Leaf Litter Mass Loss Research Articles

Linking leaf nutrient resorption and litter decomposition to plant mycorrhizal associations in boreal peatlands

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. 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. 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. 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.

Invertebrate phenology modulates the effect of the leaf economics spectrum on litter decomposition rate across 41 subtropical woody plant species

Abstract Litter quality and decomposers are critical to carbon and nutrient cycling through litter decomposition. However, how relationships between litter quality and invertebrate detritivores change litter mass loss through time is poorly known. Species’ initial leaf litter quality, as a legacy of their position on the ‘leaf economics spectrum’ (LES), may determine the invertebrate contribution to litter mass loss. This contribution may change through time, as both population peaks of invertebrate detritivores and litter quality of given species will change through time. Here we introduce invertebrate phenology into a conceptual model of drivers of litter mass loss. We hypothesized that in the early decomposition period, LES can predict litter decomposability with or without a strong invertebrate contribution, that is, litter with higher nutrient content would decompose faster. But in the later decomposition period, when higher quality litter will already have decomposed too much and lower quality litters have still been less degraded, a strong invertebrate peak would coincide with relatively more consumption of initially lower quality litters; this would lead to a humpback relationship between leaf litter mass loss and initial LES position in this period. We tested our hypothesis through a 1‐year field decomposition experiment using leaf litter of 41 woody species in each of two sites in subtropical forest in China; only one of these sites had a strong late peak of leaf litter‐feeding moth larvae in the litter layer. LES score of litter species had a positive linear relationship with litter mass loss before the key invertebrate consumer peaks in the litter layer. However, with the invertebrates peaking later into the decomposition process, the invertebrate consumption peaked at initially lower quality litters, which altered the species’ decomposability trajectory on the LES, consistent with the hypothesized humpback relationship between leaf litter mass loss and LES. This phenomenon resulted in a strongly reduced slope of cumulative mass loss on initial LES score across species. Our finding highlights the importance of considering interactions between the timing of detritivore activities and the timing of litter quality for better understanding the relationships between soil animals and ecosystem carbon and nutrient cycling. A free Plain Language Summary can be found within the Supporting Information of this article.

Decomposition rate and invertebrate colonization of seagrass detritus along a hydrodynamic gradient in a Mediterranean coastal basin: The Stagnone di Marsala (Italy) case study

AbstractSeagrass leaf litter decomposition is a key component of marine carbon flow driven by both biotic and abiotic factors, including water movement. In this study, we analyse Posidonia oceanica litter decomposition and invertebrate colonization in three sites with different hydrodynamics in a coastal basin. Litterbags were put on the sea bed along a gradient of distance from the open sea, implying a different level of water exchange. Leaf litter mass loss and carbon and nitrogen concentration were analysed, and density and biomass of benthic invertebrates colonizing litterbags were recorded after 3, 7, 14, 47, 101, 152 and 221 days. Results showed that in the most sheltered site, the leaf litter decomposition rate, the invertebrate density and biomass and the detrital carbon release were the lowest. The reduction of the decomposition rates of seagrass leaves in the site characterized by low hydrodynamic forces may promote organic matter burial and carbon stocks, emphasizing the role of coastal basins such as ponds and lagoons as sinks of carbon and the important role of seagrass detritus in the Blue Carbon global balance.

Pervasively high mangrove productivity in a major tropical delta throughout an ENSO cycle (Southern Caribbean, Colombia)

