Cover cropping is a diversifying agricultural practice that can improve soil structure and function by altering the underground litter diversity and soil microbial communities.Here,we tested how a wheat cover crop alt...Cover cropping is a diversifying agricultural practice that can improve soil structure and function by altering the underground litter diversity and soil microbial communities.Here,we tested how a wheat cover crop alters the decomposition of cucumber root litter.A three-year greenhouse litterbag decomposition experiment showed that a wheat cover crop accelerates the decomposition of cucumber root litter.A microcosm litterbag experiment further showed that wheat litter and the soil microbial community could improve cucumber root litter decomposition.Moreover,the wheat cover crop altered the abundances and diversities of soil bacterial and fungal communities,and enriched several putative keystone operational taxonomic units(OTUs),such as Bacillus sp.OTU1837 and Mortierella sp.OTU1236,that were positively related to the mass loss of cucumber root litter.The representative bacterial and fungal strains B186 and M3 were isolated and cultured.In vitro decomposition tests demonstrated that both B186 and M3 had cucumber root litter decomposition activity and a stronger effect was found when they were co-incubated.Overall,a wheat cover crop accelerated cucumber root litter decomposition by altering the soil microbial communities,particularly by stimulating certain putative keystone taxa,which provides a theoretical basis for using cover crops to promote sustainable agricultural development.展开更多
Soil organic carbon(SOC)from different sources and with distinct chemical properties exhibit variations in their accumulation mechanisms.Exploring the effects of different litter treatments on SOC storage is of great ...Soil organic carbon(SOC)from different sources and with distinct chemical properties exhibit variations in their accumulation mechanisms.Exploring the effects of different litter treatments on SOC storage is of great significance for understanding the formation and accumulation mechanisms of the SOC pool.The feedback mechanisms of new and old SOC in response to tree species and litter treatments were quantitatively analyzed by the C3 plant/C4 soil replacement method.The litter treatments included no litter,aboveground litter,belowground forest litter,and aboveground+belowground litter,totaling four treatments.The results showed that in the first year,cork oak(Quercusvariabilis)exhibited the highest net SOC content increment and net new SOC increment,but the values declined rapidly from the second year onward.The net increment in SOC content was positive at all sample sites,while the priming effect was not significant at any site.Litter treatments had a significant impact on both SOC content and net SOC increment.Compared with aboveground litter,belowground litter was more effective in increasing SOC Content and net SOC increment.展开更多
Climate warming has intensified the global hydrological cycle,amplifying the differences in precipitation and soil moisture between arid and humid areas.Such a change under regional drought may alter nitrogen(N)and ph...Climate warming has intensified the global hydrological cycle,amplifying the differences in precipitation and soil moisture between arid and humid areas.Such a change under regional drought may alter nitrogen(N)and phosphorus(P)releases during litter decomposition in terrestrial ecosystems,but how these biogeochemical processes respond to drought differently between arid and humid areas remains unclear.Here,we compiled 259 and 138 paired observations(with and without drought conditions)to assess the global variations in the drought effects on N and P releases during litter decomposition between arid(aridity index<0.5)and humid(aridity index>0.5)areas.Litter N release increased under drought in both arid(0.35%)and humid(3.62%)areas,and P release decreased by 7.32%in arid areas but increased by 2.22%in humid areas under drought.These changes in N and P releases from decomposing litter were positively correlated with drought duration in arid areas,dependent on microclimate,edaphic factors,and litter quality.Our findings highlight the contrasting effects of drought on litter N and P releases between arid and humid ecosystems,and this differential influence will greatly improve our capability to evaluate and forecast nutrient cycling during litter decomposition under different precipitation patterns.展开更多
The study determined the carbon stocks and litter nutrient concentration in tropical forests along the ecological gradient in Kenya.This could help understand the potential of mitigating climate change using tropical ...The study determined the carbon stocks and litter nutrient concentration in tropical forests along the ecological gradient in Kenya.This could help understand the potential of mitigating climate change using tropical forest ecosystems in different ecological zones,which are being affected by climate change to a level that they are becoming carbon sources instead of sinks.Stratified sampling technique was used to categorize tropical forests into rain,moist deciduous and dry zone forests depending on the average annual rainfall received.Simple random sampling technique was used to select three tropical forests in each category.Modified consistent sampling technique was used to develop 10 main 20 m×100 m plots in each forest,with 202 m×50 m sub-plots in each plot.Systematic random sampling technique was used in selecting 10 sub-plots from each main plot for inventory study.Non-destructive approach based on allometric equations using trees’diameter at breast height(DBH),total height and species’wood specific gravity were used in estimating tree carbon stock in each forest.Soil organic carbon(SOC)and litter nutrient concentration(total phosphorus and nitrogen)were determined in each forest based on standard laboratory procedures.The results indicated that,whilst trees in rain forests recorded a significantly higher(p<0.001)DBH(20.36 cm)and total tree height(12.1 m),trees in dry zone forests recorded a significantly higher(p<0.001)specific gravity(0.67 kg m^(−3)).Dry zone tropical forests stored a significantly lower amount of total tree carbon of 73 Mg ha^(−1),compared to tropical rain forests(439.5 Mg ha^(−1))and moist deciduous tropical forests(449 Mg ha^(−1)).The SOC content was significantly higher in tropical rainforests(3.9%),compared to soils from moist deciduous(2.9%)and dry zone forests(1.8%).While litter from tropical rain forests recorded a significantly higher amount of total nitrogen(3.4%),litter from dry zone forests recorded a significantly higher concentration of total phosphorus(0.27%).In conclusion,ecological gradient that is dictated by the prevailing temperatures and precipitation affects the tropical forests carbon stock potential and litter nutrient concentration.This implies that,the changing climate is having a serious implication on the ecosystem services such as carbon stock and nutrients cycling in tropical forests.展开更多
Water resources are vital for all living beings and should be managed properly to ensure the safety and well-being of humankind.Surface water bodies are constantly faced with serious contamination risks generated prim...Water resources are vital for all living beings and should be managed properly to ensure the safety and well-being of humankind.Surface water bodies are constantly faced with serious contamination risks generated primarily by human activities and urbanization.The problem of waste littering and dumping in developing countries like Nigeria is increasingly affecting environmental resources such as air and water.Several studies have revealed alarming levels of heavy metals that exceed the World Health Organization(WHO)standards.Plastic waste represents a substantial portion of litter,affecting water quality.Pollution results in the depletion of aquatic ecosystems and an increase in water-related diseases.This review aims to assess the impact of waste littering and dumping on surface water quality in Nigeria.In this review,the findings of various studies on surface water bodies in Nigeria,particularly those under the influence of urbanization and waste disposal,were compiled.This review compared numerous physical and chemical parameters like pH,dissolved oxygen,and heavy metals,and microbiological properties such as total coliforms.The water quality index(WQI)was also computed in these studies to ascertain the suitability of the water samples for human consumption.Review results showed that numerous water bodies in Nigeria have significantly diverse water quality levels,with some samples meeting or exceeding the WHO guidelines for microbiological,chemical,and physical characteristics.Notably,levels of heavy metals,turbidity,and pH frequently exceeded permissible limits,pointing to contamination from agricultural and industrial sources.The WQI results for multiple locations revealed that the majority of surface water sources were classified as“bad”to“very bad”,meaning they were unfit for human consumption.The results emphasized the critical need for immediate action to prevent further harm and deterioration of surface water bodies in Nigeria.Recommendations include strengthening waste management policies,promoting recycling initiatives,fostering collaborations among stakeholders,developing littering penalties and enforcing fines to curb the challenge,and raising educational awareness from the primary level.This review emphasizes the need for proactive measures to protect the environment and surface water quality in Nigeria.展开更多
