Background The temperate grasslands are facing numerous pressures from global change.Despite their essential ecological and economic role,how their microbial communities react to multiple varying factors remain obscur...Background The temperate grasslands are facing numerous pressures from global change.Despite their essential ecological and economic role,how their microbial communities react to multiple varying factors remain obscure.In this study,we simulated three global change drivers,i.e.,nitrogen deposition(ambient N vs.elevated N,a N vs.e N),precipitation increase(ambient precipitation vs.elevated precipitation,a P vs.e P),and mowing,represented experimentally by clipping(unclipped vs.clipped,u C vs.CL),together in all possible combinations in a temperate semi-arid grassland ecosystem.Results Nitrogen addition had negative effects on the richness of bacterial and fungal communties,significantly changed their structures(P<0.05)and increased their dissimilarities(P<0.05),while water addition had positive effects on fungal and protist communities and significantly stimulated theα-diversity of protist communities under N addition without clipping,which was in contrast to the effect in clipped plots.Clipping had a marginal effect on fungal communities and significantly affected protist communities(P<0.05).A notable interactive effect of N and precipitation on the structure of bacterial communities and a significant interactive effect of clipping and precipitation on protists were found.Combination effects of N with precipitation or clipping on module aggregation of metanetworks were also observed between u C and CL,as well as a P and e P meta-networks.Bacterial,fungal,and protist communities varied in their assembly mechanisms,and their assembly processes differed in response to the three global change factors.Conclusions Overall,N,water addition,and clipping individually and/or interactively,in distinct degrees,altered soil microbial interaction,community structure,and the potential function in a semi-arid steppe.These findings enhance our understanding of soil microbial community assembly and provide a scientific basis for managing temperate grasslands,particularly in the context of global change's impact on ecosystem function and stability.展开更多
Background The mangrove ecosystem has the highest carbon sink potential which significantly contributes to bringing carbon neutrality.Understanding the carbon stock dynamics along the age of forest stands in the mangr...Background The mangrove ecosystem has the highest carbon sink potential which significantly contributes to bringing carbon neutrality.Understanding the carbon stock dynamics along the age of forest stands in the mangrove forest ecosystem is of significance for managing the forests and their carbon accumulation.This study aimed to estimate the forest structural attributes,biomass and total ecosystem carbon stock(TECS)of old natural(age>50 years)and young planted(age~20 years)mangrove forest stands at Bichitrapur Mangrove Reserve Forest in eastern coast of India.We also attempted to understand the interrelationship of structural attributes,biomass and soil properties in the mangrove forests.To achieve the results,twenty random plots were established(size:20 m×25 m)and suitable allometric equations along with species-specific wood density values were used to estimate the biomass and carbon stock.Results Altogether,29 plant species(18 exclusive and 11 associate species)were recorded.The mean total biomass(±SE)and soil organic carbon(at 30 cm depth)were 165.31±20.89 t ha^(-1)and 40.20±1.24 t C ha^(-1)for young stands,and 586.12±56.74 t ha^(-1)and 49.68±2.39 t C ha^(-1)for old stands,respectively.Among mangrove species,Avicennia marina contributed the highest vegetation biomass in both forest stands(59.72 t ha^(-1)and 262.28 t ha^(-1)in young and old stands,respectively),followed by Avicennia officinalis(35.05 t ha^(-1))and Sonneratia apetala(26.09 t ha^(-1))in young stand and Avicennia alba(169.28 t ha^(-1))and Avicennia officinalis(115.58 t ha^(-1))in old stand.The mean TECS was 235.62±27.34 t C ha^(-1).The contribution of vegetation and soil to TECS was 63%and 37%in the young stand,whereas in the old stand it was 83%and 17%,respectively.The correlation analyses revealed that mean stand height(r=0.87),basal area(r=0.99),soil nitrogen(r=0.76),potassium(r=0.78),and carbon(r=0.80)were significantly positively correlated with total biomass at p<0.01.Conclusions Our results demonstrate that old mangrove forest stands store substantially high carbon stock than young planted forest stands,implying the role of forest age in determining the carbon storage potential of mangrove ecosystems.展开更多
Background The effects of war on biodiversity,habitats,ecosystem services,and water,seafood,and fishing resources are complex and long-lasting,yet their ongoing environmental analyses are limited.The Russia–Ukraine W...Background The effects of war on biodiversity,habitats,ecosystem services,and water,seafood,and fishing resources are complex and long-lasting,yet their ongoing environmental analyses are limited.The Russia–Ukraine War(2022–present)comprises a unique ecological situation to examine biodiversity effects on the distinctive cold-temperate northern Black Sea ecosystem,which has an intriguing biogeographic history and high endemism resulting from geographic isolation and differentiation.Results We summarize negative and positive effects from the War on the aquatic(marine,estuarine,and freshwater)biota and their habitats,focusing on investigations by the Institute of Marine Biology,National Academy of Sciences of Ukraine.Negative effects include toxins and habitat damage from oil spills,shelling,mining,explosions,flooding,and fires;along with disregard of Protected Areas.Positive effects are reduced anthropogenic loads from less shipping,fishing,trawling,recreation,hydraulic engineering,construction,and tourism.The Kakhovka Dam's destruction on June 6,2023 was the greatest ecological catastrophe to date,causing extensive downstream flooding with freshwaters and pollutants that destroyed many populations and habitats.We discern that many effects have been temporary,with habitats and species replenishing,and some reverting to their historical biota characteristic of lower salinity regimes.However,significant habitat destruction,disturbances,and pollutant damages remain.Since many of the native species evolved in conditions favoring broad salinity,temperature,and oxygen tolerances,the northern Black Sea ecosystem appears pre-adapted for ecological recovery and persistence,which may equate to ecological resilience during and after the War.Conclusions The native biota exhibits long-term adaptiveness to marked salinity and temperature fluctuations,alongside a background of invasive species.An evolutionary and recent history of broad environmental tolerances by a large proportion of Black Sea species may enhance their ability to withstand marked environmental changes,including habitat destruction,as during the Kakhovka Dam's breakage and other stressors that continue during the Russia–Ukraine War.The Black Sea community's overall ecological resilience is likely to facilitate persistence and adaptation to the War's effects and the accelerating impacts of climate change,increased global transportation,and invasive species—meriting worldwide conservation agency focus and cooperation.展开更多
Background Accurate measurements of aboveground biomass(AGB)are essential for understanding the planet's carbon balance.The Atlantic Forest of the Serra do Mar in southeastern Brazil contains large areas of well-p...Background Accurate measurements of aboveground biomass(AGB)are essential for understanding the planet's carbon balance.The Atlantic Forest of the Serra do Mar in southeastern Brazil contains large areas of well-preserved remnants,characterized by mountainous terrain with significant orographic contrasts along its elevation gradient.This diverse landscape creates a variety of biophysical factors that strongly influence the spatial distribution of AGB.This study aims to estimate AGB using a hybrid geostatistical methodology,regression kriging simulation(RKS),to analyze AGB spatial distribution at a local scale(84 plots,each 0.01 ha)across a small forest fragment covering the entire tree-covered area(8777 ha).Building on traditional regression kriging method,this study introduces an innovative approach by incorporating Gaussian simulation to interpolate residuals,allowing RKS to account for uncertainties in the estimation process and create new results.This allows us to clearly distinguish exogenous ecological processes from endogenous ones before reaching the model's final estimate.Results Four regression kriging models were created,and the best-performing model used the Enhanced Vegetation Index and direct solar radiation(DSR),achieving an R^(2) of 55%.A Gaussian simulation was performed to interpolate the residuals of this model.The final results indicate that RKS provides accurate AGB estimates(RMSE=1.333 Mg/0.01 ha and R^(2) of 77%).Additionally,the inclusion of DSR as a new predictor variable enhances the precision of AGB estimates.The analysis showed that 63%of the sample pairs exhibited measurable spatial dependence.Conclusions Regression kriging simulation is proposed using Gaussian simulation,altering the classical application of regression kriging.For this,a case study was conducted in the Atlantic Forest of Serra do Mar to estimate the spatial distribution of tree biomass in a forest fragment of this region.We demonstrate that the proposed method better captures the heterogeneity of the region and produces more comprehensive results than regression kriging.Regression kriging simulation estimates tree biomass by considering the actual fluctuations of the spatial distribution of tree biomass in the region,taking into account exogenous and endogenous ecological processes,addressing random noise,and allowing the creation of dynamic maps for use by environmental managers.展开更多
Background Fluvial fish habitat in the Northeastern and Midwestern U.S. is substantially affected by natural landscape factors and anthropogenic stressors, with climate change expected to alter natural influences and ...Background Fluvial fish habitat in the Northeastern and Midwestern U.S. is substantially affected by natural landscape factors and anthropogenic stressors, with climate change expected to alter natural influences and exacerbate stressor effects. To conserve fluvial fish species in the future, it is crucial to understand which fish habitats will be most strongly influenced by changing climate, which species are most sensitive to climate change, and how changes in individual species will affect entire assemblages. To answer these questions, we modeled fluvial fish distributions under projected changes in climate to understand how climate could affect suitability of fish habitat for 55 widely distributed fluvial fishes with differing thermal preferences in the region. Using boosted regression tree models, we predicted distributions of fishes at a stream reach scale using four contemporary climate variables including annual mean air temperature, annual precipitation, and variation in monthly air temperature and precipitation along with seven natural landscape and anthropogenic stressor variables. We then used projected values from eight general circulation models(GCMs) during 2041–2080 to evaluate potential patterns in species richness, turnover, and range shifts under climate change across the study region.Results Most cold-water and cool-water species were projected to lose habitat;however, projected habitat loss also occurred for certain small-bodied warm-water species. The percentage change in species richness of all 55 species across reaches ranged from-40.4 to 33.93%, with regions of major species richness losses occurring across southern portions of the Northeastern coast and southern Midwest regions. Species turnover ranged from 0 to 43.5% with substantial turnover occurring along the Northeastern coast and upper Midwest.Conclusions Temperature and precipitation variation will influence fish species distribution substantially. Our findings provide multiple measures describing patterns of fish community change under climate change to aid management and conservation of stream fishes in the future.展开更多