Rhizophora mangle is a mangrove forest foundation species that can create vegetated habitat, support entire animal and plant communities, and modulate ecosystem processes. Changes in freshwater subsidies over space and time may alter the performance of mangrove foundation species, presumably resulting in disproportionally large effects on energy flow. Yet the linkages between above-ground biomass and below-ground carbon reservoirs across freshwater-subsidy gradients remain poorly understood in many regions. We assessed the dynamics of litterfall production and breakdown of leaf material in a monospecific Rhizophora mangle forest thriving in a small bay in the Atrato River Delta (Southern Caribbean coast of Colombia), during a major El Niño to La Niña transition (from July 2015 to October 2016). Although parameters varied at different spatial scales within the bay, the mean annual total litter production (55 ± 15 g m−2 day−1 or 20 ± 5 Mg ha−1 yr−1) and the mean mass loss of leaf litter (1.0% and 1.7% day−1, above- and below-ground, respectively) are the highest reported for R. mangle-dominated forests worldwide. Total litter production and mass loss rates did not vary significantly over time. The lack of temporal effect was counterintuitive, because these rates typically show strong seasonal variation in mangroves elsewhere in the tropics. We concluded that mangroves in this area constitute a primary productivity hotspot (leaf fall carbon spatio-temporal range: 0.81–1.30 g C m−2 d−1). Based on a comparison of our results and data from the literature, we hypothesize that high freshwater input from the Atrato River subsidizes mangrove plants settled on the deltaic front, which sustain pervasively high litterfall rates. The high mass loss rates of leaf litter observed in this study demonstrate the importance of carbon vertical fluxes across the forest floor in fringing mangroves for carbon sinking.

Initial lignin content as an indicator for predicting leaf litter decomposition and the mixed effects of two perennial gramineous plants in a desert steppe: A 5‐year long‐term study

AbstractLeaf is the main component of litter that often exists in mixed forms in nature. However, the mixed effects of leaf litter decomposition in desert ecosystems remain unclear. To reveal the mixed effects and the influence of litter quality on leaf litter decomposition in desert ecosystems, a 5‐year long‐term study was conducted to compare the observed and expected leaf litter mass loss in single‐species and mixed (equal proportions and natural proportions) litters of two typical perennial gramineous plants (Stipa klemenzii and Achnatherum splendens) in a desert steppe in Northern China. The relationship between litter mass loss and litter qualities was also analysed. The results showed that (a) after 5 years of decomposition, the mass losses of mixed litter in natural proportions and S. klemenzii litter were significantly higher than those of mixed litter in equal proportions and A. splendens litter; (b) the mixed effects of two litters in different ratios varied with time, and the synergistic effect only appeared in the second year when an easily decomposed litter (S. klemenzii) was mixed with a slowly decomposing litter (A. splendens); and (c) litter mass loss was not correlated with the initial carbon or nitrogen content but was negatively correlated with the initial lignin content, and the initial lignin content also had a significant effect on litter mixed effects of these two perennial gramineous plant litters. These results can suggest that the initial lignin content is an indicator of predicting decomposition and mixed effects of litter with low nitrogen content.

The Effects of Plant Secondary Metabolites from Coniferous Needle Leaf Litter on the Leaf Litter Decomposition of Betula albo-sinensis Burk

In this study, leaf litters of Betula albo-sinensis and 5 coniferous species were used as samples. The B. albo-sinensis leaf litter was buried in soil and termly treated with the water extracts of five types of coniferous leaf litter for a 6-month simulation decomposition experiment. The dynamics of mass loss and nutrients (C, N, P, and K) content of leaf litter and the soil enzymatic activities were measured to investigate the effects of plant secondary metabolites (PSM) from coniferous leaf litters on the decomposition processes of B. albo-sinensis leaf litter. The results indicated that the extracts of Pinus tabuliformis, Platycladus orientalis, P. armandii and Larix principis-rupprechtii leaf litters significantly inhibited the whole decomposition process and overall nutrients release of B. albo-sinensis leaf litter, while the extracts of Picea asperata leaf litter exhibited no significant influence. The general suppression of PSM on the soil sucrase, carboxymethyl cellulase and β-glucosidase activities might be the main reason leading to the inhibitory effects of the extracts of P. tabuliformis, P. orientalis, P. armandii and L. principis-rupprechtii leaf litter. The species causing inhibitory effects, especially L. principis-rupprechtii, was not recommended to be planted mixed with B. albo-sinensis, or their planting density should be lower in the mixed forests.

