Litter Decomposition Research Articles

Produktivitas Dan Laju Dekomposisi Serasah Mangrove Sonneratia Alba, Rhizophora Apiculata Dan Rhizophora Stylosa Di Taman Nasional Bali Barat

Mangrove ecosystems produce litter and act as a source of detritus. Mangrove litter will become organic material for the environment, which can indicate that the environmental conditions are fertile. The mangrove environment is fertile, which makes the chain of life. The fallen litter then enters the decomposition process assisted by organisms such as macrozoobenthos and several other animals. In the decomposition process there are several influencing factors such as sunlight, water, substrate and other natural factors. The purpose of this study was to determine which litter productivity and decomposition rate was the highest from Sonneratia alba, Rhizophora apiculata and Rhizophora stylosa in West Bali National Park. This research was conducted for 2 months, starting in January 2021, by taking and measuring samples for 2 weeks. The method of determining the point using purposive sampling. Data analysis for litter productivity by calculating the average dry weight of litter (after oven) and decomposition rate with litter reduction every week (after oven). Productivity Sonneratia alba (3.33 g/week), Rhizophora apiculata (3.83 g/week), Rhizophora stylosa (3.05 g/week). Decomposition rate of Rhizophora stylosa (1.85 g/week), Sonneratia alba (1.71 g/week), and Rhizophora apiculata (1.39 g/week).

Effects of Land Use on Millipede Communities (Subphyllum Myriapoda, Class Diplopoda): A Review

Abstract Millipedes are soil macrodetritivores with considerable roles in decomposing organic matter and recycling nutrients. This paper aims to identify the effects of land use on millipedes based on a literature review. Land use changes impact species distribution, diversity, and behavior with consequences for litter decomposition and soil quality. Surrounding landscapes influence the millipedes’ community structure. The effects of land use under different ecological contexts and in wetlands and woody riparian zones constitute essential gaps in knowledge.

Considering the autogenic processes of the ecosystem to analyze the sensitivity of peatland carbon accumulation to temperature and hydroclimate change

Peatland carbon accumulation plays a vital role in the global carbon pool and climate change dynamics. However, understanding how peatland carbon accumulation responds to climate change is challenging due to the influence of autogenic processes on carbon dynamics. In this study, we investigate the temporal variations of the Non-autogenic Carbon Accumulation Rate (NCAR) over approximately 1500 years in a peatland located in the Amur River Basin. To remove the effects of autogenic processes, we use conceptual models of peat development and employ plant macrofossils to identify vegetation changes, particularly the fen-bog phase transition. We apply different exponential decay models to capture autogenic processes in the fen and bog phases of the peatland. Subsequently, we analyze the sensitivity of peatland carbon accumulation to temperature and hydroclimate changes in the fen and bog phases, respectively. Our findings show that in the fen phase, higher temperature increases plant litter decomposition more than the plant net primary productivity (NPP) when water content is high, leading to lower NCAR. However, as temperature rises and water content is no longer a limiting factor, plant NPP surpasses plant litter decomposition, resulting in high NCAR. In the bog phase, we find no significant correlation between NCAR and precipitation but observe a positive relationship between NCAR and temperature. These results enhance our understanding of the connections between temperature, moisture, and peatland carbon accumulation by considering the influence of autogenic processes.

Tree mycorrhizal type regulates leaf and needle microbial communities, affects microbial assembly and co-occurrence network patterns, and influences litter decomposition rates in temperate forest