Background The global freshwater biodiversity crisis has led to widespread implementation of measures to counteract environmental degradation and biodiversity loss.While these efforts aim to foster recovery,intensifyi...Background The global freshwater biodiversity crisis has led to widespread implementation of measures to counteract environmental degradation and biodiversity loss.While these efforts aim to foster recovery,intensifying stressors continue to drive complex biotic responses,the trajectories and drivers of which are insufficiently understood.This study examines the roles of abiotic stressors,biotic interactions(e.g.,competition),and land use in shaping ecological status changes across Germany,using data from 1599 river sites sampled at least twice between 2004 and 2022.Results Changes in abiotic stressors emerged as the most consistent drivers of ecological status,explaining substantial variation(R^(2)=0.39)and similar slopes for recovery(β=-0.11)and degradation(β=-0.10).Biotic interactions,particularly interspecific competition,also influenced the ecological status(R^(2)=0.11),with stronger positive effects observed during recovery(β=2.99)compared to degradation(β=1.59).Land use effects varied by context:Streams in catchments with higher cropland or urban areas showed greater likelihood of recovery,whereas streams in forested catchments were more prone to degradation.These results highlight the interplay of abiotic and biotic factors in driving ecological processes of recovery and degradation.Conclusion These findings emphasize the critical role of improving water quality for enhancing biodiversity and ecological status in rivers,while also demonstrating the importance of biotic interactions and land use context in driving recovery dynamics.Integrating these insights into management and restoration efforts can enhance freshwater ecosystem resilience in the face of escalating environmental pressures.展开更多
Background Identifying the processes that govern community assembly along elevational gradients has been a central theme in ecology,especially in montane ecosystems where abundant species and strong turnover are prese...Background Identifying the processes that govern community assembly along elevational gradients has been a central theme in ecology,especially in montane ecosystems where abundant species and strong turnover are present.However,our understanding of how the relative importance of deterministic and stochastic processes varies along elevational gradients remains limited.Here,we compiled a rigorously curated dataset of elevational distributions of 734 breeding bird species across the Hengduan Mountains in China to assess the dominant underlying mechanisms of bird community assembly at both intra-community and inter-community scales across four elevation zones:low,middle,subalpine,and alpine.Results At the intra-community scale,homogeneous dispersal played a pivotal role in driving community assembly of breeding birds across the Hengduan Mountains.Deterministic processes became more influential with increasing elevation,whereas stochastic processes prevailed in low,middle,and subalpine zones.At inter-community scale,assemblages from different elevation zones were more differentiated by dispersal limitation.Non-Passeriformes experienced more obvious influence of homogeneous dispersal but were less subject to dispersal limitation compared to Passeriformes.Conclusions Our findings highlight the role of stochastic processes in shaping biotic communities in montane ecosystems,but this effect is scale-dependent.The transition from stochastic to deterministic processes along elevational gradients suggests that environmental factors become more influential at higher elevations.Species dispersal ability may affect the relative importance of these two processes shaping community assembly.展开更多
Background Increasing atmospheric nitrogen(N)deposition is a major threat to plant diversity globally.Recent observations show that the reduced-to-oxidized(NH_(x)/NO_(y))ratio of N deposition has been changing spatial...Background Increasing atmospheric nitrogen(N)deposition is a major threat to plant diversity globally.Recent observations show that the reduced-to-oxidized(NH_(x)/NO_(y))ratio of N deposition has been changing spatially and temporally.How and to what extent different N forms(i.e.,NH_(x)and NO_(y))influence grassland plant species loss are still unclear.Methods We employed a field manipulative experiment by using three N forms[i.e.,Ca(NO_(3))_(2),NH_(4)NO_(3),and(NH_(4))_(2)SO_(4)]with six N addition levels(0,4,8,16,24,32 g N m^(-2)year^(-1))in a temperate grassland and conducted a greenhouse experiment culturing four plant species corresponding different plant functional groups under Ca(NO_(3))_(2)or(NH_(4))_(2)SO_(4)addition.Results Results from our field experiment showed that the plant species loss rate was greater under NH_(4)^(+)-N than NO_(3)^(-)-N enrichment.Plant species loss was driven by light asymmetry under NO_(3)^(-)-N enrichment,while it was co-driven by light asymmetry and soil acidification under NH_(4)NO_(3)enrichment.Under NH_(4)^(+)-N enrichment,light asymmetry,pH decrease,NH_(4)^(+) toxicity,and metal toxicity jointly affected species loss.The greenhouse experiment provided direct evidence that legumes and forbs are more physiologically susceptible to NH_(4)^(+)-induced toxicity than grasses.Conclusions Our results emphasize that N forms play a vital role in affecting grassland plant diversity.This suggests that regions with higher NH_(x) enrichment may experience more severe plant diversity losses as N deposition continues to increase.Therefore,appropriate measures should be adopted to mitigate species losses.展开更多
Background Tick borne diseases are re-emerging around the world,including India.Information about the occurrence of the tick vectors in different geographical locations is essential for controlling the diseases.Tick s...Background Tick borne diseases are re-emerging around the world,including India.Information about the occurrence of the tick vectors in different geographical locations is essential for controlling the diseases.Tick surveys have not been conducted in many parts of India and information on the current prevalence of tick vectors is not available in all states of India.Many studies have been carried out utilizing modelling methods to predict the distribution of tick species in other countries.The MaxEnt model is widely used for predicting tick species distribution using bioclimatic variables.Lyme disease vectors such as Ixodes sp.,Amblyomma sp.,and Dermacentor sp.are the most commonly predicted tick species.However,very few studies have been carried out to predict the distribution of tick species in India.Haemaphysalis spinigera,the primary Kyasanur Forest Disease vector,was predicted along the Western Ghats using the MaxEnt model.Rhipicephalus(Boophilus)microplus was predicted across India using the generalized linear model(GLM).Identifying the tick vectors in transmitting the infection through conventional survey and identification methods is cumbersome due to the less number of experienced persons available.Prediction of tick vectors of public health concern,including other tick species in different geographical regions of Tamil Nadu,India,is essential for the prevention and control of tick-borne disease in humans and domestic animals.The present study adopts the package‘SSDM’(stacked species distribution models)with R software containing ensemble species distribution models to predict the distribution of tick species using different available environmental and climatic data.Results The categorical variables such as land use and land cover(LULC),soil type,elevation,Bio1,Bio10,Bio15,Bio19 and Bio8 contributed more to modelling the distribution of tick species.MaxEnt,GLM,GBM and GAM are suitable models for predicting the tick species distribution in the present study.Among these models,MaxEnt is the most suitable model for predicting tick species distribution in Tamil Nadu,India.Conclusions Our results suggest that MaxEnt is a suitable model for predicting the distribution of tick species.Both environmental factors such as LULC,elevation and soil type and bioclimatic factors such as temperature and precipitation contribute significantly to predicting tick species distribution in domestic animals in Tamil Nadu.The SSDM package is very useful and user-friendly graphical user interface for modelling the distribution of tick species.However,the package can be further improved by using higher resolution raster variables in larger areas,which is not currently supported.The predicted elevation range of Ha.spinigera distribution could not be provided due to software limitations.展开更多
Nutrient concentrations in foliage are often used to infer whether growth of a species at a particular site is likely limited by low supply of soil nutrients.Sometimes ratios of nutrient elements(stoichiometry)are tho...Nutrient concentrations in foliage are often used to infer whether growth of a species at a particular site is likely limited by low supply of soil nutrients.Sometimes ratios of nutrient elements(stoichiometry)are thought to be useful,as if a higher supply of one element might somehow physiologically alleviate,or interfere with,a low supply of another.The growth of most forests is indeed commonly limited by low supplies of nutrients in soils,but foliar chemistry has proven unable to discern nutrient limitations.We illustrate this conclusion using two large,regional experiments with Eucalyptus in Brazil and loblolly pine(Pinus taeda L.)in the southeastern USA.In both cases,most sites showed profitable increases in growth after fertilization,and nutrient concentrations in foliage differed substantially across sites.However,foliar nutrient concentrations(and stoichiometric ratios)did not provide useful information about forest growth responses.We urge authors,reviewers,and editors not to expect foliar chemistry to be a useful tool for diagnosing nutrient limitations in forests,unless strong,local evidence demonstrates a reliable association.展开更多
