Larch (Larix olgensis), Manchurian ash (Fraxinus mandshurica), Korean pine (Pinus koraiensis) and White birch (Betula platyphylla) are the major planting species in northeast China. The samples of forest litters were ...Larch (Larix olgensis), Manchurian ash (Fraxinus mandshurica), Korean pine (Pinus koraiensis) and White birch (Betula platyphylla) are the major planting species in northeast China. The samples of forest litters were collected from the stands of the above 4 species in Laoyeling and Jianlagou experiment stations of Maorshan Exp. Forest Farm (45?2-45?0N, 127?0-127?8E), Northeast Forestry University, in early October 2002. Quantitative analysis and qualitative analysis were carried out on the organic acids existing in freshly fallen litters (L layer) and hemi-decomposed litters (F layer) of the four forest species by using Gas Chromatogram system. A wide variety of organic acids were identified, including oxalic, malonic, fumaric, succinic, maleic, malic, citric, C16:0, C18:0, C18:1, C18:2, C18:3 and C20:0 acids. In respect of L litters of all samples, the oxalic acid content (over 30 mg/g) was the highest of the seven low-molecular-weight organic acids identified, while the content of oleic or linoleic (above 40 mg/g) was found to be highest among the six high aliphatic acids identified. As to F litters, oxalic acid content was also the highest, followed by linoleic and oleic. For the same tree species or the same forest, the kinds and contents of organic acids in L litters were more abundant than that in F litters.展开更多
Earthworms are the important constituents in the decayed food web and the main ecological conditioners in the process of decomposition and nutrient mineralization. The transformation of organic carbon (C) and total ni...Earthworms are the important constituents in the decayed food web and the main ecological conditioners in the process of decomposition and nutrient mineralization. The transformation of organic carbon (C) and total nitrogen (N) in the broad-leaved litters ingested by earthworms was researched by means of a laboratory experiment. Experimental samples were collected from broad-leaved Korea Pine mixed forest in Liangshui National Natural Reserve (47°10′50″N, 128°53′20″E) in the northeastern Xiao Hinggan Mountains of Northeast China. The contents of organic C and total N in earthworms, leaf litters and earthworm faeces were analyzed. Results show that the organic C content was in the fol- lowing order: leaf litters>faeces>earthworms, while total N content was contrary to that of the organic C. The organic C contents in the different leaf litters were in the following order: Tilia amurensis>Betula costata>Acer mono, whereas the total N contents in the different leaf litters were: Betula costata>Tilia amurensis>Acer mono. The contents of organic C and total N in the faeces from the different leaf litters were almost consistent with the contents of the leaf litters. After the leaf litters were ingested by earthworms, the organic C, which was transformed to increase earthworms' weights, ac- counted for 3.90%-13.31% of the total ingestion by earthworms, while that in the earthworm faeces accounted for 6.14%-13.70%. The transformed organic C through the other metabolism (e.g., respiration) of earthworms accounted for 75.04%-89.92%. The ingested organic C by earthworms was mostly used for metabolic activities. The N ingested by earthworms was less than organic C. It is estimated that 37.08% of total N was transformed to increase the earthworm's weight, 19.97% into earthworm faeces and 47.86% for the consumption of the earthworm's activities. The earthworms not only increased the content of organic C and total N in the soil, but also decreased the values of C/N in the soil and leaf litters. Earthworms play a major role in the leaf litters' decomposition and transformation.展开更多
Allelopathic effects of different doses of Eucalyptus camaldulensis leaf litters were investigated through an experiment in the green house of Institute of Forestry and Environmental Sciences, Chittagong, Bangladesh. ...Allelopathic effects of different doses of Eucalyptus camaldulensis leaf litters were investigated through an experiment in the green house of Institute of Forestry and Environmental Sciences, Chittagong, Bangladesh. Three popular agricultural crops： Falen （Vigna unguiculata）, Chickpea （Cicer arietinum）, Arhor （Cajanus cajan） and two widely used plantation trees： Sada koroi （Albizia procera） and Ipil ipil （Leucaena leucocephala） were selected as bioassay species. Experiment was set on tray at room temperature 27℃. The effects of different doses of leaf litter extracts were compared to the control. Results suggest that leaf litters of E, camaldulesis induced inhibitory effects, It was also found that the effect depend on concentration of extract and litterfall, type of receiver species. Higher concentration of the materials had the higher effect and vice versa. Though all the bioassay species were suppressed some of them showed better performance. Vigna unguiculata, Cicer arietinum are recommended in agroforestry based on this present Experiment output. In mixed plantation, Leucaena leucochephala is a better choice while compared to Albizia procera.展开更多