BackgroundTree mycorrhizal types (arbuscular mycorrhizal fungi and ectomycorrhizal fungi) alter nutrient use traits and leaf physicochemical properties and, thus, affect leaf litter decomposition. However, little is known about how different tree mycorrhizal species affect the microbial diversity, community composition, function, and community assembly processes that govern leaf litter-dwelling microbes during leaf litter decomposition. MethodsIn this study, we investigated the microbial diversity, community dynamics, and community assembly processes of nine temperate tree species using high-resolution molecular technique (Illumina sequencing), including broadleaved arbuscular mycorrhizal, broadleaved ectomycorrhizal, and coniferous ectomycorrhizal tree types, during leaf litter decomposition.Results and discussionThe leaves and needles of different tree mycorrhizal types significantly affected the microbial richness and community composition during leaf litter decomposition. Leaf litter mass loss was related to higher sequence reads of a few bacterial functional groups, particularly N-fixing bacteria. Furthermore, a link between bacterial and fungal community composition and hydrolytic and/or oxidative enzyme activity was found. The microbial communities in the leaf litter of different tree mycorrhizal types were governed by different proportions of determinism and stochasticity, which changed throughout litter decomposition. Specifically, determinism (mainly variable selection) controlling bacterial community composition increased over time. In contrast, stochasticity (mainly ecological drift) increasingly governed fungal community composition. Finally, the co-occurrence network analysis showed greater competition between bacteria and fungi in the early stages of litter decomposition and revealed a contrasting pattern between mycorrhizal types.ConclusionOverall, we conclude that tree mycorrhizal types influence leaf litter quality, which affects microbial richness and community composition, and thus, leaf litter decomposition.

The microbial contribution to litter decomposition and plant growth.

Soil and plant roots are colonized by highly complex and diverse communities of microbes. It has been proposed that bacteria and fungi have synergistic effects on litter decomposition, but experimental evidence supporting this claim is weak. In this study, we manipulated the composition of two microbial kingdoms (Bacteria and Fungi) in experimental microcosms. In microcosms that were inoculated with fungi, litter loss was 47% higher than in microcosms that were not inoculated or only inoculated with bacteria. Combined inoculation with both bacteria and fungi did not significantly enhance decomposition compared with the fungi-only treatments, and, as such, we found no evidence for complementary effects using our experimental setup. Inoculation with fungi also had a positive impact on plant growth after 4 and 8 weeks (480% and 710% growth stimulation, respectively). After 16 weeks, plant biomass was highest in microcosms where both bacteria and fungi were present pointing to fungal-bacterial complementarity in stimulating plant growth. Overall, this study suggests that fungi are the main decomposers of plant litter and that the inoculated fungi contribute to plant growth in our experimental system.

Effects of flow reduction and artificial light at night (ALAN) on litter decomposition and invertebrate communities in streams: A flume experiment

River ecosystems are heavily impacted by multiple stressors, where effects can cascade downstream of point sources. However, a spatial approach to assess the effects of multiple stressors is missing. We assessed the local and downstream effects on litter decomposition, and associated invertebrate communities of two stressors: flow reduction and artificial light at night (ALAN). We used an 18-flow-through mesocosm system consisting of two tributaries, where we applied the stressors, merging in a downstream section. We assessed the changes in decomposition rate and invertebrate community structure in leaf bags. We found no effect of ALAN or its interaction with flow reduction on the litter decomposition or the invertebrate community in the tributaries. Flow reduction alone led to a 14.8 % reduction in decomposition rate in the tributaries. We recorded no effect of flow reduction on the macroinvertebrates community composition in the litter bags. We also observed no effects of the spatial arrangement of the stressors on the litter decomposition and macroinvertebrate community structure downstream. Overall, our results suggest the impact of stressors on litter decomposition and macroinvertebrate communities remained local in our experiment. Our work thus calls for further studies to identify the mechanisms and the conditions under which spatial effects dominate over local processes.

A 5-and a-half-year-experiment shows precipitation thresholds in litter decomposition and nutrient dynamics in arid and semi-arid regions

