Background Intensive and large-scale aquaculture has a high biological density,and a large amount of artificial feed must be provided.As a result,residual feed would be discharged into natural water bodies with water ...Background Intensive and large-scale aquaculture has a high biological density,and a large amount of artificial feed must be provided.As a result,residual feed would be discharged into natural water bodies with water exchange.Due to heavy metal pollution in surface water,residual feed may adsorb heavy metals in the water,affecting the subsequent microbial degradation of feed and the restoration of the water environment.The combined ecological impacts of these two types of pollution urgently need to be explored.Results This study explored the adsorption effect of residual feed on heavy metals and its impact on microbial degradation of residual feed.The results showed that both the insoluble component(mainly fiber,ash,and ether extract,abbreviated as FAE)and soluble component(soluble protein and starch)of the feed had adsorption effects on heavy metals.As the salinity increased,the adsorption capacity of Cu^(2+)and Cd^(2+)decreased,while the adsorption effect on Pb^(2+)was not changed significantly.The adsorption of heavy metals by residual feed could affect the biological degradation of residual feed.The residual feed could adsorb heavy metals and bacterial cells simultaneously,forming FAE-B(bacteria)-S(starch)-Pr(protein)-metal adsorption complex.This adsorption effect could reduce the negative impact of heavy metals on microbial degradation of residual feed.The simulated degradation experiments in actual water bodies also confirmed this.However,the accumulation of heavy metals in residual feed may bring negative effects,such as being consumed by aquatic organisms and entering the food chain.Conclusions The results of this study provide a basis for the collection and centralized treatment of residual feed in aquaculture,as well as the control and remediation of residual feed pollution in natural water bodies.展开更多
Background:The habitat resources are structured across different spatial scales in the environment,and thus animals perceive and select habitat resources at different spatial scales.Failure to adopt the scale-dependen...Background:The habitat resources are structured across different spatial scales in the environment,and thus animals perceive and select habitat resources at different spatial scales.Failure to adopt the scale-dependent framework in species habitat relationships may lead to biased inferences.Multi-scale species distribution models(SDMs)can thus improve the predictive ability as compared to single-scale approaches.This study outlines the importance of multi-scale modeling in assessing the species habitat relationships and may provide a methodological framework using a robust algorithm to model and predict habitat suitability maps(HSMs)for similar multi-species and multi-scale studies.Results:We used a supervised machine learning algorithm,random forest(RF),to assess the habitat relationships of Asiatic wildcat(Felis lybica ornata),jungle cat(Felis chaus),Indian fox(Vulpes bengalensis),and golden-jackal(Canis aureus)at ten spatial scales(500-5000 m)in human-dominated landscapes.We calculated out-of-bag(OOB)error rates of each predictor variable across ten scales to select the most influential spatial scale variables.The scale optimization(OOB rates)indicated that model performance was associated with variables at multiple spatial scales.The species occurrence tended to be related strongest to predictor variables at broader scales(5000 m).Multivariate RF models indicated landscape composition to be strong predictors of the Asiatic wildcat,jungle cat,and Indian fox occurrences.At the same time,topographic and climatic variables were the most important predictors determining the golden jackal distribution.Our models predicted range expansion in all four species under future climatic scenarios.Conclusions:Our results highlight the importance of using multiscale distribution models when predicting the distribution and species habitat relationships.The wide adaptability of meso-carnivores allows them to persist in human-dominated regions and may even thrive in disturbed habitats.These meso-carnivores are among the few species that may benefit from climate change.展开更多
Background:Soil erosion is among the foremost causes of declining soil resources in Ethiopia,which in turn affect agricultural productivity.To limit this problem,for the last two decades in Gumara watershed,soil and w...Background:Soil erosion is among the foremost causes of declining soil resources in Ethiopia,which in turn affect agricultural productivity.To limit this problem,for the last two decades in Gumara watershed,soil and water conservation measures have been practiced through free labor community mass-mobilization.However,their effect on soil fertility has not been evaluated.This study investigated the impact of implemented soil and water conservation measures on fertility improvement in the Gumara watershed.Both composite and core soil samples were taken from upstream,midstream,and downstream adjacent conserved and non-conserved