Photodegradation is considered as a universal contributing factor to litter decomposition and carbon(C)cycling within the Earth’s biomes.Identifying how solar radiation modifies the molecular structure of litter is e...Photodegradation is considered as a universal contributing factor to litter decomposition and carbon(C)cycling within the Earth’s biomes.Identifying how solar radiation modifies the molecular structure of litter is essen-tial to understand the mechanism controlling its decom-position and reaction to shifts in climatic conditions and land-use.In this study,we performed a spectral-attenuation experiment following litter decomposition in an understory and gap of a temperate deciduous forest.We found that short-wavelength visible light,especially blue light,was the main factor driving variation in litter molecular struc-ture of Fagus crenata Blume,Quercus crispula Blume,Acer carpinifolium Siebold&Zuccarini and Betula platyphylla Sukaczev,explaining respectively 56.5%,19.4%,66.3%,and 16.7%of variation in its chemical composition.However,the variation also depended on canopy openness:Only in the forest gap was lignin aromatic C negatively associated with C-oxygen(C–O)bonding in polysaccharides receiv-ing treatments containing blue light of the full spectrum of solar radiation.Regardless of species,the decomposition index of litter that explained changes in mass and lignin loss was driven by the relative content of C–O stretching in poly-saccharides and lignin aromatic C.The results suggest that the availability of readily degradable polysaccharides pro-duced by the reduction in lignin aromatic C most plausibly explains the rate of litter photodegradation.Photo-products of photodegradation might augment the C pool destabilized by the input of readily degradable organic compounds(i.e.,polysaccharides).展开更多
The dominant plant litter plays a crucial role in carbon(C)and nutrients cycling as well as ecosystem functions maintenance on the Qinghai-Tibet Plateau(QTP).The impact of litter decomposition of dominant plants on ed...The dominant plant litter plays a crucial role in carbon(C)and nutrients cycling as well as ecosystem functions maintenance on the Qinghai-Tibet Plateau(QTP).The impact of litter decomposition of dominant plants on edaphic parameters and grassland productivity has been extensively studied,while its decomposition processes and relevant mechanisms in this area remain poorly understood.We conducted a three-year litter decomposition experiment in the Gansu Gannan Grassland Ecosystem National Observation and Research Station,an alpine meadow ecosystem on the QTP,to investigate changes in litter enzyme activities and bacterial and fungal communities,and clarify how these critical factors regulated the decomposition of dominant plant Elymus nutans(E.nutans)litter.The results showed that cellulose and hemicellulose,which accounted for 95%of the initial lignocellulose content,were the main components in E.nutans litter decomposition.The litter enzyme activities ofβ-1,4-glucosidase(BG),β-1,4-xylosidase(BX),andβ-D-cellobiosidase(CBH)decreased with decomposition while acid phosphatase,leucine aminopeptidase,and phenol oxidase increased with decomposition.We found that both litter bacterial and fungal communities changed significantly with decomposition.Furthermore,bacterial communities shifted from copiotrophic-dominated to oligotrophic-dominated in the late stage of litter decomposition.Partial least squares path model revealed that the decomposition of E.nutans litter was mainly driven by bacterial communities and their secreted enzymes.Bacteroidota and Proteobacteria were important producers of enzymes BG,BX,and CBH,and their relative abundances were tightly positively related to the content of cellulose and hemicellulose,indicating that Bacteroidota and Proteobacteria are the main bacterial taxa of the decomposition of E.nutans litter.In conclusion,this study demonstrates that bacterial communities are the main driving forces behind the decomposition of E.nutans litter,highlighting the vital roles of bacterial communities in affecting the ecosystem functions of the QTP by regulating dominant plant litter decomposition.展开更多
Addressing the challenges in detecting surface floating litter in artificial lakes,including complex environments,uneven illumination,and susceptibility to noise andweather,this paper proposes an efficient and lightwe...Addressing the challenges in detecting surface floating litter in artificial lakes,including complex environments,uneven illumination,and susceptibility to noise andweather,this paper proposes an efficient and lightweight Ghost-YOLO(You Only Look Once)v8 algorithm.The algorithmintegrates advanced attention mechanisms and a smalltarget detection head to significantly enhance detection performance and efficiency.Firstly,an SE(Squeeze-and-Excitation)mechanism is incorporated into the backbone network to fortify the extraction of resilient features and precise target localization.This mechanism models feature channel dependencies,enabling adaptive adjustment of channel importance,thereby improving recognition of floating litter targets.Secondly,a 160×160 small-target detection layer is designed in the feature fusion neck to mitigate semantic information loss due to varying target scales.This design enhances the fusion of deep and shallow semantic information,improving small target feature representation and enabling better capture and identification of tiny floating litter.Thirdly,to balance performance and efficiency,the GhostConv module replaces part of the conventional convolutions in the feature fusion neck.Additionally,a novel C2fGhost(CSPDarknet53 to 2-Stage Feature Pyramid Networks Ghost)module is introduced to further reduce network parameters.Lastly,to address the challenge of occlusion,a newloss function,WIoU(Wise Intersection over Union)v3 incorporating a flexible and non-monotonic concentration approach,is adopted to improve detection rates for surface floating litter.The outcomes of the experiments demonstrate that the Ghost-YOLO v8 model proposed in this paper performs well in the dataset Marine,significantly enhances precision and recall by 3.3 and 7.6 percentage points,respectively,in contrast with the base model,mAP@0.5 and mAP 0.5:0.95 improve by 5.3 and 4.4 percentage points and reduces the computational volume by 1.88MB,the FPS value hardly decreases,and the efficient real-time identification of floating debris on the water’s surface can be achieved costeffectively.展开更多
Dear Editor,Numerous aspects of ecosystem ecology are influenced by insects(Prasad,2022).Herbivory of plant organs by insects may influence the biogeochemistry of forests by changing the speed of litter decomposition(...Dear Editor,Numerous aspects of ecosystem ecology are influenced by insects(Prasad,2022).Herbivory of plant organs by insects may influence the biogeochemistry of forests by changing the speed of litter decomposition(Schowalter,2022).Cycas micronesica K.D.Hill is the only native gymnosperm in the Mariana Islands.The once-abundant tree experienced no known lethal threats prior to the 2003 invasion of Guam by the scale Aulacaspis yasumatsui Takagi(Marler,2012).This insular case study has been the subject of abundant research(Marler et al.,2021).Changes to leaf litter chemistry improved litter quality following A.yasumatsui infestations(Marler and Dongol,2016),but the prediction of increased decomposition speed has not been confirmed with experimental incubations.展开更多
Background:Forest soils in tropical and subtropical areas store a significant amount of carbon.Recent framework to assess soil organic matter(SOM)dynamics under evolving global conditions suggest that dividing bulk SO...Background:Forest soils in tropical and subtropical areas store a significant amount of carbon.Recent framework to assess soil organic matter(SOM)dynamics under evolving global conditions suggest that dividing bulk SOM into particulate and mineral-associated organic matter(POM vs.MAOM)is a promising method for identifying how SOM contributes to reducing global warming.Soil macrofauna,earthworms,and millipedes have been found to play an important role in facilitating SOM processes.However,how these two co-existing macrofaunae impac the litter decomposition process and directly impact the formation of POM and MAOM remains unclear.Methods:Here,we set up a microcosm experiment,which consisted of 20 microcosms with four treatments earthworm and litter addition(E),millipedes and litter addition(M),earthworm,millipedes,and litter addition(E+M),and control(only litter addition)in five replicates.The soil and litter were sterilized prior to beginning the incubation experiment to remove any existing microbes.After incubating the samples for 42 days,the litte properties(mass,C,and N contents),soil physicochemical properties,as well as the C and N contents,and POM and MAOM^(13)C abundance in the 0–5 and 5–10 cm soil layers were measured.Finally,the relative influences o soil physicochemical and microbial properties on the distribution of C and N in the soil fractions were analyzed Results:The litter mass,C,and N associated with all four treatments significantly decreased after incubation especially under treatment E+M(litter mass:-58.8%,litter C:-57.0%,litter N:-75.1%,respectively),while earthworm biomass significantly decreased under treatment E.Earthworm or millipede addition alone showed no significant effects on the organic carbon(OC)and total nitrogen(TN)content in the POM fraction,but join addition of both significantly increased OC and TN regardless of soil depth.Importantly,all three macrofauna treatments increased the OC and TN content and decreased the^(13)C abundance in the MAOM fraction.More than65%of the total variations in the distribution of OC and TN throughout the two fractions can be explained by a combination of soil physicochemical and microbial properties.Changes in the OC distribution in the 0–5 cm soi layer are likely due to a decrease in soil pH and an increase in arbuscular mycorrhizal fungi(AMF),while those in the 5–10 cm layer are probably caused by increases in soil exchangeable Ca and Mg,in addition to fungi and gram-negative(GN)bacteria.The observed TN distribution changes in the 0–5 cm soil likely resulted from a decrease in soil pH and increases in AMF,GN,and gram-negative(GP)bacteria,while TN distribution changes in the 5–10 cm soil could be explained by increases in exchangeable Mg and GN bacteria.Conclusions:The results indicate that the coexistence of earthworms and millipedes can accelerate the litte decomposition process and store more C in the MAOM fractions.This novel finding helps to unlock the processe by which complex SOM systems serve as C sinks in tropical forests and addresses the importance of soil mac rofauna in maintaining C-neutral atmospheric conditions under global climate change.展开更多
