Litter Mass Research Articles

干旱与半干旱区灌丛微生境中红砂枯落物分解特征及中小型节肢动物的作用

PDF HTML阅读 XML下载 导出引用 引用提醒 干旱与半干旱区灌丛微生境中红砂枯落物分解特征及中小型节肢动物的作用 DOI: 10.5846/stxb202111193261 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 宁夏自然科学基金项目（2021AAC03047，2020AAC02014）；宁夏重点研发计划项目（2021BEG03007）；国家自然科学基金项目（41867005） The decomposition process of Reaumuria soongorica litter and the role of microarthropods in shrub microhabitats in arid and semi-arid regions Author: Affiliation: 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:在干旱区（内蒙古乌拉特后旗）和半干旱区（宁夏盐池）荒漠草原区，选择柠条灌丛内外微生境为研究样地，以红砂枯落物为研究对象，利用2种规格网孔分解袋（30目和250目网孔），探索中小型节肢动物在红砂枯落物分解过程中的作用规律，研究灌丛微生境中红砂枯落物质量损失变化特征及节肢动物群落的贡献。结果表明：（1）在干旱与半干旱区，红砂枯落物分解常数K均表现为灌丛内外微生境间无显著差异，且有无节肢动物参与对K的影响均较小。（2）分解至12个月时，无节肢动物参与的情况下，干旱与半干旱区红砂枯落物残留率均表现为裸地显著低于灌丛；但有节肢动物参与时，枯落物残留率则表现为灌丛内外微生境间无显著差异。分解至44个月时，无节肢动物参与的情况下，仅在干旱区枯落物残留率表现为裸地显著高于灌丛；而有节肢动物参与时，干旱与半干旱区枯落物残留率均表现为灌丛内外微生境间无显著差异。（3）节肢动物对红砂枯落物质量损失的贡献率呈现单峰值现象，且在分解至24个月时达到峰值。枯落物分解至12个月时，仅半干旱区节肢动物对红砂枯落物分解的贡献率表现为裸地显著低于灌丛；分解至44个月时，仅干旱区节肢动物对红砂枯落物分解的贡献率表现为裸地显著高于灌丛。（4）在半干旱区，节肢动物对红砂枯落物质量损失的贡献率与节肢动物类群数、土壤砂粒含量、土壤全碳和含水量密切相关；而在干旱区，节肢动物对红砂枯落物质量损失的贡献率与土壤pH值、土壤砂粒、土壤碳氮比d （C/N）和黏粉粒含量密切相关。综合表明，干旱和半干旱区灌丛微生境红砂枯落物分解特征受到节肢动物分解作用的影响较小；但在某些分解阶段，灌丛内外微生境中红砂枯落物质量损失的差异性受到节肢动物分解作用的显著影响，节肢动物的分解作用表现为弱（12个月）-强（24个月）-弱（44个月）的作用规律，而且受到气候区调节的灌丛微生境限制。 Abstract:In desertified grasslands of the arid Urad Rear Banner of the Inner Mongolia and the semi-arid Yanchi of Ningxia, the Caragana korshinskii shrub microhabitats beneath shrub canopies and in the open spaces were setup as study sites. The litter of Reaumuria soongorica was used as the research object. Two sizes of mesh (30-mesh, and 250-mesh) for litter bags were used to explore the role of soil microarthropods on litter decomposition of Reaumuria soongorica. The objective of present study was to probe into the mass loss of the litter and the contribution of soil microarthropod community in the shrub microhabitats. The results showed that:(1) there was no significant difference in decomposition constant K of litter between shrub canopy and open spaces; the presence or absence of microarthropods had little effect on K. (2) At decomposition stage of 12 months, there was significantly lower mass remaining rate of the litter in open spaces than beneath shrub canopy without the presence of microarthropods, but there was no significant difference between shrub canopy and open spaces in the case of microarthropods presence. At decomposition stage of 44 months, the mass remaining rate of litter was significantly higher in open spaces than beneath shrub canopy only in arid regions without the participation of microarthropods; however, there was no significant difference between both shrub microhabitats with microarthropod presence in both arid and semi-arid regions. (3) The contribution rate of microarthropods to the mass loss of litter showed a unimodal type during decomposition process, with a single peak at 24 months. At decomposition stage of 12 months, there was significantly lower contribution rate of microarthropods to the decomposition of litter in open spaces than beneath shrub canopy only in semi-arid region. At decomposition stage of 44 months, the contribution rate of microarthropods to the decomposition of litter was significantly higher in open spaces than beneath shrub canopy only in arid region. (4) In the semi-arid region, the contribution rate of microarthropods to litter mass loss was closely correlated to the group richness of microarthropod, soil sand content, soil total carbon, and water content. In the arid region, however, the contribution rate of microarthropods to the mass loss of litter was closely correlated to soil pH, soil sand, soil C/N, and clay and silt content. In conclusion, the overall litter decomposition in shrub microhabitats in arid and semi-arid regions was little affected by the role of microarthropods. However, at certain decomposition stages, the difference in mass loss of the litter between shrub microhabitats was affected remarkably by the role of microarthropods. There was a law of weak (12 months)-strong (24 months)-weak (44 months) role of microarthropods on litter decomposition that was regulated by the climatic factors. 参考文献 相似文献 引证文献

