Controlling Litter Decomposition Research Articles

Species-specific impact of protists in controlling litter decomposition

Protists affect soil microbiome composition and functioning, potentially increasing litter decomposition and plant growth. Yet, the role of different protist species, individually or in combinations, in regulating microbial-mediated litter decomposition remains unknown, as well as if these interactions feedback to plant growth. Using a full-factorial design of three protist species combinations with bacterial and fungal communities, we found that only one protist species reduced litter decomposition by 19%, with other species and combinations not affecting litter decomposition. Despite a positive correlation between plant growth and litter decomposition, we did not observe protist-induced changes in plant growth. Overall, our results highlight that protists affect litter decomposition in a species-specific manner, including reducing litter decomposition.

Soil microbial identity explains home-field advantage for litter decomposition.

Unraveling the mechanisms of home-field advantage (HFA) is essential to gain a complete understanding of litter decomposition processes. However, knowledge of the relationships between HFA effects and microbial communities is lacking. To examine HFA effects on litter decomposition, we identified the microbial communities and conducted a reciprocal transplant experiment, including all possible combinations of soil and litter, between sites at two elevations in cool-temperate forests. Soil origin, rather than HFA, was an important factor in controlling litter decomposition processes. Microbiome-wide association analyses identified litter fungi and bacteria specific to the source soil, which completely differed at a low taxonomic level between litter types. The relative abundance of these microbes specific to source soil was positively correlated with litter mass loss. The results indicated that the unique relationships between plant litter and soil microbes through plant-soil linkages drive litter decomposition processes. In the short term, soil disturbances resulting from land-use changes have the potential to disrupt the effect of soil origin and hinder the advancement of litter decomposition. These findings contribute to an understanding of HFA mechanisms and the impacts of land-use change on decomposition processes in forest ecosystems.

Canopy Gaps Control Litter Decomposition and Nutrient Release in Subtropical Forests

The formation of a canopy gap results in changes to the microenvironment which, in turn, affect litter decomposition and nutrient release. However, the mechanisms underlying these effects in differently sized gaps and non-gaps remain poorly understood. To address this gap in knowledge, we selected three large gaps (above 150 m2), three medium gaps (50–100 m2), three small gaps (30–50 m2), and three non-gaps with basically the same site conditions. We then used the litter bag method to investigate leaf and branch litter decomposition over a year in a Castanopsis kawakamii natural forest with the aim of characterizing the litter mass remaining and the nutrient release in canopy gaps and non-gaps. Our results revealed that the remaining litter mass of leaf and branch litter was lower in medium gaps compared to other gaps, and leaf litter decomposed faster than branch litter. Environmental factors were identified as the primary drivers of total carbon and nitrogen release during litter decomposition. Gap size (canopy openness), taxonomic Margalef index, the Brillouin index of soil microbes, soil total nitrogen content, soil pH value, and average air temperature were identified as the main factors driving carbon and nitrogen release from branch litter. In the late decomposition stage, the taxonomic Pielou index, soil total potassium content, soil water content, and average relative air humidity were the main drivers of nutrient release from branch litter. The soil water content and average relative air humidity were also found to be the main factors affecting the nutrient release from leaf litter throughout the different stages of decomposition. Overall, our study highlights the impact of canopy gaps on microenvironmental variation, taxonomic community diversity, and soil microbial functional diversity and how these factors ultimately influence litter decomposition and nutrient release. Our findings provide an important foundation for further research into soil nutrient cycling in subtropical natural forests.

Leaf litter decomposition and its drivers differ between an invasive and a native plant: Management implications.

