and biotic environments. Therefore, ecosystem carbon (C) and nitrogen (N) dynamics can be strongly affected by the combination of litter position and quality. However, it is poorly understood how C versus N turnover of litters depend on the interplay among plant functional type (PFT), organs, traits and litter position.In a semi‐arid inland dune, soil surface and buried leaf litters and buried fine roots of 25 species across three PFTs (herbs, legume shrubs and nonlegume shrubs) were incubated for 3, 6, 9, 12, 18 and 24 months to investigate litter decomposition and C and N dynamics. Morphological and chemical (nutrient and NMR carbon) traits of initial litters of leaves and fine roots were determined.The litter decomposition rates (k values) of surface leaves and buried fine roots did not differ, but buried fine roots and buried leaf litter decomposed faster than surface leaf litter. Ratios of k values of surface leaves to buried leaves decreased with leaf C:N ratio. Herbs and legume shrubs decomposed faster than nonlegume shrubs for buried fine roots, but not for leaves. At given C loss, buried fine roots had higher N loss than leaf litters; legume shrubs with relatively higher N or lower C:N ratio had higher N loss than nonlegume shrubs. Stronger positive relationships between C and N losses were shown in leaves and legume shrubs than in fine roots and nonlegume shrubs respectively.Synthesis. The generality of faster N release of legume litters at given C release highlights the importance of legumes in N cycling in semi‐arid ecosystems where N is the limiting factor. The dynamics and coordination of C versus N release as a function of litter quality are modulated by litter position and PFT. These findings have important implications for the development of process‐based models on C and N cycles in the context of on‐going global change potentially altering the functional composition of plant communities and the relative quantities and qualities of above‐ground versus below‐ground litter. [ABSTRACT FROM AUTHOR]

Plant leaf litter decomposition provides a source of energy and nutrients in forest ecosystems. In addition to traditional environmental factors, the degradation process of litter is also affected by plant functional traits and litter quality. However, at the community level, it is still unclear whether the relative importance of plant traits and litter quality on the litter decomposition rate is consistent. A year-long mixed leaf litter decomposition experiment in a similar environment was implemented by using the litterbag method in seven typical forest types in Dongling Mountain, Beijing, North China, including six monodominant communities dominated by Juglans mandshurica , Populus cathayana , Betula dahurica , Betula platyphylla , Pinus tabuliformis and Larix gmelinii var. principis-rupprechtii and one codominant community dominated by Fraxinus rhynchophylla , Quercus mongolica and Tilia mongolica. The results showed that there were considerable differences in the litter decomposition rate (k -rate) among the different forest types. The community weighted mean (CWM) traits of green leaves and litter quality explained 35.60% and 9.05% of the k -rate variations, respectively, and the interpretation rate of their interaction was 23.37%, indicating that the CWM traits and their interaction with litter quality are the main factors affecting the k-rate variations. In the recommended daily allowance, leaf nitrogen content, leaf dry matter content, leaf tannin content and specific leaf area were the main factors affecting the k -rate variations. Therefore, we suggest that future studies should focus on the effects of the CWM traits of green leaves on litter decomposition at the community level. [ABSTRACT FROM AUTHOR]

The variation within and across species has afterlife effects on carbon and nutrient cycling through the alteration of litter decomposability. However, the focus on leaves may not reflect a whole-plant economic spectrum of strategies. Here, we assessed the patterns and predictors of flower and leaf-litter decomposition at the intra- (i.e., flowers and leaves of the same species) and inter-specific (i.e., flowers and leaves from different species) levels for 29 tropical woody species in northeast Brazil. We evaluated nine functional litter traits, including structural and chemical traits. Flower litter decomposed, on average, three times faster than leaf litter (11.9% and 39.4% mass remaining, respectively) and exhibited higher water-holding capacity (WHC), leaching (LEA), and N, P, and K content. Otherwise, leaf litter showed higher density (DEN) and Ca, Mg, and Na content. The average relative differences in decomposition rate and functional traits between flower and leaf litter did not differ at both intra- and inter-specific levels. The predictors of decomposition were mostly similar, explaining 39% and 37% of flower and leaf litter, respectively. Leaching, P, Ca, Mg, and Na predict both flower and leaf-litter decomposition. However, WHC exclusively predicted flower-litter decomposition, and DEN, N, and K exclusively predicted leaf-litter decomposition. The observed differences in decomposition rate and functional traits between flower and leaf litter indicate that the afterlife effects differ between these plant organs and leverage the role of flower litter and its secondary consequences to nutrient and carbon cycling on ecosystems. [ABSTRACT FROM AUTHOR]

Litter decomposition contributes largely to global carbon (C) and nitrogen (N) cycling, and it is strongly determined by litter quality and microbial community composition in ways that are poorly understood.Here, we conducted a 2‐year field litter decomposition experiment by collecting leaf and root litter of crops (from cropland), shrubs (from shrubland) and wood (from woodland) and placing samples for decomposition in woodland soil in central China to investigate the effects of litter quality and microbial community composition on C and N losses of leaf and root litter of three species under different decomposition stages.Our results showed that the leaf litter C and N losses of shrubs were significantly higher than those of crops and wood, whereas the root litter C and N losses of crops were significantly higher than those of shrubs and wood. Generally, the leaf litter C and N losses of the three species were higher on average than those of fine root litter during the whole decomposition period. For the C loss of the three species, litter lignin and phosphorus as well as initial litter quality were predominant drivers of root litter decomposition, while litter lignin, cellulose and hemicellulose concentrations were dominant for leaf litter decomposition.For N loss, litter stoichiometry and litter quality directly governed leaf and root litter N loss, and the initial litter quality largely regulated N loss at the late decomposition stage. Unexpectedly, the effect of microbial community composition on litter C and N losses was relatively weak and only exhibited an effect on litter C and N losses during the early stage of decomposition.Thus, our results revealed the huge disparity in C and N loss of plant species and litter types at different decomposition stages, which should be considered jointly when evaluating their roles in plant–soil feedbacks under global land use change. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Aims: Changes caused by single herbivore species grazing to soil and plant interfaces can significantly affect the leaf litter decomposition rates within ecosystems. However, we intended to study how grazing by multiple herbivore species regulate the litter decomposition process and associated soil or plant properties in Leymus chinensis dominant meadow steppe. Methods: Two consecutive randomized field experiments were conducted between May 2017 and May 2019: 1) a grazing experiment with four (control or no, sheep, cattle, and mixed (sheep + cattle)) grazing treatments to explore the effects of moderate grazing on soil properties and L. chinensis litter quality and 2) the litter decomposition experiment to evaluate the decay rate in grazed or non-grazed litter by using litter bag technique. Results: Litter decay rate was the highest in mixed grazed litter as compared to litter grazed by individual herbivore species. Both herbivore grazing and incubation time affected decay rate of L. chinensis litter by modifying soil moisture and nitrogen (N) content, as well as, litter N and lignin contents. Plant litter quality has been displayed to be a dominant regulator of litter decay rate than soil physical or chemical properties in mixed grazed litter. Conclusions: Livestock diversification benefited litter decomposition indirectly by modifying plant litter quality with time. Therefore, herbivore assemblages should be given more importance in future research on litter decomposition process to mediate nutrient cycling in grassland. [ABSTRACT FROM AUTHOR]