Regulation of initial soil environmental factors on litter decomposition rate affects the estimation accuracy of litter mass loss in a subtropical forest

Regulation of initial soil environmental factors on litter decomposition rate affects the estimation accuracy of litter mass loss in a subtropical forest

Clipping decreases plant cover, litter mass, and water infiltration rate in soil across six plant community sites in a semiarid grassland

Water infiltration in the soil is a crucial hydrological function in the land water cycle, especially in the semiarid region where water is relatively scarce. The semiarid grassland in Northern China represents the regional vegetation in the vast area of Eurasian continent and is sensitive to land use change. However, no clear patterns exist regarding the comprehensive examination of water infiltration in relation to clipping across six plant community sites. This study aimed to test the effect of clipping and plant community sites, which were dominated by Agropyron cristatum, Stipa krylovii, Leymus chinensis, Potentilla tanacetifolia, Artemisia frigida, or Lespedeza davurica, on the water infiltration rate in the semiarid grassland. Clipping significantly decreased the water initial, steady, and average infiltration rates by 39.13, 4.36, and 12.46 mm h−1, respectively, across the six plant community sites. Clipping-induced changes in the average infiltration rate positively correlated with the changes in the plant cover (r = 0.60, P < 0.01), litter mass (r = 0.53, P < 0.01), forb functional group ratio (r = 0.46, P = 0.03), and total porosity (r = 0.49, P = 0.02), and negatively with water-holding capacity (r = −0.45, P = 0.03). Further, the water infiltration rate significantly differed among the six plant community sites. The L.davurica site had the highest water initial infiltration rate with a value of 137.63 ± 17.76 mm h−1, while the L. chinensis site had the lowest rate with a value of 74.08 ± 5.26 mm h−1. Principal component analysis showed that the total porosity, litter mass, plant cover, and forb functional group ratio were the main factors affecting water infiltration rates in the control grassland. Overall, our findings suggested that local governments and herders should implement unclipping as a potential sustainable management for improving hydrological function in the semiarid grassland.

Mixed plantation regulates forest floor water retention and temperature sensitivity in restored ecosystems on the Loess Plateau, China

Ongoing warming and frequent extreme rainfall are endangering hydrological functioning in reforested ecologically vulnerable areas. The forest floor plays an important role in water conservation; however, knowledge of water retention of forest floor and its temperature sensitivity under climate change remains limited particularly in restored ecosystems. Here, we investigated and sampled litter and topsoil from three monoculture plantations, two mixed plantations, and one natural grassland on the hilly and gullied Loess Plateau. We used an artificial climate incubator to simulate different climate conditions and measure the effects on litter and topsoil water retention. Generalized additive models were used to explore the relationships between temperature sensitivity of water-retention capacity and influencing factors. The results showed that mixed plantations shortened the water retention time of litter and topsoil. In addition, mixed plantations significantly improved the maximum water-holding capacity of litter, but reduced the maximum water-holding capacity of topsoil. Litter water-retention capacity temperature sensitivity (LTS) was significantly greater than that of soil (STS). Moreover, communities with strong LTS generally had weak STS. Nonetheless, mixed plantations tend to have a more stable forest floor water-retention capacity. Soil porosity, bulk density, litter mass, and canopy openness were the key factors affecting the maximum water-holding capacity and water-retention capacity of forest floors. Overall, our results indicated that mixed plantations adjusted the water retention time of the forest floor and had a more stable water-retention capacity, which was of great significance for plantation management in arid and semi-arid regions.