Litter decomposition is a key process of the carbon cycle in terrestrial and aquatic ecosystems. The dominant conceptual model of litter decomposition assumes that environmental conditions, litter traits, and decomposer composition control litter decomposition in a decreasing order, yet whether this hierarchical model applies to both invasive and native plant species is unknown. Here, by comparing a widespread invasive plant and its native counterpart in Chinese coastal saltmarshes, we aimed to examine whether the hierarchy of factors controlling litter decomposition varies with plant species in the face of plant invasions. Leaf litter of invasive Spartina alterniflora and native Phragmites australis was collected across an 18° latitudinal range to capture wide variation in litter traits. These leaf litter samples were transported to three saltmarsh sites of different latitudes and were incubated in litterbags varying in mesh size (0.1, 2, and 5mm) to manipulate decomposer composition. After 90-day incubation, we found a parallel latitudinal pattern in leaf litter decomposition rate (k) between S. alterniflora and P. australis regardless of saltmarsh site and mesh size. Nonetheless, the k value of S. alterniflora was 2.2-fold higher than that of P. australis. Moreover, there was a shift in the hierarchy of factors controlling k values between S. alterniflora and P. australis: environmental conditions (climate and soil) dominated other factors in P. australis, whereas litter traits contributed more than environmental conditions in S. alterniflora. Overall, our findings show that leaf litter decomposition and its dominant controlling factors across broad geographical ranges can vary with plant invasions, having important implications for managing invasive plants in the context of conserving coastal blue carbon.

The influence of increased precipitation and nitrogen deposition on the litter decomposition and soil microbial community structure in a semiarid grassland

Litter decomposition is a major method in which nutrients are recycled, especially carbon and nitrogen elements, in terrestrial ecosystems. However, how the responses of litter quality and soil microbial communities to global changes alter litter decomposition remains unclear. A 4-year field manipulative experiment based on the litterbag method was conducted in a typical temperate semiarid grassland in China to explore how increased precipitation and nitrogen deposition affect decomposition processes via litter quality and soil microbial communities. Our results showed that water and nitrogen addition treatments could accelerate litter carbon release and promote mass loss through different pathways. Water addition had a direct positive effect on litter decomposition. However, nitrogen addition could indirectly promote litter decomposition by improving litter quality and increasing the bacterial and fungal ratios. The water addition treatment increased litter mass loss by 7.37 %, and the N addition treatments increased litter mass loss by 5.83 %–16.93 %. Moreover, water and nitrogen additions had antagonistic effects on litter decomposition. These findings revealed that litter quality and the soil bacterial to fungal ratio were the factors controlling litter decomposition. The changes in precipitation and nitrogen deposition will impact ecosystem carbon and nitrogen cycling by altering litter decomposition processes in semiarid grassland ecosystems under the context of climate change.

Litter decomposition and nutrient release from monospecific and mixed litters: Comparisons of litter quality, fauna and decomposition site effects

Abstract Litter decomposition and nutrient release are key processes for soil C and nutrient cycling. However, the relative importance of the effects of litter quality, fauna and decomposition site on litter decomposition remains poorly understood. Moreover, the macronutrient and micronutrient (C, N, P, K, Ca, Mg, Mn, Cu and Zn) release in the decomposition process are even less well‐known. In this study, we performed 5040 litterbag samplings of monospecific (Larix gmelinii, Acer mono, Quercus mongolica and Juglans mandshurica) and mixed (Larix with each broad‐leaved litter) litter treatments using litterbags with three mesh sizes (for different‐sized fauna) in four paired stands of natural secondary forests compared with adjacent Larix plantations in a temperate forest ecosystem in China. Litter decomposition rate and macronutrient and micronutrient release during decomposition were assessed. We found that variation in litter quality had a considerably greater effect on litter decomposition than fauna and decomposition site. The decomposition constant was significantly related to the initial litter Mg concentration and lignin/P ratio, suggesting the importance of the Mg content and lignin/P ratio in controlling litter decomposition in temperate tree species. We also showed that macrofauna significantly increased monospecific but not mixed litter decomposition. In addition, the decomposition site conditions further influenced monospecific litter decomposition. Furthermore, the litter quality significantly influences N and Mn release in both monospecific and mixed litters. Compared with Larix litter, the average of N and Mn increased 33.9% and 53.8% in three broad‐leaved litters, and 21.4% and 38.0% in three mixed litters respectively. Synthesis. Litter quality is a relatively more important factor than fauna and decomposition site for the decomposition of both monospecific and mixed litters when studied at a local scale in temperate forests. Moreover, litter decomposition enhanced in plantation sites with poor soil nutrient status, which has implications for C and nutrient cycling and long‐term below‐ground forest ecosystem functions.