The conversion of riparian vegetation into monocultures alters the input of allochthonous energy and the heterotrophy of streams. Here, we aimed to assess the implication of leaf litter inputs from plant species of agricultural importance on decomposition in Amazonian streams. We hypothesized that decomposition is low in litter with high concentrations of lignin and cellulose, regardless of the origin of plant species (exotic or native). We incubated leaf litter from plant species of agricultural importance, such as cocoa (native) and oil palm (exotic), as a control, leaf litter of Hymenaea courbaril (native) in four streams for 60 days. Contrary to our initial expectations, the leaf litter from oil palm, which was of higher quality and had lower concentrations of structuring compounds (lignin and cellulose), did not differ in decomposition rates from the lower quality leaf litter of the control species, which presented higher concentrations of structuring compounds. We recorded higher decomposition rate in cocoa, which had intermediate concentrations of structural compounds. Our results indicate a negative effect of the conversion of riparian vegetation into oil palm monocultures (Elaeis guineensis) for the processing of organic matter in Amazonian streams, due to the slower decomposition rate of the leaf litter of this species. [ABSTRACT FROM AUTHOR]

Phenolic compounds in plant litter influence decomposition process both directly by their own degree of decomposability and indirectly by affecting decomposer processes. While phenolic characteristics of aboveground plant biomass are well-known, the fate of litter phenolics and their regulatory effects on belowground decomposition remain unclear. We conducted a two-year decomposition experiment distributing litterbags of spruce, pine, and bilberry along a gradient from mesic spruce-dominated to xeric pine-dominated forests. Litter material was analysed for mass loss, low molecular weight phenolic compounds, condensed tannins, fungal biomass, and fungal community composition (using DNA metabarcoding). Bilberry litter initially decayed more rapidly than the conifer litter, but the remaining mass of bilberry litter was the same as for pine and higher than that of spruce litter after two years. The concentration and composition of phenolic compounds decreased with time, with mainly MeOH-insoluble condensed tannins remaining at the end of the experiment. Correspondingly, fungal biomass increased in the first year, while all litter types underwent rapid changes in fungal community composition. The species-specific pattern of temporal change in mass loss, as well as in the synchronic shift in composition of phenolic compounds and fungal community, give new insights in the importance of litter quality for the decomposition process. [ABSTRACT FROM AUTHOR]

The feedback between plant, soil and climate is partly determined by plant litter turnover time, which is influenced by climate, litter quality and soil properties. However, the spatial patterns of litter turnover time and its interrelation with these variables are rarely quantified. With a database of 1,378 litter turnover times and key associated climate, litter quality and soil properties (total of 20 variables), this study investigated the driving factors and spatial patterns of litter turnover time across Chinese terrestrial ecosystems. The mean litter turnover time was the longest in forest ecosystems, followed by that in grassland and cropland ecosystems. The litter turnover time varied significantly depending on the litter quality and climate zone, and increased exponentially as latitude increased. Mean annual temperature (MAT) and mean annual precipitation (MAP) could accurately predict litter turnover time via negative exponential equations. Among these variables, MAT had the greatest influence on litter turnover time, which accounted for 37.4% of the variation, followed by litter quality (ecosystem types, litter types, C:N of litter and lignin content; 33.4%) and soil properties (sand content, soil pH and soil organic carbon (SOC); 29.2%) based on a boosted regression tree (BRT) model. Path analysis identified that MAT negatively affected litter turnover time both directly and indirectly through regulating soil properties and litter quality, which positively and directly affected litter turnover time. Finally, the spatial patterns of litter turnover time were obtained with a regional dataset of ecosystem types, MAT, sand content, soil pH and SOC as BRT model drivers. Overall, our results suggest that climate variables have contrasting effects on litter turnover time and could mediate the impact on litter turnover time by litter quality and soil properties. These results highlight important implications for climate‐smart soil management and can be used to create reliable model predictions. Highlights: We explored the driving factors and spatial patterns of litter turnover time in various ecosystemsAccurate estimates of litter turnover time were obtained from dataset from 1,378 experimental sitesLitter turnover time exponentially increased as latitude increasedClimate‐mediated litter quality and soil properties controlled the litter turnover time [ABSTRACT FROM AUTHOR]

Aims: Mycorrhizal type has been proposed as an effective trait integrator capturing varying biogeochemical syndromes in terrestrial ecosystems. However, for boreal peatlands, it is still unclear whether mycorrhizal associations of vascular plants can indicate leaf nutrient resorption patterns and litter decomposition rates. Methods: We determined leaf nitrogen (N) and phosphorus (P) resorption efficiency and proficiency of 11 common vascular plants belonging to three mycorrhizal types (ectomycorrhizal, ECM; ericoid mycorrhizal, ERM; and non-mycorrhizal, NM) in boreal peatlands of Northeast China, and measured leaf litter mass loss and N remaining of these 11 species after one and 3 years of decomposition using the litterbag method. Results: Leaf nutrient resorption and litter decomposition rates varied significantly among the three mycorrhizal types. Specifically, ECM plants had greater green leaf nutrient (N and P) concentrations and lower leaf nutrient resorption efficiency and proficiency than ERM and NM plants. Moreover, ECM plants had higher leaf litter mass loss and lower N remaining than ERM and NM plants after one and 3 years of decomposition, respetively. In addition, both leaf litter mass loss and N remaining significantly correlated with N and P resorption efficiency and proficiency, indicating that plant nutrient resorption and litter decomposition were coupled. Conclusions: These results suggest that leaf nutrient resorption and litter decomposition are tightly linked to the mycorrhizal associations of vascular plants, and highlight that mycorrhizal type can be applied to explain and predict the dynamics of plant-mediated carbon and nutrient cycles in boreal peatlands. [ABSTRACT FROM AUTHOR]