The response of litter decomposition to extreme drought modified by plant species, plant part, and soil depth in a temperate grassland.

Plant litter decomposition is a key ecosystem process in carbon and nutrient cycling, and is heavily affected by changing climate. While the direct effects of drought on decomposition are widely studied, in order to better predict the overall drought effect, indirect effects associated with various drought-induced changes in ecosystems should also be quantified. We studied the effect of an extreme (5-month) experimental drought on decomposition, and if this effect varies with two dominant perennial grasses, plant parts (leaves vs. roots), and soil depths (0-5cm vs. 10-15 cm) in a semi-arid temperate grassland. After 12 months, the average litter mass loss was 43.5% in the control plots, while only 25.7% in the drought plots. Overall, mass loss was greater for leaves (44.3%) compared to roots (24.9%), and for Festuca vaginata (38.6%) compared to Stipa borysthenica (30.5%). This variation was consistent with the observed differences in nitrogen and lignin content between plant parts and species. Mass loss was greater for deep soil (42.8%) than for shallow soil (26.4%). Collectively, these differences in decomposition between the two species, plant parts, and soil depths were similar in magnitude to direct drought effect. Drought induces multiple changes in ecosystems, and our results highlight that these changes may in turn modify decomposition. We conclude that for a reliable estimate of decomposition rates in an altered climate, not only direct but also indirect climatic effects should be considered, such as those arising from changing species dominance, root-to-shoot ratio, and rooting depth.

Impact of land use type on soil erodibility in a small watershed of rolling hill northeast China

Land use type can impact soil properties and the characteristics of plant community, which in turn likely affect soil erodibility. The irrational land use induced by the fast conversion from natural forestland to cropland certainly leads to serious soil erosion. Few studies have been conducted to assess the potential effect of land use type on soil erodibility at small watershed scale. The aim of this study was to quantify the effects of six typical land use types on soil erodibility reflected by soil penetration resistance (PR), mean weigh diameter (MWD), mean number of drop impact (MND), slaking rate (SR), soil erodibility of K factor, soil organic matter content (SOM), soil structural stability index (SSI), soil cohesion (Coh), saturated hydraulic conductivity (Ks) and an integrated comprehensive soil erodibility index (CSEI) in a small watershed of rolling hill northeast China. The results revealed that MWD, MND, SOM, Coh and Ks varied significantly with land use type, with their maximum appeared in forest belt and their minimum occurred in road. The measured PR and SR exhibited an opposite trend. The calculated K factor and SSI were relatively stable or slightly fluctuating with land use type. Significant differences were found in soil texture, bulk density, root mass density and litter mass density between different land use types. CSEI varied extremely with land use type. CSEI of road was the maximum (0.855), while transverse forest belt had the minimum one (0.136). Compared to road, CSEI decreased by 14.3%, 10.8%, 26.5%, 36.9%, 33.3% and 65.7% for maize, soybean, grassland, shrub land, woodland and longitudinal forest belt, respectively. CSEI was significantly decreased and increased linearly with root mass density and bulk density. The results provide insights to understand the differences in soil erosion under different land use types in agricultural small watershed characterized by rolling hills.

Tropical stream microcosms of isolated fungal species suggest nutrient enrichment does not accelerate decomposition but might inhibit fungal biomass production.

Terrestrial leaf litter is an essential energy source in forest streams and in many tropical streams, including Cerrado, litter undergoes biological decomposition mainly by fungi. However, there is a limited understanding of the contribution of isolated fungal species to in-stream litter decomposition in the tropics. Here we set a full factorial microcosms experiment using four fungal species (Aquanectria penicillioides, Lunulospora curvula, Pestalotiopsis submerses, and Pestalotiopsis sp.) incubated in isolation, two litter types (rapid and slow decomposing litter) and two nutrient levels (natural and enriched), all characteristics of Cerrado streams, to elucidate the role of isolated fungal species on litter decomposition. We found that all fungal species promoted litter mass loss but with contributions that varied from 1% to 8% of the initial mass. The fungal species decomposed 1.5 times more the slow decomposing litter and water nutrient enrichment had no effect on their contribution to mass loss. In contrast, fungal biomass was reduced by nutrient enrichment and was different among fungal species. We showed fungal contribution to decomposition depends on fungal identity and litter type, but not on water nutrients. These findings suggest that the identity of fungal species and litter types may have more important repercussions to in-stream decomposition than moderate nutrient enrichment in the tropics.