Mycelium chemistry differs markedly between ectomycorrhizal and arbuscular mycorrhizal fungi

The chemical quality of soil carbon (C) inputs is a major factor controlling litter decomposition and soil C dynamics. Mycorrhizal fungi constitute one of the dominant pools of soil microbial C, while their litter quality (chemical proxies of litter decomposability) is understood poorly, leading to major uncertainties in estimating soil C dynamics. We examined litter decomposability of arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungal species using samples obtained from in vitro cultivation. We showed that the chemical composition of AM and EM fungal mycelium differs significantly: EM fungi have higher concentrations of labile (water-soluble, ethanol-soluble) and recalcitrant (non-extractable) chemical components, while AM fungi have higher concentrations of acid-hydrolysable components. Our results imply that differences in decomposability traits among mycorrhizal fungal guilds represent a critically important driver of the soil C cycle, which could be as vital as is recognized for differences among aboveground plant litter.

Predominant role of air warming in regulating litter decomposition in a Tibetan alpine meadow: A multi-factor global change experiment

Alpine ecosystems worldwide are experiencing multi-faceted climate changes, but the interactive effects of these drivers on litter decomposition are poorly understood. Here, we examined the effects of air warming, nitrogen (N) addition and altered precipitation, and their interactions on litter decomposition originating from four species (Elymus nutans, Kobresia capillifolia, Thermopsis lanceolata, Saussurea nigrescens) in a Tibetan alpine meadow. Among the three factors, air warming by open top chambers (OTCs) significantly decreased all litter decomposition except for K. capillifolia with the highest C:N ratio over one-year field decomposition. The reduced litter mass loss in the chambered plots was mainly attributed to OTC-induced decrease in soil temperature, with more negative effects of OTC on litter decomposition in winter and spring than in summer. However, N addition offset the negative effects of OTC on litter mass loss of K. capillifolia, likely by alleviating N limitation to this poor-quality litter decomposition. In addition, simulated precipitation increase promoted decomposition of high-quality litter (T. lanceolata and S. nigrescens) in the dry winter, likely by alleviating water stress. Together, our findings highlight the predominant role of climate in controlling litter decomposition in alpine ecosystems.

Dominant plants affect litter decomposition mainly through modifications of the soil microbial community

Litter decomposition is a key step in biogeochemical cycling and energy flow underlying ecosystem function. It is well established that dominant plants influence litter decomposition through their litter quality, and by modifying edaphic properties and soil microbial activity at the local scale. Despite this, the pathways through which dominant plants influence litter decomposition remains insufficiently understood. In an alpine meadow on the Tibetan Plateau, we manipulated vegetation structure by factorial removal of shrubs (Dasiphora fruticosa) and graminoids (mainly Elymus nutans) to elucidate their effects on litter decomposition of D. fruticosa and E. nutans via changes in edaphic properties and microbial assemblages. The decomposition of D. fruticosa litter was lower when graminoids were removed, while the removal of either of the dominant species had a negative effect on E. nutant litter decomposition. These effects were attributed to changes in the relative abundance of microbial groups associated with litter decomposition induced by the dominant plants. Specifically, shifts in a subset of the bacterial community was a good predictor of litter decomposition rates, particular of E. nutans, while shifts in the composition and richness of a subset of fungal explained well D. fruticosa litter decomposition rates. This is likely due to the affinity of bacteria to utilize high quality litter (i.e. greater N content), whereas fungi are considered dominant in decomposing more recalcitrant litter. We conclude that dominant plants moderate litter decomposition through their influences on microbial taxa associated with decomposition processes. Our results provide a better understanding of the relative importance of abiotic and biotic factors in controlling litter decomposition.

Nitrogen Deposition Effects on Soil Properties, Microbial Abundance, and Litter Decomposition Across Three Shrublands Ecosystems From the Mediterranean Basin