Despite cities being recognized as being potential sources of microplastic pollution to the wider environment, most surveys of COVID-19 plastic-based litter have been undertaken through linear transects of marine beac...Despite cities being recognized as being potential sources of microplastic pollution to the wider environment, most surveys of COVID-19 plastic-based litter have been undertaken through linear transects of marine beaches. For the far fewer number of studies conducted on inland and urban locations, the site-specific focus has primarily been surveys along the length of streets. The present study is the first to specifically assess the standing stock (i.e., moment-in-time) of littered face masks for the entire surface area of urban parking lots. The density of face masks in 50 parking lots in a Canadian coastal town (0.00054 m2 ± 0.00051 m2) was found to be significantly greater than the background level of littering of town streets. Face mask density was significantly related to visitation “usage” of parking lots as gauged by the areal size of the lots and of their onsite buildings, as well as the number of vehicles present. Neither parking lot typology nor estimates of inferred export (various measures of wind exposure) and entrapment (various metrics of obstruction) of face masks had a significant influence on the extent of whole-lot littering. In consequence, modelling of the potential input of mask-derived microplastics to the marine environment from coastal communities can use the areal density of face masks found here in association with the total surface area of lots for individual municipalities as determined through GIS analysis.展开更多
Fecal coliform bacteria such as Escherichia coli (E. coli) are one of the main sources of groundwater pollution. An assessment of the transport and Persistence of E. coli in poultry litter amended Decatur silty Clay s...Fecal coliform bacteria such as Escherichia coli (E. coli) are one of the main sources of groundwater pollution. An assessment of the transport and Persistence of E. coli in poultry litter amended Decatur silty Clay soil and Hartsells Sandy soil was conducted using soil columns and simulated groundwater leaching. Enumeration of initial E. coli was determined to range from 2.851 × 10<sup>3</sup> to 3.044 × 10<sup>3</sup> CFU per gram of soil. These results have been used in a batch study to determine the persistence rate of E. coli in Decatur silty Clay soil and Hartsells Sandy soil. Results prove that E. coli survival growth rate increases for clay soil later than and at a higher rate than sandy soil. The column study has determined that E. coli was transported at a rate of 3.7 × 10<sup>6</sup><sup> </sup>CFU for Decatur silty loam and 6.3 × 10<sup>6</sup><sup> </sup>CFU for Hartsells sandy per gram of soil. Further, linear regression analysis predictions show higher porosity and soil moisture content affect transport, and Hartsells sandy soil has higher transport of E. coli due to its higher porosity and lower volumetric water content.展开更多
Identification of management practices that can improve soil health is critical to improving the sustainability of soybean [Glycine max (L.) Merr.] production. The objective of this study was to examine the long-term ...Identification of management practices that can improve soil health is critical to improving the sustainability of soybean [Glycine max (L.) Merr.] production. The objective of this study was to examine the long-term effects of continuous soybean, corn-soybean, and soybean-cotton rotations with chicken litter and cover crops (hairy vetch, wheat, fallow) on soil health parameters, including nutrient accumulation and soil organic matter dynamics under a split plot design. The depth intervals of soil sampling were 0 - 15, 15 - 30, 30 - 60, and 60 - 90 cm. Chicken litter resulted in 62.1% and 32.8% higher water extractable organic soil N content than fallow and wheat, respectively, in the surface 0 - 15 cm of soil only. However, there was no significant difference in 1-day Solvita respiration, water extractable organic C, C/N ratio, health score, moisture, earthworm, organic matter, pH, or CEC of soil among fallow, hairy vetch, chicken litter, and wheat regardless of soil depth. Unexpectedly, annual application of chicken litter at 4.4 Mg ha−1 as an N source or growing a winter-season cover crop such as hairy vetch or wheat for continuous 16 years did not significantly increase soil organic matter or water extractable organic soil C. Annual application of chicken litter at 4.4 metric tons (Mg) ha–1 for 16 years increased soil nitrate-nitrogen (NO3−-N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), and zinc (Zn) contents by 92%, 400%, 134%, 20%, 43%, 206%, and 430% in 0 - 15 cm depth compared with their initial soil values, respectively, extracted with Haney H3A-2 (2 g L–1 lithium citrate + 0.6 g L–1 citric acid + 0.4 g L–1 malic acid + 0.4 g L–1 oxalic acid) solution. The increases enhanced soil supply of these nutrients to following crops, but also increased the risks of losing them to the environment. Hairy vetch caused higher H3A extracted soil manganese (Mn) content than fallow and chicken litter in 0 - 60 cm. There was no significant difference in 1-day Solvita respiration, water extractable organic C and N, health score, moisture, organic matter, pH, CEC, or population of earthworm of soil among continuous soybean, corn-soybean, and soybean-cotton in any soil depth. Another major finding of this study was that continuous soybean exerted no adverse effect on soil health relative to the commonly used corn (Zea mays L.)-soybean and soybean-cotton (Gossypium hirsutum L.) rotations under no-tillage after 16 years. To mitigate the risks of nutrient runoff and leaching from long-term chicken litter application, we recommend reducing litter application rates and integrating cover crops into crop rotations to enhance nutrient cycling and reduce environmental impacts.展开更多
Objective: The paper aims to analyze the dynamic characteristics of litter production and nutrient return of the forest ecosystems in subtropical areas, and provide a theoretical basis for the nutrient cycling study i...Objective: The paper aims to analyze the dynamic characteristics of litter production and nutrient return of the forest ecosystems in subtropical areas, and provide a theoretical basis for the nutrient cycling study in southwest Hubei Province and carbon sink function of the whole forest ecosystem. Methods: Three typical forest stands (Chinese fir plantation, Cryptomeria fortunei plantation and evergreen and deciduous broad-leaved mixed forest) in Golden Mountain Forest Farm in southwest Hubei Province were investigated and monitored continuously for the litter types and productivity and nutrient return. Results: The annual litter productivity of the three forest stands ranged from 161.77 to 396.26 kg·hm<sup>-2</sup>;Litters of branches, leaves and reproductive organs accounted for 14.14% - 20.85%, 33.26% - 78.33%, 7.52% - 42.18% of the total, respectively;The litter productivity and total litter productivity of each composition in the three forest stands show unimodal or bimodal changes over months, and the total litter productivity reached the highest value in January, April and October respectively. For different nutrient contents of the three forest stands, the common feature is C > N. The order of nutrient return amount from greatest to least is evergreen and deciduous broad-leaved mixed forest, Cryptomeria fortunei plantation and Chinese fir plantation. For different nutrient return amounts, the common feature is C > N, and the nutrient return amounts are 76.51-180.69 kg·hm<sup>-2</sup> and 2.3 - 5.71 kg·hm<sup>-2</sup> respectively. Conclusion: The annual litter productivity and nutrient return amount of the evergreen and deciduous broad-leaved mixed forest are the highest among the three forest stands. Therefore, protecting the evergreen and deciduous broad-leaved mixed forest and studying the litter changes of Chinese fir plantation and Cryptomeria fortunei plantation are of far-reaching significance for the development of sustainable forest management in this region and the further improvement of the carbon sequestration function of the whole forest ecosystem.展开更多
The effect of litter on forest regeneration depends on the characteristics of regional climate and also shows community specificity. The influences of plant litter on seed germination and seedling growth of Larch Sibe...The effect of litter on forest regeneration depends on the characteristics of regional climate and also shows community specificity. The influences of plant litter on seed germination and seedling growth of Larch Siberian forest in the Altai Mountains were investigated through two simulated experiments including litter coverage and litter aqueous extracts. In the litter coverage experiment, three litter coverage methods including above (D), below (S) and in the middle (Z) of litter were set with the litter coverage thickness of 0, 1, 2, and 4 cm, while two aqueous extract obtained methods using the air-dried litter and litter ash after fir were used with the concentration of 10%, 40%, 80% and 100% in the present study. Results showed that: the aqueous extracts obtained using the air-dried litter restrained the seed germination, while the aqueous extracts obtained using litter ash improved the seed germination. Compared with other litter concentration, the influences of 100% concentration reach highest. The seed germination rate, seed germination potential and vital index under the treatment of seeds above the litter coverage were highest, which were significantly higher than other treatments. The above-ground biomass was significantly higher and the inhibition index of below-ground bio-mass was significantly lower under the treatment of seed above the litter with thin litter cover-age (S1) compared to other litter coverage treatments. These results indicated that the litter aqueous extract and the litter coverage had a combined effect on the seed germination and seedling growth of Siberian larch forest. Fire disturbance could promote seed germination by modifying the adverse effects of litter aqueous extracts and litter coverage, and thus plays an important role in the regeneration of Siberian larch in the Altai Mountains.展开更多