Background Biochar is widely recognized for its capacity to capture and store carbon in soil attributed to its stable structure. However, in most field studies examining the effects of biochar application on soil resp...Background Biochar is widely recognized for its capacity to capture and store carbon in soil attributed to its stable structure. However, in most field studies examining the effects of biochar application on soil respiration, the impact of rainfall events on the experimental outcomes has not been taken into account. To address the existing gap in this research field, we conducted a one-year study on soil respiration in an urban camphor forest and collected the data of soil respiration, soil temperature, soil moisture, and the rainfall events closest to the soil respiration monitoring time. We specifically examined how different stages of rainfall events influenced soil respiration in relation to biochar application.Results This study found that the annual average soil respiration rate increased with the doses of biochar application, and the soil respiration rate under the biochar application at the dose of 45 t/ha showed a significant rise. The stages of rainfall events, rainfall amount, and the interaction effect of the two, and biochar doses significantly affected soil respiration. The parameters in the regression model for soil respiration, soil temperature and moisture varied with the different stages of rainfall events and the doses of biochar application. The biochar application eliminated the significant effect of soil moisture on soil respiration during one day after rainfall events. The significant correlation between soil moisture and the temperature sensitivity of soil respiration(Q10) was eliminated by biochar application, both during one day after rainfall events and more than eight days after rainfall events.Conclusions Our findings indicated that the rice straw biochar application has a short-term positive effect on soil respiration in urban camphor forests. The rainfall events affect the field soil respiration monitored in the biochar applications, possibly by affecting the soil respiration response to soil temperature and moisture under different doses of biochar application. The impact of rainfall events on soil respiration in biochar application experiments should be considered in future forest monitoring management and practice.展开更多
Background Soil respiration(Rs)is critical for maintaining the terrestrial carbon(C)cycling,and considerable research has focused on its response to climate warming.However,our knowledge of the mechanistic basis of th...Background Soil respiration(Rs)is critical for maintaining the terrestrial carbon(C)cycling,and considerable research has focused on its response to climate warming.However,our knowledge of the mechanistic basis of the plant functional composition on Rs is limited.We conducted a 2-year field warming experiment to explore Rs responses to different warming levels across three types of alpine grasslands:alpine steppe(AS)dominated by grasses,alpine meadow(AM)and alpine swamp meadow(ASM),both of the latter two dominated by sedges.Results Our findings revealed contrasting effects of warming on Rs across three alpine grassland types:minimal change in the AS,a significant 24%increase in the AM,and a 20%decrease in the ASM.Dominant plant functional groups in each grassland type play an important role in regulating the response of Rs to warming.Moreover,we found a negative correlation between plant height and Rs in the grass-dominated AS and sedge-dominated AM.However,there was no correlation between plant height and Rs in ASM.Furthermore,Rs was regulated by both soil moisture and soil temperature,while in ASM it was constrained by soil moisture levels.Conclusions Our results underscore the importance of incorporating plant functional composition mechanisms when assessing ecosystem C balance under climate warming.Future studies should consider the ecosystem-specific characteristics when investigating the connections between plant community structure,traits,and ecosystem function.展开更多
Background The forest floor humus layer is an important carbon pool and serves as a key interface that influences forest soil carbon and nutrient cycling,especially in temperate and boreal forests.Over the past decade...Background The forest floor humus layer is an important carbon pool and serves as a key interface that influences forest soil carbon and nutrient cycling,especially in temperate and boreal forests.Over the past decades,China has implemented numerous forestry ecological programs,leading to an increasing quantity of forest floor litter and the formation of humus layers,which has altered the interface between aboveground litter and surface soil.Our previous study revealed that these alterations affect the litter decomposition rate;however,it is still unclear how the litter decomposition process changes,how nutrients are released or imported and the extent to which these changes depend on the humus layer.Results In this study,we used a 535-day in situ litterbag experiment to monitor the litter decomposition process and nutrient variations under forest floor humus layer removal in a Pinus sylvestris var.mongolica plantation in Northeast China.The results revealed that the litter decomposed quickly when a forest floor humus layer was present,with the decomposition rate constant(k value)increasing from 0.122 to 0.328.Accordingly,during decomposition,the litter C,N and P concentrations increased,whereas their contents varied only slightly(with the exception of the litter P content,which decreased significantly)compared with those in the treatment where the humus layer was removed.However,both the litter C and N contents decreased,whereas the litter P content increased significantly compared with the initial litter content.Moreover,the litter C:N,C:P and N:P ratios decreased significantly during decomposition.In addition,the microbial community diversity of the litter showed no significant change,whereas the relative abundances of several major fungal and bacterial taxa at the phylum and genus levels varied significantly.Furthermore,redundancy analysis revealed effective relationships among the k values,chemical traits and microbial communities,and the least squares method suggested that the C,P and C:P ratios of the litter were significantly correlated with the litter decomposition rate.Conclusions These results enhance our understanding of the role of the humus layer in forest soil-plant carbon and nutrient cycling and should be considered in carbon cycle models in the future.展开更多
Background Climate change associated with droughts has led to widespread forest decline.Hydraulic and carbonrelated performances are key physiological processes for the tolerance of trees to environmental changes,yet ...Background Climate change associated with droughts has led to widespread forest decline.Hydraulic and carbonrelated performances are key physiological processes for the tolerance of trees to environmental changes,yet our current understanding of such physiological performances for forest decline is still limited.Here,we investigated the hydraulic and carbohydrate performances of healthy and declining(canopy dieback)trees in temperate larch(Larix principis-rupprechtii)plantations.Results Relative to healthy trees,the higher native percentage loss of xylem hydraulic conductivity and lower xylem hydraulic conductivity indicated a deterioration of the integrity of the hydraulic system in declining trees.Additionally,the comparable Huber value,intrinsic water-use efficiency,and leaf mass per area between healthy and declining trees suggest a relatively profligate water-use strategy by declining trees.Declining trees had lower nonstructural carbohydrate concentrations in leaves,branches,and twigs but higher soluble sugars concentration in fine roots than conspecific healthy trees.Conclusions Overall,declining trees in larch plantations would be more vulnerable to drought due to the higher risk of hydraulic dysfunction and carbohydrate depletion.展开更多
Background Mineral-rich licks are known to provide mineral supplements to wildlife species,including mammals.Artificial salt licks have been provided as habitat enrichment in protected areas and secondary forests in P...Background Mineral-rich licks are known to provide mineral supplements to wildlife species,including mammals.Artificial salt licks have been provided as habitat enrichment in protected areas and secondary forests in Peninsular Malaysia since 2012.However,few studies have investigated artificial salt licks,particularly their mineral composition and roles in different habitats.We used 40 camera traps to assess mammal species diversity and assemblages at 20 salt licks(nine natural and 11 artificial licks)in three forest reserves in Peninsular Malaysia.Nine mineral elements from water and soil samples from natural and artificial licks in primary and secondary forests were analysed.Results Twenty-nine mammal species were identified across salt licks,with 16 species being salt lick users,including eight herbivorous,five frugivorous and three carnivorous mammals,most of which moved in groups and solitarily.The mammal species assemblages across both salt lick and habitat types demonstrated a predominantly nested pattern,with herbivorous and frugivorous mammals being the primary users.The artificial salt licks in both habitats showcased the same feeding guilds including species that are resilient to habitat changes.The visitation frequency at both types of licks and habitats suggests that each salt lick user had its own preferences for minerals from salt lick water and soil.Conclusions This study suggests that artificial licks may be as effective as natural licks in providing minerals to many mammal species both in primary and secondary forests.Thus,they could be used to enrich degraded habitats.Enriching degraded habitats is essential for supporting the ecosystem,especially in carbon reduction,biodiversity conservation and connectivity between degraded forests and intact forests.展开更多
Background Establishing mixed-species plantations is increasingly recognized as an important silvicultural measure because they are more productive than monocultures.This over-yielding is attributed to the complementa...Background Establishing mixed-species plantations is increasingly recognized as an important silvicultural measure because they are more productive than monocultures.This over-yielding is attributed to the complementary resource use between component tree species,yet it remains largely unknown whether and how component tree species adjust nutrient acquisition and utilization strategies to achieve complementary nutrient use.Here,we measured soil nitrogen(N)availability and transformation rates,leaf N resorption efficiency and proficiency,and nine root morphological,physiological and mycorrhizal traits tightly related to N acquisition in 20-year-old pure and mixed stands of Pinus sylvestris var.mongolica(Mongolian pine)and Populus simonii(Simon poplar),northeast China.Results Tree species mixing had negative effects on soil nitrate concentration and net N mineralization rate,but had positive effects on absorptive fine root biomass.Compared to growing alone,Mongolian pine in mixed stands had higher leaf N resorption efficiency,and produced more absorptive fine roots with more-efficient morphological features in nutrient acquisition characterized by higher specific root length and lower root tissue density.Additionally,Simon poplar had greater root length density,root area index,and the relative abundance of ectomycorrhizal fungi with genetic potential to produce class II peroxidases in mixed than pure stands.Conclusions These findings highlight that component species express high plasticity in nutrient acquisition and utilization traits in response to tree species mixing,and suggest that this high plasticity could be responsible for the over-yielding of mixed-species plantations.展开更多