AbstractPrecipitation is a key driver of litter decomposition in arid/semiarid regions; where soils are poor in organic matter, and thus re-incorporation of litter is key for soil nutrient accumulation and soil structure. It remains unclear, though, whether litter decomposition responds symmetrically to precipitation variation (e.g., if precipitation surpluses produce a stimulatory effect of a similar magnitude, but opposite direction to inhibitory effects of precipitation deficits), and whether litter decomposition and litter nutrient dynamics in arid and semiarid ecosystems that differ in climate show similar responses to precipitation. We set up a 5-and-a-half-year experiment that manipulated rainfall along a gradient (7 treatments): increases by 20%, 40%, and 60%, background precipitation, and reductions by the same 3 percentages. We applied such experiment in two sites with different pattens of precipitation (Urat: arid; and Naiman: semiarid) in Inner Mongolia to elucidate our questions. Litter mass loss and all nutrients that we measured (carbon, nitrogen, phosphorous, potassium, plus lignin) decomposed faster at the highest level of surplus precipitation, and more slowly in the two largest precipitation reductions. This indicates that these levels of precipitation constitute thresholds (value of precipitation beyond which ecosystem function is critically altered). Litter decomposition in the semiarid site was faster and more complete, but decomposition in the direr Urat was more efficient per unit cumulative rainfall. Thus, site specific effects played an important role in decomposition. Reductions in precipitation decreased the loss of C, N, P, K, and lignin from litter; and clear precipitation thresholds in the dynamic of these nutrients in litter were observed. Overall, this indicated the importance of precipitation limitation at controlling nutrient release. Our study highlights the importance of long-term studies on litter decomposition in environments with slow decomposition rates, and the importance of taking into account mechanistic effects of water availability on decomposition.

Insects in the city: Determinants of a contained aquatic microecosystem across an urbanized landscape.

Cities can have profound impacts on ecosystems, yet our understanding of these impacts is currently limited. First, the effects of the socioeconomic dimensions of human society are often overlooked. Second, correlative analyses are common, limiting our causal understanding of mechanisms. Third, most research has focused on terrestrial systems, ignoring aquatic systems that also provide important ecosystem services. Here we compare the effects of human population density and low-income prevalence on the macroinvertebrate communities and ecosystem processes within water-filled artificial tree holes. We hypothesized that these human demographic variables would affect tree holes in different ways via changes in temperature, water nutrients, and the local tree hole environment. We recruited community scientists across Greater Vancouver (Canada) to provide host trees and tend 50 tree holes over 14 weeks of colonization. We quantified tree hole ecosystems in terms of aquatic invertebrates, litter decomposition, and chlorophyll a (chl a). We compiled potential explanatory variables from field measurements, satellite images, or census databases. Using structural equation models, we showed that invertebrate abundance was affected by low-income prevalence but not human population density. This was driven by cosmopolitan species of Ceratopogonidae (Diptera) with known associations to anthropogenic containers. Invertebrate diversity and abundance were also affected by environmental factors, such as temperature, elevation, water nutrients, litter quantity, and exposure. By contrast, invertebrate biomass, chl a, and litter decomposition were not affected by any measured variables. In summary, this study shows that some urban ecosystems can be largely unaffected by human population density. Our study also demonstrates the potential of using artificial tree holes as a standardized, replicated habitat for studying urbanization. Finally, by combining community science and urban ecology, we were able to involve our local community in this pandemic research pivot.

Functional redundancy across space and time in litter‐degrading fungal communities

AbstractIntroductionMicrobial‐driven litter decomposition contributes significantly to global carbon (C) turnover. Fungi play central roles in the degradation process due to their ability to hydrolyse recalcitrant litter components. The spatiotemporal variations in taxonomic composition of litter‐degrading fungi have been well documented. However, associated variations in litter‐degradation‐related functional composition of fungal communities remain unexplored.Materials and MethodsIn this study, a 16‐week field‐based buried rice straw experiment was conducted at three experimental sites across subtropical China in combination with laboratory 13C‐straw‐based DNA stable‐isotope probing (DNA‐SIP) microcosm experiments. Amplicon sequencing combined with shotgun metagenomic sequencing were the approaches of choice.ResultsThe field experiment showed that the taxonomic composition of the straw‐degrading fungal community was highly variable while the functional composition was rather stable. The higher permutational multivariate analysis of variation F scores (20.904−48.660) and the steeper slopes (1.92 E‐04−4.15E‐04) of the distance decay relationship for taxonomic composition than for function across periods (with lower F scores = 7.047−21.601 and gradual slopes = −1.33 E‐05 to −1.03E‐04) both indicated that the spatiotemporal patterns of functional composition in litter‐degrading fungi community were more conserved. The laboratory DNA‐SIP confirmed the field observations and showed that the conserved functional composition in litter‐degrading fungi was underpinned by a high functional redundancy of Basidiomycota.ConclusionFunction and taxonomy of litter‐degrading fungi were decoupled. The functional composition of the litter‐degrading fungal community was highly conserved in space and time, the taxonomic composition less so. The main drivers behind the observed taxonomic decoupling are probably/most likely functional redundancy and metabolic niche selection resulting in conservation of function, with changing environmental conditions and dispersal limitation drove the observed high taxonomic turnover of the community over the course of the litter degradation progression. Our study provides valuable insights in the ecology of fungi and their roles in in global C sequestration for ecosystem sustainable development.