Epi-anecic rather than strict-anecic earthworms enhance soil enzymatic activities

Earthworms in interaction with soil microorganisms play a key role in litter decomposition. Moreover, as soil engineers, earthworms modify microbial communities and their enzymatic activities. Most studies focusing on earthworms and soil enzymatic activities compare distinct ecological categories of earthworms whereas their contributions and interactions within a given ecological category remain largely unknown. In this context, the aims of the present study were to determine and compare the contribution of (1) three strict-anecic earthworm species, (2) three epi-anecic earthworm species and (3) the pairwise interactions between these different species on Lolium perenne leaf litter decomposition and soil microbial activity. After 30 days of incubation, the surface litter mass loss and five soil enzymatic activities (FDAse, β-D-glucosidase, cellobiohydrolase, leucine amino-peptidase and acid phosphatase) were measured in both earthworm burrows and middens. In mono-specific assemblages, leaf litter mass loss and enzymatic activities were significantly higher in the presence of epi-anecic compared to strict-anecic species, whatever the species identity. These differences were higher for the β-D-glucosidase, leucine amino-peptidase and FDAse (+78%, +57% and +34%, respectively). Earthworm species interactions at both intra- and inter-ecological sub-categories did not enhance either leaf litter mass loss or enzymatic activities. Interestingly, FDAse activity was higher in earthworm burrows whereas acid phosphatase activity was higher in earthworm middens. These results indicate that the two anecic ecological sub-categories have different impacts on soil functioning and each of them regroups earthworm species with similar behaviour. This functional distinction highlights the key role of epi-anecic earthworms in fresh surface litter burial and decomposition, featuring their importance on nutrient cycling in soil and for microbial activities stimulation through resource availability.

Experimental test of water, nutrients, and microclimate on leaf litter mass loss in headwater riparian forests

AbstractLeaf litter decomposition is an essential function in forest ecosystems, and riparian areas may contribute to faster rates of litter mass loss due to higher moisture and nutrient levels in riparian than upland soils. We experimentally tested whether mass loss of red alder leaf litter was (1) greater closer to the stream than further away and (2) increased by nutrient and water additions in riparian habitat near four headwater streams in southwestern British Columbia. We set up blocks of nine transects extending from the bankfull edge of the stream into upland habitat. Leaf litter bags were placed at 1, 5, 10, 20, and 40 m from the stream along each transect, and data loggers recorded ambient air temperature and relative humidity at each distance. Litterbags received either water or fertilizer additions, both, or neither along each transect. Four trials were run which varied in duration (3 months to 1 yr). Relative humidity was on average 2.6% higher, air temperature 0.25°C lower, and vapor pressure deficit 0.14 kPa lower at 1 m from the stream compared to distances further upland. The addition of water significantly increased litter mass loss by 0.14 g (4%) on average than control litterbags. The addition of fertilizer was a significant factor in some trials but not in others, and its effect on mass loss varied. Although distance from the stream was not a significant parameter in the averaged models for each trial, it was in several top models. We conclude that (1) riparian communities within 1 m of the stream experience a different microclimate during the warmer, drier summer than those communities further upland, though this was not generally reflected in alder mass loss rates, and (2) water was a primary limiting factor to alder leaf mass loss in our study sites.

Feeding behaviour of epi-anecic earthworm species and their impacts on soil microbial communities

Earthworms contribute to numerous ecosystem services provided by soils. Most of the studies focusing on the contributions of earthworms on leaf litter decomposition were conducted by comparing distinct ecological categories (epigeic, epi-anecic, anecic strict and endogeic), whereas their specific contributions within a given ecological category remains largely unknown. In this context, the aim of this study was to determine the contribution of four epi-anecic earthworm species (Lumbricus rubellus, Lumbricus festivus, Lumbricus centralis and Lumbricus terrestris) to the leaf litter decomposition of three plant species (Lolium perenne, Holcus lanatus and Corylus avellana) with contrasted litter traits located at both the soil surface and at a depth of 10 cm. Fungal and bacterial communities inhabiting epi-anecic earthworm burrows were also assessed using T-RFLP analysis. Epi-anecic earthworms improved the leaf litter mass loss solely at the soil surface, while leaf litter mass loss was mainly due to microbial activity at 10 cm deep. Leaf litter mass loss was positively correlated to the initial biomass of the epi-anecic earthworms and the intensity of this relationship was dependent on litter type. Interestingly, L. festivus seemed to have a higher contribution to surface leaf litter mass loss that was linked to a stimulation of the fungal communities in its burrows. Fungal communities were thus impacted by both the litter type and the epi-anecic earthworm identity whereas soil bacterial diversity and richness were stimulated in the earthworm burrows whatever the epi-anecic earthworm species considered. Overall, epi-anecic earthworms contributed to enhance the diversity of the drilospheric microbiota.