Fauna access outweighs litter mixture effect during leaf litter decomposition

Decomposition rates of litter mixtures reflect the combined effects of litter species diversity, litter quality, decomposers, their interactions with each other and with the environment. The outcomes of those interactions remain ambiguous and past studies have reported conflicting results (e.g., litter mixture richness effects). To date, how litter diversity and soil fauna interactions shape litter mixture decomposition remains poorly understood. Through a sixteen month long common garden litter decomposition experiment, we tested these interaction effects using litterbags of three mesh sizes (micromesh, mesomesh, and macromesh) to disentangle the contributions of different fauna groups categorized by their size at Wuhan botanical garden (subtropical climate). We examined the decomposition of five single commonly available species litters and their full 26 mixtures combination spanning from 2 to 5 species. In total, 2325 litterbags were incubated at the setup of the experiment and partly harvested after 1, 3, 6, 9, and 16 months after exposure to evaluate the mass loss and the combined effects of soil fauna and litter diversity. We predicted that litter mixture effects should increase with increased litter quality dissimilarity, and soil fauna should enhance litter (both single species litter and litter mixtures) decomposition rate. Litter mass loss ranged from 26.9 % to 87.3 %. Soil fauna access to litterbags accelerated mass loss by 29.8 % on average. The contribution of soil mesofauna did not differ from that of soil meso- and macrofauna. Incubation duration and its interactions with litter quality dissimilarities together with soil fauna determined the litter mixture effect. Furthermore, the litter mixture effect weakened as the decomposition progresses. Faunal contribution was broadly additive to the positive mixture effect irrespective of litter species richness or litter dissimilarity. This implies that combining the dissimilarity of mixture species and contributions of different soil fauna provides a more comprehensive understanding of mixed litter decomposition.

Differential Hydrological Properties of Forest Litter Layers in Artificial Afforestation of Eroded Areas of Latosol in China

Litter is one of the key components of the forest ecosystem and plays a role as the second active layer influencing hydrological processes, which has affected the global water cycle. Soil- and water-conservation forests were constructed by artificial afforestation as a part of vegetation restoration in the eroded area of Latosol, and little is known about the differences in the hydrological properties of vegetation restoration in the eroded area of Latosol in the tropical region. We investigated the litter thickness, mass, and hydrological properties in three soil- and water-conservation forests (Eucalyptus robusta, Hevea brasiliensis, and Acacia mangium) through in situ surveys and laboratory experiments. The results showed that (1) the total litter thickness varied from 2.16 to 5.53 cm and was highest in the A. mangium forest. The total litter mass for A. mangium, 14.66 ± 1.09 t·ha−1, was significantly higher than that for E. robusta (5.45 ± 0.59 t·ha−1) and H. brasiliensis (3.01 ± 0.14 t·ha−1). The mass of the semi-decomposed litter (SDL) layer was markedly higher than that of the un-decomposed litter (UDL) layer. (2) The maximum water-retention capacity (Wmax) and effective water-retention capacity (Weff) of the SDL layer were larger than the UDL layer for three forest plantations. The Wmax and Weff for the A. mangium stand were significantly higher than those for the E. robusta and H. brasiliensis stand. (3) The water-absorption rate of the SDL and UDL layer were highest at the onset of the immersion experiment, declined exponentially with time, and especially declined rapidly in the first 2 h. A higher water-holding capacity of A. mangium may be more effective in enhancing rainfall interception, minimizing splash erosion, and decreasing surface runoff. These results indicate that planting A. mangium in E. robusta and H. brasiliensis forests and then turning them into mixed forests should improve soil and water conservation and maximize their ecological benefits.