Litter production, components and dynamics were investigated and forest floor litter was quantified throughout awhole year in three subalpine forests, dominated by tree species of spruce (SF), fir (FF) and birch (BF),...Litter production, components and dynamics were investigated and forest floor litter was quantified throughout awhole year in three subalpine forests, dominated by tree species of spruce (SF), fir (FF) and birch (BF), in WesternSichuan, China, in order to understand the key factors that influenced litter production and dynamics. Litterfall in thethree forests consisted mainly of leaves, woody litter, reproductive organs and moss. Contribution of leaf litter to thetotal litterfall was significantly (P < 0.05) greater than that of woody litter, reproductive organs or moss. Regardlessof the stands, litterfall exhibited a marked monthly variation with the maximum litterfall peaks occurring in October,with smaller peaks occurring in February for SF and FF, and May for BF. The analysis indicated that tree species,stand density, leaf area index (LAI), stand basal area and stand age were the key factors determining litter production.Meanwhile tree species and phenology controlled the litter dynamics, with wind and snow modifying the litter componentsand dynamics.展开更多
Decomposition dynamics were compared among green tree leaves, partially decomposed tree leaf litter （i.e., decayed tree leaf litter on forest floor） and a mixture of the two in a warm temperate forest ecosystem in c...Decomposition dynamics were compared among green tree leaves, partially decomposed tree leaf litter （i.e., decayed tree leaf litter on forest floor） and a mixture of the two in a warm temperate forest ecosystem in central China to test the influence of litter chemical quality on the degree of decomposition. The study was conducted in situ at two contrasting forest sites, an oak forest dominated by Quercus aliena var. acuteserrata Maxim., and a mixed pine and oak forest dominated by Pinus armandii Franch. and Q. aliena var. acuteserrata. We found marked differences in the rate of decomposition among litter types at both forest sites; the litter decom- position constant, k, was about 39 % greater at the oak forest site and more than 70 % greater at the pine-oak forest site, for green leaves than for partially decomposed leaf litter. The decomposition dynamics and temporal changes in litter chemistry of the three litter types also greatly differed between the two forest sites. At both forest sites, the higher rate of decomposition for the green leaves was associated with a and lower carbon to N ratio higher nitrogen （N） content （C/N） and acid-unhydrolyz- able residue to N ratio （AUR/N）. We did not find any non- additive effects when mixing green leaves and partially decomposed leaf litter. Our findings support the con- tention that litter chemical quality is one of the most important determinants of litter decomposition in forest ecosystems at the local or regional scale, but the effect of litter chemical quality on decomposition differs between the contrasting forest types and may vary with the stage of decomposition.展开更多
Litter phosphorus （P） return is important to maintain the P cycle and balance in the sandy land of arid areas. In this study, we determined the loss and return of litter P in sand dune areas and elucidated their rel...Litter phosphorus （P） return is important to maintain the P cycle and balance in the sandy land of arid areas. In this study, we determined the loss and return of litter P in sand dune areas and elucidated their relation- ship. We investigated litter production and litter P amount, and simulated leaf litter moving dynamics to understand the relationships between the loss of litter P and the total litter P, and between the return of litter P and the total litter P in active （AD）, semi-stabilized （SSD） and stabilized （SD） dunes in Inner Mongolia, northeastern China. The vegetation litter P was 12.6, 94.5, and 201.6 mg P/m2 in AD, SSD, and SD, respectively. A significant movement and loss of leaf litter P with time occurred on the three types of sand dunes. As a result, the loss of P was 7.4, 46.9, and 69.8 mg P/m2 and the return of P was 5.5, 47.6, and 131.8 mg P/m2 in AD, SSD, and SD, respectively. The rela- tionship between both loss and return of P and total litter P in AD, SSD, and SD was revealed by linear regression. The slope of the regression line indicated the rate of loss or return of litter P. From AD to SD, the loss rate showed a declining slope （0.52, 0.32, and 0.17 for AD, SSD, and SD, respectively）, and the return rate showed a rising slope （0.48, 0.67, and 0.83 for AD, SSD, and SD, respectively）. The loss of litter P should be regarded in the local man- agement of vegetation and land in sand dune areas. Improved vegetation restoration measures are necessary to decrease litter P loss to maintain the stability of ecosystems in sand dune areas.展开更多
Background:Litter traits critically affect litter decomposition from local to global scales.However,our understanding of the temporal dynamics of litter trait-decomposition linkages,especially their dependence on plan...Background:Litter traits critically affect litter decomposition from local to global scales.However,our understanding of the temporal dynamics of litter trait-decomposition linkages,especially their dependence on plant functional type remains limited.Methods:We decomposed the leaf litter of 203 tree species that belong to two different functional types(deciduous and evergreen)for 2 years in a subtropical forest in China.The Weibull residence model was used to describe the different stages of litter decomposition by calculating the time to 10%,25%and 50%mass loss(Weibull t_(1/10),t_(1/4),and t_(1/2)respectively)and litter mean residence time(Weibull MRT).The resulting model parameters were used to explore the control of litter traits(e.g.,N,P,condensed tannins and tensile strength)over leaf litter decomposition across different decomposition stages.Results:The litter traits we measured had lower explanatory power for the early stages(Weibull t_(1/10)and t_(1/4))than for the later stages(Weibull t_(1/2)and MRT)of decomposition.The relative importance of different types of litter traits in influencing decomposition changed dramatically during decomposition,with physical traits exerting predominant control for the stages of Weibull t_(1/10)and MRT and nutrient-related traits for the stages of Weibull t_(1/4),and t_(1/2).Moreover,we found that litter decomposition of the early three stages(Weibull t_(1/10),t_(1/4),and t_(1/2))of the two functional types was controlled by different types of litter traits;that is,the litter decomposition rates of deciduous species were predominately controlled by nutrient-related traits,while the litter decomposition rates of evergreen species were mainly controlled by carbon-related traits.Conclusions:This study suggests that litter trait-decomposition linkages vary with decomposition stages and are strongly mediated by plant functional type,highlighting the necessity to consider their temporal dynamics and plant functional types for improving predictions of litter decomposition.展开更多
Background:Attempts to restore degraded highlands by tree planting are common in East Africa.However,up till now,little attention has been given to effects of tree species choice on litter decomposition and nutrient r...Background:Attempts to restore degraded highlands by tree planting are common in East Africa.However,up till now,little attention has been given to effects of tree species choice on litter decomposition and nutrient recycling.Method:In this study,three indigenous and two exotic tree species were selected for a litter decomposition study.The objective was to identify optimal tree species combinations and tree diversity levels for the restoration of degraded land via enhanced litter turnover.Litterbags were installed in June 2019 into potential restoration sites(disturbed natural forest and forest plantation)and compared to intact natural forest.The tested tree leaf litters included five monospecific litters,ten mixtures of three species and one mixture of five species.Standard green and rooibos tea were used for comparison.A total of 1,033 litters were retrieved for weight loss analysis after one,three,six,and twelve months of incubation.Results:The finding indicates a significant effect of both litter quality and litter diversity on litter decomposition.The nitrogen-fixing native tree Millettia ferruginea showed a comparable decomposition rate as the fast decom-posing green tea.The exotic conifer Cupressus lusitanica and the native recalcitrant Syzygium guineense have even a lower decomposition rate than the slowly decomposing rooibos tea.A significant correlation was observed be-tween litter mass loss and initial leaf litter chemical composition.Moreover,we found positive non-additive ef-fects for litter mixtures including nutrient-rich and negative non-additive effects for litter mixtures including poor leaf litters respectively.Conclusion:These findings suggest that both litter quality and litter diversity play an important role in decom-position processes and therefore in the restoration of degraded tropical moist evergreen forest.展开更多
基金supported by the National Natural Science Foundation of China(32072655 and 32272792)。
文摘Cover cropping is a diversifying agricultural practice that can improve soil structure and function by altering the underground litter diversity and soil microbial communities.Here,we tested how a wheat cover crop alters the decomposition of cucumber root litter.A three-year greenhouse litterbag decomposition experiment showed that a wheat cover crop accelerates the decomposition of cucumber root litter.A microcosm litterbag experiment further showed that wheat litter and the soil microbial community could improve cucumber root litter decomposition.Moreover,the wheat cover crop altered the abundances and diversities of soil bacterial and fungal communities,and enriched several putative keystone operational taxonomic units(OTUs),such as Bacillus sp.OTU1837 and Mortierella sp.OTU1236,that were positively related to the mass loss of cucumber root litter.The representative bacterial and fungal strains B186 and M3 were isolated and cultured.In vitro decomposition tests demonstrated that both B186 and M3 had cucumber root litter decomposition activity and a stronger effect was found when they were co-incubated.Overall,a wheat cover crop accelerated cucumber root litter decomposition by altering the soil microbial communities,particularly by stimulating certain putative keystone taxa,which provides a theoretical basis for using cover crops to promote sustainable agricultural development.