Effect of bacterial community succession on environmental factors during litter decomposition of the seaweed Gracilaria lemaneiformis

In large-scale seaweed farming, an understanding of the decomposition process plays a pivotal role in optimizing cultivation practices by considering the influence of the bacterial community. Therefore, we assessed the bacterial community structure and its influence on environmental factors during Gracilaria lemaneiformis decomposition, utilizing both microcosms and in-situ simulations. The decomposition rates in the microcosms and in situ simulations reached 79 % within 180 days and 81 % within 50 days, respectively In the microcosms, the dissolved oxygen content decreased from 5.3 to 0.4 mg/L, while the concentrations of total organic carbon, nitrogen, and phosphorus in the water increased by 165 %, 1636 %, and 2360 %, respectively. The common dominant bacteria included Proteobacteria, Planctomycetes, Firmicutes, Bacteroidetes, and Spirochaetae. Planctomycetes and Firmicutes were positively correlated with the total organic carbon, nitrogen, and phosphorus concentrations. Planctomycetes species played significant roles during the decomposition process. The overall findings of this study could inform more sustainable seaweed cultivation practices.

Functional Diversity Accelerates the Decomposition of Litter Recalcitrant Carbon but Reduces the Decomposition of Labile Carbon in Subtropical Forests

The biodiversity of litter can regulate carbon and nutrient cycling during mixed decomposition. It is common knowledge that the decomposition rates of mixed litters frequently deviate from those predicted for these component litter species. However, the direction and magnitude of the nonadditive effects on the degradation of mixed litters remain difficult to predict. Previous studies have reported that the different carbon fractions of leaf litters responded to litter mixture differently, which may help to explain the ambiguous nonadditive effect of diversity on bulk litter decomposition. Therefore, we conducted decomposition experiments on 32 litter mixtures from seven common tree species to test the responses of different carbon fractions to litter diversity in subtropical forests. We found that the overall mass loss of the mixed litter was faster than that estimated from single species. The relative mixing effects (RMEs) of different carbon fractions exhibited different patterns to litter diversity and were driven by different aspects of litter functional dissimilarity. Soluble carbon fractions decomposed more slowly than expected from single species, while lignin fractions decayed more quickly. Moreover, we found that the RMEs of bulk litter decomposition may be determined by the lignin fraction decomposition. Our findings further support that distinguishing the response of different carbon fractions to litter diversity is important for elucidating the nonadditive effects of total litter decomposition.

Effects of environmental factors on leaf litter decomposition of three species of Stipa