The impacts of petroleum contamination on the litter decomposition of shrub-grass land would directly influence nutrient cycling, and the stability and function of ecosystem. Ten common shrub and grass species from Yu...The impacts of petroleum contamination on the litter decomposition of shrub-grass land would directly influence nutrient cycling, and the stability and function of ecosystem. Ten common shrub and grass species from Yujiaping oil deposits were studied. Litters from these species were placed into litterbags and buried in petroleum-contaminated soil with 3levels of contamination（slight, moderate and serious pollution with petroleum concentrations of 15, 30 and 45 g/kg, respectively）. A decomposition experiment was then conducted in the lab to investigate the impacts of petroleum contamination on litter decomposition rates. Slight pollution did not inhibit the decomposition of any litters and significantly promoted the litter decomposition of Hippophae rhamnoides, Caragana korshinskii, Amorpha fruticosa, Ziziphus jujuba var. spinosa, Periploca sepium, Medicago sativa and Bothriochloa ischaemum. Moderate pollution significantly inhibited litter decomposition of M. sativa,Coronilla varia, Artemisia vestita and Trrifolium repens and significantly promoted the litter decomposition of C. korshinskii, Z. jujuba var. spinosa and P. sepium. Serious pollution significantly inhibited the litter decomposition of H. rhamnoides, A. fruticosa, B. ischaemum and A. vestita and significantly promoted the litter decomposition of Z. jujuba var. spinosa, P.sepium and M. sativa. In addition, the impacts of petroleum contamination did not exhibit a uniform increase or decrease as petroleum concentration increased. Inhibitory effects of petroleum on litter decomposition may hinder the substance cycling and result in the degradation of plant communities in contaminated areas.展开更多
Irnazaquin applied in legume crops has a long residual time in soil, which often impacts safety of the susceptible crops. To increase safety of imazaquin application, two composted litters, bovine manure （BM） and ch...Irnazaquin applied in legume crops has a long residual time in soil, which often impacts safety of the susceptible crops. To increase safety of imazaquin application, two composted litters, bovine manure （BM） and chicken manure （CM）, were used to determine their effects on imazaquin environmental behavior by incorporating each kind of manure into the tested sandy loam soil at 10% （w/w）. The degradation of imazaquin in BM- and CM-amended soil was about 2.4 and 1.5 times, respectively, faster than that in unamended soil. The half-lives of imazaquin in BM-amended soil varied between 6.7 and 15.4 d over the temperature range of 20 to 40℃, and the degradation rate constant （k） increased by a factor of about 1.5 for every 10℃ change. Higher mix ratio did not significantly increase the degradation, and the optimal active degradation of imazaquin was observed approximately at the mix ratio of 10：1 of soil to BM. The different moisture levels had negligible effect on imazaquin degradation. In both unamended and BM-amended treatments, two metabolites were observed at 5, 10 and 30 d after treatment. One metabolite at retention time （RT） of 8.4 rain was identified as 2-（4- hydroxyl-5-oxo-2-imidazolin-2-yl） quinoline acid, originating from the loss of isopropyl group and hydroxylation at the 4-position of imidazolinone ring. The other at RT of 12.9 rain was identified as quinoline-2,3-dicarboxylic anhydride, resulting from detachment of imidazolinone ring and the forming of dicarboxylic anhydride. This finding suggested that the addition of farm litters into soil might be a good management option since it can not only increase soil fertility but also contribute to increase safety of imazaquin application to the following susceptible crops.展开更多
Recent publication attested that in the urban forest of Brazzaville, litter decomposition is faster with almost 45% of initial weight loss than in the dry season, where an average loss of 26% in initial litter weight ...Recent publication attested that in the urban forest of Brazzaville, litter decomposition is faster with almost 45% of initial weight loss than in the dry season, where an average loss of 26% in initial litter weight is noted (Ifo et al., 2018). This study was carried out in the urban forest of Brazzaville to follow the decomposition of some organic compounds/secondary metabolites (reducing Sugars, total Flavonoid and Polyphenols) of the leaves litters of two tropical species Antiaris toxicaria Lesch and Millettia laurentii De Wild. Thin-layer chromatography and spectrophotometric assay of these metabolites were used on the samples of litters collected in the field on various dates of follow-up of the decomposition (0 d, 14 d, 28 d, 42 d, 56 d, 72 d and 84 d). The chromatographic profile of initial litters shows a series of spots on yellow florescence materializing presence of flavonoids, green fluorescence revealing the presence of the acids phenols derived from the cinnamic acid. But the chromatographic profile of the two litters in decomposition after two weeks remains without structural information, being able to characterize the decomposition of the chemical families highlighted in the initial litters. Also, the analysis of quantitative total reducing sugar in the initial litters, gives average concentrations of 64.4, 58.6, 57.5 g EG/kg Ms respectively for the litters of Millettia laurentii De Wild, Antiaris toxicaria Lesch and the mixed litters (Millettia laurentii and Antiaris toxicaria). Comparatively with the other types of litters, the initial average concentrations in phenolic compounds (polyphenols and flavonoids