The diet of ungulates is often characterized by low protein levels and the presence of indigestible and defensive compounds.It also often lacks micronutrients(vitamins and minerals)essential for growth,health and repr...The diet of ungulates is often characterized by low protein levels and the presence of indigestible and defensive compounds.It also often lacks micronutrients(vitamins and minerals)essential for growth,health and reproduction.Ungulates select rich plant organs to compensate for nutrient shortages and may consume soil,faeces and even bones.It is common for ungulates to incidentally ingest plant-dwelling insects(PDI)while feeding.It is well known that insects contain protein and essential nutrients that can feed livestock,potentially replacing conventional feed.Based on this,we propose the‘nutritional benefit of incidental ingestion'hypothesis,suggesting that ungulates may nutritionally benefit from ingesting PDI while foraging.Based on evidence from the literature on PDI ingestion by ungulates and on the nutritional properties of different insects,we discuss how and whether the ingestion of PDI while foraging might improve the nutrient balance of ungulates and recommend a set of controlled experiments to test it.We provide a new and unfamiliar dimension of nutritional ecology,which is relevant to various grazing ecosystems.We propose to modify“trivial”food web structures,as direct trophic interactions between ungulates and PDI may hold greater significance for ungulate performance and behaviour.展开更多
Background The invasion of apple snails(Pomacea spp.)has a serious negative impact on the yield of aquatic crops,including rice,which is a vital food source for more than half of the global population and irreplaceabl...Background The invasion of apple snails(Pomacea spp.)has a serious negative impact on the yield of aquatic crops,including rice,which is a vital food source for more than half of the global population and irreplaceable in maintaining the global food security of human society.So far,it has been unclear whether jasmonic acid(JA)application can enhance the effects of silicon addition on the defense of crops like rice against the invasion of apple snails.Rice plants were grown in a greenhouse and subjected to treatments involving the addition of silicon(sodium silicate)and JA(methyl jasmonate).Then,in an indoor experiment,apple snails were fed with the leaves of the rice plants that had undergone the treatments.Growth and growth-related traits for rice plants and apple snails and defense-related mechanic characters for rice plants were measured.Results Silicon addition significantly increased rice growth,leading to improved biomass and relative chlorophyll content.JA application did not affect the growth of rice plants but increased their foliar nitrogen and carbon content disproportionally,leading to a reduced C/N ratio.JA application increased the levels of tannins,total phenolics,and flavonoids in rice leaves.Silicon addition increased the tannin,total phenolic,and flavonoid content in rice leaves,particularly when supplied with JA.Silicon addition could also enhance the force of fracture in rice leaves.In addition,the foliar sulfur and silicon content increased with the addition of silicon,and the combination of silicon addition and JA application resulted in the highest foliar silicon content.Both silicon addition and JA application significantly decreased weight gain,leaf consumption,relative growth rate,and cellulase activity of apple snails,indicating a strong interaction.Conclusions Overall,these findings indicated that both silicon addition and JA application enhanced the defense of rice against apple snails and impeded the growth of these snails.JA application amplified the impact of silicon addition on rice's defense mechanism.This study provides new insights into controlling biological invasions and their impact on crop yield.展开更多
Background Acacia dealbata Link is a problematic invasive alien tree in South Africa,with severe environment effects such as native plant displacement and soil nutrient manipulation(nitrogen fixation).Most studies on ...Background Acacia dealbata Link is a problematic invasive alien tree in South Africa,with severe environment effects such as native plant displacement and soil nutrient manipulation(nitrogen fixation).Most studies on A.dealbata invasion are on aboveground vegetation effects,with a few studies on belowground soil seed bank impacts associated with both invasion and removal for restoration purposes.This study assessed the impact of A.dealbata invasion and removal on soil seed banks in grasslands targeted for ecological restoration in the upper Tsitsana communal area of Eastern Cape Province,South Africa.Soils were collected from A.dealbata invaded,cleared,and uninvaded treatments and germinated in an ambient greenhouse over 11 months.We measured species diversity,density,frequency of occupancy,and identified all the seedlings that germinated in trays measuring 20 cm wide×20 cm long×15 cm deep.Results Species richness and abundance were significantly(P<0.001)lower in the cleared and invaded treatments compared to the uninvaded treatment,with this trend being more pronounced for forbs and graminoids than for trees and shrubs,indicating that soil seed bank impacts are growth-form specific.Species density for all species was significantly(P<0.001)lower in the invaded treatment compared to the cleared and uninvaded treatments.The removal of A.dealbata increased species composition in the cleared treatment with woody species such as Diospyrus and Searsia species occurring in the cleared than invaded treatment.Conclusions The study concludes that A.dealbata invasion reduces soil seed bank community diversity and composition in upper Tsitsana grasslands.However,seed banks in the cleared treatment appear adequate to facilitate grassland recovery following the removal of A.dealbata.展开更多
Background The Zoige Plateau hosts the largest alpine peatland in the world,playing a crucial role in carbon sequestration and biodiversity conservation.However,this valuable ecosystem has been significantly impacted ...Background The Zoige Plateau hosts the largest alpine peatland in the world,playing a crucial role in carbon sequestration and biodiversity conservation.However,this valuable ecosystem has been significantly impacted by anthropogenic drainage for various purposes,prompting increased interests in ecological restoration efforts.This study evaluates changes in plant diversity,community composition,and biomass allocation across natural,drained,and rewetted peatlands,with a particular focus on variations in microtopography,including hollows and hummocks.Results Restoration showed significantly higher soil water content,which was 11.6%higher in hollows(to 88.5±0.09%)and 14.4%higher in hummocks(to 81.1±1.6%)of rewetted peatlands compared to natural peatlands(p<0.001).However,the water table depth did not differ significantly from that of natural peatlands(p=0.61).While peatland management did not significantly affect plant diversity,microtopography had a considerable impact on plant species richness,dominance,the Shannon-Wiener index,and evenness.Conversely,plant community com-position exhibited significant differences among natural,drained,and rewetted peatlands at both hollow and hum-mock microsites.Aboveground biomass was significantly higher in drained and rewetted peatlands compared to natural peatlands at both microsites,whereas belowground biomass was significantly lower in drained and rewet-ted peatlands,particularly in hummocks.Conclusions Rewetting raises water table depth but does not fully restore the original plant community compo-sition or biomass.Microtopography plays a vital role in influencing plant diversity and community composition,with hummocks showing greater resilience to drainage impacts.Our findings emphasize ecological consequences of peatland management practices and highlight the need for targeted restoration strategies to strengthen the resil-ience of these vital ecosystems.展开更多
基金financially supported by grants from the National Natural Science Foundation of China (41930643 and 42273084)Natural Science Foundation of Henan Province (242300421039)Science and Technology Development Plan Project of Henan Province (242102110186)
文摘Background The temperate grasslands are facing numerous pressures from global change.Despite their essential ecological and economic role,how their microbial communities react to multiple varying factors remain obscure.In this study,we simulated three global change drivers,i.e.,nitrogen deposition(ambient N vs.elevated N,a N vs.e N),precipitation increase(ambient precipitation vs.elevated precipitation,a P vs.e P),and mowing,represented experimentally by clipping(unclipped vs.clipped,u C vs.CL),together in all possible combinations in a temperate semi-arid grassland ecosystem.Results Nitrogen addition had negative effects on the richness of bacterial and fungal communties,significantly changed their structures(P<0.05)and increased their dissimilarities(P<0.05),while water addition had positive effects on fungal and protist communities and significantly stimulated theα-diversity of protist communities under N addition without clipping,which was in contrast to the effect in clipped plots.Clipping had a marginal effect on fungal communities and significantly affected protist communities(P<0.05).A notable interactive effect of N and precipitation on the structure of bacterial communities and a significant interactive effect of clipping and precipitation on protists were found.Combination effects of N with precipitation or clipping on module aggregation of metanetworks were also observed between u C and CL,as well as a P and e P meta-networks.Bacterial,fungal,and protist communities varied in their assembly mechanisms,and their assembly processes differed in response to the three global change factors.Conclusions Overall,N,water addition,and clipping individually and/or interactively,in distinct degrees,altered soil microbial interaction,community structure,and the potential function in a semi-arid steppe.These findings enhance our understanding of soil microbial community assembly and provide a scientific basis for managing temperate grasslands,particularly in the context of global change's impact on ecosystem function and stability.