Plant litter decomposition plays an important role in carbon and nutrient cycling in terrestrial ecosystems. The influence of abiotic factors on the decomposition of plants in humid ecosystems is higher due to the favorable moisture conditions and the abundance of decomposer microorganisms. However, in arid and semi-arid ecosystems, plant litter decomposition is influenced by both abiotic and biotic factors, depending on sparse plant cover, high soil temperature, and low rainfall. The effects of environmental factors on leaf litter decomposition in arid and semi-arid Mongolian steppes are unclear. A field experiment was carried out in meadow steppe, typical steppe, and desert steppes of Mongolia to investigate the effect of environmental factors such as light-expose, shade, and climate conditions on three species of Stipa (Stipa baicalensis, Stipa grandis, Stipa gobica) representing different litter qualities over a two year of incubation (6, 12, 18 and 24 months). The results of the study revealed that the leaf litter decomposition rate differed among the three species, in which Stipa gobica had a relatively high leaf litter decomposition rate. Also, the rate of leaf decomposition of Stipa gobica was directly and indirectly correlated with leaf traits, while it was positively correlated to climatic conditions (r=0.55). However, for Stipa baicalensis, was negatively correlated to leaf traits (r=-0.56 – -0.63) and on the contrary, Stipa grandis was strongly positively correlated to leaf traits (r=0.68-0.89). Seasonality has an effect on the leaf litter decomposition, with the highest decomposition rate occurring from April to October, while the decomposition rate was very low from November to March. Гурван зүйл хялганын навчны задралд хүрээлэн буй орчны хүчин зүйлсийн үзүүлэх нөлөө Хураангуй. Ургамлын задрал нь хуурай газрын экосистем дэх нүүрстөрөгч болон шим тэжээлийн бодисын эргэлтэд чухал үүрэг гүйцэтгэдэг. Чийглэг экосистемийн ургамлын задралд абиотик хүчин зүйлийн нөлөө их байдаг нь чийгийн таатай нөхцөл, задлагч микрорганизм их байдагтай холбоотой. Харин хуурай болон хагас хуурай экосистемийн хувьд ургамлын бүрхэвч сийрэг, хөрсний температур өндөр, хур тунадасны хэмжээ бага байдгаас хамаарч ургамлын задралд абиоток, биотик хүчин зүйл нөлөөлдөг. Хуурай болон хагас хуурай Монгол орны нугажуу, хуурай болон цөлөрхөг хээрийн ургамлын навчны задралд хүрээлэн буй орчны хүчин зүйлс хэрхэн нөлөөлж байгаа нь тодорхойгүй хэвээр байна. Тиймээс энэхүү судалгааны ажлаар нугажуу хээр, хуурай хээр болон цөлөрхөг хээрийн зонхилогч үетэн ургамал болох гурван зүйл хялганын (Stipa baicalensis, Stipa grandis, Stipa gobica) навчны задралд хүрээлэн буй орчны хүчин зүйлс болон ургамлын шинж чанар хэрхэн нөлөөлж буй болон бүлгэмдэл хоорондын ялгааг илрүүлэх зорилготой ажиллалаа. Бид туршилтыг гэрэлтэй болон сүүдэрлэсэн хоёр хувилбартай 2 жилийн хугацаанд 4 удаагийн дээж хураалттай (6, 12, 18 болон 24 сар) хийж гүйцэтгэсэн. Судалгааны үр дүнд ургамлын навчны задрал нь хялганын гурван зүйл хооронд ялгаатай бөгөөд үүнээс Stipa gobica-ийн навчны задралын хурд харьцангуй өндөр болохыг тогтоов. Мөн Stipa gobica зүйлийн навчны задралын хурд нь навчны шинж чанараас эерэг болон сөрөг хамаарч байсан бол цаг уурын үзүүлэлтүүдтэй эерэг (r=0.55) хамааралтай байсан. Харин Stipa baicalensis зүйлийн хувьд навчны шинж чанараас сөрөг (r=-0.56 – -0.63) хамааралтай, Stipa grandis зүйлийн тухайд навчны шинж чанараас эерэг хүчтэй хамааралтай байна (r=0.68-0.89). Ургамлын навчны задралд улирлын байдал нөлөөтэй бөгөөд 4-р сараас 10-р сарын хооронд задралын хэмжээ хамгийн өндөр байсан бол 11-р сараас 3-р сар хүртэл задралын хурд маш бага байв. Үүнээс харахад нугажуу хээр болон хуурай хээрийн ургамлын задрал тухайн ургамлын шинж чанараас хамаардаг бол цөлөрхөг хээрийн ургамлын задралд хүрээлэн буй орчны хүчин зүйлс чухал нөлөөтэй байна. Түлхүүр үгс: Хялгана, навчны задрал, нарны гэрэл, сүүдэр, навчны шинж чанар, нугажуу хээр, хуурай хээр, цөлөрхөг хээр

Differences in carbon, nitrogen and phosphorus release of decomposed branch litter due to potential sea level rise