Investigation of Salix alba and Populus tremula leaf litter decomposition in the area of Lake Balaton and Kis-Balaton Wetland

Plant litter decomposition in inland waters contributes significantly to nutrient load, particularly in still waters, such as shallow lakes and wetlands. The decomposition rates of Salix alba and Populus tremula leaf litter was examined in Lake Balaton and Kis-Balaton Wetland, using litter bag technique. Leaf litter was incubated in small (ᴓ=3 mm) and large (ᴓ=900 μm) mesh size bags for the assessment of the relative contribution of macroinvertebrates to leaf litter decomposition. Dry mass, exponential decay coefficient and chemical parameters of water (pH, conductivity, NH4 +, NO3 -, SO4 2-, PO4 3-, Cl-) were determined. Leaf mass loss showed negative exponential pattern during the 168 days of the decomposition period. Leaf litter mass loss generally did not differ between the small and large mesh sizes, suggesting that macroinvertebrates generally have a negligible role in leaf decomposition in the winter period.

Interactions among decaying leaf litter, root litter and soil organic matter vary with mycorrhizal type

Abstract Root‐derived inputs are increasingly viewed as primary controls of soil organic matter (SOM) formation; however, we have a limited understanding of how root decay rates depend on soil factors, and how decaying roots influence the breakdown of leaf litter and SOM. We incubated root and leaf litter (alone and in combination) from arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) trees in soils collected from forest plots dominated by AM and ECM trees in a factorial design. In each microcosm, we quantified litter decay rates and the effects of decaying litters on soil C balance. We hypothesized that (1) AM root litters would decompose faster than ECM root litters, (2) root litter decay would be greatest when decomposed in “home” soils (e.g. AM litters in AM soils and ECM litters in ECM soils) and (3) root and leaf litters would decompose faster when decaying in the same microcosms than when decaying in separate microcosms, resulting in the largest CO2 losses. Overall, AM root litter decomposed faster than ECM root litter, and the magnitude of this effect depended on soil origin. AM litters decayed fastest in AM soils, but ECM and mixed AM–ECM litters were unaffected by soil origin. Decaying roots increased leaf litter mass loss, but only in microcosms containing soils of the same origin (e.g. AM litters in AM soils; mixed litters in mixed soils). Carbon losses were dominated by microbial respiration, and the magnitude of this flux depended on litter type and soil origin. When leaves and roots decayed together, respiratory losses exceeded those from microcosms containing leaves and roots alone, with the largest losses occurring in each litters' “home” soil. In AM soils, elevated losses were driven by roots accelerating leaf decay, while in ECM soils, elevated losses resulted from roots and leaves accelerating the decay of SOM; in mixed soils, root‐induced increases in leaf and SOM decay contributed to elevated C losses. Synthesis. Our results suggest that root, leaf and SOM decay are intertwined, and that measurements of these processes in isolation may lead to incorrect estimates of the magnitude and source of C losses from soils.

Microbial decomposition is highly sensitive to leaf litter emersion in a permanent temperate stream