文摘Background The mangrove ecosystem has the highest carbon sink potential which significantly contributes to bringing carbon neutrality.Understanding the carbon stock dynamics along the age of forest stands in the mangrove forest ecosystem is of significance for managing the forests and their carbon accumulation.This study aimed to estimate the forest structural attributes,biomass and total ecosystem carbon stock(TECS)of old natural(age>50 years)and young planted(age~20 years)mangrove forest stands at Bichitrapur Mangrove Reserve Forest in eastern coast of India.We also attempted to understand the interrelationship of structural attributes,biomass and soil properties in the mangrove forests.To achieve the results,twenty random plots were established(size:20 m×25 m)and suitable allometric equations along with species-specific wood density values were used to estimate the biomass and carbon stock.Results Altogether,29 plant species(18 exclusive and 11 associate species)were recorded.The mean total biomass(±SE)and soil organic carbon(at 30 cm depth)were 165.31±20.89 t ha^(-1)and 40.20±1.24 t C ha^(-1)for young stands,and 586.12±56.74 t ha^(-1)and 49.68±2.39 t C ha^(-1)for old stands,respectively.Among mangrove species,Avicennia marina contributed the highest vegetation biomass in both forest stands(59.72 t ha^(-1)and 262.28 t ha^(-1)in young and old stands,respectively),followed by Avicennia officinalis(35.05 t ha^(-1))and Sonneratia apetala(26.09 t ha^(-1))in young stand and Avicennia alba(169.28 t ha^(-1))and Avicennia officinalis(115.58 t ha^(-1))in old stand.The mean TECS was 235.62±27.34 t C ha^(-1).The contribution of vegetation and soil to TECS was 63%and 37%in the young stand,whereas in the old stand it was 83%and 17%,respectively.The correlation analyses revealed that mean stand height(r=0.87),basal area(r=0.99),soil nitrogen(r=0.76),potassium(r=0.78),and carbon(r=0.80)were significantly positively correlated with total biomass at p<0.01.Conclusions Our results demonstrate that old mangrove forest stands store substantially high carbon stock than young planted forest stands,implying the role of forest age in determining the carbon storage potential of mangrove ecosystems.
文摘Background The effects of war on biodiversity,habitats,ecosystem services,and water,seafood,and fishing resources are complex and long-lasting,yet their ongoing environmental analyses are limited.The Russia–Ukraine War(2022–present)comprises a unique ecological situation to examine biodiversity effects on the distinctive cold-temperate northern Black Sea ecosystem,which has an intriguing biogeographic history and high endemism resulting from geographic isolation and differentiation.Results We summarize negative and positive effects from the War on the aquatic(marine,estuarine,and freshwater)biota and their habitats,focusing on investigations by the Institute of Marine Biology,National Academy of Sciences of Ukraine.Negative effects include toxins and habitat damage from oil spills,shelling,mining,explosions,flooding,and fires;along with disregard of Protected Areas.Positive effects are reduced anthropogenic loads from less shipping,fishing,trawling,recreation,hydraulic engineering,construction,and tourism.The Kakhovka Dam's destruction on June 6,2023 was the greatest ecological catastrophe to date,causing extensive downstream flooding with freshwaters and pollutants that destroyed many populations and habitats.We discern that many effects have been temporary,with habitats and species replenishing,and some reverting to their historical biota characteristic of lower salinity regimes.However,significant habitat destruction,disturbances,and pollutant damages remain.Since many of the native species evolved in conditions favoring broad salinity,temperature,and oxygen tolerances,the northern Black Sea ecosystem appears pre-adapted for ecological recovery and persistence,which may equate to ecological resilience during and after the War.Conclusions The native biota exhibits long-term adaptiveness to marked salinity and temperature fluctuations,alongside a background of invasive species.An evolutionary and recent history of broad environmental tolerances by a large proportion of Black Sea species may enhance their ability to withstand marked environmental changes,including habitat destruction,as during the Kakhovka Dam's breakage and other stressors that continue during the Russia–Ukraine War.The Black Sea community's overall ecological resilience is likely to facilitate persistence and adaptation to the War's effects and the accelerating impacts of climate change,increased global transportation,and invasive species—meriting worldwide conservation agency focus and cooperation.
文摘Background Accurate measurements of aboveground biomass(AGB)are essential for understanding the planet's carbon balance.The Atlantic Forest of the Serra do Mar in southeastern Brazil contains large areas of well-preserved remnants,characterized by mountainous terrain with significant orographic contrasts along its elevation gradient.This diverse landscape creates a variety of biophysical factors that strongly influence the spatial distribution of AGB.This study aims to estimate AGB using a hybrid geostatistical methodology,regression kriging simulation(RKS),to analyze AGB spatial distribution at a local scale(84 plots,each 0.01 ha)across a small forest fragment covering the entire tree-covered area(8777 ha).Building on traditional regression kriging method,this study introduces an innovative approach by incorporating Gaussian simulation to interpolate residuals,allowing RKS to account for uncertainties in the estimation process and create new results.This allows us to clearly distinguish exogenous ecological processes from endogenous ones before reaching the model's final estimate.Results Four regression kriging models were created,and the best-performing model used the Enhanced Vegetation Index and direct solar radiation(DSR),achieving an R^(2) of 55%.A Gaussian simulation was performed to interpolate the residuals of this model.The final results indicate that RKS provides accurate AGB estimates(RMSE=1.333 Mg/0.01 ha and R^(2) of 77%).Additionally,the inclusion of DSR as a new predictor variable enhances the precision of AGB estimates.The analysis showed that 63%of the sample pairs exhibited measurable spatial dependence.Conclusions Regression kriging simulation is proposed using Gaussian simulation,altering the classical application of regression kriging.For this,a case study was conducted in the Atlantic Forest of Serra do Mar to estimate the spatial distribution of tree biomass in a forest fragment of this region.We demonstrate that the proposed method better captures the heterogeneity of the region and produces more comprehensive results than regression kriging.Regression kriging simulation estimates tree biomass by considering the actual fluctuations of the spatial distribution of tree biomass in the region,taking into account exogenous and endogenous ecological processes,addressing random noise,and allowing the creation of dynamic maps for use by environmental managers.