Atmospheric nitrogen (N) inputs in the Mediterranean Basin are projected to increase due to fossil fuel combustion, fertilizer use, and the exacerbation of agricultural production processes. Although increasing N deposition is recognized as a major threat to ecosystem functioning, little is known about how local environmental conditions modulate ecosystem function response to N addition, particularly in the context of Mediterranean-Basin ecosystems. Here, we assess how N addition affects important ecosystem properties associated with litter decomposition, soil physical-chemical properties, soil extracellular enzymatic activity and microbial abundance across three long-term N addition experimental sites in the Mediterranean Basin. Sites were located in El Regajal (Madrid, Spain), Capo Caccia (Alghero, Italy), and Arrábida (Lisbon, Portugal) and are all representative of Mediterranean shrublands. No common pattern for litter decomposition process or other studied variables emerged among the control plots of the studied sites. Nitrogen supply only affected soil pH, a major driver of decomposition, in two out of three experimental sites. Moreover, when we explored the role of N addition and soil pH in controlling litter decay, we found that the effects of these factors were site-dependent. Our results point out to local ecosystem features modulating N addition effects in controlling litter decomposition rates in Mediterranean ecosystems, suggesting that the responses of soil functioning to N deposition are site-dependent. These findings provide further knowledge to understand contrasting ecosystem responses to N additions based on a single field experiments.

Factors controlling Carex brevicuspis leaf litter decomposition and its contribution to surface soil organic carbon pool at different water levels

Abstract. Litter decomposition plays a vital role in wetland carbon cycling. However, the contribution of aboveground litter decomposition to the wetland soil organic carbon (SOC) pool has not yet been quantified. Here, we conducted a Carex brevicuspis leaf litter input experiment to clarify the intrinsic factors controlling litter decomposition and quantify its contribution to the SOC pool at different water levels. The Carex genus is ubiquitous in global freshwater wetlands. We sampled this plant leaf litter at −25, 0, and +25 cm relative to the soil surface over 280 d and analysed leaf litter decomposition and its contribution to the SOC pool. The percentage litter dry weight loss and the instantaneous litter dry weight decomposition rate were the highest at +25 cm water level (61.8 %, 0.01307 d−1), followed by the 0 cm water level (49.8 %, 0.00908 d−1), and the lowest at −25 cm water level (32.4 %, 0.00527 d−1). Significant amounts of litter carbon, nitrogen, and phosphorus were released at all three water levels. Litter input significantly increased the soil microbial biomass and fungal density but had nonsignificant impacts on soil bacteria, actinomycetes, and the fungal∕bacterial concentrations at all three water levels. Compared with litter removal, litter addition increased the SOC by 16.93 %, 9.44 %, and 2.51 % at the +25, 0, and −25 cm water levels, respectively. Hence, higher water levels facilitate the release of organic carbon from leaf litter into the soil via water leaching. In this way, they increase the soil carbon pool. At lower water levels, soil carbon is lost due to the slower litter decomposition rate and active microbial (actinomycete) respiration. Our results revealed that the water level in natural wetlands influenced litter decomposition mainly by leaching and microbial activity, by extension, and affected the wetland surface carbon pool.

Quality dependence of litter decomposition and its carbon, nitrogen and phosphorus release under simulated acid rain treatments.

Litter decomposition is of utmost importance to elemental cycling in terrestrial ecosystems, with litter quality being frequently considered to predominantly control litter decomposition. However, how acid rain (AR) would affect litter decomposition and its elements release remains inconclusive, although AR has widely occurred in Europe, North America, and East Asia. This study was conducted to observe leaf litter decomposition and release of carbon (C), nitrogen (N), and phosphorus (P) of three crops (maize, rice, and soybean) under simulated AR treatments. Results showed that the accumulated mass loss during decomposition was significantly different among species, supporting the view of litter quality predominantly controlling decomposition. Specifically, quality dependence of litter decomposition was observed in the late stage of decomposition, while mass loss of litters was comparable in the first month among species. With decomposition, the litter C/N ratio significantly increased for the three species while the C/P and N/P ratios significantly decreased or tended to decrease, suggesting that litter N was releasedpreferentially over C and P. However, AR treatments did not significantly affect litter decomposition and its elements release in our investigation period. Moreover, litter P content appeared to strongly affect the release of C, N, and P during litter decomposition, and such P dependence could to some extentbe alleviated by AR treatments. Our results suggest that AR may change the quality dependence of litter decomposition and further studies are needed to illustrate its potential mechanisms.

Do litter-feeding macroarthropods disrupt cascading effects of land use on microbial decomposer activity?