Drought frequency and intensity in some temperate regions are forecasted to increase under the ongoing global change, which might expose permanent streams to intermittence and have severe repercussions on stream communities and ecosystem processes. In this study, we investigated the effect of drought duration on microbial decomposition of Populus nigra leaf litter in a temperate permanent stream (Oliveira, NW Portugal). Specifically, we measured the response of the structural (assemblage composition, bacterial and fungal biomass) and functional (leaf litter decomposition, extracellular enzyme activities (EEA), and fungal sporulation) parameters of fungal and bacterial communities on leaf litter exposed to emersion during different time periods (7, 14 and 21d). Emersion time affected microbial assemblages and litter decomposition, but the response differed among variables. Leaf decomposition rates and the activity of β-glucosidase, cellobiohydrolase and phosphatase were gradually reduced with increasing emersion time, while β-xylosidase reduction was similar when emersion last for 7 or more days, and the phenol oxidase reduction was similar at 14 and 21days of leaf emersion. Microbial biomass and fungal sporulation were reduced after 21days of emersion. The structure of microbial assemblages was affected by the duration of the emersion period. The shifts in fungal assemblages were correlated with a decreased microbial capacity to degrade lignin and hemicellulose in leaf litter exposed to emersion. Additionally, some resilience was observed in leaf litter mass loss, bacterial biomass, some enzyme activities and structure of fungal assemblages. Our study shows that drought can strongly alter structural and functional aspects of microbial decomposers. Therefore, the exposure of leaf litter to increasing emersion periods in temperate streams is expected to affect decomposer communities and overall decomposition of plant material by decelerating carbon cycling in streams.

Land use not litter quality is a stronger driver of decomposition in hyperdiverse tropical forest.

In hyperdiverse tropical forests, the key drivers of litter decomposition are poorly understood despite its crucial role in facilitating nutrient availability for plants and microbes. Selective logging is a pressing land use with potential for considerable impacts on plant–soil interactions, litter decomposition, and nutrient cycling. Here, in Borneo's tropical rainforests, we test the hypothesis that decomposition is driven by litter quality and that there is a significant “home‐field advantage,” that is positive interaction between local litter quality and land use. We determined mass loss of leaf litter, collected from selectively logged and old‐growth forest, in a fully factorial experimental design, using meshes that either allowed or precluded access by mesofauna. We measured leaf litter chemical composition before and after the experiment. Key soil chemical and biological properties and microclimatic conditions were measured as land‐use descriptors. We found that despite substantial differences in litter quality, the main driver of decomposition was land‐use type. Whilst inclusion of mesofauna accelerated decomposition, their effect was independent of land use and litter quality. Decomposition of all litters was slower in selectively logged forest than in old‐growth forest. However, there was significantly greater loss of nutrients from litter, especially phosphorus, in selectively logged forest. The analyses of several covariates detected minor microclimatic differences between land‐use types but no alterations in soil chemical properties or free‐living microbial composition. These results demonstrate that selective logging can significantly reduce litter decomposition in tropical rainforest with no evidence of a home‐field advantage. We show that loss of key limiting nutrients from litter (P & N) is greater in selectively logged forest. Overall, the findings hint at subtle differences in microclimate overriding litter quality that result in reduced decomposition rates in selectively logged forests and potentially affect biogeochemical nutrient cycling in the long term.

Soil Biology Research across Latitude, Elevation and Disturbance Gradients: A Review of Forest Studies from Puerto Rico during the Past 25 Years

Progress in understanding changes in soil biology in response to latitude, elevation and disturbance gradients has generally lagged behind studies of above-ground plants and animals owing to methodological constraints and high diversity and complexity of interactions in below-ground food webs. New methods have opened research opportunities in below-ground systems, leading to a rapid increase in studies of below-ground organisms and processes. Here, we summarize results of forest soil biology research over the past 25 years in Puerto Rico as part of a 75th Anniversary Symposium on research of the USDA Forest Service International Institute of Tropical Forestry. These results are presented in the context of changes in soil and forest floor biota across latitudinal, elevation and disturbance gradients. Invertebrate detritivores in these tropical forests exerted a stronger influence on leaf decomposition than in cold temperate forests using a common substrate. Small changes in arthropods brought about using different litterbag mesh sizes induced larger changes in leaf litter mass loss and nutrient mineralization. Fungi and bacteria in litter and soil of wet forests were surprisingly sensitive to drying, leading to changes in nutrient cycling. Tropical fungi also showed sensitivity to environmental fluctuations and gradients as fungal phylotype composition in soil had a high turnover along an elevation gradient in Puerto Rico. Globally, tropical soil fungi had smaller geographic ranges than temperate fungi. Invertebrate activity accelerates decomposition of woody debris, especially in lowland dry forest, but invertebrates are also important in early stages of log decomposition in middle elevation wet forests. Large deposits of scoltine bark beetle frass from freshly fallen logs coincide with nutrient immobilization by soil microbial biomass and a relatively low density of tree roots in soil under newly fallen logs. Tree roots shifted their foraging locations seasonally in relation to decaying logs. Native earthworms were sensitive to disturbance and were absent from tree plantations, whereas introduced earthworms were found across elevation and disturbance gradients.