totals) were the highest for the litters of Antiaris toxicaria Lesch (27.3 g EAG/kg Ms and 13.07 g EC/kg Ms) (P = 0.001). The losses of organic chemical compounds are more significant during the first two weeks of experiment than after this period. Antiaris toxicaria Lesch loses on average 43.8 g EG/kg Ms of reducing Sugars, 12.21 g EC/kg Ms of totals flavonoids and 26.4 g EAG/kg Ms of total polyphenols, equivalent to 30% of loss of the initial weight. Average losses of 45.7 g EG/kg Ms were obtained for reducing sugars, 1.5 g EC/kg Ms for totals flavonoids and 8.72 g EAG/kg Ms for totally phenols in for the litters of Millettia laurentii, comparable to 24% in initial weight loss. This study showed on the one hand, the direct link between rainfall and litters decomposition and the losses in weight of the litters resulted in dissolution in the water of the studied compounds.展开更多
Exotic plant invasions and increased atmospheric carbon dioxide(CO_(2))concentration have been determined to independently affect soil nematodes,a key component of soil biota.However,little is known about the long-ter...Exotic plant invasions and increased atmospheric carbon dioxide(CO_(2))concentration have been determined to independently affect soil nematodes,a key component of soil biota.However,little is known about the long-term effects of these two global change factors and their interactive effects.Over three consecutive years,we cultivated invasive alien plant Xanthium strumarium and its two phylogenetically related natives under both ambient(aCO_(2))and elevated(eCO_(2))atmospheric CO_(2)concentrations,and determined the effects of the invader and natives on soil nematodes under different CO_(2)concentrations and the relevant mechanism.The abundance of total soil nematodes and that of the dominant trophic group(herbivores)were significantly affected by plant species and CO_(2)concentration,and these effects were dependent on the experimental duration,however,the Shannon-diversity of nematodes was not affected by these factors.Under aCO_(2),both invasive and native species significantly increased the total nematode abundance and that of the dominant trophic group with increasing experimental duration,and the amplitude of the increase was greater under the invader relative to the natives.The eCO_(2)increased total nematode abundance(second year)and that of the dominant trophic group(third year)under the invader,but not under the natives(or even decreased)with increasing experimental duration.Root litter had greater effects on soil nematode abundance than leaf litter and root exudates did.This study indicates that eCO_(2)would aggravate effects of invasive plants on soil nematodes by increasing abundance,and these effects would vary with the duration.展开更多
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
Symbiotic and asymbiotic nitrogen fixation(SNF and ANF),two forms of biological nitrogen(N)fixation,are the main pathways for external N inputs into natural terrestrial ecosystems.However,the regulatory mechanisms of ...Symbiotic and asymbiotic nitrogen fixation(SNF and ANF),two forms of biological nitrogen(N)fixation,are the main pathways for external N inputs into natural terrestrial ecosystems.However,the regulatory mechanisms of SNF and ANF,particularly in response to changing environmental conditions,remain poorly understood.Here,we investigated changes in SNF and ANF rates along two altitudinal gradients in two subtropical forests on soils with granite and slate parent materials.Our results revealed distinct patterns for SNF and ANF rates.SNF rates consistently declined with increasing altitude,whereas ANF rates initially increased at lower altitudes but declined at higher altitudes.These contrasting trends were attributed to divergent regulatory mechanisms of SNF and ANF rates.Specifically,the decrease in SNF rates was primarily driven by increased soil N availability and decreased air temperature.However,the drivers of ANF rates shifted from soil properties(e.g.,phosphorus,iron,and moisture)at lower altitudes to climatic factors(e.g.,air temperature)at higher altitudes.We also observed opposite trends of SNF and ANF between forests on granite and slate,demonstrating that lithology is an important driver of both SNF and ANF.Collectively,our findings highlight the divergent mechanisms regulating SNF and ANF in subtropical forests,which contribute to improving the mechanistic representation of biological N fixation in Earth system models.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
Experiments were conducted to investigate the influences of type of litter,initial moisture content(IMC)of litter,and dry weight ratio of manure to litter(DWRML)on ammonia emissions from chicken manure and the effects...Experiments were conducted to investigate the influences of type of litter,initial moisture content(IMC)of litter,and dry weight ratio of manure to litter(DWRML)on ammonia emissions from chicken manure and the effects of pH values of tea leaves and the mixtures of tea leaves and other litter on the ammonia emissions from chicken manure.For the experiments,four kinds of litter,Northeast pine sawdust(sawdust),rice husk,tea leaves,and wheat straw,were selected.The IMCs of the litter were(20±2)%,(30±2)%,and(40±2)%;and the DWRML values were 1:4,1:6 and 1:8,respectively.The different litters adjusted at different moisture contents were mixed with chicken manure in different DWRML and then placed in different static test