Plant traits are known to control litter decomposition rates through afterlife effects on litter quality. Land-use practices that modify plant traits, e.g. livestock grazing and soil fertilization, also have cascading effects on litter decomposition. However, almost all studies of these afterlife effects ignored the role of soil detritivores in the decomposition processes. We explored how the feeding activities of a macroarthropod modify microbial activity in leaf litter. Dead leaves from two grassland species, Bromopsis erecta and Potentilla verna, were collected in fertilized or unfertilized grazed plots and fertilized or unfertilized ungrazed plots. We determined how intraspecific variation in litter quality in response to sheep grazing and soil fertilization (i) influences the consumption and assimilation of leaf litter by the millipede Glomeris marginata, and (ii) affects the activity of microbial decomposers, assessed by substrate-induced respiration (SIR), in leaf litter before consumption and in faecal pellets and litter remains processed by Glomeris under all treatments. In the absence of millipedes, microbial activity was significantly higher in leaf litter from fertilized plots. Glomeris consumed larger amounts of leaf litter from fertilized grazed plots, owing to increased consumption of the otherwise poorly palatable Bromopsis, and produced larger amounts of faecal pellets when fed on this food. However, irrespective of the food consumed, SIR in faecal pellets was found to be similar in all treatments. Moreover, SIR in litter remains unconsumed at the end of the experiment was reduced to low and similar levels in all treatments. Overall, homogenization of microbial activity by Glomeris suppressed differences in SIR between leaf litter from fertilized and unfertilized plots, in both Bromopsis and Potentilla. Our results suggest that studies that assess afterlife effects of plant traits on decomposition using methods that exclude soil macrofauna may prove inadequate in ecosystems with abundant populations of detritivores.

Altitude and species identity drive leaf litter decomposition rates of ten species on a 2950 m altitudinal gradient in Neotropical rain forests

AbstractIdentifying the environmental factors controlling litter decomposition is key to understanding the magnitude and rates of nutrient cycling in tropical forests, and how they may be influenced by climate variability and environmental change. We carried out a leaf litter translocation experiment in mature rain forest over a 2,520 m altitudinal gradient in Costa Rica. Leaf litter decomposition rates (k) of ten tree species, two dominant species from each ecosystem, plus two standard species, were calculated over 540 days in four life zones. k was lowest in montane with 0.83 per year and lower montane forests with 2.21 per year. k did not differ between lowland and premontane forests at 3.12 per year, in spite of the 3℃ difference of mean annual temperature between these life zones. k varied fourfold among species. Species decomposition rates ranked as follows, and were predictably related to leaf economic spectrum traits of the species: Acalypha communis (standard, fast decomposer)» Hyeronima oblonga > Alchornea latifolia, Quercus bumelioides, Jarava ichu (standard, slow decomposer)> Minquartia guianensis > Magnolia sororum > Vochysia allenii > Pourouma bicolor, Carapa guianensis. These two slowest‐decomposing species were native premontane and lowland forest dominants, respectively, with tough, low‐nutrient leaves. The ranking of species by k varied very little among life zones suggesting that decomposer organisms in very different ecosystems and environments react in similar ways to the litter quality in general. We conclude that while k decreases with temperature in rain forests on tropical mountains, bioclimatic zones defined as premontane may be “functionally lowland.” The effects of species identity on decomposition rates on tropical mountains are consistent and independent of environment for both standard and native species. Under climate change on these mountains, if moisture regimes do not change, decomposition rates will increase due to rising temperatures. Soil carbon storage may therefore decrease. Changes in the altitudinal distributions of currently dominant species will also affect this critically important biogeochemical process.

Leaf litter traits predominantly control litter decomposition in streams worldwide