Chronic nitrogen deposition influences the chemical dynamics of leaf litter and fine roots during decomposition

Atmospheric nitrogen deposition induces a forest carbon sink across broad parts of the Northern Hemisphere; this carbon sink may partly result from slower litter decomposition. Although microbial responses to experimental nitrogen deposition have been well-studied, evidence linking these microbial responses to changes in the degradation of specific compounds in decaying litter is sparse. We used wet chemistry and Fourier transform infrared spectroscopy (FTIR) methods to study effects of chronic simulated nitrogen deposition on leaf litter and fine root chemistry during a three-year decomposition experiment at four northern hardwood forests in the north-central USA. Leaf litter and fine roots were highly different in initial chemistry, such as concentrations of acid-insoluble fraction (AIF, or Klason lignin) and condensed tannins (CTs). These initial differences persisted over the course of decomposition. Gravimetrically-defined AIF and lignin/carbohydrate reference IR peak ratios both provide evidence that lignin in fine roots was selectively preserved under simulated nitrogen deposition. Lignin/carbohydrate peak ratios were strongly correlated with AIF, suggesting that AIF is a good predictor of lignin. Because AIF is abundant in fine roots, slower AIF degradation was the major driver of the slower fine root decomposition under nitrogen enrichment, explaining 73.5% of the additional root mass retention. Nitrogen enrichment also slowed the loss of CTs and proteins in fine roots. Nitrogen additions initially slowed the loss of AIF, CTs, and proteins in leaf litter, which was comparatively low in AIF, but these effects disappeared at the later stage and did not affect leaf litter mass loss during the experiment. Our results suggest that decomposition of chemical classes subject to oxidative degradation, such as lignin and CTs, is generally inhibited by nitrogen enrichment; but whether this inhibition eventually slows litter mass loss and leads to organic matter accumulation depends on the initial quantities of these classes in litter.

Early drivers of Black Mangrove (Avicennia germinans) leaf litter decomposition in the water column

Sequestration of carbon and nutrients, and sustained productivity of estuaries depend on organic turnover and nutrient remineralization. Decomposition of abundant plant material produced by mangroves and other macrophytes in estuaries occurs in both the sediments and the water column. Early and intense processing could be more common in the water. In a previous study, in situ decomposition rates of Black Mangrove (Avicennia germinans) leaf litter suspended in the water column differed among four estuaries in south Texas with moderate differences in salinity, water temperature, available nitrogen (N), and tidal flow. A series of microcosm experiments were conducted to determine the influence, within observed ranges in the estuaries, of these water variables on mass loss of mangrove leaf litter over 60 days. High salinity (66 psu) delayed decomposition, but low temperature (20°C) was a retardant at lower salinities (20–43 psu). Water turbulence greatly accelerated mass loss, whereas N additions and the presence of sediments had minimal effects. The faster decomposition observed in the estuaries compared to the microcosms may be explained by the synergistic effect of these and other environmental factors.

Interacting effects of yak dung deposition and litter quality on litter mass loss and nitrogen dynamics in Tibetan alpine grassland

AbstractThe effects of grazing‐induced dung deposition on plant growth and soil attributes are well established, but little is known about dung effects on litter decomposition. Here, we tested effects of yak dung on litter decomposition and nutrient content in a Tibetan alpine meadow. We incubated litter of four common alpine meadow species using litter bags in the field. Two low‐quality species (Kobresia capillifoliaandElymus nutans) with low nitrogen (N), high C/N and Lignin/N, and two high‐quality species, (Saussurea nigrescensandThermopsis lanceolata) were incubated in monoculture with and without dung addition. Mass loss of leaf litter, fibre fraction (cellulose, hemi‐cellulose and lignin), N and phosphorus (P) were measured after 6, 12 and 18 months of incubation in the field. Dung addition significantly increased decomposition constants for low‐quality litter species, but not for high‐quality litter species. Dung addition promoted cellulose and hemi‐cellulose loss, but lignin loss was not affected by dung addition, except after 12 months for high‐quality litter species. Dung reduced N immobilization after 6 months and did not affect subsequent release in low‐quality litter species, and promoted N release after 6 and 12 months in high‐quality litter species. Regardless of litter quality, dung increased P release after 6 and 12 months. Our results suggest grazing‐induced dung deposition may accelerate C and nutrient turnover, primarily through increasing the mass loss of low‐quality litter, P release from litter and N release from high‐quality litter. The mechanisms underlying the effects of dung deposition need to be clarified in future studies.