Influences of potential sea level rise on the carbon, nitrogen and phosphorus release of decomposed branch litter (an important component of the total litter production) in mangrove forests have seldom been reported. In the present study, differences in carbon, nitrogen and phosphorus release of decomposed branch litter due to potential sea level rise were analyzed at three sites with different inundation situations, simulating tidal flooding situations with rising sea level of 0, 40 and 80 cm (R0, R40 and R80). Sea level rise significantly decreased mean decomposition rate of branch litter, while dry weight loss rate of branch litter was not significantly changed with rising sea level. Release percentage of carbon, nitrogen and phosphorus in branch litter within 50 weeks of decomposition at site R0 was approximately 35%, 32% and 60%, respectively. Compared with site R0, changes in mean decomposition rate caused by sea level rise resulted in lower release rates of carbon, nitrogen and phosphorus in branch litter at site R40 and site R80. These results suggested that ecological role of nutrient (carbon, nitrogen and phosphorus) release through branch litter decomposition on mangrove forests and adjacent coastal ecosystems should be considered. Sea level rise will reduce the chance of carbon, nitrogen and phosphorus in branch litter to be transferred into adjacent coastal ecosystems through branch litter decomposition.

Unveiling the impacts moso bamboo invasion on litter and soil properties: A meta-analysis

Moso bamboo invasion potentially alters litter, soil properties and soil microbial communities in forest ecosystems. However, the overall direction and magnitude of this alteration at a large spatial scale remain unclear. Here, we conducted a meta-analysis of 72 experimental studies on the impact of moso bamboo invasion on litter, soil physicochemical properties, and soil microbial communities. Overall, the moso bamboo invasion increased litter decomposition, soil pH, and NH4+-N, while concurrently leading to a decrease in soil bulk density, soil electrical conductivity, soil TN: TP ratio, soil NO3−-N, and available potassium. Moreover, we observed that the invasion significantly enhanced soil microbial biomass nitrogen, fungal ACE diversity index, fungal biomass, and bacterial Shannon diversity index, while decreasing the ratio of Gram-positive to Gram-negative bacteria and the biomass of Gram-positive bacteria. Furthermore, we identified the primary factors influencing specific soil properties and microbial community responses to moso bamboo invasion. Specifically, the response of NH4+-N, NO3−-N, soil bulk density, fungal diversity and pH were found to be primarily influenced by climatic factors (mean annual temperature, mean annual precipitation), topographic factors (aspect), and invasion stage, respectively. In addition, we further revealed a close relationship between soil physicochemical properties and microbial communities during moso bamboo invasion. Specifically, the response of soil microbial biomass nitrogen was positively correlated with the responses of soil organic nitrogen and total nitrogen content, Gram-positive bacteria biomass was positively correlated with soil total nitrogen but negatively correlated with soil pH. Meanwhile, soil bacterial diversity showed a significant positive correlation with soil pH but exhibited a negative correlation with soil SOC. Our study suggests that macro-climatic conditions, local microenvironment, and invasion stage co-regulate the important effects of moso bamboo invasion on litter, soil physicochemical properties, and microbial communities.

Taxonomy and evolution history of two new litter-decomposing Ciliochorella (Amphisphaeriales, Sporocadaceae).

The genus Ciliochorella is a group of pestalotioid fungi, which typically occurs in subtropical and tropical areas. Species from the Ciliochorella genus play important roles in the decomposition of litter. In this study, we introduce two new species (Ciliochorellachinensissp. nov. and C.savannicasp. nov.) that were found on leaf litter collected from savanna-like vegetation in hot dry valleys of southwestern China. Phylogenetic analyses of combined LSU, ITS and tub2 sequence datasets indicated that C.chinensis and C.savannica respectively form a distinct clade within the Ciliochorella genus. The comparison of the morphological characteristics indicated that the two new species are well differentiated within this genus species. Analysis of the evolutionary history suggests that Ciliochorella originated from the Eurasian continent during the Paleogene (38 Mya). Further, we find that both new species can produce cellulase and laccase, playing a decomposer role.