AbstractAimLeaf litter decomposition in freshwater ecosystems is a vital process linking ecosystem nutrient cycling, energy transfer and trophic interactions. In comparison to terrestrial ecosystems, in which researchers find that litter traits predominantly regulate litter decomposition worldwide, the dominant factors controlling its decomposition in aquatic ecosystems are still debated, with global patterns not well documented. Here, we aimed to explore general patterns and key drivers (e.g., litter traits, climate and water characteristics) of leaf litter decomposition in streams worldwide.LocationGlobal.Time period1977–2018.Major taxa studiedLeaf litter.MethodsWe synthesized 1,707 records of litter decomposition in streams from 275 studies. We explored variations in decomposition rates among climate zones and tree functional types and between mesh size groups. Regressions were performed to identify the factors that played dominant roles in litter decomposition globally.ResultsLitter decomposition rates did not differ among tropical, temperate and cold climate zones. Decomposition rates of litter from evergreen conifer trees were much lower than those of deciduous and evergreen broadleaf trees, attributed to the low quality of litter from evergreen conifers. No significant differences were found between decomposition rates of litter from deciduous and evergreen broadleaf trees. Additionally, litter decomposition rates were much higher in coarse‐ than in fine‐mesh bags, which controled the entrance of decomposers of different body sizes. Multiple regressions showed that litter traits (including lignin, C:N ratio) and elevation were the most important factors in regulating leaf litter decomposition.Main conclusionsLitter traits predominantly control leaf litter decomposition in streams worldwide. Although further analyses are necessary to explore whether commonalities of the predominant role of litter traits in decomposition exist in both aquatic and terrestrial ecosystems, our findings could contribute to the use of trait‐based approaches in modelling the decomposition of litter in streams globally and exploring mechanisms of land–water–atmosphere carbon fluxes.

Plant interactions modulate root litter decomposition and negative plant-soil feedback with an invasive plant

Invasive plants often modify soil biota to benefit their own fitness over native species, and create a positive plant-soil feedback (PSF). Rhizosphere effect (RE), the alterations of decomposition processes by living roots and associated rhizodeposits, may act as a mechanism that contributes to the positive PSF via accelerating litter decomposition and subsequent soil nutrient turnover. However, the relative effects attributable to litter quality versus plant composition and edaphic conditions on RE remain unclear. A reciprocal translocation decomposition experiment was conducted in a screenhouse with root litter from an invasive (Flaveria bidentis) and a native species (Bidens maximowicziana) in two types of soils (one dominated by the invasive species and another by the native species) with four plantings (two monocultures, one mixture with both species, and one without living plants). We examined the performance of invasive and native species responses to different soils (PSF) and quantified the RE on litter decomposition. PSF and RE were dependent on whether focal species grew in the monocultures or mixture, and interspecific competition ameliorated negative PSF of F. bidentis when it competed with a weaker competitor. All RE values associated with B. maximowicziana litter under the monocultures were positive, whereas F. bidentis litter exhibited neutral to negative REs, mainly depending on the soil type examined. The RE values in the invaded soil were significantly greater than those in the native soil under the monocultures. However, mixture planting tended to decrease REs on decomposition, which in turn feedback to host plant by affecting soil N availability and microbial composition. Our study showed that innate differences between the two litters in terms of their decomposability and edaphic conditions are likely to exert a much greater impact in controlling litter decomposition. Importantly, rhizosphere-mediate belowground process has the potential to be an important contributor to plant-interaction outcomes.

Ecosystem type and resource quality are more important than global change drivers in regulating early stages of litter decomposition

Litter decomposition is fundamental for nutrient and carbon (C) cycling, playing a major role in regulating the Earth's climate system. Climate change and fertilization are expected to largely shift litter decomposition rates in terrestrial ecosystems, however, studies contextualizing the relative importance of these major global change drivers versus other key decomposition drivers such as substrate quality and ecosystem type are lacking. Herein, we used two independent field experiments in an Eastern Australian grassland (Experiment 1) and a forest (Experiment 2) to evaluate the role of (i) litter quality, (ii) nutrient addition (N, P and K in full factorial combination; Experiment 1), and (iii) a combination of N addition and irrigation (Experiment 2) in litter decomposition, substrate-induced respiration and microbial abundance. Regardless of experimental treatments, forest soils decomposed litter between 2 and 5 times faster than grassland soils. This was principally controlled by the greater ability of forest microbes to respire C-based substrates and, ultimately, by soil N availability. The experimental treatments accounted for only relatively small differences in our measured variables, ranging from 10 to 15% in the case of the irrigation-by-N-addition forest experiment to almost negligible in most of the grassland nutrient addition plots. In the latter experiment, decomposition and soil activity responses were associated with either K addition or interactions between K and other nutrients, suggesting a key role for this often-neglected soil nutrient in controlling litter decomposition. Our study provides evidence that while nutrient enrichment and/or irrigation have the potential to affect litter decomposition rates in grassland and forest ecosystems, land use change that results in loss or gain of forested area is likely to exert a much greater impact than these other two drivers.