基金Sponsored by The National Natural Science Foundation of China(32271848).
文摘Soil organic carbon(SOC)from different sources and with distinct chemical properties exhibit variations in their accumulation mechanisms.Exploring the effects of different litter treatments on SOC storage is of great significance for understanding the formation and accumulation mechanisms of the SOC pool.The feedback mechanisms of new and old SOC in response to tree species and litter treatments were quantitatively analyzed by the C3 plant/C4 soil replacement method.The litter treatments included no litter,aboveground litter,belowground forest litter,and aboveground+belowground litter,totaling four treatments.The results showed that in the first year,cork oak(Quercusvariabilis)exhibited the highest net SOC content increment and net new SOC increment,but the values declined rapidly from the second year onward.The net increment in SOC content was positive at all sample sites,while the priming effect was not significant at any site.Litter treatments had a significant impact on both SOC content and net SOC increment.Compared with aboveground litter,belowground litter was more effective in increasing SOC Content and net SOC increment.
基金financially supported by the National Key R&D Program of China(No.2023YFF1305500)the National Natural Science Foundation of China(Nos.32022056,32101509,and 32171641)。
文摘Climate warming has intensified the global hydrological cycle,amplifying the differences in precipitation and soil moisture between arid and humid areas.Such a change under regional drought may alter nitrogen(N)and phosphorus(P)releases during litter decomposition in terrestrial ecosystems,but how these biogeochemical processes respond to drought differently between arid and humid areas remains unclear.Here,we compiled 259 and 138 paired observations(with and without drought conditions)to assess the global variations in the drought effects on N and P releases during litter decomposition between arid(aridity index<0.5)and humid(aridity index>0.5)areas.Litter N release increased under drought in both arid(0.35%)and humid(3.62%)areas,and P release decreased by 7.32%in arid areas but increased by 2.22%in humid areas under drought.These changes in N and P releases from decomposing litter were positively correlated with drought duration in arid areas,dependent on microclimate,edaphic factors,and litter quality.Our findings highlight the contrasting effects of drought on litter N and P releases between arid and humid ecosystems,and this differential influence will greatly improve our capability to evaluate and forecast nutrient cycling during litter decomposition under different precipitation patterns.
基金funded by the Kenya National Research Fund(NRF-Kenya,2018).
文摘The study determined the carbon stocks and litter nutrient concentration in tropical forests along the ecological gradient in Kenya.This could help understand the potential of mitigating climate change using tropical forest ecosystems in different ecological zones,which are being affected by climate change to a level that they are becoming carbon sources instead of sinks.Stratified sampling technique was used to categorize tropical forests into rain,moist deciduous and dry zone forests depending on the average annual rainfall received.Simple random sampling technique was used to select three tropical forests in each category.Modified consistent sampling technique was used to develop 10 main 20 m×100 m plots in each forest,with 202 m×50 m sub-plots in each plot.Systematic random sampling technique was used in selecting 10 sub-plots from each main plot for inventory study.Non-destructive approach based on allometric equations using trees’diameter at breast height(DBH),total height and species’wood specific gravity were used in estimating tree carbon stock in each forest.Soil organic carbon(SOC)and litter nutrient concentration(total phosphorus and nitrogen)were determined in each forest based on standard laboratory procedures.The results indicated that,whilst trees in rain forests recorded a significantly higher(p<0.001)DBH(20.36 cm)and total tree height(12.1 m),trees in dry zone forests recorded a significantly higher(p<0.001)specific gravity(0.67 kg m^(−3)).Dry zone tropical forests stored a significantly lower amount of total tree carbon of 73 Mg ha^(−1),compared to tropical rain forests(439.5 Mg ha^(−1))and moist deciduous tropical forests(449 Mg ha^(−1)).The SOC content was significantly higher in tropical rainforests(3.9%),compared to soils from moist deciduous(2.9%)and dry zone forests(1.8%).While litter from tropical rain forests recorded a significantly higher amount of total nitrogen(3.4%),litter from dry zone forests recorded a significantly higher concentration of total phosphorus(0.27%).In conclusion,ecological gradient that is dictated by the prevailing temperatures and precipitation affects the tropical forests carbon stock potential and litter nutrient concentration.This implies that,the changing climate is having a serious implication on the ecosystem services such as carbon stock and nutrients cycling in tropical forests.
基金support received by the University of South Africa for a conducive research environment。
文摘Water resources are vital for all living beings and should be managed properly to ensure the safety and well-being of humankind.Surface water bodies are constantly faced with serious contamination risks generated primarily by human activities and urbanization.The problem of waste littering and dumping in developing countries like Nigeria is increasingly affecting environmental resources such as air and water.Several studies have revealed alarming levels of heavy metals that exceed the World Health Organization(WHO)standards.Plastic waste represents a substantial portion of litter,affecting water quality.Pollution results in the depletion of aquatic ecosystems and an increase in water-related diseases.This review aims to assess the impact of waste littering and dumping on surface water quality in Nigeria.In this review,the findings of various studies on surface water bodies in Nigeria,particularly those under the influence of urbanization and waste disposal,were compiled.This review compared numerous physical and chemical parameters like pH,dissolved oxygen,and heavy metals,and microbiological properties such as total coliforms.The water quality index(WQI)was also computed in these studies to ascertain the suitability of the water samples for human consumption.Review results showed that numerous water bodies in Nigeria have significantly diverse water quality levels,with some samples meeting or exceeding the WHO guidelines for microbiological,chemical,and physical characteristics.Notably,levels of heavy metals,turbidity,and pH frequently exceeded permissible limits,pointing to contamination from agricultural and industrial sources.The WQI results for multiple locations revealed that the majority of surface water sources were classified as“bad”to“very bad”,meaning they were unfit for human consumption.The results emphasized the critical need for immediate action to prevent further harm and deterioration of surface water bodies in Nigeria.Recommendations include strengthening waste management policies,promoting recycling initiatives,fostering collaborations among stakeholders,developing littering penalties and enforcing fines to curb the challenge,and raising educational awareness from the primary level.This review emphasizes the need for proactive measures to protect the environment and surface water quality in Nigeria.