Macrofauna amplify plant litter decomposition and stabilization in arctic soils in a warming climate

The soil organic carbon (SOC) pool of the Arctic region is currently protected by low temperatures, but is likely to decrease due to greater organic matter (OM) decomposition under a warmer climate. Negative feedback for climate warming can, however, be reversed by SOC accrual as climate warming leads to shifts in arctic vegetation (from grass to shrub) and soil faunal (introduction of macrofauna) communities affecting plant-soil C allocation. To decipher these contrasting effects, we performed a laboratory experiment with soils from dry tundra to test the interacting effects of plant litter quality (high-quality grass litter vs. the intermediate- and low-quality litter of shrubs) and soil fauna functional grouping (micro-, meso- and macrofauna [millipede]) on the processes of litter decomposition and OM stabilization.Our findings showed that macrofauna largely promoted decomposition of shrub litter, while soil micro- and mesofauna were mainly responsible for the decomposition of grass litter. Our study thus confirmed that, when introduced and established in a warmer Arctic, macrofauna may become an important agent in shrub litter decomposition. Our data also showed that with shrub litter, higher C content was stabilized as particulate OM (POM) in aggregates, whereas in grass litter and low-quality shrub litter, higher C content was stabilized as mineral-associated OM (MAOM). Both these effects were larger in the presence of macrofauna and with a higher abundance of fungi. This suggests that consequent shrub OM stabilization in occluded POM and MAOM fractions will be carried out jointly by macrofauna and fungi, which will probably lead to more efficient OM stabilization in Arctic soils than in the case of grass litter OM stabilization by micro- and mesofauna and bacteria. In conclusion, our study suggests that vegetation changes and the introduction of macrofauna in a warming climate will most probably lead to higher OM stabilization in Arctic soils.

Vegetation-cover control of between-site soil temperature evolution in a sandy desertland

Vegetation has an important influence on soil temperature (ST). However, the possible effects of surface vegetation on ST and their feedback on microclimate remain uncertain due to the lack of in-situ and long-term environmental records, especially for arid and semiarid regions of the world. A continuous, two-year study was implemented over a bare sand dune (BF) and two scrub-vegetation sites of variable cover in the Mu Us Desert of northwest China. Surface vegetation at the two non-bare sites varied from about 40% (moderate cover, MF) and 80 % (high cover, HF) of their respective surface area. Depiction of the vertical ST-profile was based on an array of field-based measurements taken within the uppermost 180 cm of the soil complex at each site. Compared with the BF site, mean ST at MF and HF decreased by 1.2 and 1.6 °C during the uniform thaw period and increased by 0.1 and 1 °C during uniform freezing. Amplitude of seasonal variation in ST for both vegetated sites, i.e., MF and HF, was reduced by 2.4 and 4.9 °C, respectively. As soil cooling during the uniform thaw period was greater than soil warming during uniform freezing, annual mean ST decreased at both vegetated sites by 1.6 and 1.2 °C (for MF and HF, respectively) compared to ST at BF. Differences in ST among the three sites during the uniform freeze and thaw periods were exponentially correlated with the extent of site vegetation cover, leaf area index, aboveground biomass, and on-the-ground litter thickness. Vegetation cover was shown to reduce the depth of the frost layer by 30 cm and prolonged the uniform thaw period by 1–35 days at the HF site. Mean daily STs at the center of each soil layer at the three sites were simulated with a two-equation model developed for this study, yielding a coefficient of determination (R2) of 0.91 when modeled STs were compared against their corresponding field observations. Increases in winter ST has potential to safeguard ground-dwelling grubs and other agriculturally harmful insects from freezing and dying. Likewise, decreases in annual ST could help promote decreases in litter decomposition, potentially lessening the effects of wind erosion.

Chronic anthropogenic disturbance alters litter decomposition and nutrient concentrations and stocks across a Caatinga dry forest chronosequence

Litter decomposition plays a key role in the cycling and storage of nutrients in terrestrial ecosystems. However, very little is known about decomposition processes and their underlying drivers in tropical dry forests, particularly in human-modified landscapes. Here, we evaluate decomposition rates and nutrient concentrations and stocks in the litter of a Caatinga dry forest chronosequence, in northeast Brazil. Litter decomposition was monitored for a year across forest stands of varying ages and old-growth forests. The litter decomposition rate was highly variable across forest stands, although on average decomposition occurred slowly, with approximately 50% of the initial litter mass still present after one year. The decomposition rate is responsive to forest type and negatively affected by chronic disturbance. Litter nutrient concentration decreased along the decomposition process, exhibiting a nutrient-specific mineralization rate. Response to drivers was also nutrient specific, with precipitation and chronic disturbances playing prominent roles. Nutrient stocks in the remaining litter were higher in old-growth forests, and final stocks of certain nutrients also responded to multiple drivers. Our results suggest that the Caatinga dry forest experiences a slow rate of litter decomposition and mineralization, although rates exhibit considerable variability across forest stands and environmental conditions. Thus, chronic disturbance plays a role by either facilitating or reducing litter decomposition, mineralization rate, and the stocks transferred to the soil. Consequently, these factors have implications for nutrient availability, including goat consumption and subsequent loss of nutrients.