基金funded by the United States Geological Survey Aquatic GAP Project
文摘Background Fluvial fish habitat in the Northeastern and Midwestern U.S. is substantially affected by natural landscape factors and anthropogenic stressors, with climate change expected to alter natural influences and exacerbate stressor effects. To conserve fluvial fish species in the future, it is crucial to understand which fish habitats will be most strongly influenced by changing climate, which species are most sensitive to climate change, and how changes in individual species will affect entire assemblages. To answer these questions, we modeled fluvial fish distributions under projected changes in climate to understand how climate could affect suitability of fish habitat for 55 widely distributed fluvial fishes with differing thermal preferences in the region. Using boosted regression tree models, we predicted distributions of fishes at a stream reach scale using four contemporary climate variables including annual mean air temperature, annual precipitation, and variation in monthly air temperature and precipitation along with seven natural landscape and anthropogenic stressor variables. We then used projected values from eight general circulation models(GCMs) during 2041–2080 to evaluate potential patterns in species richness, turnover, and range shifts under climate change across the study region.Results Most cold-water and cool-water species were projected to lose habitat;however, projected habitat loss also occurred for certain small-bodied warm-water species. The percentage change in species richness of all 55 species across reaches ranged from-40.4 to 33.93%, with regions of major species richness losses occurring across southern portions of the Northeastern coast and southern Midwest regions. Species turnover ranged from 0 to 43.5% with substantial turnover occurring along the Northeastern coast and upper Midwest.Conclusions Temperature and precipitation variation will influence fish species distribution substantially. Our findings provide multiple measures describing patterns of fish community change under climate change to aid management and conservation of stream fishes in the future.
基金funded by the Deutsche Forschungsgemeinschaft(DFG,German Research FoundationCRC 1439/1,project number:426547801)
文摘Background The global freshwater biodiversity crisis has led to widespread implementation of measures to counteract environmental degradation and biodiversity loss.While these efforts aim to foster recovery,intensifying stressors continue to drive complex biotic responses,the trajectories and drivers of which are insufficiently understood.This study examines the roles of abiotic stressors,biotic interactions(e.g.,competition),and land use in shaping ecological status changes across Germany,using data from 1599 river sites sampled at least twice between 2004 and 2022.Results Changes in abiotic stressors emerged as the most consistent drivers of ecological status,explaining substantial variation(R^(2)=0.39)and similar slopes for recovery(β=-0.11)and degradation(β=-0.10).Biotic interactions,particularly interspecific competition,also influenced the ecological status(R^(2)=0.11),with stronger positive effects observed during recovery(β=2.99)compared to degradation(β=1.59).Land use effects varied by context:Streams in catchments with higher cropland or urban areas showed greater likelihood of recovery,whereas streams in forested catchments were more prone to degradation.These results highlight the interplay of abiotic and biotic factors in driving ecological processes of recovery and degradation.Conclusion These findings emphasize the critical role of improving water quality for enhancing biodiversity and ecological status in rivers,while also demonstrating the importance of biotic interactions and land use context in driving recovery dynamics.Integrating these insights into management and restoration efforts can enhance freshwater ecosystem resilience in the face of escalating environmental pressures.
基金supported by the National Natural Science Foundation of China(32130013)the National Key Research and Development Program of China(2022YFC2601601)+2 种基金the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK05010112,2019QZKK0304-02)Dynamic Monitoring of Distribution,Quantity and Activity of Typical Large and Medium-sized Mammals in the Yarlung Tsangpo River Basin(54000022T000000071200)the Institute of Zoology,Chinese Academy of Sciences(2023IOZ0104)
文摘Background Identifying the processes that govern community assembly along elevational gradients has been a central theme in ecology,especially in montane ecosystems where abundant species and strong turnover are present.However,our understanding of how the relative importance of deterministic and stochastic processes varies along elevational gradients remains limited.Here,we compiled a rigorously curated dataset of elevational distributions of 734 breeding bird species across the Hengduan Mountains in China to assess the dominant underlying mechanisms of bird community assembly at both intra-community and inter-community scales across four elevation zones:low,middle,subalpine,and alpine.Results At the intra-community scale,homogeneous dispersal played a pivotal role in driving community assembly of breeding birds across the Hengduan Mountains.Deterministic processes became more influential with increasing elevation,whereas stochastic processes prevailed in low,middle,and subalpine zones.At inter-community scale,assemblages from different elevation zones were more differentiated by dispersal limitation.Non-Passeriformes experienced more obvious influence of homogeneous dispersal but were less subject to dispersal limitation compared to Passeriformes.Conclusions Our findings highlight the role of stochastic processes in shaping biotic communities in montane ecosystems,but this effect is scale-dependent.The transition from stochastic to deterministic processes along elevational gradients suggests that environmental factors become more influential at higher elevations.Species dispersal ability may affect the relative importance of these two processes shaping community assembly.
基金financially supported by the National Natural Science Foundation of China(42203077,32192462)the Chinese Universities Scientific Fund(2020RC009)the 2115 Talent Development Program of China Agricultural University(1201-00109017)
文摘Background Increasing atmospheric nitrogen(N)deposition is a major threat to plant diversity globally.Recent observations show that the reduced-to-oxidized(NH_(x)/NO_(y))ratio of N deposition has been changing spatially and temporally.How and to what extent different N forms(i.e.,NH_(x)and NO_(y))influence grassland plant species loss are still unclear.Methods We employed a field manipulative experiment by using three N forms[i.e.,Ca(NO_(3))_(2),NH_(4)NO_(3),and(NH_(4))_(2)SO_(4)]with six N addition levels(0,4,8,16,24,32 g N m^(-2)year^(-1))in a temperate grassland and conducted a greenhouse experiment culturing four plant species corresponding different plant functional groups under Ca(NO_(3))_(2)or(NH_(4))_(2)SO_(4)addition.Results Results from our field experiment showed that the plant species loss rate was greater under NH_(4)^(+)-N than NO_(3)^(-)-N enrichment.Plant species loss was driven by light asymmetry under NO_(3)^(-)-N enrichment,while it was co-driven by light asymmetry and soil acidification under NH_(4)NO_(3)enrichment.Under NH_(4)^(+)-N enrichment,light asymmetry,pH decrease,NH_(4)^(+) toxicity,and metal toxicity jointly affected species loss.The greenhouse experiment provided direct evidence that legumes and forbs are more physiologically susceptible to NH_(4)^(+)-induced toxicity than grasses.Conclusions Our results emphasize that N forms play a vital role in affecting grassland plant diversity.This suggests that regions with higher NH_(x) enrichment may experience more severe plant diversity losses as N deposition continues to increase.Therefore,appropriate measures should be adopted to mitigate species losses.
基金funded through the internal funds of the ICMR-VCRC,Puducherry,India
文摘Background Tick borne diseases are re-emerging around the world,including India.Information about the occurrence of the tick vectors in different geographical locations is essential for controlling the diseases.Tick surveys have not been conducted in many parts of India and information on the current prevalence of tick vectors is not available in all states of India.Many studies have been carried out utilizing modelling methods to predict the distribution of tick species in other countries.The MaxEnt model is widely used for predicting tick species distribution using bioclimatic variables.Lyme disease vectors such as Ixodes sp.,Amblyomma sp.,and Dermacentor sp.are the most commonly predicted tick species.However,very few studies have been carried out to predict the distribution of tick species in India.Haemaphysalis spinigera,the primary Kyasanur Forest Disease vector,was predicted along the Western Ghats using the MaxEnt model.Rhipicephalus(Boophilus)microplus was predicted across India using the generalized linear model(GLM).Identifying the tick vectors in transmitting the infection through conventional survey and identification methods is cumbersome due to the less number of experienced persons available.Prediction of tick vectors of public health concern,including other tick species in different geographical regions of Tamil Nadu,India,is essential for the prevention and control of tick-borne disease in humans and domestic animals.The present study adopts the package‘SSDM’(stacked species distribution models)with R software containing ensemble species distribution models to predict the distribution of tick species using different available environmental and climatic data.Results The categorical variables such as land use and land cover(LULC),soil type,elevation,Bio1,Bio10,Bio15,Bio19 and Bio8 contributed more to modelling the distribution of tick species.MaxEnt,GLM,GBM and GAM are suitable models for predicting the tick species distribution in the present study.Among these models,MaxEnt is the most suitable model for predicting tick species distribution in Tamil Nadu,India.Conclusions Our results suggest that MaxEnt is a suitable model for predicting the distribution of tick species.Both environmental factors such as LULC,elevation and soil type and bioclimatic factors such as temperature and precipitation contribute significantly to predicting tick species distribution in domestic animals in Tamil Nadu.The SSDM package is very useful and user-friendly graphical user interface for modelling the distribution of tick species.However,the package can be further improved by using higher resolution raster variables in larger areas,which is not currently supported.The predicted elevation range of Ha.spinigera distribution could not be provided due to software limitations.