chambers,which were real-time monitored the ammonia concentrations.Pure chicken manure without any litter was used as a control group.The four kinds of litter had obvious inhibitory effects on the ammonia emissions from chicken manure under various conditions.There were significant differences among four kinds of litter(p<0.01).Under the same conditions,the best inhibitory effect was achieved by using tea leaves,followed by straw,rice husk,and sawdust.The IMC of litter had no significant effects on the ammonia inhibition(p>0.05).The DWRML had no significant effects on ammonia emission inhibition for tea leaves(p>0.05),but had a significant effects on the ammonia emission inhibition for the other three kinds of litter(p<0.05).The pH value of tea leaves had no significant effects on the inhibition of ammonia emissions(p>0.05).The mixed litter made of tea leaves and sawdust,rice husk,or straw were significantly better than the tea leaves and other single litter(p<0.01).It indicated that adding appropriate amount of tea leaves in the litter can effectively inhibit ammonia emissions from chicken manure.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
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
Plant roots and their associated mycorrhizal fungi critically mediate the decomposition of soil organic carbon(C),but the general patterns of their impacts over a broad geographical range and the primary mediating fac...Plant roots and their associated mycorrhizal fungi critically mediate the decomposition of soil organic carbon(C),but the general patterns of their impacts over a broad geographical range and the primary mediating factors remain unclear.Based on a synthesis of 596 paired observations from both field and greenhouse experiments,we found that living roots and/or mycorrhizal fungi increased organic C decomposition by 30.9%,but low soil nitrogen(N)availability(i.e.,high soil C:N ratio)critically mitigated this promotion effect.In addition,the positive effects of living roots and/or mycorrhizal fungi on organic C decomposition were higher under herbaceous and leguminous plants than under woody and non-leguminous plants,respectively.Surprisingly,there was no significant difference between arbuscular mycorrhizal fungi and ectomycorrhizal fungi in their effects on organic C decomposition.Furthermore,roots and/or mycorrhizal fungi significantly enhanced the decomposition of leaf litter but not root litter.These findings advance our understanding of how roots and their symbiotic fungi modulate soil C dynamics in the rhizosphere or mycorrhizosphere and may help improve predictions of soil global C balance under a changing climate.展开更多
In this study,we investigated how tree species affect N mineralization in connection to some soil properties and seconder metabolite levels of litter,in the soil of the old-est native forest communities.In the oldest ...In this study,we investigated how tree species affect N mineralization in connection to some soil properties and seconder metabolite levels of litter,in the soil of the old-est native forest communities.In the oldest pure communi-ties of Pinus nigra(PN),Fagus orientalis(FO),and Abies bornmuelleriana(AB)in the mountain range of Mount Uludağ,Bursa,Turkey,annual net yield and N mineraliza-tion in the 0-5-and 5-20-cm soil layers were determined in a field incubation study over 1 year.Sampling locations were chosen from 1300 to 1600 m a.s.l.,and moisture content(%),pH,water-holding capacity(%),organic C,total N,and C/N ratio,and annual net mineral N yield of the soil and hydro-lyzed tannic acid and total phenolic compounds in litter were compared for these forest communities.F.orientalis had the highest annual net Nmin yield(43.9±4.8 kg ha^(-1) a^(-1)),P.nigra the lowest(30.5±4.2 kg ha^(-1) a^(-1)).Our findings show that in the oldest forest ecosystems,the seasonal soil moisture content and tree species play an essential role in N cycling and that hydrolyzed tannic acids and total phenolic compounds effectively control N turnover.Tannic acid and total phenolics in the litter were found to inhibit nitrification,but total phenolics were found to stimulate ammonification.展开更多
The forest headwater streams are important hubs for connecting terrestrial and aquatic ecosystems,with plant litter and sediments as the major carriers for material migrations;however,until now we knew little about th...The forest headwater streams are important hubs for connecting terrestrial and aquatic ecosystems,with plant litter and sediments as the major carriers for material migrations;however,until now we knew little about the dynamics of trace elements such as iron(Fe)and aluminum(Al)in forest headwater streams.Here,we quantitatively identified the spatiotemporal dynamics of Fe and Al storages in plant litter and sediments and their influencing factors in a subtropical forest headwater stream,and assessed the potential pollution risk.The results showed that:(1)the mean concentrations of Fe and Al in plant litter(sediments)were 5.48 and 8.46(7.39 and 47.47)g·kg^(-1),and the mean storages of Fe and Al in plant litter(sediments)were 0.26 and 0.43(749.04 and 5030.90)g·m^(-2),respectively;(2)the storages of Fe and Al in plant litter and sediments significantly fluctuated from January to December,and showed a decreasing pattern from the source to mouth;and(3)storages of Fe and Al had no significant correlation with riparian forest type and the present of tributary and the Fe and Al storages in plant litter were mainly affected by water temperature and water alkalinity,and their storages in sediments were mainly affected by water temperature and frequency of rainfall;and(4)there were no anthropogenic pollution in Fe and Al in the forest headwater stream.Our study revealed the primary factors of concentrations and storages of Fe and Al in plant litter and sediments in a forest headwater stream,which will improve our understanding of the role of headwater streams in forest nutrient storage and cycling along with hydrological processes.展开更多