Decomposition and nutrient release patterns of municipal solid waste compost in two agro-ecological zones of Uganda

BackgroundDeteriorating soil fertility is a major constraint to agricultural production and food security among smallholder farmers in Uganda and throughout sub-Saharan Africa, where the majority of the population relies on subsistence farming for its livelihoods.Unfortunately, inorganic fertiliser used as a significant soil nutrient replenishment is unsustainable, causing adverse environmental effects, including soil acidification and pollution of water bodies. Therefore, finding alternative, more sustainable, low-cost nutrient management systems is vital. This study assessed the decomposition and nutrient release patterns of municipal solid waste compost (MSWC) in a 36 weeks litter bag experiment under field conditions in two agro-ecological zones (AEZs) of Uganda.ResultsWe found a higher rate of decomposition in the South-western Grass Farmlands (SGF) agro-ecological zone (0.041 week−1, with 20% of initial compost mass remaining after 36 weeks of decay) compared to Southern and Eastern Lake Kyoga Basin (SEKB) (0.043 week−1, 32% of initial litter mass remaining). The half-life values were 16 and 17 weeks for SGF and SEKB AEZs, respectively. The nutrient release rates differed between the two study sites. The macronutrient release pattern in both sites followed the order K > P > N. The secondary macronutrients release followed the order Ca > Mg in the SGF, while in SEKB, the order was reversed. The micronutrients followed the order Cu > Mn > Fe > Zn and Cu > Mn > Zn > Fe in SGF and SEKB AEZs, respectively. The MSWC mass loss during decomposition was negatively correlated with rainfall in both AEZs and with temperature in SGF AEZ, while it was positively correlated with temperature in SEKB AEZ. However, the relationship with nutrient release rates was inconsistent in both AEZs.ConclusionsOur results showed consistent release of nutrients in all AEZs throughout the study period, which coincides with the two cropping seasons in Uganda, suggesting that smallholder farmers can use MSWC as a soil amendment to address soil fertility decline and improve crop productivity. However, because most nutrients were released almost right away in both AEZs, planting should be done at the beginning of high rainfall months when soil moisture is high to synchronise nutrient release from MSWC with crop demand and maximise nutrient uptake by crops while minimising losses to the environment. Furthermore, the inconsistent relationships between the climatic variables and nutrient release suggest that other factors, such as site-specific microbial composition, influenced MSWC nutrient release. Therefore, long-term research is needed to examine other factors affecting nutrient release in these AEZs.

Species loss and nitrogen pollution alter litter decomposition dynamics in coastal salt marshes.

Litter decomposition is a central ecosystem function because dead plant biomass plays a critical role in carbon storage, the nitrogen (N) cycle, and as food/habitat for animals and microorganisms. In the face of global change, interactions between organisms that participate in litter decomposition are likely to change due to species loss and N pollution. To understand how these global change factors may interact to alter litter decomposition, we manipulated the detritivore community and N concentrations in a coastal salt marsh for 2 years. We chose to manipulate densities of a dominant, detritivorous snail (Melampus bidentatus) because its population size is expected to decline due to climate change, yet its impact on litter decomposition has not been tested in the field. We measured litter decomposition rates, detritivore densities, and the N concentrations of sediment and litter. We found that endogenous N enrichment (N added live plants before decomposition), exogenous N enrichment (N added to decomposing plants) and higher densities of Melampus increased litter decomposition rates. Linear mixed models further revealed that snails, other detritivores, and soil NH4+ were the best predictors of litter mass loss in the middle stages of decomposition. Notably, exogenous N added to litter already enriched with N further increased mass loss but did not increase litter %N. Our study reveals how global change in the form species loss and N pollution can have palpable impacts on carbon cycling and ecosystem function.

Differences in leaf and root litter decomposition in tropical montane rainforests are mediated by soil microorganisms not by decomposer microarthropods.

Plant litter decomposition is a key process in carbon and nutrient cycling. Among the factors determining litter decomposition rates, the role of soil biota in the decomposition of different plant litter types and its modification by variations in climatic conditions is not well understood. In this study, we used litterbags with different mesh sizes (45 µm, 1 mm and 4 mm) to investigate the effect of microorganisms and decomposer microarthropods on leaf and root litter decomposition along an altitudinal gradient of tropical montane rainforests in Ecuador. We examined decomposition rates, litter C and N concentrations, microbial biomass and activity, as well as decomposer microarthropod abundance over one year of exposure at three different altitudes (1,000, 2,000 and 3,000 m). Leaf litter mass loss did not differ between the 1,000 and 2,000 m sites, while root litter mass loss decreased with increasing altitude. Changes in microbial biomass and activity paralleled the changes in litter decomposition rates. Access of microarthropods to litterbags only increased root litter mass loss significantly at 3,000 m. The results suggest that the impacts of climatic conditions differentially affect the decomposition of leaf and root litter, and these modifications are modulated by the quality of the local litter material. The findings also highlight litter quality as the dominant force structuring detritivore communities. Overall, the results support the view that microorganisms mostly drive decomposition processes in tropical montane rainforests with soil microarthropods playing a more important role in decomposing low-quality litter material.