文摘Nutrient concentrations in foliage are often used to infer whether growth of a species at a particular site is likely limited by low supply of soil nutrients.Sometimes ratios of nutrient elements(stoichiometry)are thought to be useful,as if a higher supply of one element might somehow physiologically alleviate,or interfere with,a low supply of another.The growth of most forests is indeed commonly limited by low supplies of nutrients in soils,but foliar chemistry has proven unable to discern nutrient limitations.We illustrate this conclusion using two large,regional experiments with Eucalyptus in Brazil and loblolly pine(Pinus taeda L.)in the southeastern USA.In both cases,most sites showed profitable increases in growth after fertilization,and nutrient concentrations in foliage differed substantially across sites.However,foliar nutrient concentrations(and stoichiometric ratios)did not provide useful information about forest growth responses.We urge authors,reviewers,and editors not to expect foliar chemistry to be a useful tool for diagnosing nutrient limitations in forests,unless strong,local evidence demonstrates a reliable association.
基金funded by the Forestry Science and Technology Research and Innovation Project of China(grant no.XLKY202322)Joint Funds of National Natural Science Foundation of China(grant no.U21A20187)+6 种基金Key Research and Development Program of Hunan province(grant no.2023SK2055)National Key R&D Program of China(grant no.2020YFA0608100)Creative Research Groups of Provincial Natural Science Foundation of Hunan(grant no.2024JJ1016)Water Science and Technology Project of Hunan province(grant no.XSKJ2022068-35)Hunan Provincial Natural Science Foundation of China(grant no.2024JJ5639)Changsha Municipal Natural Science Foundation(grant no.kq2402249)Three Gorges follow-up project of the Ministry of Water Resources(grant no.HY110161A0012022)
文摘Background Biochar is widely recognized for its capacity to capture and store carbon in soil attributed to its stable structure. However, in most field studies examining the effects of biochar application on soil respiration, the impact of rainfall events on the experimental outcomes has not been taken into account. To address the existing gap in this research field, we conducted a one-year study on soil respiration in an urban camphor forest and collected the data of soil respiration, soil temperature, soil moisture, and the rainfall events closest to the soil respiration monitoring time. We specifically examined how different stages of rainfall events influenced soil respiration in relation to biochar application.Results This study found that the annual average soil respiration rate increased with the doses of biochar application, and the soil respiration rate under the biochar application at the dose of 45 t/ha showed a significant rise. The stages of rainfall events, rainfall amount, and the interaction effect of the two, and biochar doses significantly affected soil respiration. The parameters in the regression model for soil respiration, soil temperature and moisture varied with the different stages of rainfall events and the doses of biochar application. The biochar application eliminated the significant effect of soil moisture on soil respiration during one day after rainfall events. The significant correlation between soil moisture and the temperature sensitivity of soil respiration(Q10) was eliminated by biochar application, both during one day after rainfall events and more than eight days after rainfall events.Conclusions Our findings indicated that the rice straw biochar application has a short-term positive effect on soil respiration in urban camphor forests. The rainfall events affect the field soil respiration monitored in the biochar applications, possibly by affecting the soil respiration response to soil temperature and moisture under different doses of biochar application. The impact of rainfall events on soil respiration in biochar application experiments should be considered in future forest monitoring management and practice.
基金supported by the National Natural Science Foundation of China Joint Fund Project(U21A20186)the International Cooperation Project of Key Research and Development and Transformation in Qinghai Province(2024-HZ-810)+1 种基金the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK0302)the project of“No-till replanting technology to promote the production and ecological function of heavily degraded alpine grasslands”(QLC2024TG14)
文摘Background Soil respiration(Rs)is critical for maintaining the terrestrial carbon(C)cycling,and considerable research has focused on its response to climate warming.However,our knowledge of the mechanistic basis of the plant functional composition on Rs is limited.We conducted a 2-year field warming experiment to explore Rs responses to different warming levels across three types of alpine grasslands:alpine steppe(AS)dominated by grasses,alpine meadow(AM)and alpine swamp meadow(ASM),both of the latter two dominated by sedges.Results Our findings revealed contrasting effects of warming on Rs across three alpine grassland types:minimal change in the AS,a significant 24%increase in the AM,and a 20%decrease in the ASM.Dominant plant functional groups in each grassland type play an important role in regulating the response of Rs to warming.Moreover,we found a negative correlation between plant height and Rs in the grass-dominated AS and sedge-dominated AM.However,there was no correlation between plant height and Rs in ASM.Furthermore,Rs was regulated by both soil moisture and soil temperature,while in ASM it was constrained by soil moisture levels.Conclusions Our results underscore the importance of incorporating plant functional composition mechanisms when assessing ecosystem C balance under climate warming.Future studies should consider the ecosystem-specific characteristics when investigating the connections between plant community structure,traits,and ecosystem function.
基金supported by the National Key Research and Development Program of China(2024YFD150140302)the Natural Science Foundation of China(Nos.32271843,41888101 and 41871027)the project of forestry science and technology innovation platform(No.LLC20245)
文摘Background The forest floor humus layer is an important carbon pool and serves as a key interface that influences forest soil carbon and nutrient cycling,especially in temperate and boreal forests.Over the past decades,China has implemented numerous forestry ecological programs,leading to an increasing quantity of forest floor litter and the formation of humus layers,which has altered the interface between aboveground litter and surface soil.Our previous study revealed that these alterations affect the litter decomposition rate;however,it is still unclear how the litter decomposition process changes,how nutrients are released or imported and the extent to which these changes depend on the humus layer.Results In this study,we used a 535-day in situ litterbag experiment to monitor the litter decomposition process and nutrient variations under forest floor humus layer removal in a Pinus sylvestris var.mongolica plantation in Northeast China.The results revealed that the litter decomposed quickly when a forest floor humus layer was present,with the decomposition rate constant(k value)increasing from 0.122 to 0.328.Accordingly,during decomposition,the litter C,N and P concentrations increased,whereas their contents varied only slightly(with the exception of the litter P content,which decreased significantly)compared with those in the treatment where the humus layer was removed.However,both the litter C and N contents decreased,whereas the litter P content increased significantly compared with the initial litter content.Moreover,the litter C:N,C:P and N:P ratios decreased significantly during decomposition.In addition,the microbial community diversity of the litter showed no significant change,whereas the relative abundances of several major fungal and bacterial taxa at the phylum and genus levels varied significantly.Furthermore,redundancy analysis revealed effective relationships among the k values,chemical traits and microbial communities,and the least squares method suggested that the C,P and C:P ratios of the litter were significantly correlated with the litter decomposition rate.Conclusions These results enhance our understanding of the role of the humus layer in forest soil-plant carbon and nutrient cycling and should be considered in carbon cycle models in the future.
基金supported by the National Natural Science Foundation of China(32171762 and 32122061)the Natural Science Foundation of Gansu Province(22JR5RA460)
文摘Background Climate change associated with droughts has led to widespread forest decline.Hydraulic and carbonrelated performances are key physiological processes for the tolerance of trees to environmental changes,yet our current understanding of such physiological performances for forest decline is still limited.Here,we investigated the hydraulic and carbohydrate performances of healthy and declining(canopy dieback)trees in temperate larch(Larix principis-rupprechtii)plantations.Results Relative to healthy trees,the higher native percentage loss of xylem hydraulic conductivity and lower xylem hydraulic conductivity indicated a deterioration of the integrity of the hydraulic system in declining trees.Additionally,the comparable Huber value,intrinsic water-use efficiency,and leaf mass per area between healthy and declining trees suggest a relatively profligate water-use strategy by declining trees.Declining trees had lower nonstructural carbohydrate concentrations in leaves,branches,and twigs but higher soluble sugars concentration in fine roots than conspecific healthy trees.Conclusions Overall,declining trees in larch plantations would be more vulnerable to drought due to the higher risk of hydraulic dysfunction and carbohydrate depletion.