基金This paper is supported by National Natural Science Foundation of China (30170768)
文摘Larch (Larix olgensis), Manchurian ash (Fraxinus mandshurica), Korean pine (Pinus koraiensis) and White birch (Betula platyphylla) are the major planting species in northeast China. The samples of forest litters were collected from the stands of the above 4 species in Laoyeling and Jianlagou experiment stations of Maorshan Exp. Forest Farm (45?2-45?0N, 127?0-127?8E), Northeast Forestry University, in early October 2002. Quantitative analysis and qualitative analysis were carried out on the organic acids existing in freshly fallen litters (L layer) and hemi-decomposed litters (F layer) of the four forest species by using Gas Chromatogram system. A wide variety of organic acids were identified, including oxalic, malonic, fumaric, succinic, maleic, malic, citric, C16:0, C18:0, C18:1, C18:2, C18:3 and C20:0 acids. In respect of L litters of all samples, the oxalic acid content (over 30 mg/g) was the highest of the seven low-molecular-weight organic acids identified, while the content of oleic or linoleic (above 40 mg/g) was found to be highest among the six high aliphatic acids identified. As to F litters, oxalic acid content was also the highest, followed by linoleic and oleic. For the same tree species or the same forest, the kinds and contents of organic acids in L litters were more abundant than that in F litters.
基金Under the auspices of the National Natural Science Foundation of China (No. 40171053)
文摘Earthworms are the important constituents in the decayed food web and the main ecological conditioners in the process of decomposition and nutrient mineralization. The transformation of organic carbon (C) and total nitrogen (N) in the broad-leaved litters ingested by earthworms was researched by means of a laboratory experiment. Experimental samples were collected from broad-leaved Korea Pine mixed forest in Liangshui National Natural Reserve (47°10′50″N, 128°53′20″E) in the northeastern Xiao Hinggan Mountains of Northeast China. The contents of organic C and total N in earthworms, leaf litters and earthworm faeces were analyzed. Results show that the organic C content was in the fol- lowing order: leaf litters>faeces>earthworms, while total N content was contrary to that of the organic C. The organic C contents in the different leaf litters were in the following order: Tilia amurensis>Betula costata>Acer mono, whereas the total N contents in the different leaf litters were: Betula costata>Tilia amurensis>Acer mono. The contents of organic C and total N in the faeces from the different leaf litters were almost consistent with the contents of the leaf litters. After the leaf litters were ingested by earthworms, the organic C, which was transformed to increase earthworms' weights, ac- counted for 3.90%-13.31% of the total ingestion by earthworms, while that in the earthworm faeces accounted for 6.14%-13.70%. The transformed organic C through the other metabolism (e.g., respiration) of earthworms accounted for 75.04%-89.92%. The ingested organic C by earthworms was mostly used for metabolic activities. The N ingested by earthworms was less than organic C. It is estimated that 37.08% of total N was transformed to increase the earthworm's weight, 19.97% into earthworm faeces and 47.86% for the consumption of the earthworm's activities. The earthworms not only increased the content of organic C and total N in the soil, but also decreased the values of C/N in the soil and leaf litters. Earthworms play a major role in the leaf litters' decomposition and transformation.
基金Intercooperation,Agroforestry Improvement Project and Village and Farm Forestry Project (IC-VFFP, AFIP) Rajshahi (Funded by Swiss Agency for Development Cooperation,SDC)
文摘Allelopathic effects of different doses of Eucalyptus camaldulensis leaf litters were investigated through an experiment in the green house of Institute of Forestry and Environmental Sciences, Chittagong, Bangladesh. Three popular agricultural crops： Falen （Vigna unguiculata）, Chickpea （Cicer arietinum）, Arhor （Cajanus cajan） and two widely used plantation trees： Sada koroi （Albizia procera） and Ipil ipil （Leucaena leucocephala） were selected as bioassay species. Experiment was set on tray at room temperature 27℃. The effects of different doses of leaf litter extracts were compared to the control. Results suggest that leaf litters of E, camaldulesis induced inhibitory effects, It was also found that the effect depend on concentration of extract and litterfall, type of receiver species. Higher concentration of the materials had the higher effect and vice versa. Though all the bioassay species were suppressed some of them showed better performance. Vigna unguiculata, Cicer arietinum are recommended in agroforestry based on this present Experiment output. In mixed plantation, Leucaena leucochephala is a better choice while compared to Albizia procera.