Ecological shifts that enhance the efficiency of resource acquisition by consumers can affect the fate of resource subsidies in recipient ecosystems. To date, findings have been mixed about whether plant litter breakdown by stream decomposers is faster in locations where the litter originates from (i.e. home region) compared with other locations (away region). This phenomenon, known as home‐field advantage (HFA), may be influenced by litter quality and particularly decomposer groups (shredders versus microbes), rather than being an inherent consequence of the breakdown of locally native litter.We studied the effects of HFA on litter breakdown and litter‐associated communities in streams within mid‐ to late‐successional forests. Two pairs of riparian broadleaf and one pair of conifer litter species with contrasting chemical quality were reciprocally incubated across two temperate regions (˜3,000 km apart). Species in each pair are congeneric and allopatric. The HFA was assessed using within‐pair litter comparisons in home and away regions. Coarse‐ and fine‐mesh litterbags were used to separate the contributions to litter breakdown by microbial decomposition and shredder feeding.Conifer litter species used in this study were more recalcitrant than broadleaf litter species. Consequently, there was a significant positive HFA for the microbial decomposition of conifer litter. In contrast, there was no HFA for either microbial or shredder‐mediated breakdown of broadleaf litter, which might have been overridden by catchment‐scale differences in biophysical variables affecting breakdown. The effects of HFA on shredder colonisation and feeding on broadleaf litter were more variable among streams. Numerically abundant shredder taxa tended to have higher rates of colonisation and consumption on higher‐quality litter than on low‐quality litter, irrespective of litter origin.Our results suggest that prior (evolutionary and/or contemporary) litter exposure could strongly influence the litter‐processing capacity of microbial decomposers, but not shredders, at the community level. In particular, microbial decomposers specialised in degrading conifer litter probably had lower resource‐use plasticity than those processing broadleaf litter. Inter‐stream differences in riparian vegetation and habitat conditions could influence the HFA through altering the litter exposure history of decomposer communities. Our findings highlight the importance of prior litter–microbe interactions in determining the rates of microbial decomposition of native and exotic litter species. [ABSTRACT FROM AUTHOR]

Background: Soil aggregate-size classes, structural units of soil, are the important factors regulating soil organic carbon (SOC) turnover. However, the processes of litter C mineralization and storage in different aggregates-size classes are poorly understood, especially in the highly alkaline soils of north China. Here, we ask how four different aggregate sizes influence rates of C release (Cr) and SOC storage (Cs) in response to three types of plant litter added to an un-grazed natural grassland. Methods: Highly alkaline soil samples were separated into four dry aggregate classes of different sizes (2–4, 1–2, 0.25–1, and <0.25 mm). Three types of dry dead plant litter (leaf, stem, and all standing dead aboveground litter) of Leymus chinensis were added to each of the four aggregate class samples. Litter mass loss rate, Cr, and Cs were measured periodically during the 56-day incubation. Results: The results showed that the mass loss in 1–2 mm aggregates was significantly greater than that in other size classes of soil aggregates on both day 28 and day 56. Macro-aggregates (1–2 mm) had the highest Cr of all treatments, whereas 0.25–1 mm aggregates had the lowest. In addition, a significant negative relationship was found between Cs/Cr and soil pH. After incubation for 28 and 56 days, the Cs was also highest in the 1–2 mm aggregates, which implied that the macro-aggregates had not only a higher CO2 release capacity, but also a greater litter C storage capacity than the micro-aggregates in the highly alkaline soils of north China. [ABSTRACT FROM AUTHOR]

Plant litter decomposition in forested soil and watershed is an important source of phosphorus (P) for plants in forest ecosystems. Understanding P dynamics during litter decomposition in forested aquatic and terrestrial ecosystems will be of great importance for better understanding nutrient cycling across forest landscape. However, despite massive studies addressing litter decomposition have been carried out, generalizations across aquatic and terrestrial ecosystems regarding the temporal dynamics of P loss during litter decomposition remain elusive. We conducted a two-year field experiment using litterbag method in both aquatic (streams and riparian zones) and terrestrial (forest floors) ecosystems in an alpine forest on the eastern Tibetan Plateau. By using multigroup comparisons of structural equation modeling (SEM) method with different litter mass-loss intervals, we explicitly assessed the direct and indirect effects of several biotic and abiotic drivers on P loss across different decomposition stages. The results suggested that (1) P concentration in decomposing litter showed similar patterns of early increase and later decrease across different species and ecosystems types; (2) P loss shared a common hierarchy of drivers across different ecosystems types, with litter chemical dynamics mainly having direct effects but environment and initial litter quality having both direct and indirect effects; (3) when assessing at the temporal scale, the effects of initial litter quality appeared to increase in late decomposition stages, while litter chemical dynamics showed consistent significant effects almost in all decomposition stages across aquatic and terrestrial ecosystems; (4) microbial diversity showed significant effects on P loss, but its effects were lower compared with other drivers. Our results highlight the importance of including spatiotemporal variations and indicate the possibility of integrating aquatic and terrestrial decomposition into a common framework for future construction of models that account for the temporal dynamics of P in decomposing litter. [ABSTRACT FROM AUTHOR]

Mineral-associated organic matter (MAOM) is a key component of the global carbon (C) and nitrogen (N) cycles, but the processes controlling its formation from plant litter are not well understood. Recent evidence suggests that more MAOM will form from higher quality litters (e.g., those with lower C/N ratios and lower lignocellulose indices), than lower quality litters. Shoots and roots of the same non-woody plant can provide good examples of high and low quality litters, respectively, yet previous work tends to show a majority of soil organic matter is root-derived. We investigated the effect of litter quality on MAOM formation from shoots versus roots using a litter-soil slurry incubation of isotopically labeled (13C and 15N) shoots or roots of Big Bluestem (Andropogon gerardii) with isolated silt or clay soil fractions. The slurry method minimized the influence of soil structure and maximized contact between plant material and soil. We tracked the contribution of shoot- and root-derived C and N to newly formed MAOM over 60 days. We found that shoots contributed more C and N to MAOM than roots. The formation of shoot-derived MAOM was also more efficient, meaning that less CO2 was respired per unit MAOM formed. We suggest that these results are driven by initial differences in litter chemistry between the shoot and root material, while results of studies showing a majority of soil organic matter is root-derived may be driven by alternate mechanisms, such as proximity of roots to mineral surfaces, greater contribution of roots to aggregate formation, and root exudation. Across all treatments, newly formed MAOM had a low C/N ratio compared to the parent plant material, which supports the idea that microbial processing of litter is a key pathway of MAOM formation. [ABSTRACT FROM AUTHOR]