马尾松人工林林窗大小对四种凋落叶质量损失和养分释放的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 马尾松人工林林窗大小对四种凋落叶质量损失和养分释放的影响 DOI: 10.5846/stxb201507161501 作者: 作者单位: 四川农业大学林学院生态林业研究所;四川农业大学林学院生态林业研究所;四川农业大学林学院生态林业研究所,四川生态林业工程重点实验室;四川农业大学林学院生态林业研究所;四川农业大学林学院生态林业研究所;四川农业大学林学院生态林业研究所,四川生态林业工程重点实验室;四川农业大学林学院生态林业研究所;四川农业大学林学院生态林业研究所;四川农业大学林学院生态林业研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31370628）；国家科技支撑计划项目（2011BAC09B05）；四川省科技支撑计划项目（12ZC0017）；四川省科技厅应用基础项目（2012JY0047）；四川省教育厅科技创新团队计划项目（11TD006） Effects of forest gap size on leaf litter weight loss and nutrient release of four species in Pinus massoniana plantations Author: Affiliation: Institute of Ecology & Forestry, College of Forestry, Sichuan Agricultural University,Institute of Ecology & Forestry, College of Forestry, Sichuan Agricultural University,Institute of Ecology & Forestry, College of Forestry, Sichuan Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:马尾松人工林乔木层植物凋落物的分解对林地养分平衡和系统物质循环具有重要意义，并可能受不同大小林窗下微环境差异的影响。采用凋落物袋分解法，以马尾松（Pinus massoniana）人工林人为砍伐形成的7个不同大小林窗（G1：100 m2、G2：225 m2、G3：400 m2、G4：625 m2、G5：900 m2、G6：1225m2、G7：1600 m2）为研究对象，林下（G0）为对照，研究林窗大小对红椿（Toona ciliata）、桢楠（Phoebe zhennan）、香樟（Cinnamomum camphora）和马尾松4种乡土树种凋落叶质量损失及养分释放的影响。结果显示：1）林窗大小（G0-G7）显著影响林窗中心放置的红椿和桢楠凋落叶N和P释放率、香樟凋落叶失重率和N、P、K释放率以及马尾松凋落叶P和K释放率。相对于林下，中小型林窗（G1-G4）的凋落叶失重率和N、P释放率明显较大，而大型林窗（G6-G7）的凋落叶K释放率明显较大。2）林窗内放置位置显著影响红椿、桢楠和马尾松凋落叶的K释放率及香樟凋落叶的P释放率。红椿和桢楠的凋落叶K释放率从林窗中心到边缘显著减少，而马尾松凋落叶K释放率及香樟P释放率从林窗中心到边缘显著增加。3）4种凋落叶类型中，红椿凋落叶分解最快，其分解50%和95%所需时间分别为5.29和23.14个月。上述结果表明，林窗大小和林窗内位置对凋落物质量损失及其养分释放具有显著影响，但影响大小及趋势随物种初始基质质量的差异具有明显变化，研究结果为亚热带低山丘陵区马尾松人工低效林的科学经营及管理提高了一定的科学依据。 Abstract:Litter decomposition is an essential component of the nutrient balance and material cycling in Pinus massoniana plantations. Forest gap size could play an important role in litter decomposition due to its effects on the microenvironment. To evaluate the effects of forest gap size on leaf litter mass loss and nutrient release of four native species (Toona ciliata, Phoebe zhennan, Cinnamomum camphora, Pinus massoniana), a field experiment consisting of seven gap sizes (i.e., G1:100 m2, G2:225 m2, G3:400 m2, G4:625 m2, G5:900 m2, G6:1225m2, and G7:1600 m2) was established in 2013. The results showed that:1) Forest gap size significantly affected leaf litter mass loss of C. camphora, but not the mass loss of the other three species. The litter nutrient release rate at the gap center for T. ciliata (N, P), P. zhennan (N, P), C. camphora (N, P, K) and P. massoniana (P, K) were significantly influenced by forest gap size. Furthermore, leaf litter mass loss rate, and N and P release rates were significantly higher in small and medium sized gaps (G1-G4) than in large gaps (G5-G7) (P < 0.05). However, litter K release rates were significantly lower in small and medium sized gaps (G1-G4) than in the larger gaps (P < 0.05). 2) The leaf litter collection location in the forest gaps influenced the litter K release rate of T. ciliata, P. zhennan, and P. massoniana. The K release rate of T. ciliata and P. zhennan litter at the gap centers were significantly higher than those at the gap edges (P < 0.05). In contrast, P release rates of C. camphora litter and K release rates of P. massoniana litter at the gap center were significantly lower than rates at the gap edges (P < 0.05). 3) Litter mass loss and nutrient release rates of T. ciliata were the highest among the four species. According to the fitting equation, the 50% and 95% decomposition times for T. ciliata were 5.29 and 23.14 months, respectively. Overall, forest gap size and litter sampling location in the gaps significantly affected litter mass loss and nutrient release. However, the extent of these effects and dynamic changes depended on the initial litter quality. These results can be beneficial for the scientific management of P. Massoniana plantations in low mountainous and hilly areas of subtropical zones. 参考文献 相似文献 引证文献