文摘The impacts of petroleum contamination on the litter decomposition of shrub-grass land would directly influence nutrient cycling, and the stability and function of ecosystem. Ten common shrub and grass species from Yujiaping oil deposits were studied. Litters from these species were placed into litterbags and buried in petroleum-contaminated soil with 3levels of contamination（slight, moderate and serious pollution with petroleum concentrations of 15, 30 and 45 g/kg, respectively）. A decomposition experiment was then conducted in the lab to investigate the impacts of petroleum contamination on litter decomposition rates. Slight pollution did not inhibit the decomposition of any litters and significantly promoted the litter decomposition of Hippophae rhamnoides, Caragana korshinskii, Amorpha fruticosa, Ziziphus jujuba var. spinosa, Periploca sepium, Medicago sativa and Bothriochloa ischaemum. Moderate pollution significantly inhibited litter decomposition of M. sativa,Coronilla varia, Artemisia vestita and Trrifolium repens and significantly promoted the litter decomposition of C. korshinskii, Z. jujuba var. spinosa and P. sepium. Serious pollution significantly inhibited the litter decomposition of H. rhamnoides, A. fruticosa, B. ischaemum and A. vestita and significantly promoted the litter decomposition of Z. jujuba var. spinosa, P.sepium and M. sativa. In addition, the impacts of petroleum contamination did not exhibit a uniform increase or decrease as petroleum concentration increased. Inhibitory effects of petroleum on litter decomposition may hinder the substance cycling and result in the degradation of plant communities in contaminated areas.
基金Project supported by the Natural Science Foundation of Hubei Province(No.2006ABA182).
文摘Irnazaquin applied in legume crops has a long residual time in soil, which often impacts safety of the susceptible crops. To increase safety of imazaquin application, two composted litters, bovine manure （BM） and chicken manure （CM）, were used to determine their effects on imazaquin environmental behavior by incorporating each kind of manure into the tested sandy loam soil at 10% （w/w）. The degradation of imazaquin in BM- and CM-amended soil was about 2.4 and 1.5 times, respectively, faster than that in unamended soil. The half-lives of imazaquin in BM-amended soil varied between 6.7 and 15.4 d over the temperature range of 20 to 40℃, and the degradation rate constant （k） increased by a factor of about 1.5 for every 10℃ change. Higher mix ratio did not significantly increase the degradation, and the optimal active degradation of imazaquin was observed approximately at the mix ratio of 10：1 of soil to BM. The different moisture levels had negligible effect on imazaquin degradation. In both unamended and BM-amended treatments, two metabolites were observed at 5, 10 and 30 d after treatment. One metabolite at retention time （RT） of 8.4 rain was identified as 2-（4- hydroxyl-5-oxo-2-imidazolin-2-yl） quinoline acid, originating from the loss of isopropyl group and hydroxylation at the 4-position of imidazolinone ring. The other at RT of 12.9 rain was identified as quinoline-2,3-dicarboxylic anhydride, resulting from detachment of imidazolinone ring and the forming of dicarboxylic anhydride. This finding suggested that the addition of farm litters into soil might be a good management option since it can not only increase soil fertility but also contribute to increase safety of imazaquin application to the following susceptible crops.
文摘Recent publication attested that in the urban forest of Brazzaville, litter decomposition is faster with almost 45% of initial weight loss than in the dry season, where an average loss of 26% in initial litter weight is noted (Ifo et al., 2018). This study was carried out in the urban forest of Brazzaville to follow the decomposition of some organic compounds/secondary metabolites (reducing Sugars, total Flavonoid and Polyphenols) of the leaves litters of two tropical species Antiaris toxicaria Lesch and Millettia laurentii De Wild. Thin-layer chromatography and spectrophotometric assay of these metabolites were used on the samples of litters collected in the field on various dates of follow-up of the decomposition (0 d, 14 d, 28 d, 42 d, 56 d, 72 d and 84 d). The chromatographic profile of initial litters shows a series of spots on yellow florescence materializing presence of flavonoids, green fluorescence revealing the presence of the acids phenols derived from the cinnamic acid. But the chromatographic profile of the two litters in decomposition after two weeks remains without structural information, being able to characterize the decomposition of the chemical families highlighted in the initial litters. Also, the analysis of quantitative total reducing sugar in the initial litters, gives average concentrations of 64.4, 58.6, 57.5 g EG/kg Ms respectively for the litters of Millettia laurentii De Wild, Antiaris toxicaria Lesch and the mixed litters (Millettia laurentii and Antiaris toxicaria). Comparatively with the other types of litters, the initial average concentrations in phenolic compounds (polyphenols and flavonoids totals) were the highest for the litters of Antiaris toxicaria Lesch (27.3 g EAG/kg Ms and 13.07 g EC/kg Ms) (P = 0.001). The losses of organic chemical compounds are more significant during the first two weeks of experiment than after this period. Antiaris toxicaria Lesch loses on average 43.8 g EG/kg Ms of reducing Sugars, 12.21 g EC/kg Ms of totals flavonoids and 26.4 g EAG/kg Ms of total polyphenols, equivalent to 30% of loss of the initial weight. Average losses of 45.7 g EG/kg Ms were obtained for reducing sugars, 1.5 g EC/kg Ms for totals flavonoids and 8.72 g EAG/kg Ms for totally phenols in for the litters of Millettia laurentii, comparable to 24% in initial weight loss. This study showed on the one hand, the direct link between rainfall and litters decomposition and the losses in weight of the litters resulted in dissolution in the water of the studied compounds.