基金supported by the National Natural Science Foundation of China (32122059)the National Key R&D Program of China(2021YFD2200402)+5 种基金the Chinese Academy of Sciences Young Talents Programthe LiaoNing Revitalization Talents Program (XLYC2007016) to QWW2024 Joint Fund Project Funding Program (2023-MSBA-137) to JJDChinese Academy of Sciences President's International Fellowship Initiative (2022VCA0010)the Japan Society for the Promotion of Science (KAKENHI,17F17403) to QWW and HKAcademy of Finland Project(324555) to TMR
文摘Photodegradation is considered as a universal contributing factor to litter decomposition and carbon(C)cycling within the Earth’s biomes.Identifying how solar radiation modifies the molecular structure of litter is essen-tial to understand the mechanism controlling its decom-position and reaction to shifts in climatic conditions and land-use.In this study,we performed a spectral-attenuation experiment following litter decomposition in an understory and gap of a temperate deciduous forest.We found that short-wavelength visible light,especially blue light,was the main factor driving variation in litter molecular struc-ture of Fagus crenata Blume,Quercus crispula Blume,Acer carpinifolium Siebold&Zuccarini and Betula platyphylla Sukaczev,explaining respectively 56.5%,19.4%,66.3%,and 16.7%of variation in its chemical composition.However,the variation also depended on canopy openness:Only in the forest gap was lignin aromatic C negatively associated with C-oxygen(C–O)bonding in polysaccharides receiv-ing treatments containing blue light of the full spectrum of solar radiation.Regardless of species,the decomposition index of litter that explained changes in mass and lignin loss was driven by the relative content of C–O stretching in poly-saccharides and lignin aromatic C.The results suggest that the availability of readily degradable polysaccharides pro-duced by the reduction in lignin aromatic C most plausibly explains the rate of litter photodegradation.Photo-products of photodegradation might augment the C pool destabilized by the input of readily degradable organic compounds(i.e.,polysaccharides).
基金funded by the National Natural Science Foundation of China(31870435)the European Union's Marie Sklodowska-Curie Action Postdoctoral Fellowship(101061660)the China Scholarship Council(202106180060).
文摘The dominant plant litter plays a crucial role in carbon(C)and nutrients cycling as well as ecosystem functions maintenance on the Qinghai-Tibet Plateau(QTP).The impact of litter decomposition of dominant plants on edaphic parameters and grassland productivity has been extensively studied,while its decomposition processes and relevant mechanisms in this area remain poorly understood.We conducted a three-year litter decomposition experiment in the Gansu Gannan Grassland Ecosystem National Observation and Research Station,an alpine meadow ecosystem on the QTP,to investigate changes in litter enzyme activities and bacterial and fungal communities,and clarify how these critical factors regulated the decomposition of dominant plant Elymus nutans(E.nutans)litter.The results showed that cellulose and hemicellulose,which accounted for 95%of the initial lignocellulose content,were the main components in E.nutans litter decomposition.The litter enzyme activities ofβ-1,4-glucosidase(BG),β-1,4-xylosidase(BX),andβ-D-cellobiosidase(CBH)decreased with decomposition while acid phosphatase,leucine aminopeptidase,and phenol oxidase increased with decomposition.We found that both litter bacterial and fungal communities changed significantly with decomposition.Furthermore,bacterial communities shifted from copiotrophic-dominated to oligotrophic-dominated in the late stage of litter decomposition.Partial least squares path model revealed that the decomposition of E.nutans litter was mainly driven by bacterial communities and their secreted enzymes.Bacteroidota and Proteobacteria were important producers of enzymes BG,BX,and CBH,and their relative abundances were tightly positively related to the content of cellulose and hemicellulose,indicating that Bacteroidota and Proteobacteria are the main bacterial taxa of the decomposition of E.nutans litter.In conclusion,this study demonstrates that bacterial communities are the main driving forces behind the decomposition of E.nutans litter,highlighting the vital roles of bacterial communities in affecting the ecosystem functions of the QTP by regulating dominant plant litter decomposition.
基金Supported by the fund of the Henan Province Science and Technology Research Project(No.242102210213).
文摘Addressing the challenges in detecting surface floating litter in artificial lakes,including complex environments,uneven illumination,and susceptibility to noise andweather,this paper proposes an efficient and lightweight Ghost-YOLO(You Only Look Once)v8 algorithm.The algorithmintegrates advanced attention mechanisms and a smalltarget detection head to significantly enhance detection performance and efficiency.Firstly,an SE(Squeeze-and-Excitation)mechanism is incorporated into the backbone network to fortify the extraction of resilient features and precise target localization.This mechanism models feature channel dependencies,enabling adaptive adjustment of channel importance,thereby improving recognition of floating litter targets.Secondly,a 160×160 small-target detection layer is designed in the feature fusion neck to mitigate semantic information loss due to varying target scales.This design enhances the fusion of deep and shallow semantic information,improving small target feature representation and enabling better capture and identification of tiny floating litter.Thirdly,to balance performance and efficiency,the GhostConv module replaces part of the conventional convolutions in the feature fusion neck.Additionally,a novel C2fGhost(CSPDarknet53 to 2-Stage Feature Pyramid Networks Ghost)module is introduced to further reduce network parameters.Lastly,to address the challenge of occlusion,a newloss function,WIoU(Wise Intersection over Union)v3 incorporating a flexible and non-monotonic concentration approach,is adopted to improve detection rates for surface floating litter.The outcomes of the experiments demonstrate that the Ghost-YOLO v8 model proposed in this paper performs well in the dataset Marine,significantly enhances precision and recall by 3.3 and 7.6 percentage points,respectively,in contrast with the base model,mAP@0.5 and mAP 0.5:0.95 improve by 5.3 and 4.4 percentage points and reduces the computational volume by 1.88MB,the FPS value hardly decreases,and the efficient real-time identification of floating debris on the water’s surface can be achieved costeffectively.
文摘Dear Editor,Numerous aspects of ecosystem ecology are influenced by insects(Prasad,2022).Herbivory of plant organs by insects may influence the biogeochemistry of forests by changing the speed of litter decomposition(Schowalter,2022).Cycas micronesica K.D.Hill is the only native gymnosperm in the Mariana Islands.The once-abundant tree experienced no known lethal threats prior to the 2003 invasion of Guam by the scale Aulacaspis yasumatsui Takagi(Marler,2012).This insular case study has been the subject of abundant research(Marler et al.,2021).Changes to leaf litter chemistry improved litter quality following A.yasumatsui infestations(Marler and Dongol,2016),but the prediction of increased decomposition speed has not been confirmed with experimental incubations.
基金supported by the GuangDong Basic and Applied Basic Research Foundation(2022A1515110439)the National Natural Science Foundation of China(32101393)+1 种基金China Postdoctoral Science Foundation(2023M7339832023M743547)。
文摘Background:Forest soils in tropical and subtropical areas store a significant amount of carbon.Recent framework to assess soil organic matter(SOM)dynamics under evolving global conditions suggest that dividing bulk SOM into particulate and mineral-associated organic matter(POM vs.MAOM)is a promising method for identifying how SOM contributes to reducing global warming.Soil macrofauna,earthworms,and millipedes have been found to play an important role in facilitating SOM processes.However,how these two co-existing macrofaunae impac the litter decomposition process and directly impact the formation of POM and MAOM remains unclear.Methods:Here,we set up a microcosm experiment,which consisted of 20 microcosms with four treatments earthworm and litter addition(E),millipedes and litter addition(M),earthworm,millipedes,and litter addition(E+M),and control(only litter addition)in five replicates.The soil and litter were sterilized prior to beginning the incubation experiment to remove any existing microbes.After incubating the samples for 42 days,the litte properties(mass,C,and N contents),soil physicochemical properties,as well as the C and N contents,and POM and MAOM^(13)C abundance in the 0–5 and 5–10 cm soil layers were measured.Finally,the relative influences o soil physicochemical and microbial properties on the distribution of C and N in the soil fractions were analyzed Results:The litter mass,C,and N associated with all four treatments significantly decreased after incubation especially under treatment E+M(litter mass:-58.8%,litter C:-57.0%,litter N:-75.1%,respectively),while earthworm biomass significantly decreased under treatment E.Earthworm or millipede addition alone showed no significant effects on the organic carbon(OC)and total nitrogen(TN)content in the POM fraction,but join addition of both significantly increased OC and TN regardless of soil depth.Importantly,all three macrofauna treatments increased the OC and TN content and decreased the^(13)C abundance in the MAOM fraction.More than65%of the total variations in the distribution of OC and TN throughout the two fractions can be explained by a combination of soil physicochemical and microbial properties.Changes in the OC distribution in the 0–5 cm soi layer are likely due to a decrease in soil pH and an increase in arbuscular mycorrhizal fungi(AMF),while those in the 5–10 cm layer are probably caused by increases in soil exchangeable Ca and Mg,in addition to fungi and gram-negative(GN)bacteria.The observed TN distribution changes in the 0–5 cm soil likely resulted from a decrease in soil pH and increases in AMF,GN,and gram-negative(GP)bacteria,while TN distribution changes in the 5–10 cm soil could be explained by increases in exchangeable Mg and GN bacteria.Conclusions:The results indicate that the coexistence of earthworms and millipedes can accelerate the litte decomposition process and store more C in the MAOM fractions.This novel finding helps to unlock the processe by which complex SOM systems serve as C sinks in tropical forests and addresses the importance of soil mac rofauna in maintaining C-neutral atmospheric conditions under global climate change.