cultivated and grazing plots.Selected soil fertility indicators were analyzed using standard laboratory procedures.Results:Soil and water conservation practices have resulted in a statistically significantly higher mean values of total nitrogen,exchangeable Na+and Mg2+at p<0.01,and of soil organic carbon and organic matter at p<0.05 in the watershed.The clay content,soil reaction,cation exchange capacity,and exchangeable K+showed nonsignificant,but higher mean values in conserved plots.Furthermore,the effects of conservation practices on soil properties were found more effective in cultivated land uses as compared to that of grazing land uses.This is because conservation treatments had significant effects on organic carbon,total nitrogen,exchangeable Na+and Mg2+in cultivated land uses but only on exchangeable Na+in grazing land uses.The interaction effect of treatments and land uses did not reach a statistically significant result for any of the soil properties considered in this study.Conclusion:Conservation measures have important implications for improving soil fertility in the Gumara watershed.Therefore,proper guidance and follow-up,use of agro-forestry and grass strips,and maintenance are required for the watershed’s sustainability and good soil conditions.展开更多
Introduction:The purpose of this study is to evaluate the associated impact of adoption of adaptation options to climate change and variability on household food security in the Muger sub-basin of the upper Blue-Nile ...Introduction:The purpose of this study is to evaluate the associated impact of adoption of adaptation options to climate change and variability on household food security in the Muger sub-basin of the upper Blue-Nile of Ethiopia using a comprehensive data of 442 sampled households from four representative districts’in the sub-basin.The study used a propensity score matching approach to evaluate the impact of adaptation options on household food security.Results:Results show that the decision to adopt adaptation options is found to be positively influenced by male household heads,family size,access to extension service,the size of landholding,and frequency of drought and floods over the past many years.The results further reveal that farmers adopting any of the adaptation options had higher food calorie intake per day per adult equivalent than those who did not.Conclusions:A policy that promotes the adoption of soil and water conservation measures,small-scale irrigation,agronomic practices,and livelihood diversification strategies should be central to food security strategy in the study area.展开更多
Introduction:Evidence is mounting that traditional knowledge can play a critical role in shaping the biodiversity conservation strategies and maintaining ecosystem services.This study was conducted with Adi community ...Introduction:Evidence is mounting that traditional knowledge can play a critical role in shaping the biodiversity conservation strategies and maintaining ecosystem services.This study was conducted with Adi community of Arunachal Pradesh(Ar P)state in the Eastern Indian Himalayas to understand as how local systems of forest classification governs conservation tradition and influences subsistence livelihoods.Twenty Adi villages were sampled from East Siang district of Ar P.A total of 197 men and 204 women(total of 401)Adi respondents were selected for this study.A combination of methodologies including in-depth interview,transect walks,focus group discussion,participant observation and informal interactions were combined for data collection.Results:Local forests are classified into 10 different categories based on indicators such as topography,cultural significance,use typology,ownership rights and plant diversity indicators.Local people assign different values(economic,cultural and ecological)to different forest types.Overall,morang followed by regpi and homegardens are perceived to be more valuable to the local needs than other forests with relative ranking of a particular forest reflecting its sustainability.Adis access several diverse services from these community-managed forests.Compared to men(3–35%),the role of women was assessed to be much higher(65 to 100%)in conserving forest biodiversity.Woman-led practices,instrumental in sustainable forest management,included deliberate manipulations of micro-habitats,sustainable harvesting strategies and species domestication.Men were mostly involved in ownership and decision-making roles and in devising social norms to ensure sustainability.Adi celebrate a number of cultural events to sustain biodiversity.Forest-based livelihoods are intrinsically connected to forest resource conservation and are governed by community approaches.Most of the community members gather plants,hunt wild animals and access other ecosystem services from these forests to sustain their livelihoods.Community-owned forests are collectively managed by an indigenous institution‘Kebang’.Conflicts relating to forest land use and resource management are resolved by the customary chief‘Gaon Burha’and his associates using traditional norms.Conclusions:Adi’s system of forest classification,based on ecological,socio-cultural and livelihood indicators,is a location-specific yet comprehensive in nature.Study suggests that integrating the local indicators applied in classifying and strategies applied in managing the local forests can provide valuable insights to the policy makers for the sustainable conservation of forest resources.展开更多