Plant contributions to the nitrogen (N) cycle from decomposition are likely to be altered by vegetation shifts associated with climate change. Roots account for the majority of soil organic matter input from vegetation, but little is known about differences between vegetation types in their root contributions to nutrient cycling. Here, we examine the potential contribution of fine roots to the N cycle in forest and tundra to gain insight into belowground consequences of the widely observed increase in woody vegetation that accompanies climate change in the Arctic. We combined measurements of root production from minirhizotron images with tissue analysis of roots from differing root diameter and color classes to obtain potential N input following decomposition. In addition, we tested for changes in N concentration of roots during early stages of decomposition, and investigated whether vegetation type (forest or tundra) affected changes in tissue N concentration during decomposition. For completeness, we also present respective measurements of leaves. The potential N input from roots was twofold greater in forest than in tundra, mainly due to greater root production in forest. Potential N input varied with root diameter and color, but this variation tended to be similar in forest and tundra. As for roots, the potential N input from leaves was significantly greater in forest than in tundra. Vegetation type had no effect on changes in root or leaf N concentration after 1 year of decomposition. Our results suggest that shifts in vegetation that accompany climate change in the Arctic will likely increase plant-associated potential N input both belowground and aboveground. In contrast, shifts in vegetation might not alter changes in tissue N concentration during early stages of decomposition. Overall, differences between forest and tundra in potential contribution of decomposing roots to the N cycle reinforce differences between habitats that occur for leaves. [ABSTRACT FROM AUTHOR]

Despite the essential role of litter decomposition in carbon (C) and nutrient cycle in terrestrial ecosystems, some uncertainties remain about how this fundamental process is affected by increasing nitrogen (N) deposition. Based on a large dataset comprising 1108 observations from 162 studies, we conducted a meta-analysis to explore the effect of N addition on litter decomposition rate under three kinds of litter decomposition experiments (i.e., common litter experiment (litter collected from control plot is decomposed in N addition plots); common site experiment (litter collected from N addition plots is decomposed in control plot); in situ experiment (litter collected from control and N addition plots is decomposed in situ)). In general, N addition significantly decreased litter decomposition rate by 2.3% across the three kinds of litter decomposition experiments. However, litter decomposition rate responded differently to N addition among different kinds of litter decomposition experiments. N addition significantly decreased litter decomposition rate by 5.1% in common litter experiment. In contrast, N addition significantly increased litter decomposition rate by 9.2% and 10.3% in common site and in situ experiments, respectively. The response of litter decomposition rate to N addition was positively correlated with initial N and phosphorous (P) concentrations, but negatively correlated with initial C:N and lignin:N ratios of plant litter in common litter experiment. For common site and in situ experiments, the N-induced increase in litter decomposition rate was attributed to the increased N and P concentrations and decreased C:N and lignin: N ratios of plant litter under N addition. Collectively, our results suggest that common litter experiment might underestimate the positive effect of N addition on litter decomposition. By contrast, the overall stimulatory effect of N addition on litter decomposition rate under in situ experiment should be more realistic, and its adoption could improve the prediction of ecosystem consequences of increased anthropogenic N deposition. N addition decreased litter decomposition rate in common litter experiment (litter collected from control plot is decomposed in N addition plots), but increased it in common site (litter collected from N addition plots is all decomposed in control plot) and in situ experiment (litter collected from control and N addition plots is decomposed in situ). Thus, studies only considered how N addition affect litter decomposition rate via its effect on soil environment or microbial properties (common litter experiment), or synthesis studies which mixed different kinds of litter decomposition experiments together might all underestimate the promoting effect of N addition on litter decomposition. Increased litter decomposition rate under in situ experiment could be partially explained by the positive effects of improved litter quality exceeding the negative effect of inhibited microbial activity. Our results could help to improve the prediction of ecosystem consequences of increased anthropogenic N deposition. [Display omitted] • N addition decreased litter decomposition rate in common litter experiment. • N addition enhanced litter decomposition in common site and in situ experiments. • The increased decomposition rate was associated with the improved litter quality. • Common litter experiment underestimated the positive effect of N addition. [ABSTRACT FROM AUTHOR]

Aims: Moso bamboo ( Phyllostachys pubescens) is a typical native invasive plant imposing serious threats on ecosystem processes and functions. A primary concern is alterations of litter and soil N mineralization in evergreen broadleaved forests coupled with bamboo population expansion. Methods: We conducted a field study to determine the litter production, quality, N resorption efficiency, and soil N mineralization rates in bamboo-dominated forest (BDF) and adjacent uninvaded evergreen broadleaved forest (EBF) in subtropical China. Results: The mean annual litter production for BDF was 5.82 Mg ha, 36.0 % lower than that for EBF (9.09 Mg ha). Litter N concentration was also lower, but C: N was higher after bamboo expansion, coupled with higher N resorption efficiency for Moso bamboo and lower litterfall, resulting in potential N return decreasing as much as 60.41 kg N ha yr to the soil. The soil N net nitrification and mineralization rates exhibited lower values in BDF than in EBF. In addition, annual soil N mineralization rate was positively correlated with litter production but negatively with C: N ratio of litter. Conclusions: Expansion of bamboo into neighboring EBF decreased litter production and quality, reduced soil N mineralization rate, and ultimately retarded N cycling. These effects should be carefully considered in the design of restoration strategies for ecosystems impacted by bamboo species. [ABSTRACT FROM AUTHOR]

Plant litter breakdown is a key ecological process in terrestrial and freshwater ecosystems. Streams and rivers, in particular, contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter breakdown in fresh waters, particularly at large scales. We present a global-scale study of litter breakdown in streams to compare the roles of biotic, climatic and other environmental factors on breakdown rates. We conducted an experiment in 24 streams encompassing latitudes from 47.88N to 42.88 S, using litter mixtures of local species differing in quality and phylogenetic diversity (PD), and alder (Alnus glutinosa) to control for variation in litter traits. Our models revealed that breakdown of alder was driven by climate, with some influence of pH, whereas variation in breakdown of litter mixtures was explained mainly by litter quality and PD. Effects of litter quality and PD and stream pH were more positive at higher temperatures, indicating that different mechanisms may operate at different latitudes. These results reflect global variability caused by multiple factors, but unexplained variance points to the need for expanded global-scale comparisons. [ABSTRACT FROM AUTHOR]

The common notion for describing N mineralization in models is that it results from decomposer organisms trying to meet their stoichiometric demands based on their own elemental composition and that of the resource. However, in addition to influencing C and nutrient availability, plant litter also influences the composition of both the litter and mineral soil community e importantly not in the same manner e resulting in altered trophic interactions. Since decomposer groups and their consumers vary in their elemental composition and demands, a change in composition and abundance of soil functional groups may result in a change in the stoichiometry of the whole soil food web, thus altering their stoichiometric relations with the available resource with potential functional consequences. We use experimental data and quantitative food web modeling to investigate the impact of the changes in the litter and soil food webs brought about by the differing stoichiometry of plant litter on (a) N mineralization, (b) the contribution of different functional groups to mineralization, and (c) the stoichiometric flexibility of the system, assessed as the ability to mineralize materials with different stoichiometry. Our simulations suggested that the effects of litter stoichiometry on trophic interactions, their impacts on N mineralization and the relative contribution of functional groups may not behave as a continuum across the litter and soil interface. Further, changes in food webs associated with variation in plant stoichiometric traits can influence the relative importance of functional groups, which given their particular stoichiometric demands may affect ecosystem-level N cycling. Our results suggested that litter materials of intermediate N contents, or litter mixtures encompassing materials with different nutrient contents and thus resulting in mixtures of intermediate stoichiometry, may promote food webs that are better suited to deal with changing substrate stoichiometry. [ABSTRACT FROM AUTHOR]