基金supported by the National Key R&D Program of China(2023YFC2604500)the National Natural Science Foundation of China(32171662,32471753 and 32171666)the Natural Science Foundation of Liaoning(2020-MS-199).
文摘Exotic plant invasions and increased atmospheric carbon dioxide(CO_(2))concentration have been determined to independently affect soil nematodes,a key component of soil biota.However,little is known about the long-term effects of these two global change factors and their interactive effects.Over three consecutive years,we cultivated invasive alien plant Xanthium strumarium and its two phylogenetically related natives under both ambient(aCO_(2))and elevated(eCO_(2))atmospheric CO_(2)concentrations,and determined the effects of the invader and natives on soil nematodes under different CO_(2)concentrations and the relevant mechanism.The abundance of total soil nematodes and that of the dominant trophic group(herbivores)were significantly affected by plant species and CO_(2)concentration,and these effects were dependent on the experimental duration,however,the Shannon-diversity of nematodes was not affected by these factors.Under aCO_(2),both invasive and native species significantly increased the total nematode abundance and that of the dominant trophic group with increasing experimental duration,and the amplitude of the increase was greater under the invader relative to the natives.The eCO_(2)increased total nematode abundance(second year)and that of the dominant trophic group(third year)under the invader,but not under the natives(or even decreased)with increasing experimental duration.Root litter had greater effects on soil nematode abundance than leaf litter and root exudates did.This study indicates that eCO_(2)would aggravate effects of invasive plants on soil nematodes by increasing abundance,and these effects would vary with the duration.
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supported by the Guangdong Basic and Applied Basic Research Foundation(No.2025A1515011004)the Shenzhen Science and Technology Program(No.JCYJ20220530150015035)+1 种基金the National Natural Science Foundation of China(No.42367035)the Chinese Scholarship Council(No.202306380142).
文摘Symbiotic and asymbiotic nitrogen fixation(SNF and ANF),two forms of biological nitrogen(N)fixation,are the main pathways for external N inputs into natural terrestrial ecosystems.However,the regulatory mechanisms of SNF and ANF,particularly in response to changing environmental conditions,remain poorly understood.Here,we investigated changes in SNF and ANF rates along two altitudinal gradients in two subtropical forests on soils with granite and slate parent materials.Our results revealed distinct patterns for SNF and ANF rates.SNF rates consistently declined with increasing altitude,whereas ANF rates initially increased at lower altitudes but declined at higher altitudes.These contrasting trends were attributed to divergent regulatory mechanisms of SNF and ANF rates.Specifically,the decrease in SNF rates was primarily driven by increased soil N availability and decreased air temperature.However,the drivers of ANF rates shifted from soil properties(e.g.,phosphorus,iron,and moisture)at lower altitudes to climatic factors(e.g.,air temperature)at higher altitudes.We also observed opposite trends of SNF and ANF between forests on granite and slate,demonstrating that lithology is an important driver of both SNF and ANF.Collectively,our findings highlight the divergent mechanisms regulating SNF and ANF in subtropical forests,which contribute to improving the mechanistic representation of biological N fixation in Earth system models.
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We acknowledge that the present study was financially supported by the National Key Research and Development Program of China(2018YFD0500700)Hubei Provincial Natural Science Foundation Youth Project(2017CFB160).
文摘Experiments were conducted to investigate the influences of type of litter,initial moisture content(IMC)of litter,and dry weight ratio of manure to litter(DWRML)on ammonia emissions from chicken manure and the effects of pH values of tea leaves and the mixtures of tea leaves and other litter on the ammonia emissions from chicken manure.For the experiments,four kinds of litter,Northeast pine sawdust(sawdust),rice husk,tea leaves,and wheat straw,were selected.The IMCs of the litter were(20±2)%,(30±2)%,and(40±2)%;and the DWRML values were 1:4,1:6 and 1:8,respectively.The different litters adjusted at different moisture contents were mixed with chicken manure in different DWRML and then placed in different static test chambers,which were real-time monitored the ammonia concentrations.Pure chicken manure without any litter was used as a control group.The four kinds of litter had obvious inhibitory effects on the ammonia emissions from chicken manure under various conditions.There were significant differences among four kinds of litter(p<0.01).Under the same conditions,the best inhibitory effect was achieved by using tea leaves,followed by straw,rice husk,and sawdust.The IMC of litter had no significant effects on the ammonia inhibition(p>0.05).The DWRML had no significant effects on ammonia emission inhibition for tea leaves(p>0.05),but had a significant effects on the ammonia emission inhibition for the other three kinds of litter(p<0.05).The pH value of tea leaves had no significant effects on the inhibition of ammonia emissions(p>0.05).The mixed litter made of tea leaves and sawdust,rice husk,or straw were significantly better than the tea leaves and other single litter(p<0.01).It indicated that adding appropriate amount of tea leaves in the litter can effectively inhibit ammonia emissions from chicken manure.