Introduction:Construction activities in and along urban streams increase the sediment input into surface waters,causing an overall decline in water quality and aquatic ecosystems.In this case study,we investigate the ...Introduction:Construction activities in and along urban streams increase the sediment input into surface waters,causing an overall decline in water quality and aquatic ecosystems.In this case study,we investigate the water quality impacts of local hydromodification in an urban stream(discharge 0.4 m^(3)/s).At the site of interest,workers removed a stream crossing consisting of an embankment with culverts and replaced it with a small bridge(single span of 25 m)in an effort to improve flow capacity.Methods:Water samples were taken at four sites along the North Branch Park River in Connecticut,Northeastern United States.Turbidity and dissolved oxygen(DO)were measured in situ,and nitrate and total phosphorus(TP)were measured in the laboratory.Benthic macroinvertebrate samples were also collected and analyzed for taxon richness and Shannon-Weaver species diversity.Data were compared between upstream and downstream sites and before,during,and after hydromodification.We used one-way ANOVA combined with the post hoc Turkey test to derive statistical significance.Results:During construction,turbidity increased temporarily by 60.9%[from 2.48 Nephelometric Turbidity Units(NTU)over ambient to 4.00 NTU].Once construction was completed,DO increased locally from 11.0 to 13.0 mg/L.Benthic macroinvertebrate taxon richness and species diversity declined by 61.6 and 32.6%respectively,with no recovery observed in the year following construction.Water quality was only affected within 50 m downstream.Nitrate and TP concentrations were unaffected.Conclusions:Small-scale hydromodification temporarily increased the turbidity as a result of increased sediment input,approaching the maximum level for clean water(5 NTU).Benthic macroinvertebrate communities declined in the immediate downstream vicinity of construction but are expected to recover soon given that turbidity recovered to pre-construction levels,and DO increased.These outcomes emphasize that environmental assessment is important not only for large-scale hydromodification but also for smaller scale stream modifications.展开更多
Introduction:The lagoon is a component of coastal zones,whose populations of autotrophic picoplankton(APP)remain largely unstudied.These lagoons display high-nutrient productivity and additionally may also be subjecte...Introduction:The lagoon is a component of coastal zones,whose populations of autotrophic picoplankton(APP)remain largely unstudied.These lagoons display high-nutrient productivity and additionally may also be subjected to anthropogenic activities.This study selected Laguna Macapule,located on the eastern shore in the mid-region of the Gulf of California,due to the fact that a drainage network servicing the surrounding agricultural region(>230,000 hectares under cultivation)directs irrigation runoff,shrimp farm effluents,and urban wastewater containing large quantities of nutrients to be discharged into this lagoon.We propose to identify the APP’s response to various types of environmental and anthropogenic influence in this highly impacted coastal lagoon.Methods:Two sites(separated by 2.7 km)were monitored from December 2007 to December 2008.One,located at the entrance to Laguna Macapule(oceanic influence)and the other a discharge canal(eutrophic conditions)inside the lagoon at El Tortugón.Results:APP was the numerically dominant phytoplankton fraction(15×106 to 620×106 cells L−1)with coccoidal cyanobacteria as the dominant fraction throughout the year.Peak levels were reached in spring-early autumn and they were the second largest contributor to biomass.Abundance of APP cells corresponds to the lagoon’s eutrophic status.Maximum numbers and a higher average of APP were recorded at the El Tortugón channel during the warm season(months with SST higher than 24°C).The general positive relationship of the APP’s annual cycle at both sites as well as a negative relationship with heterotrophic nanoflagellates(HNF)abundance,supports the idea that natural forcing,in particular sea surface temperature(SST)is the predominant influences on APP’s seasonal variability.Conclusions:Distinguishable significant differences in APP abundances and nutrients were recognizable between the two sites.The interplay of these variables contributed to lower densities of APP in winter and high densities in springearly autumn.N:P=~4 suggests that spring-early autumn abundance of the APP autotrophic component was sustained by urea from shrimp farm discharge water.Thus,a total nutrient-based approach is likely the most suitable tool for establishing nitrogen limitation of biological production in Laguna Macapule and similarly impacted ecosystems around the world.展开更多