Suppression of plant-parasitic nematodes and decomposition of organic matter are important soil food web functions. The availability and nature of carbon substrates in soil drive the structure, dynamics, and activities of soil food webs and may alter the way they function in the ecosystem. In this study, we assessed the effects on nematode communities of incorporating litter from three cover crops with contrasting biochemical characteristics into soil taken from a banana field. The litter type influenced nematode taxa and functional guilds during the 90-day assay. The cellulose- and hemicellulose-rich litters of Crotalaria zanzibarica and Paspalum notatum induced similar nematode successions, causing bacterivorous and fungivorous nematode populations to increase early in the study period and promoting a fungal decomposition pathway at the end of the trial. These two litters were the most effective at decreasing the soil’s nematode infective potential with regard to major banana plant-parasitic nematodes, such as Pratylenchus coffeae , Helicotylenchus multicinctus , and Rotylenchulus reniformis . C. zanzibarica showed good potential as a green manure plant, as it increased the soil mineral nitrogen content during the 45 days following incorporation of litter. By contrast, litter from Acacia auriculiformis , which had high lignin content, induced immobilization of soil nitrogen and did not significantly increase microbivorous nematodes before day 45. This treatment failed to reduce the soil’s nematode infective potential for H. multicinctus and R. reniformis populations. Our study also showed that the dynamics of nitrogen mineralisation in soil were related to the C:N ratio of litters but not to the decomposition pathway. The biochemical characteristics of litters appear to be critical drivers of nematode ecological successions and decomposition pathways following plant litter amendments to soil taken from a banana field. [ABSTRACT FROM AUTHOR]

Most studies of forest litter dynamics examine the biochemical characteristics and decomposition of leaf litter, but fine roots are also a large source of litter in forests., We quantified the concentrations of eight biochemical fractions and nitrogen (N) in leaf litter and fine roots at four sugar maple ( Acer saccharum)-dominated hardwood forests in the north-central United States. We combined these results with litter production data to estimate ecosystem biochemical fluxes to soil. We also compared how leaf litter and fine root biochemistry responded to long-term simulated N deposition., Compared with leaf litter, fine roots contained 2.9-fold higher acid-insoluble fraction ( AIF) and 2.3-fold more condensed tannins; both are relatively difficult to decompose. Comparatively, leaf litter had greater quantities of more labile components: nonstructural carbohydrates, cellulose and soluble phenolics. At an ecosystem scale, fine roots contributed over two-thirds of the fluxes of AIF and condensed tannins to soil. Fine root biochemistry was also less responsive than leaf litter to long-term simulated N deposition., Fine roots were the dominant source of difficult-to-decompose plant carbon fractions entering the soil at our four study sites. Based on our synthesis of the literature, this pattern appears to be widespread in boreal and temperate forests. [ABSTRACT FROM AUTHOR]

The transformation of leaf litter into fecal pellets by saprophagous macroarthropods has long been suggested to play an important role in litter decomposition by altering microbial processes. However, conflicting results are reported in the literature, and it is currently not clear to what extent varying initial litter quality contributes to distinct microbial responses to the transformation of litter into feces. Here we performed a screening test using a wide range of distinct leaf litter from 26 tree species. We fed these litters to the macroarthropod species Glomeris marginata during one week under controlled conditions, and compared microbial responses in uningested leaf litter with that of feces produced from the 26 different leaf litter types. We assessed substrate induced respiration (SIR) as an integrative measure of microbial responses. We found that litter SIR was highly variable across species and well related to initial litter quality. However, variability in feces SIR was strongly reduced and only weakly related to initial litter quality. Moreover, the difference between feces and litter SIR decreased with increasing litter SIR as a result of higher microbial stimulation in litter with low associated litter SIR. Our data clearly showed that the direction and magnitude of microbial stimulation in feces depend strongly on the litter type. Therefore, the consequence of litter transformation into macroarthropod fecal pellets for microbial decomposers and possibly for subsequent decomposition of feces is specific to litter species. [ABSTRACT FROM AUTHOR]

The magnitude of the carbon flux between soil and atmosphere has prompted efforts to better understand the controls over the fate of carbon in plant litter that re-enters the atmosphere as carbon dioxide or is sequestered as soil organic carbon (SOC). It remains unresolved if the long-term fate of litter carbon is driven by biochemical properties of litter or by soil properties that reduce the ability of soil organisms to decompose litter-derived carbon. The prominent role that reactive soil minerals play in stabilising SOC have hindered investigation into the single role of litter quality on long-term SOC stability. Here we investigated the independent effects of litter quality on soil carbon stabilisation across a 460,000 year sand dune chronosequence characterised by a pronounced nutrient and litter quality gradient with minimum presence of interfering soil minerals. Using a steady state turnover model to interpret radiocarbon activity in soils collected ≈40 years apart, we show that the turnover time of SOC in the A horizon averaged 22 years (ranging from 16 to 27 years) across the chronosequence. This finding strongly contrasts other chronosequences where SOC turnover rates range from 60 to 726 years in concert with changing abundance and composition of soil minerals. Our study demonstrates that the long-term stability of SOC in surface horizons may be largely determined by interaction with soil minerals and that litter quality per se does not govern carbon stabilisation. [ABSTRACT FROM AUTHOR]

Tree species interact with soil biota to impact soil organic carbon (C) pools, but it is unclear how this interaction is shaped by various ecological factors. We used multiple regression to describe how ~100 variables were related to soil organic C pools in a common garden experiment with 14 temperate tree species. Potential predictor variables included: (i) the abundance, chemical composition, and decomposition rates of leaf litter and fine roots, (ii) species richness and abundance of bacteria, fungi, and invertebrate animals in soil, and (iii) measures of soil acidity and texture. The amount of organic C in the organic horizon and upper 20 cm of mineral soil (i.e. the combined C pool) was strongly negatively correlated with earthworm abundance and strongly positively correlated with the abundance of aluminum, iron, and protons in mineral soils. After accounting for these factors, we identified additional correlations with soil biota and with litter traits. Rates of leaf litter decomposition, measured as litter mass loss, were negatively correlated with size of the combined soil organic C pool. Somewhat paradoxically, the combined soil organic C pool was also negatively related to the ratio of recalcitrant compounds to nitrogen in leaf litter. These apparent effects of litter traits probably arose because two independent components of litter 'quality' were controlling different aspects of decomposition. Leaf litter mass loss rates were positively related with leaf litter calcium concentrations, reflecting greater utilization and depolymerization of calcium-rich leaf litter by earthworms and other soil biota, which presumably led to greater proportional losses of litter C as CO or dissolved organic C. The fraction of depolymerized and metabolized litter that is ultimately lost as CO is an inverse function of microbial C use efficiency, which increases with litter nutrient concentrations but decreases with concentrations of recalcitrant compounds (e.g. lignin); thus, high ratios of recalcitrant compounds to nitrogen in leaf litter likely caused a greater fraction of depolymerized litter to be lost as CO. Existing conceptual models of soil C stabilization need to reconcile the effects of litter quality on these two potentially counteracting factors: rates of litter depolymerization and microbial C use efficiency. [ABSTRACT FROM AUTHOR]