基金provided by the Tenaga Nasional Berhad Research(TNBR)Sdn Bhd under research codes ST-2017-009,ST-2017-007 and ST-2022-019
文摘Background Mineral-rich licks are known to provide mineral supplements to wildlife species,including mammals.Artificial salt licks have been provided as habitat enrichment in protected areas and secondary forests in Peninsular Malaysia since 2012.However,few studies have investigated artificial salt licks,particularly their mineral composition and roles in different habitats.We used 40 camera traps to assess mammal species diversity and assemblages at 20 salt licks(nine natural and 11 artificial licks)in three forest reserves in Peninsular Malaysia.Nine mineral elements from water and soil samples from natural and artificial licks in primary and secondary forests were analysed.Results Twenty-nine mammal species were identified across salt licks,with 16 species being salt lick users,including eight herbivorous,five frugivorous and three carnivorous mammals,most of which moved in groups and solitarily.The mammal species assemblages across both salt lick and habitat types demonstrated a predominantly nested pattern,with herbivorous and frugivorous mammals being the primary users.The artificial salt licks in both habitats showcased the same feeding guilds including species that are resilient to habitat changes.The visitation frequency at both types of licks and habitats suggests that each salt lick user had its own preferences for minerals from salt lick water and soil.Conclusions This study suggests that artificial licks may be as effective as natural licks in providing minerals to many mammal species both in primary and secondary forests.Thus,they could be used to enrich degraded habitats.Enriching degraded habitats is essential for supporting the ecosystem,especially in carbon reduction,biodiversity conservation and connectivity between degraded forests and intact forests.
基金supported by the National Natural Science Foundation of China(No.32471838)the National Key Research and Development Program of China(No.2023YFF1304201)
文摘Background Establishing mixed-species plantations is increasingly recognized as an important silvicultural measure because they are more productive than monocultures.This over-yielding is attributed to the complementary resource use between component tree species,yet it remains largely unknown whether and how component tree species adjust nutrient acquisition and utilization strategies to achieve complementary nutrient use.Here,we measured soil nitrogen(N)availability and transformation rates,leaf N resorption efficiency and proficiency,and nine root morphological,physiological and mycorrhizal traits tightly related to N acquisition in 20-year-old pure and mixed stands of Pinus sylvestris var.mongolica(Mongolian pine)and Populus simonii(Simon poplar),northeast China.Results Tree species mixing had negative effects on soil nitrate concentration and net N mineralization rate,but had positive effects on absorptive fine root biomass.Compared to growing alone,Mongolian pine in mixed stands had higher leaf N resorption efficiency,and produced more absorptive fine roots with more-efficient morphological features in nutrient acquisition characterized by higher specific root length and lower root tissue density.Additionally,Simon poplar had greater root length density,root area index,and the relative abundance of ectomycorrhizal fungi with genetic potential to produce class II peroxidases in mixed than pure stands.Conclusions These findings highlight that component species express high plasticity in nutrient acquisition and utilization traits in response to tree species mixing,and suggest that this high plasticity could be responsible for the over-yielding of mixed-species plantations.
文摘The diet of ungulates is often characterized by low protein levels and the presence of indigestible and defensive compounds.It also often lacks micronutrients(vitamins and minerals)essential for growth,health and reproduction.Ungulates select rich plant organs to compensate for nutrient shortages and may consume soil,faeces and even bones.It is common for ungulates to incidentally ingest plant-dwelling insects(PDI)while feeding.It is well known that insects contain protein and essential nutrients that can feed livestock,potentially replacing conventional feed.Based on this,we propose the‘nutritional benefit of incidental ingestion'hypothesis,suggesting that ungulates may nutritionally benefit from ingesting PDI while foraging.Based on evidence from the literature on PDI ingestion by ungulates and on the nutritional properties of different insects,we discuss how and whether the ingestion of PDI while foraging might improve the nutrient balance of ungulates and recommend a set of controlled experiments to test it.We provide a new and unfamiliar dimension of nutritional ecology,which is relevant to various grazing ecosystems.We propose to modify“trivial”food web structures,as direct trophic interactions between ungulates and PDI may hold greater significance for ungulate performance and behaviour.
基金supported by"Pioneer"and"Leading Goose"R&D Program of Zhejiang(2024C03226)NSFC(grant no.32371580)
文摘Background The invasion of apple snails(Pomacea spp.)has a serious negative impact on the yield of aquatic crops,including rice,which is a vital food source for more than half of the global population and irreplaceable in maintaining the global food security of human society.So far,it has been unclear whether jasmonic acid(JA)application can enhance the effects of silicon addition on the defense of crops like rice against the invasion of apple snails.Rice plants were grown in a greenhouse and subjected to treatments involving the addition of silicon(sodium silicate)and JA(methyl jasmonate).Then,in an indoor experiment,apple snails were fed with the leaves of the rice plants that had undergone the treatments.Growth and growth-related traits for rice plants and apple snails and defense-related mechanic characters for rice plants were measured.Results Silicon addition significantly increased rice growth,leading to improved biomass and relative chlorophyll content.JA application did not affect the growth of rice plants but increased their foliar nitrogen and carbon content disproportionally,leading to a reduced C/N ratio.JA application increased the levels of tannins,total phenolics,and flavonoids in rice leaves.Silicon addition increased the tannin,total phenolic,and flavonoid content in rice leaves,particularly when supplied with JA.Silicon addition could also enhance the force of fracture in rice leaves.In addition,the foliar sulfur and silicon content increased with the addition of silicon,and the combination of silicon addition and JA application resulted in the highest foliar silicon content.Both silicon addition and JA application significantly decreased weight gain,leaf consumption,relative growth rate,and cellulase activity of apple snails,indicating a strong interaction.Conclusions Overall,these findings indicated that both silicon addition and JA application enhanced the defense of rice against apple snails and impeded the growth of these snails.JA application amplified the impact of silicon addition on rice's defense mechanism.This study provides new insights into controlling biological invasions and their impact on crop yield.
基金funded by South Africa’s National Research Foundation(NRF:research grant UID number 137789)the Centre of Excellence for Invasion Biology(CIB)
文摘Background Acacia dealbata Link is a problematic invasive alien tree in South Africa,with severe environment effects such as native plant displacement and soil nutrient manipulation(nitrogen fixation).Most studies on A.dealbata invasion are on aboveground vegetation effects,with a few studies on belowground soil seed bank impacts associated with both invasion and removal for restoration purposes.This study assessed the impact of A.dealbata invasion and removal on soil seed banks in grasslands targeted for ecological restoration in the upper Tsitsana communal area of Eastern Cape Province,South Africa.Soils were collected from A.dealbata invaded,cleared,and uninvaded treatments and germinated in an ambient greenhouse over 11 months.We measured species diversity,density,frequency of occupancy,and identified all the seedlings that germinated in trays measuring 20 cm wide×20 cm long×15 cm deep.Results Species richness and abundance were significantly(P<0.001)lower in the cleared and invaded treatments compared to the uninvaded treatment,with this trend being more pronounced for forbs and graminoids than for trees and shrubs,indicating that soil seed bank impacts are growth-form specific.Species density for all species was significantly(P<0.001)lower in the invaded treatment compared to the cleared and uninvaded treatments.The removal of A.dealbata increased species composition in the cleared treatment with woody species such as Diospyrus and Searsia species occurring in the cleared than invaded treatment.Conclusions The study concludes that A.dealbata invasion reduces soil seed bank community diversity and composition in upper Tsitsana grasslands.However,seed banks in the cleared treatment appear adequate to facilitate grassland recovery following the removal of A.dealbata.
基金The National Natural Science Foundation of China(32241035,32471767)the“Kezhen-Bingwei”Young Talents(2022RC004)
文摘Background The Zoige Plateau hosts the largest alpine peatland in the world,playing a crucial role in carbon sequestration and biodiversity conservation.However,this valuable ecosystem has been significantly impacted by anthropogenic drainage for various purposes,prompting increased interests in ecological restoration efforts.This study evaluates changes in plant diversity,community composition,and biomass allocation across natural,drained,and rewetted peatlands,with a particular focus on variations in microtopography,including hollows and hummocks.Results Restoration showed significantly higher soil water content,which was 11.6%higher in hollows(to 88.5±0.09%)and 14.4%higher in hummocks(to 81.1±1.6%)of rewetted peatlands compared to natural peatlands(p<0.001).However,the water table depth did not differ significantly from that of natural peatlands(p=0.61).While peatland management did not significantly affect plant diversity,microtopography had a considerable impact on plant species richness,dominance,the Shannon-Wiener index,and evenness.Conversely,plant community com-position exhibited significant differences among natural,drained,and rewetted peatlands at both hollow and hum-mock microsites.Aboveground biomass was significantly higher in drained and rewetted peatlands compared to natural peatlands at both microsites,whereas belowground biomass was significantly lower in drained and rewet-ted peatlands,particularly in hummocks.Conclusions Rewetting raises water table depth but does not fully restore the original plant community compo-sition or biomass.Microtopography plays a vital role in influencing plant diversity and community composition,with hummocks showing greater resilience to drainage impacts.Our findings emphasize ecological consequences of peatland management practices and highlight the need for targeted restoration strategies to strengthen the resil-ience of these vital ecosystems.