Introduction:The persistence of generalists and specialists is a topical question in community ecology and results from both ecological and evolutionary processes.At fine taxonomical scales,ecological specialisation,i...Introduction:The persistence of generalists and specialists is a topical question in community ecology and results from both ecological and evolutionary processes.At fine taxonomical scales,ecological specialisation,i.e.organisms preferentially exploiting a subset of available habitats,is thought to be a driver promoting niche diversity.It is not clear,however,how different mechanisms interact to shape specialist-generalist coexistence.Methods:We reconstruct the structure of five bacteria-phage networks from soil isolates,and perform an analysis of the relationships between host phylogenetic diversity,parasite specialism,and parasite performance.Results:We show that the co-occurrence of species on a continuum of specialism/generalism is influenced by niche overlap,phage impact on bacterial hosts,and host phylogenetic structure.In addition,using a null-model analysis we show that infection strategies of the phages have more explanatory power than bacterial defenses on key structural features of these antagonistic communities.Conclusions:We report that generalists have more impact on their hosts than specialists,even when the phylogenetic heterogeneity of hosts is controlled for.We discuss our results in the light of their implications for the evolution of biotic interactions.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 Forest ecosystems undergo significant transformations due to harvesting and climate fluctuations,emphasizing the critical role of seeding in natural regeneration and long-term structural preservation.Climat...Background Forest ecosystems undergo significant transformations due to harvesting and climate fluctuations,emphasizing the critical role of seeding in natural regeneration and long-term structural preservation.Climate change further amplifies these dynamics,affecting phenology across species and regions.In Tierra del Fuego(Argentina),Nothofagus pumilio(lenga)forests represent the most important timber resource,and it is managed through different silvicultural strategies.This species demonstrates notable post-disturbance regeneration,yet seed fall exhibits signifi-cant variability,leading to variations in seed quality(e.g.,viability).This study aims to assess fluctuations in N.pumilio seed quality,determine how it varies concerning forest management strategies,annual productivity,and the co-occurrence of climatic phenomena including El Ni?o-Southern Oscillation(ENSO)and the Southern Annular Mode(SAM).Results Viable seeds represented 18.4%of the total,notably higher in unharvested than in managed areas.Con-versely,empty seeds were more prevalent in harvested areas(>75%).Seed quality exhibited significant differences across silvicultural treatments,except for insect-predated seeds,which had similar proportions across all areas,though dispersed retention showed higher predation.When considering years with varying production levels,high-production years favoured full and viable seeds,particularly in unharvested forests and aggregated retention,while low-production years saw reduced viability across all treatments.Quadratic models revealed that viability increased with seed production,where unharvested forests achieved the highest values.Climate variability influenced seed proportions,where ENSO+/SAM+promoting more full and viable seeds,while ENSO–/SAM+favoured non-predated seeds,especially in unharvested stands.Conclusions Seed quality varies among treatments and years with different levels of seeding.Variations in seed qual-ity,linked to climatic events,influence seed viability.Seed quality plays a critical role in forest regeneration,ensuring a seedling bank for harvested stands to face climate variability.These findings are relevant for forest management and ecosystem services,considering the increasing climate variability and extreme events.Understanding these influ-ences is crucial for Nothofagus pumilio forests'sustainability and global forest adaptation strategies.展开更多
This paper lays out a hierarchical,appropriate-complexity framework for conceptualizing movement-path segments at different spatiotemporal scales in a way that facilitates comparative analyses and bridges behavior and...This paper lays out a hierarchical,appropriate-complexity framework for conceptualizing movement-path segments at different spatiotemporal scales in a way that facilitates comparative analyses and bridges behavior and mathematical concepts.It then outlines a process for generating a multimode,multiscale stochastic simulation model that can be used to test animal movement hypotheses and make predictions of movement responses to management and global change.Many methods for analyzing movement data begin by generating step-length(SL)and turning-angle(TA)distributions from relocation time-series data,some of which are linked to ecological,landscape,and environmental covariates.The frequency at which these data are collected may vary from sub-seconds to several hours.The kinds of questions that may be asked of these data,however,are