In biodiverse ecosystems, leaf litter of different plant species decomposes in mixtures, for which decomposition rates notoriously deviate from that expected from monospecific treatments. Despite important research efforts in past decades, these litter diversity effects remain difficult to predict. We hypothesized that this is due to a focus on bulk litter decomposition, while different carbon fractions constituting the litter may respond differently to litter diversity, thereby blurring the overall response. To test this hypothesis, we determined how the decomposition of (i) soluble compounds, (ii) cellulose, and (iii) lignin responded to litter mixing in a 3.5-year field experiment in an alpine forest. We found that the decomposition of soluble compounds and cellulose in mixtures was faster than expected from monospecific treatments, while that of lignin was slower. These deviations from expected decomposition rates of each litter carbon fraction were driven by different aspects of the litter functional diversity. This suggests that different mechanisms operating on distinct litter fractions lead to synergistic and antagonistic interactions that simultaneously affect bulk litter decomposition. Furthermore, the magnitude of these fraction-specific deviations from expected decomposition rates consistently decreased throughout decomposition. Considering the response of litter fractions and their temporality, rather than focusing on bulk litter thus seems critical to evaluate the response of decomposition to plant diversity and identify underlying mechanisms. • We disentangled the response of different litter fractions to litter diversity. • Litter functional diversity increased labile compound decomposition. • Litter functional diversity decreased recalcitrant compound decomposition. • These effects were driven by different aspects of litter functional diversity. • The strength of litter diversity effects faded throughout decomposition. [ABSTRACT FROM AUTHOR]

• Litter decomposition is a key ecosystem process, yet our understanding of the drivers in chemical changes in leaves during decay is limited. Our aim was to determine the comparative differences (chemical divergence or convergence) between sites and the drivers of decay pathways. • We used the litterbag method ('in situ' litterfall and standardized 'control' leaves) in Australian tropical rainforests and near-infrared spectrometry to show the chemical pathways during decomposition (c. 360 d; 12 control sites; 17 in situ sites). Chemical convergence/divergence was determined from spectral dissimilarity and quantile regression along a mass loss moving average. The influence of environment (climate and soil) and litter quality on decay pathways was determined between sites using correlation analysis. • Throughout the region, litter composition in both treatments converged chemically during decay. However, divergent chemical pathways were shown for some samples/sites (especially with high initial lignin, phenolics and carbon (C), poor soil phosphorus (P), sodium (Na) and more seasonal moisture), and the diversity of decay residues increased with mass loss despite overall chemical convergence. • Our study suggests that there is general chemical convergence of leaf litter during early decay, but also that divergent chemical pathways occur in locations that experience more intense seasonal drying, and contain species or conditions that promote poor-quality litter. [ABSTRACT FROM AUTHOR]

The knowledge about element leaching and biogeochemical cycles during initial stages of soil development is very limited. Therefore, we studied the effects of parent material characteristics and plant litter addition on element leaching from young sandy soils in a microcosm experiment. Our objective was to evaluate the function of young soils as a source and/or sink for nutrients during initial pedogenesis and to identify main processes which are involved in the initial development of biogeochemical cycles. The main research questions were: (1) How do differences in parent material characteristics affect nutrient leaching?; and (2) How is nutrient leaching of young soils influenced by litter addition of different plant functional groups ( e.g., legume and grass species)? Combined treatments of two minimally weathered parent materials (pure sand and loamy sand) with plant litter of two plant species ( Lotus corniculatus L. and Calamagrostis epigejos L.) were investigated in a soil column experiment. In addition, control columns with parent material or plant litter only were included. Carbonate weathering as a main source for calcium leaching was induced by the moderately acidic irrigation solution used in the experiment. It was 7.5 fold greater for the loamy sand parent material compared to the pure sand despite lower carbonate contents in the loamy sand. Leaching of K was very low for both parent materials but greater for the loamy sand parent material, likely due to transfer processes from fixed to exchangeable potassium forms in the clay minerals of the loamy sand. Plant litter addition generally increased leaching losses. Carbonate dissolution was intensified by both plant litter types, especially by L. corniculatus, very likely due to H+ released during nitrification of N released from plant litter and an increase in partial pressure of CO2 from microbial respiration. In contrast, K was largely retained in the soils, probably due to fixation by clay minerals and microbial immobilization. Only the pure sand treated with L. corniculatus litter leached K, resulting in 4-6 fold greater leaching losses compared to all other treatments. Nitrogen released from L. corniculatus litter was almost completely nitrified and was nearly doubled as compared to that from C. epigejos, resulting in greater N leaching. The results of our study allow identifying the general function and processes of vegetation patches in young ecosystems formed as a result of initial parent material characteristics and invading vegetation with respect to litter decomposition, soil solution composition, nutrient retention and leaching, and effects on the soil mineral phase. These patterns are not mere additive effects of parent materials plus plant litter, but reflect differences in biogeochemical process intensities and could result in an increasing heterogeneity of soil properties, nutrient availability, and element leaching fluxes with time. [ABSTRACT FROM AUTHOR]

Highlights: [•] We test litter biochemical quality as a controlling factor for soil fungistasis. [•] A new bioassay evaluates fungistasis in soil amended with 42 litter types. [•] After amendment fungistasis is relieved with lignin-poor, but labile C-rich materials. [•] Intensity and duration of the relief correlate with litter 13C NMR spectral data. [•] Observations support the competition based hypothesis of soil fungistasis. [ABSTRACT FROM AUTHOR]