Effects of temperature on the performance of a freshwater amphipod

Temperature drives the metabolism of ectothermic organisms and impacts ecosystem functioning. Anthropogenic activities have been changing historical temperatures of freshwater ecosystems with a wide range of consequences for ecosystem processes such as leaf litter decomposition. Here we explored temperature effects on the performance of the amphipod Gammarus pseudolimnaeus, a dominant detritivore in its range. We first measured oxygen consumption under six temperatures and fitted a thermal performance curve which yielded an optimal range between 24 and 26°C. We then measured several organismal traits at four temperatures leading up to the determined optimal range. We quantified leaf litter mass loss (through feeding), somatic growth and survival under starvation at 7, 11, 17 and 23°C. Leaf litter loss was significantly lower only at the lowest temperature, with no detected differences among other treatments. Somatic growth rates increased with increasing temperature within the tested range. Organisms at warmer temperatures tended to die of starvation faster in comparison to those at colder temperatures. Our results suggest that warming may enhance leaf litter loss in certain parts of the year, but that warming could intensify organism mortality under starvation and compromise local population persistence.

Leaf litter decomposition on insular lentic systems: effects of macroinvertebrate presence, leaf species, and environmental conditions

The decomposition of leaf litter of terrestrial origin is a fundamental process in aquatic ecosystems in forest contexts. Little is known about what drives leaf litter decomposition in oceanic islands. We examined the relative importance of leaf litter identity (Acacia melanoxylon, Pittosporum undulatum, Morella faya) and environmental conditions on litter decomposition in seven lakes in the oceanic archipelago of Azores for 28 and 56 days. Leaf litter was incubated in coarse and fine mesh bags for the assessment of the relative contribution of macroinvertebrates to leaf litter decomposition. Leaf litter mass loss generally did not differ between mesh sizes, suggesting that in these lakes macroinvertebrates generally have a negligible role on leaf decomposition. Leaf litter decomposition was in the order M. faya < A. melanoxylon < P. undulatum. A negative correlation was found between leaf litter mass loss and lignin concentration. Mass loss of P. undulatum was related to lake elevation and chlorophyll a (taken as surrogates for water temperature and dissolved nutrient availability, respectively), whereas mass loss of M. faya was related to chlorophyll a on day 56. These results suggest that changes in the composition of the leaf litter input and environmental conditions can affect leaf litter decomposition in Azorean lakes, with potential consequences for nutrient cycling.