very much scale dependent.The hierarchical path-segmentation(HPS)framework presented here clarifies how the scale at which SL and TA data are collected relates to other sub-and super-diel scales.Difficulties arise because the information contained in SL and TA time series are often not directly relatable to the physiological,ecological,and sociological factors that drive the structure of movement paths at longer scales.These difficulties are overcome by anchoring the classification of movement types around the concept of fixed-period(24 h)diel activity routines and providing a bridge between behavioral/ecological and stochastic-walk concepts(means,variances,correlations,individual-state and local environmental covariates).This bridge is achieved through the generation of relatively short segments conceived as characteristic sequences of fundamental movement elements.These short segments are then used to characterize longer canonical-activity-mode segments that emerge through movement at behaviorally relevant sub-diel scales.HPS thus provides a novel system for integrating sub-minute movement sequences into canonical activity modes(CAMs)that,in turn,can be strung together into various types of diel activity routines(DARs).These DARs both vary among individuals within a given day,and for any given individual across time and under the influence of landscape factors.An understanding of how DARs are influenced by environmental inputs will help us predict the response of supra-diel lifetime movement phases(LiMPs)of individuals,as well as their complete lifetime tracks(LiTs),to anthropogenically induced global change.展开更多
Background:Soil erosion is one of the major threats in the Ethiopian highlands.In this study,soil erosion in the Muga watershed of the Upper Blue Nile Basin(Abay)under historical and future climate and land use/land c...Background:Soil erosion is one of the major threats in the Ethiopian highlands.In this study,soil erosion in the Muga watershed of the Upper Blue Nile Basin(Abay)under historical and future climate and land use/land cover(LULC)change was assessed.Future LULC was predicted based on LULC map of 1985,2002,and 2017.LULC maps of the historical periods were delineated from Landsat images,and future LULC was predicted using the CA–Markov chain model.Precipitation for the future period was projected from six regional circulation models.The RUSLE model was used to estimate the current and future soil erosion rate in Muga watershed.Results:The average annual rate of soil erosion in the study area was increased from about 15 t ha^(−1) year^(−1) in 1985 to 19 t ha^(−1) year^(−1) in 2002,and 19.7 t ha^(−1) year^(−1) in 2017.Expansion of crop cultivation and loss of vegetation caused an increase in soil erosion.Unless proper measure is taken against the LULC changes,the rate of soil loss is expected to increase and reach about 20.7 t ha^(−1) year^(−1) in 2033.In the 2050s,soil loss is projected to increase by 9.6%and 11.3%under RCP4.5 and RCP8.5,respectively,compared with the baseline period.Thus,the soil loss rate is expected to increase under both scenarios due to the higher erosive power of the future intense rainfall.When both LULC and climate changes act together,the mean annual soil loss rate shows a rise of 13.2%and 15.7%in the future under RCP4.5 and RCP8.5,respectively,which is due to synergistic efects.Conclusions:The results of this study can be useful for formulating proper land use planning and investments to mitigate the adverse efect of LULC on soil loss.Furthermore,climate change will exacerbate the existing soil erosion problem and would need for vigorous proper conservation policies and investments to mitigate the negative impacts of climate change on soil loss.展开更多
Background:Current forests of the eastern USA have the potential to succeed in composition to more shade-tolerant species.However,long-term processes of transition from fire-tolerant tree species to fire-sensitive spe...Background:Current forests of the eastern USA have the potential to succeed in composition to more shade-tolerant species.However,long-term processes of transition from fire-tolerant tree species to fire-sensitive species and effects of current land use on forests may interfere with successional progression.Methods:I examined if forests in three regions have increased in shade tolerance and if life history strategy groups that represent response to disturbance(i.e.,fire-tolerance,early-successional species based on low shade tolerance,mid-successional species,late-successional species,and trees valued for traits related to short harvest rotations)have changed,using Forest Inventory and Analysis surveys,adjusted for comparison,and generalized linear mixed models to assess approximately 30 year trends,with adjustments to equalize different survey methods.Results:Although statistically significant,a slight increase of 2 to 4%in regional mean shade tolerance may not be ecologically significant.In the central East,mid-successional species replaced early-successional species and early-successional species replaced fire-tolerant oaks,resulting in an overall shift from fire-tolerant oaks to mid-successional species.Decreased fire-tolerant pine species and increased planted pine species were the major changes in the northern Southeast and Coastal Plain.Conclusions:The successional process of increased composition by shade-tolerant species over time was overshadowed by land use changes that resulted in decreased fire-tolerant species and increased planted pine.Furthermore,frequent land use disturbance may continue to prevent the slow progress of compositional succession to very shade-tolerant species.展开更多