Abnormal Litter Induced by Typhoon Disturbances Had Higher Rates of Mass Loss and Carbon Release than Physiological Litter in Coastal Subtropical Urban Forest Ecosystems

The decomposition of abnormal litter caused by extreme weather events might play an increasingly important role in carbon and nutrient cycling in forest ecosystems under climate change scenarios, which needs to be fully investigated. In August 2020, the abnormal foliar litter of the goldenrain tree (Koelreuteria bipinnata var. Integrifoliola), the camphor tree (Cinnamomum camphora), and the weeping willow (Salix babylonica) after Typhoon Hagupit disturbance were collected and incubated on the soil surface at the Plant Ecology Research Base at Taizhou University, which is located on the eastern coast of China. Simultaneously, the physiological foliar litter of these three trees collected in the spring litter peak was incubated at the same site. The abnormal litter had higher concentrations of carbon (C), nitrogen (N), and phosphorus (P) and lower concentrations of lignin and cellulose than the physiological litter. The accumulative mass loss rates of abnormal litter in the goldenrain tree, the camphor tree, and the weeping willow during the incubation period increased by 7.72%, 29.78%, and 21.76% in comparison with physiological litter, and the corresponding carbon release increased by 9.10%, 24.15% and 19.55%, respectively. The autumn litter peak period and plum-rain season had higher rates of litter mass loss and carbon release, while the winter nongrowing season had lower rates. Accumulative mass loss, accumulative carbon release, daily mass loss and the daily carbon release of foliar litter were significantly and positively correlated with temperature and initial P concentrations, and significantly and negatively correlated with the initial C/P ratio, lignin/N ratio, and lignin/P ratio (p &lt; 0.05). Compared with the physiological litter, abnormal litter had higher initial substrate quality, which may be the most important factor contributing to their high rates of mass loss and carbon release. The results imply that increasing tropical cyclones under climate change scenarios will facilitate carbon cycling in coastal urban forest ecosystems.

Reproductive traits and change in body shape of neonates in the Oak Forest Skink, Plestiodon lynxe

AbstractReproductive traits are critically important for understanding how organisms adapt to their respective environments. In this study, we provide information on relative litter mass (RLM) and other litter and neonate related characters of nine female Plestiodon lynxe captured in the field. We also recorded seven body dimensions in 16 neonates and 15 two‐month juveniles, and on the basis of these dimensions we compared the body shape of these two age classes to detect changes in the proportions of body parts. The average litter size (4.55) is larger than that found in other viviparous species of Plestiodon, but smaller than those of congeneric oviparous species of similar size. However, the average body size of newborns (25.49 mm) is similar to that of other oviparous and viviparous species of Plestiodon. The average RLM was relatively high (0.36). The relative size of the head and limbs becomes proportionally smaller, whereas the axilla‐groin length becomes proportionally larger in the first 2 months of life. We suggest that these changes are related to changes in locomotion and microhabitat use.

Soil mite communities structure (Acari, Mesostigmata) during litter decomposition of seven tree species in pure Scots pine stands (Pinus sylvestris L.) growing on a reclaimed post‐industrial area