Climate warming enhances microbial network complexity by increasing bacterial diversity and fungal interaction strength in litter decomposition

Microbial communities are important drivers of plant litter decomposition; however, the mechanisms of microbial co-occurrence networks and their network interaction dynamics in response to climate warming in wetlands remain unclear. Here, we conducted a 1.5-year warming experiment on the bacterial and fungal communities involved in litter decomposition in a typical wetland. The results showed that warming accelerated the decomposition of litter and had a greater effect on the diversity of bacteria than on that of fungi. Dominant bacterial communities, such as Bacteroidia, Alphaproteobacteria, and Actinobacteria, and dominant fungal communities, such as Leotiomycetes and Sordariomycetes, showed significant positive correlations with lignin and cellulose. Co-occurrence networks revealed that the average path length and betweenness centrality under warming conditions increased in the bacterial community but decreased in the fungal community. Both bacterial and fungal networks in the 2.0 °C warming treatment had the highest ratio of positive links (58.53 % and 98.14 %), indicating that moderate warming can promote the positive correlations and symbiotic relationships observed in the microbial community. This also suggests that small-world characteristics and weak-link advantages accelerate diffusion, and scale-free features facilitate propagation in microbial communities in response to climate warming. Logistic growth and Lotka-Volterra competition models revealed that climate warming enhances microbial network complexity mainly by increasing bacterial diversity and fungal interaction strength in litter decomposition. However, the symbiotic relationship decreased slightly under 4.0 °C warming, indicating that climate warming is a random attack rather than a targeted attack, and the microbial network has strong resistance to random attack, as shown by the highly robust dynamic performance of the microbial network in litter decomposition. Overall, the microbial community in litter decomposition responded to climate warming and shifted its network interactions, leading to further changes in emergent network topology and dynamics, thus accelerating litter decomposition in wetlands.

Soil phosphorus fractions dynamics along a 22-ka chronosequence of landslides, western Sichuan, China

Landslides significant influence on bedrock weathering, pedogenesis, and ecological succession, thereby playing a pivotal role in driving biogeochemical cycles. Landslide chronosequences have traditionally served as invaluable study systems for investigating vegetation succession and exploring soil development and nutrient dynamics. In this study, we analyzed soil phosphorus fractions across a 22,000-year landslide chronosequence. Our investigation examined the impact of environmental factors on these fractions and elucidated the supply of bioavailable phosphorus. Our findings revealed a decline in the concentration of all phosphorus fractions with soil age. Notably, even at an age exceeding 22,000 years, primary mineral phosphorus constituted 23 % of the total phosphorus pool at the later stages of soil development, while organic phosphorus accounted for a mere 7 %. This discrepancy can be attributed to frequent landslides replenishing phosphorus stocks. These findings indicate that the Walker and Syers model may not adequately anticipate alterations in soil phosphorus fractions under geologically unstable landscapes. Environmental factors had limited impact on primary mineral phosphorus concentrations. Yet, they significantly influenced occluded and nonoccluded phosphorus. Changes in organic phosphorus concentrations cannot be fully explained by the examined environmental factors, as organic phosphorus in the soil primarily originates from plant litter decomposition. The sources of bioavailable phosphorus in the investigated region were elucidated using structural equation modeling. The bioavailable phosphorus in the study area is mainly derived from nonoccluded phosphorus rather than organic phosphorus. This observation can be attributed to the distinct landform conditions, which sustain elevated levels of primary mineral phosphorus during soil development. Consequently, the continuous availability of nonoccluded phosphorus ensures a reliable supply of bioavailable phosphorus. In conclusion, the landslide chronosequence serves as a vital example of long-term ecosystem development under unstable landforms. Its refinement of the Walker and Syers model under unstable landscapes.