Direct and legacy effects of plant-traits control litter decomposition in a deciduous oak forest in Mexico.

BackgroundLitter decomposition is a key process in the functioning of forest ecosystems, because it strongly controls nutrient recycling and soil fertility maintenance. The interaction between the litter chemical composition and the metabolism of the soil microbial community has been described as the main factor of the decomposition process based on three hypotheses: substrate-matrix interaction (SMI), functional breadth (FB) and home-field advantage (HFA). The objective of the present study was to evaluate the effect of leaf litter quality (as a direct plant effect, SMI hypothesis), the metabolic capacity of the microbial community (as a legacy effect, FB hypothesis), and the coupling between the litter quality and microbial activity (HFA hypothesis) on the litter decomposition of two contiguous deciduous oak species at a local scale.MethodsTo accomplish this objective, we performed a litterbag experiment in the field for 270 days to evaluate mass loss, leaf litter quality and microbial activity in a complete factorial design for litter quality and species site.ResultsThe litter of Quercus deserticola had higher rate of decomposition independently of the site, while the site of Quercus castanea promoted a higher rate of decomposition independently of the litter quality, explained by the specialization of the soil microbial community in the use of recalcitrant organic compounds. The Home-Field Advantage Index was reduced with the decomposition date (22% and 4% for 30 and 270 days, respectively).DiscussionWe observed that the importance of the coupling of litter quality and microbial activity depends on decomposition stage. At the early decomposition stage, the home-advantage hypothesis explained the mass loss of litter; however, in the advanced decomposition stage, the litter quality and the metabolic capacity of the microbial community can be the key drivers.

Sheep grazing and local community diversity interact to control litter decomposition of dominant species in grassland ecosystem

Large herbivore grazing, a major land use in grasslands, can constitute a feedback loop with local plant diversity to affect litter decomposition. Here we examined the interactive effects of sheep grazing and local plant community diversity on decomposition of litter of the dominant plant species (Leymus chinensis) in the meadow steppe of China. We found a faster litter decomposition rate in the local species-rich communities compared to the local species-poor communities in the absence of sheep grazing. However, in the presence of sheep grazing, the decomposition rate was significantly reduced in the local species-rich communities while increased in the local species-poor communities. Therefore, sheep grazing and local community diversity constituted a negative feedback loop to modify litter decomposition in this grassland ecosystem. The findings of this study indicate one outcome of herbivore grazing could be to homogenize grassland nutrient cycling in space by balancing litter decomposition rate among local communities, which therefore could increase the homogenization of metacommunity structure. Furthermore, reduced local community diversity may slow ecosystem process rates. Our study indicates that sheep grazing, or equivalent, offsets this negative effect of local plant diversity loss on litter decomposition.

Litter decomposition of woody species in shrublands of NW Patagonia: how much do functional groups and microsite conditions influence decomposition?

The study examined the effects of leaf traits, soil microsite, and microclimate characteristics on litter decomposition of the dominant species in two functional groups (FG), deciduous and evergreen, in shrublands in NW Patagonia, Argentina. Leaf traits considered were nutrient concentration (C, N, P, C/N, and N/P) and physical characteristics (area, strength, specific leaf area, and dry matter content). Soil microsite characteristics measured were pH, C, N, P, C/N and water retention capacity, while soil microclimate characteristics recorded were soil and air, temperature and moisture, and solar radiation. Five evergreen and five deciduous woody shrub species were selected. During 1 year, litter and microsite properties were measured below canopy: (i) senescent leaf chemical and physical properties, and the quantity as well as field decomposition of litter and (ii) soil chemistry, and soil and air physical properties. The factors controlling litter decomposition were different for each FG. In deciduous species, C/N ratio had a negative effect on decomposition. In evergreen species, decomposition was affected negatively by leaf carbon and dry matter content. Litter decomposition depended exclusively on the inherent senescent leaves traits. The common decomposition pattern between species of both FG could be attributed to similar leaf traits and the correlation between variables that control decomposition in both groups. Plant nutrient inputs associated with the litter decomposition process did not explain the soil nutrient content. These results suggest that other organic matter sources (roots, branches, and fruits) are more important than leaves on soil fertility.