AbstractOur knowledge about mites, including mesostigmatids, compared to their significant role in soil‐forming processes on post‐industrial areas, is currently insufficient. Therefore, our study aim was to analyze the succession of mesostigmatid communities in relation to litter decomposition of seven tree species [Acer pseudoplatanus L., Alnus glutinosa (L.) Gaertn., Fagus sylvatica L., Pinus sylvestris L., Prunus serotina Ehrh., Quercus rubra L., Robinia pseudoacacia L.] in pure Scots pine stands growing on a reclaimed spoil heap. In December 2011, 1439 litterbags were placed on plots and collected after ca. 3, 6, 9, 13, 19, 25, 31, 37 months since the experiment started. In total, we recorded 9653 mites classified into 67 taxa. The mesostigmatid abundance was affected by percentage initial litter mass loss. Interestingly, litter type shaped species richness and diversity, but not abundance. The highest abundance, almost two‐times higher compared to other tree species, was recorded in Prunus serotina litter (352.73 ± 105.22 ind.; calculated per 100 g of dry litter mass) and the lowest in Quercus rubra (81.23 ± 9.82 ind.). Furthermore, the lowest richness (2.39 ± 0.07; calculated per sample) and diversity (0.33 ± 0.02; calculated per sample) was recorded in Pinus sylvestris litter, therefore, our results are in contradiction to the home‐field advantage assumptions that the ‘home’ litter has a positive effect on soil fauna structure compared to the ‘foreign’ litter. Nevertheless, the greatest abundance share of Asca bicornis and Amblyseius tubae, the most numerous species, was recorded for Pinus sylvestris litter.

Litter facilitates plant development but restricts seedling establishment during vegetation regeneration

Abstract Rapid vegetation regeneration and increased litter production have been predicted under the global greening scenario, but the overall relationship between litter production and vegetation regeneration has not been well addressed. To bridge this knowledge gap, we quantified the responses of the seed stage, seedling stage, plant development stage and vegetation community to litter using 3193 paired observations at the global scale based on the effect size across different categories. Overall, litter significantly decreased seedling establishment and density by 28.4% and 27.7%, increased plant height by 17.4% and decreased species richness by 15.4%. Seed germination at the seed stage was not directly controlled by litter but was positively regulated by changes in soil moisture from litter. In contrast, litter type and litter mass displayed negative effects on the seedling stage, but litter promoted seedling survival with increasing elevation. Moreover, litter composition and plant type dominated the effects of litter on the plant development stage, showing that the increase in litter production might favour the development of broadleaved trees rather than other plants. The present results suggest that litter could restrict the stage from seed to seedling but facilitate plant development after the seedling establishment and slightly affect the vegetation community except for species richness. These results provide deep insight into the relationships between litter production and vegetation regeneration at different stages, which are important for developing models accounting for vegetation regeneration responses to ongoing global greening. Read the free Plain Language Summary for this article on the Journal blog.

The persistent effects of corticosterone administration during lactation on the physiology of maternal and offspring mitochondria.

Reproduction and environmental stressors are generally thought to be associated with a cost to the individual experiencing them, but the physiological mechanisms mediating costs of reproduction and maternal effects remain poorly understood. Studies examining the effects of environmental stressors on a female's physiological state and body condition during reproduction, as well as the physiological condition of offspring, have yielded equivocal results. Mitochondrial physiology and oxidative stress have been implicated as important mediators of life-history trade-offs. The goal of this investigation was to uncover the physiological mechanisms responsible for the enhanced trade-off between self-maintenance and offspring investment when an animal is exposed to stressful conditions during reproduction. To that end, we manipulated circulating corticosterone (CORT) levels by orally supplementing lactating female mice with CORT and investigated mitochondrial physiology and oxidative stress of both the reproductive females and their young. We found that maternal CORT exposure resulted in lower litter mass at weaning, but mitochondrial performance and oxidative status of females were not impacted. We also found potential beneficial effects of maternal CORT on mitochondrial function (e.g. higher respiratory control ratio) and oxidative stress (e.g. lower reactive oxygen species production) of offspring in adulthood, suggesting that elevated maternal CORT may be a signal for early-life adversity and prepare the organism with a predictive, adaptive response to future stressors.

Environmental Impact of Triclopyr on Habitat Quality in Boreal Rights-of-Way.