文摘Despite cities being recognized as being potential sources of microplastic pollution to the wider environment, most surveys of COVID-19 plastic-based litter have been undertaken through linear transects of marine beaches. For the far fewer number of studies conducted on inland and urban locations, the site-specific focus has primarily been surveys along the length of streets. The present study is the first to specifically assess the standing stock (i.e., moment-in-time) of littered face masks for the entire surface area of urban parking lots. The density of face masks in 50 parking lots in a Canadian coastal town (0.00054 m2 ± 0.00051 m2) was found to be significantly greater than the background level of littering of town streets. Face mask density was significantly related to visitation “usage” of parking lots as gauged by the areal size of the lots and of their onsite buildings, as well as the number of vehicles present. Neither parking lot typology nor estimates of inferred export (various measures of wind exposure) and entrapment (various metrics of obstruction) of face masks had a significant influence on the extent of whole-lot littering. In consequence, modelling of the potential input of mask-derived microplastics to the marine environment from coastal communities can use the areal density of face masks found here in association with the total surface area of lots for individual municipalities as determined through GIS analysis.
文摘Fecal coliform bacteria such as Escherichia coli (E. coli) are one of the main sources of groundwater pollution. An assessment of the transport and Persistence of E. coli in poultry litter amended Decatur silty Clay soil and Hartsells Sandy soil was conducted using soil columns and simulated groundwater leaching. Enumeration of initial E. coli was determined to range from 2.851 × 10<sup>3</sup> to 3.044 × 10<sup>3</sup> CFU per gram of soil. These results have been used in a batch study to determine the persistence rate of E. coli in Decatur silty Clay soil and Hartsells Sandy soil. Results prove that E. coli survival growth rate increases for clay soil later than and at a higher rate than sandy soil. The column study has determined that E. coli was transported at a rate of 3.7 × 10<sup>6</sup><sup> </sup>CFU for Decatur silty loam and 6.3 × 10<sup>6</sup><sup> </sup>CFU for Hartsells sandy per gram of soil. Further, linear regression analysis predictions show higher porosity and soil moisture content affect transport, and Hartsells sandy soil has higher transport of E. coli due to its higher porosity and lower volumetric water content.
文摘Identification of management practices that can improve soil health is critical to improving the sustainability of soybean [Glycine max (L.) Merr.] production. The objective of this study was to examine the long-term effects of continuous soybean, corn-soybean, and soybean-cotton rotations with chicken litter and cover crops (hairy vetch, wheat, fallow) on soil health parameters, including nutrient accumulation and soil organic matter dynamics under a split plot design. The depth intervals of soil sampling were 0 - 15, 15 - 30, 30 - 60, and 60 - 90 cm. Chicken litter resulted in 62.1% and 32.8% higher water extractable organic soil N content than fallow and wheat, respectively, in the surface 0 - 15 cm of soil only. However, there was no significant difference in 1-day Solvita respiration, water extractable organic C, C/N ratio, health score, moisture, earthworm, organic matter, pH, or CEC of soil among fallow, hairy vetch, chicken litter, and wheat regardless of soil depth. Unexpectedly, annual application of chicken litter at 4.4 Mg ha−1 as an N source or growing a winter-season cover crop such as hairy vetch or wheat for continuous 16 years did not significantly increase soil organic matter or water extractable organic soil C. Annual application of chicken litter at 4.4 metric tons (Mg) ha–1 for 16 years increased soil nitrate-nitrogen (NO3−-N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), and zinc (Zn) contents by 92%, 400%, 134%, 20%, 43%, 206%, and 430% in 0 - 15 cm depth compared with their initial soil values, respectively, extracted with Haney H3A-2 (2 g L–1 lithium citrate + 0.6 g L–1 citric acid + 0.4 g L–1 malic acid + 0.4 g L–1 oxalic acid) solution. The increases enhanced soil supply of these nutrients to following crops, but also increased the risks of losing them to the environment. Hairy vetch caused higher H3A extracted soil manganese (Mn) content than fallow and chicken litter in 0 - 60 cm. There was no significant difference in 1-day Solvita respiration, water extractable organic C and N, health score, moisture, organic matter, pH, CEC, or population of earthworm of soil among continuous soybean, corn-soybean, and soybean-cotton in any soil depth. Another major finding of this study was that continuous soybean exerted no adverse effect on soil health relative to the commonly used corn (Zea mays L.)-soybean and soybean-cotton (Gossypium hirsutum L.) rotations under no-tillage after 16 years. To mitigate the risks of nutrient runoff and leaching from long-term chicken litter application, we recommend reducing litter application rates and integrating cover crops into crop rotations to enhance nutrient cycling and reduce environmental impacts.
文摘Objective: The paper aims to analyze the dynamic characteristics of litter production and nutrient return of the forest ecosystems in subtropical areas, and provide a theoretical basis for the nutrient cycling study in southwest Hubei Province and carbon sink function of the whole forest ecosystem. Methods: Three typical forest stands (Chinese fir plantation, Cryptomeria fortunei plantation and evergreen and deciduous broad-leaved mixed forest) in Golden Mountain Forest Farm in southwest Hubei Province were investigated and monitored continuously for the litter types and productivity and nutrient return. Results: The annual litter productivity of the three forest stands ranged from 161.77 to 396.26 kg·hm<sup>-2</sup>;Litters of branches, leaves and reproductive organs accounted for 14.14% - 20.85%, 33.26% - 78.33%, 7.52% - 42.18% of the total, respectively;The litter productivity and total litter productivity of each composition in the three forest stands show unimodal or bimodal changes over months, and the total litter productivity reached the highest value in January, April and October respectively. For different nutrient contents of the three forest stands, the common feature is C > N. The order of nutrient return amount from greatest to least is evergreen and deciduous broad-leaved mixed forest, Cryptomeria fortunei plantation and Chinese fir plantation. For different nutrient return amounts, the common feature is C > N, and the nutrient return amounts are 76.51-180.69 kg·hm<sup>-2</sup> and 2.3 - 5.71 kg·hm<sup>-2</sup> respectively. Conclusion: The annual litter productivity and nutrient return amount of the evergreen and deciduous broad-leaved mixed forest are the highest among the three forest stands. Therefore, protecting the evergreen and deciduous broad-leaved mixed forest and studying the litter changes of Chinese fir plantation and Cryptomeria fortunei plantation are of far-reaching significance for the development of sustainable forest management in this region and the further improvement of the carbon sequestration function of the whole forest ecosystem.