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.
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 China Postdoctoral Science Foundation(No.2023M741742)the National Key R&D Program of China(No.2023YFD1501600)+1 种基金Jiangsu Funding Program for Excellent Postdoctoral Talent,China(No.2023ZB122)the National Natural Science Foundation of China(No.32371626)。
文摘Plant roots and their associated mycorrhizal fungi critically mediate the decomposition of soil organic carbon(C),but the general patterns of their impacts over a broad geographical range and the primary mediating factors remain unclear.Based on a synthesis of 596 paired observations from both field and greenhouse experiments,we found that living roots and/or mycorrhizal fungi increased organic C decomposition by 30.9%,but low soil nitrogen(N)availability(i.e.,high soil C:N ratio)critically mitigated this promotion effect.In addition,the positive effects of living roots and/or mycorrhizal fungi on organic C decomposition were higher under herbaceous and leguminous plants than under woody and non-leguminous plants,respectively.Surprisingly,there was no significant difference between arbuscular mycorrhizal fungi and ectomycorrhizal fungi in their effects on organic C decomposition.Furthermore,roots and/or mycorrhizal fungi significantly enhanced the decomposition of leaf litter but not root litter.These findings advance our understanding of how roots and their symbiotic fungi modulate soil C dynamics in the rhizosphere or mycorrhizosphere and may help improve predictions of soil global C balance under a changing climate.
文摘In this study,we investigated how tree species affect N mineralization in connection to some soil properties and seconder metabolite levels of litter,in the soil of the old-est native forest communities.In the oldest pure communi-ties of Pinus nigra(PN),Fagus orientalis(FO),and Abies bornmuelleriana(AB)in the mountain range of Mount Uludağ,Bursa,Turkey,annual net yield and N mineraliza-tion in the 0-5-and 5-20-cm soil layers were determined in a field incubation study over 1 year.Sampling locations were chosen from 1300 to 1600 m a.s.l.,and moisture content(%),pH,water-holding capacity(%),organic C,total N,and C/N ratio,and annual net mineral N yield of the soil and hydro-lyzed tannic acid and total phenolic compounds in litter were compared for these forest communities.F.orientalis had the highest annual net Nmin yield(43.9±4.8 kg ha^(-1) a^(-1)),P.nigra the lowest(30.5±4.2 kg ha^(-1) a^(-1)).Our findings show that in the oldest forest ecosystems,the seasonal soil moisture content and tree species play an essential role in N cycling and that hydrolyzed tannic acids and total phenolic compounds effectively control N turnover.Tannic acid and total phenolics in the litter were found to inhibit nitrification,but total phenolics were found to stimulate ammonification.
基金financially supported by the National Natural Science Foundation of China(32271633)founded by the National Natural Science Foundation of China(32201342)+1 种基金Natural Science Foundation of Fujian Province(2022J01642)supported by the National Natural Science Foundation of China(32171641)。
文摘The forest headwater streams are important hubs for connecting terrestrial and aquatic ecosystems,with plant litter and sediments as the major carriers for material migrations;however,until now we knew little about the dynamics of trace elements such as iron(Fe)and aluminum(Al)in forest headwater streams.Here,we quantitatively identified the spatiotemporal dynamics of Fe and Al storages in plant litter and sediments and their influencing factors in a subtropical forest headwater stream,and assessed the potential pollution risk.The results showed that:(1)the mean concentrations of Fe and Al in plant litter(sediments)were 5.48 and 8.46(7.39 and 47.47)g·kg^(-1),and the mean storages of Fe and Al in plant litter(sediments)were 0.26 and 0.43(749.04 and 5030.90)g·m^(-2),respectively;(2)the storages of Fe and Al in plant litter and sediments significantly fluctuated from January to December,and showed a decreasing pattern from the source to mouth;and(3)storages of Fe and Al had no significant correlation with riparian forest type and the present of tributary and the Fe and Al storages in plant litter were mainly affected by water temperature and water alkalinity,and their storages in sediments were mainly affected by water temperature and frequency of rainfall;and(4)there were no anthropogenic pollution in Fe and Al in the forest headwater stream.Our study revealed the primary factors of concentrations and storages of Fe and Al in plant litter and sediments in a forest headwater stream,which will improve our understanding of the role of headwater streams in forest nutrient storage and cycling along with hydrological processes.