The indirect effects of herbicides on habitat quality in boreal ecoregions remain poorly understood. Herbicides are commonly applied on boreal rights-of-way to control vegetation below power lines, where they can indirectly enter the soil ecosystem after leaf abscission. Key soil processes such as litter decomposition and soil nutrient cycling can be influenced by altering litter chemistry and/or impacting decomposer species. Disruption of these soil processes could lead to changes in ecosystem health of boreal systems. The indirect impacts of triclopyr on habitat quality of treated boreal rights-of-way were examined through litter mass loss and quality (carbon-to-nitrogen ratios) and the response of boreal invertebrates (Folsomia candida and Oppia nitens) in microcosms and avoidance tests. Litter breakdown rates were not significantly different within a year of treatment. However, we did observe nitrogen profile differences between field-treated and untreated samples, which likely resulted from triclopyr-induced repression of natural leaf senescence processes. At field application rates, there were no differences in survival and reproduction rates of F. candida, which is key in litter breakdown. The triclopyr concentrations that caused 50% of tested F. candida and O. nitens to avoid treated litter were above field application rates. Therefore, field application rates of triclopyr are not expected to impair habitat quality and ecosystem services of boreal ecoregions based on the parameters we evaluated. Our study improves understanding of the effects of herbicide application on habitat quality and is critical for responsible herbicide use on boreal rights-of-way. Environ Toxicol Chem 2022;41:2955-2967. © 2022 SETAC.

Phosphorus dynamics in litter–soil systems during litter decomposition in larch plantations across the chronosequence

The dynamics of phosphorus (P) in litter–soil systems during litter decomposition across a plantation chronosequence remain to be underinvestigated, especially in terms of the nutrient cycle in plantations. In this study, the P dynamics in a litter–soil system of larch (Larix kaempferi) plantations at three stand ages (10, 25, and 50 years old) were examined through a 4-year in situ decomposition experiment (experiment 1) and a 360-day indoor incubation experiment (experiment 2). The aim of experiment 1 and experiment 2 is to determine the P dynamics in litter and soil, respectively. The results in experiment 1 suggested that litter mass retained 34.1%–42.5% of the initial mass after a 4-year decomposition period, and the turnover time (t0.95) of the decomposition was 11.3, 13.9, and 11.8 years for 10-, 25- and 50-year-old stand larch plantations, respectively. Litter exhibited a net P decrease during the first 180 days, followed by a phase of a net P increase. The lowest P accumulation rate was found in the 25-year-old stand during the P immobilization stage. This immobilization phase was followed by a slow litter P decrease. Highly correlated relations were found between the litter decomposition rate and the initial litter N concentration and C/N, whereas the P accumulation rate was noticeably correlated with the initial litter P and C/P. The results in experiment 2 showed that litter addition promoted the accumulation of the highly labile P (resin P, NaHCO3-Pi, and NaHCO3-Po), as well as moderately labile Pi (NaOH-Pi) in the soil. The findings obtained suggest that soil microbial biomass P and acid phosphatase activity were the primary factors driving the activation of soil P during litter decomposition. These findings would be beneficial to the systematic understanding of the nutrient cycle in plant–soil systems and litter management during the development of larch plantations.

Grazing season regulates plant community structure and production by altering plant litter mass in a typical steppe

AbstractAimsGrazing different grasslands with seasonal changes is the tradition in pastoral systems in natural grassland regions worldwide. The effects and mechanisms of different grazing seasons on semi‐arid steppe vegetation are less explored on the Mongolian Plateau. Therefore, we assessed the impact and underlying mechanisms of grazing seasons on grassland community structure and production.LocationXilingol, Inner Mongolia, China.MethodsWe conducted a three‐year experiment to investigate the effects of grazing in four different seasons under the same grazing intensities on plant community structure and production in a typical steppe rangeland. The experiment was a random‐block design, with 20 grassland paddocks of 50 m × 50 m, representing five treatments (i.e., early spring, summer, autumn, mid‐winter, and no grazing), replicated by four blocks. We monitored the changes in soil properties, plant litter mass (i.e., standing dead biomass and dead plant material on the soil surface) and plant species composition and production across grazing treatments.ResultsPlant community height and above‐ground biomass were higher under early spring and winter grazing than autumn and summer grazing and no grazing. This divergence in plant community structure was mainly mediated by the seasonal patterns of plant litter mass across the grazing regimes. A high plant litter mass enhanced soil moisture by accumulating snow in winter and reducing soil evaporation during the growing season, which benefit plant growth. The removal of plant litter before the growing season increased the reception of solar radiation, thus improving soil temperature and plant production. The changes in community microenvironment and selective grazing led to the changes in plant species composition especially under summer and autumn grazing.ConclusionsOur results imply that grazing in winter or in early spring before plants start to turn green is more efficient than the complete animal exclusion for the natural recovery of degraded grassland in Inner Mongolia. It is suitable to incorporate cold‐season grazing in the development of sustainable grassland management systems.