文摘The effect of litter on forest regeneration depends on the characteristics of regional climate and also shows community specificity. The influences of plant litter on seed germination and seedling growth of Larch Siberian forest in the Altai Mountains were investigated through two simulated experiments including litter coverage and litter aqueous extracts. In the litter coverage experiment, three litter coverage methods including above (D), below (S) and in the middle (Z) of litter were set with the litter coverage thickness of 0, 1, 2, and 4 cm, while two aqueous extract obtained methods using the air-dried litter and litter ash after fir were used with the concentration of 10%, 40%, 80% and 100% in the present study. Results showed that: the aqueous extracts obtained using the air-dried litter restrained the seed germination, while the aqueous extracts obtained using litter ash improved the seed germination. Compared with other litter concentration, the influences of 100% concentration reach highest. The seed germination rate, seed germination potential and vital index under the treatment of seeds above the litter coverage were highest, which were significantly higher than other treatments. The above-ground biomass was significantly higher and the inhibition index of below-ground bio-mass was significantly lower under the treatment of seed above the litter with thin litter cover-age (S1) compared to other litter coverage treatments. These results indicated that the litter aqueous extract and the litter coverage had a combined effect on the seed germination and seedling growth of Siberian larch forest. Fire disturbance could promote seed germination by modifying the adverse effects of litter aqueous extracts and litter coverage, and thus plays an important role in the regeneration of Siberian larch in the Altai Mountains.
基金the National Natural Science Foundation of China (Nos. 30471378, 90202010 and 30211130504),and the Program of 100 Distinguished Young Scientists of the Chinese Academy of Sciences.
文摘Litter production, components and dynamics were investigated and forest floor litter was quantified throughout awhole year in three subalpine forests, dominated by tree species of spruce (SF), fir (FF) and birch (BF), in WesternSichuan, China, in order to understand the key factors that influenced litter production and dynamics. Litterfall in thethree forests consisted mainly of leaves, woody litter, reproductive organs and moss. Contribution of leaf litter to thetotal litterfall was significantly (P < 0.05) greater than that of woody litter, reproductive organs or moss. Regardlessof the stands, litterfall exhibited a marked monthly variation with the maximum litterfall peaks occurring in October,with smaller peaks occurring in February for SF and FF, and May for BF. The analysis indicated that tree species,stand density, leaf area index (LAI), stand basal area and stand age were the key factors determining litter production.Meanwhile tree species and phenology controlled the litter dynamics, with wind and snow modifying the litter componentsand dynamics.
基金supported by the National Basic Research Program(Grant No.2011CB403205)
文摘Decomposition dynamics were compared among green tree leaves, partially decomposed tree leaf litter （i.e., decayed tree leaf litter on forest floor） and a mixture of the two in a warm temperate forest ecosystem in central China to test the influence of litter chemical quality on the degree of decomposition. The study was conducted in situ at two contrasting forest sites, an oak forest dominated by Quercus aliena var. acuteserrata Maxim., and a mixed pine and oak forest dominated by Pinus armandii Franch. and Q. aliena var. acuteserrata. We found marked differences in the rate of decomposition among litter types at both forest sites; the litter decom- position constant, k, was about 39 % greater at the oak forest site and more than 70 % greater at the pine-oak forest site, for green leaves than for partially decomposed leaf litter. The decomposition dynamics and temporal changes in litter chemistry of the three litter types also greatly differed between the two forest sites. At both forest sites, the higher rate of decomposition for the green leaves was associated with a and lower carbon to N ratio higher nitrogen （N） content （C/N） and acid-unhydrolyz- able residue to N ratio （AUR/N）. We did not find any non- additive effects when mixing green leaves and partially decomposed leaf litter. Our findings support the con- tention that litter chemical quality is one of the most important determinants of litter decomposition in forest ecosystems at the local or regional scale, but the effect of litter chemical quality on decomposition differs between the contrasting forest types and may vary with the stage of decomposition.
基金supported by the National Natural Science Foundation of China(30800163)
文摘Litter phosphorus （P） return is important to maintain the P cycle and balance in the sandy land of arid areas. In this study, we determined the loss and return of litter P in sand dune areas and elucidated their relation- ship. We investigated litter production and litter P amount, and simulated leaf litter moving dynamics to understand the relationships between the loss of litter P and the total litter P, and between the return of litter P and the total litter P in active （AD）, semi-stabilized （SSD） and stabilized （SD） dunes in Inner Mongolia, northeastern China. The vegetation litter P was 12.6, 94.5, and 201.6 mg P/m2 in AD, SSD, and SD, respectively. A significant movement and loss of leaf litter P with time occurred on the three types of sand dunes. As a result, the loss of P was 7.4, 46.9, and 69.8 mg P/m2 and the return of P was 5.5, 47.6, and 131.8 mg P/m2 in AD, SSD, and SD, respectively. The rela- tionship between both loss and return of P and total litter P in AD, SSD, and SD was revealed by linear regression. The slope of the regression line indicated the rate of loss or return of litter P. From AD to SD, the loss rate showed a declining slope （0.52, 0.32, and 0.17 for AD, SSD, and SD, respectively）, and the return rate showed a rising slope （0.48, 0.67, and 0.83 for AD, SSD, and SD, respectively）. The loss of litter P should be regarded in the local man- agement of vegetation and land in sand dune areas. Improved vegetation restoration measures are necessary to decrease litter P loss to maintain the stability of ecosystems in sand dune areas.
基金supported by the National Natural Science Foundation of China(Grant Nos.31830015 and 32171752)。
文摘Background:Litter traits critically affect litter decomposition from local to global scales.However,our understanding of the temporal dynamics of litter trait-decomposition linkages,especially their dependence on plant functional type remains limited.Methods:We decomposed the leaf litter of 203 tree species that belong to two different functional types(deciduous and evergreen)for 2 years in a subtropical forest in China.The Weibull residence model was used to describe the different stages of litter decomposition by calculating the time to 10%,25%and 50%mass loss(Weibull t_(1/10),t_(1/4),and t_(1/2)respectively)and litter mean residence time(Weibull MRT).The resulting model parameters were used to explore the control of litter traits(e.g.,N,P,condensed tannins and tensile strength)over leaf litter decomposition across different decomposition stages.Results:The litter traits we measured had lower explanatory power for the early stages(Weibull t_(1/10)and t_(1/4))than for the later stages(Weibull t_(1/2)and MRT)of decomposition.The relative importance of different types of litter traits in influencing decomposition changed dramatically during decomposition,with physical traits exerting predominant control for the stages of Weibull t_(1/10)and MRT and nutrient-related traits for the stages of Weibull t_(1/4),and t_(1/2).Moreover,we found that litter decomposition of the early three stages(Weibull t_(1/10),t_(1/4),and t_(1/2))of the two functional types was controlled by different types of litter traits;that is,the litter decomposition rates of deciduous species were predominately controlled by nutrient-related traits,while the litter decomposition rates of evergreen species were mainly controlled by carbon-related traits.Conclusions:This study suggests that litter trait-decomposition linkages vary with decomposition stages and are strongly mediated by plant functional type,highlighting the necessity to consider their temporal dynamics and plant functional types for improving predictions of litter decomposition.
基金This research was financially and logistically supported by the AMU-IUC program of the Belgium Government through the Flemish interuni-versity council(VLIR-UOS).
文摘Background:Attempts to restore degraded highlands by tree planting are common in East Africa.However,up till now,little attention has been given to effects of tree species choice on litter decomposition and nutrient recycling.Method:In this study,three indigenous and two exotic tree species were selected for a litter decomposition study.The objective was to identify optimal tree species combinations and tree diversity levels for the restoration of degraded land via enhanced litter turnover.Litterbags were installed in June 2019 into potential restoration sites(disturbed natural forest and forest plantation)and compared to intact natural forest.The tested tree leaf litters included five monospecific litters,ten mixtures of three species and one mixture of five species.Standard green and rooibos tea were used for comparison.A total of 1,033 litters were retrieved for weight loss analysis after one,three,six,and twelve months of incubation.Results:The finding indicates a significant effect of both litter quality and litter diversity on litter decomposition.The nitrogen-fixing native tree Millettia ferruginea showed a comparable decomposition rate as the fast decom-posing green tea.The exotic conifer Cupressus lusitanica and the native recalcitrant Syzygium guineense have even a lower decomposition rate than the slowly decomposing rooibos tea.A significant correlation was observed be-tween litter mass loss and initial leaf litter chemical composition.Moreover,we found positive non-additive ef-fects for litter mixtures including nutrient-rich and negative non-additive effects for litter mixtures including poor leaf litters respectively.Conclusion:These findings suggest that both litter quality and litter diversity play an important role in decom-position processes and therefore in the restoration of degraded tropical moist evergreen forest.