Abstract: Saprophagous macroarthropods reach high population densities in many Mediterranean terrestrial ecosystems of southern Europe but their impact on decomposition processes remains unclear. We studied the direct and indirect effects of the millipede Ommatoiulus sabulosus on the decomposition of litter from four shrub species (Cistus albidus, Quercus coccifera, Rosmarinus officinalis and Ulex parviflorus) in a 1-month laboratory experiment. Litter mass loss, substrate-induced respiration (SIR) in litter and faecal pellets, and microbial community structure and biomass in litter (using PLFA profiles) were determined under three sets of conditions: (1) litter and microorganisms; (2) litter, microorganisms and millipedes; (3) litter, microorganisms and millipede faecal pellets regularly added to litter. Two watering frequencies were used to study the effects of simulated drought on the measured variables. Millipedes consumed large amounts of shrub litter with low assimilation efficiency. The largest effect was observed for Cistus that showed also the highest rate of microbial-driven decomposition. Conversion of litter into faecal pellets by millipedes did not increase organic matter decomposition and there was no evidence for a stimulation of microbial activity in faecal pellets compared to uningested litter. Faecal pellet deposition on litter, which was maximal in Cistus, did not change mass loss and SIR rates of litter but significantly changed microbial community structure. Bacterial biomass was lower and fungal:bacterial ratio was higher in moist, but not in dry Cistus litter, after 1 month of regular faeces addition. Simulated drought strongly decreased microbial-driven decomposition but not millipede feeding. The resulting sustained production of faecal pellets, however, did not offset the slower microbial-driven decomposition under dry conditions. We conclude that the transformation of large amounts of shrub litter into faeces by macroarthropods and the resultant interactions with microorganisms do not enhance carbon mineralization in the short term, regardless of litter humidity. We however expect that faeces could be incorporated into the soil more easily than intact plant litter, with important consequences for carbon and nutrient cycling in Mediterranean ecosystems under increasing drought. [Copyright &y& Elsevier]

Litter decomposition is a major fundamental ecological process that regulates nutrient cycling, thereby affecting net ecosystem carbon (C) storage as well as primary productivity in forest ecosystems. Litter decomposes in its home environment faster than in any other environment. However, evidence for this phenomenon, which is called the home-field advantage (HFA), has not been universal. We provide the first HFA quantification of litter decomposition and nutrient release through meta-analysis of published data in global forest ecosystems. Litter mass loss was 4.2 % faster on average, whereas nitrogen (N) release was 1.7 % lower at the home environment than in another environment. However, no HFA of phosphorus (P) release was observed. Broadleaf litter (4.4 %) had a higher litter mass loss HFA than coniferous litter (1.0 %). The positive HFA of N release was found in the coniferous litter. Mass loss HFA was significantly and negatively correlated with the initial lignin:N litter ratio. The litter decomposition and N release HFAs were obtained when mesh size ranged from 0.15 mm to 2.0 mm. The HFA of litter decomposition increased with decomposition duration during the early decomposition stage. The HFA of N release was well correlated with mass loss, and the greatest HFA was at mass loss less than 20 %. Our results suggest that the litter decomposition and N release HFAs are widespread in forest ecosystems. Furthermore, soil mesofauna is significantly involved in the HFA of litter decomposition. [ABSTRACT FROM AUTHOR]

Domestication took plants from natural environments to agro-ecosystems, where resources are generally plentiful and plant life is better buffered against environmental risks such as drought or pathogens. We hypothesized that predictions derived from the comparison of low vs high resource ecosystems (faster-growing plants promoting faster nutrient cycling in the latter) extrapolate to the process of domestication., We conducted the first comprehensive assessment of the consequences of domestication on litter quality and key biogeochemical processes by comparing 24 domesticated crops against their closest wild ancestors. Twelve litter chemistry traits, litter decomposability and indicators of soil carbon ( C) and nitrogen ( N) cycling were assessed in each domesticated vs wild ancestor pair. These assessments were done in microbial-poor and microbial-rich soils to exemplify intensively and extensively managed agricultural soils, respectively., Plant domestication has increased litter quality, encouraging litter decomposability (36% and 44% increase in the microbial-rich and microbial-poor soils, respectively), higher soil [ABSTRACT FROM AUTHOR]

Abstract: Laboratory decomposition experiments measuring the mineralization of C from plant residue are increasingly used to test the effects of different litter sources and soil conditions. To date, the most widely used methods are infra-red gas analysis (IRGA) and gas chromatography, which are time-consuming, and relatively expensive and complex to operate. The aim of this study was to devise a simple and rapid laboratory method to assess litter decomposition rates at frequent time intervals. We modified the MicroResp™ system to measure the amount of CO2 produced by two soils supporting contrasting microbial communities and containing the litter of eight crop species. The method was sensitive enough to differentiate both soil microbial communities and litter qualities. The method combines the accuracy of gas chromatography with the speed of absorbance measurements obtained via microplate readers. This technique provides an effective means for devising complex litter decomposition experiments capable of addressing the joint influence of multiple species, soil communities, environmental conditions, and their multiple interactions. [Copyright &y& Elsevier]

Abstract: Microbes decompose fresh organic carbon inputs, such as plant litter, to CO2. Due to a high water-level (WL) in pristine peatlands the decomposition process is retarded and therefore, northern peatlands contain about 30% of the global soil carbon (C) pool. Global warming will decrease the WL of these soil C hotspots and therefore, the responses of the decomposition process of plant litter to shifts in WL regime is of interest. Two important decomposer communities, fungi and actinobacteria, were studied in a diverse set of litters incubated over two years in a boreal peatland. The experimental design involved a non-treatment control and plots experiencing short-term (ca 4 yrs) and long-term (ca 40 yrs) WL drawdown. The responses of litter-inhabiting fungal and actinobacterial decomposers to environmental variables (WL regime, site type, litter quality) were evaluated using PCR-DGGE fingerprinting and direct sequencing of regions within the 16S and 18S ribosomal RNA genes after reverse transcription of RNA into its complementary DNA. The fungal sequences found in the decomposing litters represented organisms from a variety of fungal taxa, whereas most of the actinobacterial sequences were only distantly similar to known actinobacteria. Our results indicated that: (1) WL regime and site type had minor impacts on the litter-inhabiting microbial community composition, (2) litter quality had the strongest impact on the communities, especially on fungi; (3) decomposition stage had an impact on the fungal community composition, showing a possible change from mycorrhizal to saprotrophic fungi and (4) mass loss of the litters after the two-year-decomposition period was not related to the variation in fungal community composition and only to a negligible extent to the actinobacterial community composition. In relation to the decomposition process these results align with the idea of functional redundancy in microbial communities, which does not seem to be modified by moderate WL drawdown. Overall, our results indicate that the WL regime modifies the litter-inhabiting microbial communities largely indirectly via litter quality. [Copyright &y& Elsevier]

The aim of this research was to compare the amounts of existing mineral elements in plant aerial parts, litter and soil of three range species (Bromus tomentellus, Psathyrostachys fragilis, Agropyron tauri) in order to investigate the litter effect of species on soil properties of Taleghan rangeland. The measured mineral elements include carbon, nitrogen, phosphorous and potassium. After selection of the appropriate plant species and suitable sites, random- systematic sampling method was used to plant aerial part, litter and soil sampling. Soil data were taken of 0-30 cm depth and in addition to above mineral elements, soil texture, EC, pH and lime percentage was measured in soils of the sites. The data was analyzed by analysis of variance (ANOVA), Duncan's test and t-test. Results of analysis of variance of different elements showed that the amounts of nitrogen, carbon and C/N ratio of the species litter had significant differences, so that A. tauri had the highest concentration of nitrogen and B. tomentellus had those of Carbon and C/N ratio. Results also indicated that there are significant difference among the amounts of nitrogen, phosphorous and carbon in plant aerial part of the mentioned species (P<0.01). P. fragilis had the highest amount of nitrogen and both P. fragilis and B. tomentellus had higher amount of carbon and phosphorous than A. tauri. Soil under the species and control showed significant differences so that the mentioned species improve soil productivity. Totally, A. tauri had the highest litter quality and decomposition rate. [ABSTRACT FROM AUTHOR]

Abstract: Macrophyte decomposition is critical for eutrophic shallow lakes because it can influence the accumulation of the sediment layer and lake terrestrialization processes. As three dominant macrophytes in Lake Baiyangdian, N. nucifera (Nelumbo nucifera), P. australis (Phragmites australis), and T. latifolia L (Typha latifolia L) have spread quickly and covered a large proportion of the lake as a result of water nutrient enrichment over the past 30 years. In this study, we investigated the decomposition processes of these three plants using the litterbag method to demonstrate their roles in lake degradation. Decomposition rates of plant tissues (leaves, stems, and roots) and whole plants were determined at three sampling sites that had different nutrient levels. The litter samples displayed a wide range of decomposition rates. Of all samples, the leaves of N. nucifera decomposed the most rapidly, while the stems of P. australis had the lowest decomposition rates. The decomposition correlated significantly with the initial litter phosphorus (P) and nitrogen (N) content, and the ratios of carbon (C) to N (C:N) and C to P (C:P), especially the P-related indicators, implying a relative shortage of P in the sampled species. Although not as strong as litter quality, site chemistry effects also can be observed during decomposition. The site with a high nutrient level in the water body exhibited rapid decomposition and high decomposition rates. Interactions of plant tissues (expressed as the differences between observed and expected decomposition rates) were tested when we investigated the decomposition processes of the whole plants. Observed decomposition rates of the whole plant individuals significantly deviated from the expected rates that were calculated based on the mass losses of plant tissues of the corresponding species. The strengths of the interactions varied greatly with plant species. T. latifolia L displayed significantly positive interactions among plant tissues, while significantly negative interactions of plant tissues were observed for the other two species. Moreover, our results suggest that the interactions of plant tissues greatly vary among the three sampling sites, indicating that both the biotic and abiotic characteristics of an ecosystem can be important drivers controlling litter decomposition. [Copyright &y& Elsevier]

Abstract: Plant chemical composition and the soil community are known to influence litter and soil organic matter decomposition. Although these two factors are likely to interact, their mechanisms and outcomes of interaction are not well understood. Studies of their interactive effects are rare and usually focus on carbon dynamics of litter, while nutrient dynamics in the underlying soil have been ignored. A potential mechanism of interaction stems from the role fauna plays in regulating availability of litter-derived materials in the mineral soil. We investigated the role of soil fauna (meso, macro) in determining the effect of surface-litter chemical composition on nitrogen mineralization and on the micro-food web in mineral soils. In a field setting we exposed mineral soil to six types of surface-applied litter spanning wide ranges of multiple quality parameters and restricted the access of larger soil animals to the soils underlying these litters. Over six months we assessed litter mass and nitrogen loss, nitrogen mineralization rates in the mineral soils, and soil microbes and microfauna. We found evidence that the structure of the soil community can alter the effect of surface-litter chemical composition on nitrogen dynamics in the mineral soil. In particular, we found that the presence of members of the meso- and macrofauna can magnify the control of nitrogen mineralization by litter quality and that this effect is time dependent. While fauna were able to affect the size of the micro-food web they did not impact the effect of litter composition on the abundance of the members of the micro-food web. By enhancing the strength of the impact of litter quality on nitrogen dynamics, the larger fauna can alter nitrogen availability and its temporal dynamics which, in turn, can have important implications for ecosystem productivity. These findings contribute to evidence demonstrating that soil fauna shape plant litter effects on ecosystem function. [Copyright &y& Elsevier]

Abstract: Aboveground litter decomposition is controlled mainly by substrate quality and climate factors across terrestrial ecosystems, but photodegradation from exposure to high-intensity ultraviolet-B (UVB) radiation may also be important in arid and semi-arid environments. We investigated the interactive effects of UVB exposure and litter quality on decomposition in a Tamarix-invaded riparian ecosystem during the establishment of an insect biological control agent in northern Nevada. Feeding by the northern tamarisk beetle (Diorhabda carinulata) on Tamarix spp. trees leads to altered leaf litter quality and increased exposure to solar UVB radiation from canopy opening. In addition, we examined the dynamics of litter decomposition of the invasive exotic Lepidium latifolium, because it is well-situated to invade beetle-infested Tamarix sites. Three leaf litter types (natural Tamarix, beetle-affected Tamarix, and L. latifolium) differing in substrate quality were decomposed in litterbags for one year in the field. Litterbags were subjected to one of three treatments: (1) Ambient UVB or (2) Reduced UVB (where UVB was manipulated by using clear plastic films that transmit or block UVB), and (3) No Cover (a control used to test for the effect of using the plastic films, i.e. a cover effect). Results showed a large cover effect on rates of decomposition and nutrient release, and our findings suggested that frequent cycles of freeze–thaw, and possibly rainfall intensity, influenced decomposition at this site. Contrary to our expectations, greater UVB exposure did not result in faster rates of decomposition. Greater UVB exposure resulted in decreased rates of decomposition and P release for the lower quality litter and no change in rates of decomposition and nutrient release for the two higher quality litter types, possibly due to a negative effect of UVB on soil microbes. Among litter types, rates of decomposition and net release of N and P followed this ranking: L. latifolium > beetle-affected Tamarix > natural Tamarix. Altered nutrient dynamics with beetle introduction as well as the rapid decomposition rates exhibited by L. latifolium are consistent with vulnerability to secondary invasion. In this desert ecosystem, decomposition and nutrient release were strongly affected by litter type and much less so by UVB exposure. [Copyright &y& Elsevier]

The article presents a study which examines the impact of short- but not long-term soil carbon dynamic in its aggregate fractions. It assumes that complex molecules are stabilized soil organic carbon (SOC) in the context of chemical decomposition. It also examines the relationship between litter quality and the latter. The study found out that SOC's formation and stabilization are controlled by the quality of litter input and its interaction with the soil matrix.