Water is essential to life on Earth.Ecohydrology,the study of interactions between ecological and hydrological processes,is fundamental to our understanding and quantification of services provided by ecosystems.Our kn...Water is essential to life on Earth.Ecohydrology,the study of interactions between ecological and hydrological processes,is fundamental to our understanding and quantification of services provided by ecosystems.Our knowledge of ecohydrology is incomplete due to the complex nature of ecosystems,which are constantly changing under multiple stresses from air pollution to climate change,from deforestation to urbanization,and from soil erosion to soil pollution.Ecosystem services,the goods and services that ecosystems provide for human wellbeing,are increasingly adopted as a framework worldwide for ecological restoration and conservation,watershed management,and sustainable development policy making.展开更多
Introduction:Understanding how mangroves respond to rare cold events has implications for both restoration and conservation under climate change scenarios.This study investigated the responses of photosynthesis and ac...Introduction:Understanding how mangroves respond to rare cold events has implications for both restoration and conservation under climate change scenarios.This study investigated the responses of photosynthesis and activities of key enzymes involving carbon and nitrogen metabolism at different ages of Kandelia obovata to a rare cold event in the winter of 2010.Methods:This study took place on Ximen Island,Zhejiang Province,China.We measured the physiological recovery of 2-3-,5-6-,9-10-and 54-55-year-old K.obovata trees after freezing injury in February and March in 2011 and 2012,respectively.Results:Chilling injury index and electrolyte leakage of K.obovata increased with increasing tree age in the winter of 2010,and electrolyte leakage in K.obovata at different ages in the winter of 2010 was far higher than that in the winter of 2011.The rare cold events significantly changed the recoveries of the leaf net photosynthetic rate(Pn)and stomatal conductance(Gs);ratios of chlorophyll a/chlorophyll b(Chl a/Chl b);contents of total soluble sugar(TSS),sucrose,free amino acid(FAA),and soluble protein;and activities of sucrose phosphate synthase(SPS),endopeptidase,and carboxypeptidase in K.obovata at different ages.These effects were mainly due to changes in the physiological mechanism in the 2-year-old trees.A clear decrease in Pn of the 2-year-old trees was observed in February 2011,as exemplified by reductions in ratios of Chl a/Chl b and chlorophyll/carotenoid(Chl/Car),as well as inhibition of the levels of TSS and FAA(osmotic substances).During recovery in 2011 and 2012,the activities of SPS and sucrose synthase(SS)were responsible for sucrose synthesis after the rare cold events in 2011,but only SPS activity was one of the main factors contributing to the metabolism of stachyose to sucrose without cold damage in 2012.Carboxypeptidase played a more important role than endopeptidase during protein hydrolysis after the rare cold events.Conclusions:The results suggest that the recovery of photosynthetic capacity in K.obovata was changed after a rare cold event,which is associated with pigment components and activities of SS,SPS,and carboxypeptidase,especially the seedlings.展开更多
Introduction:Low energy balance closure(EBC)at a particular eddy-covariance flux site has increased the uncertainties of carbon,water,and energy measurements and has thus hampered the urgent research of scaling up and...Introduction:Low energy balance closure(EBC)at a particular eddy-covariance flux site has increased the uncertainties of carbon,water,and energy measurements and has thus hampered the urgent research of scaling up and modeling analyses through site combinations in regional or global flux networks.Methods:A series of manipulative experiments were conducted in this study to explore the role of net radiation(Rn)in the EBC in relation to spatial variability of vegetation characteristics,source area,and sensor type in three sites of the Inner Mongolian grassland of northern China.Results:At all three sites,the residual fluxes of EBC peaked consistently at 110 W m^(-2).The spatial variability in net radiation was 19 W m^(-2)(5%of R_(n))during the day and 7 W m^(-2)(16%)at night,with an average of 13 W m^(-2)(11%)from eight plot measurements across the three sites.Large area measurements of Rn significantly increased by 9 W m^(-2)during the day and decreased by 4 W m^(-2)at night in the unclipped treatments.Net radiation decreased by 25 W m^(-2)(6%of Rn)at midday and 81 MJ m^(-2)(6%)during a growing season with heavier regular clipping than that in unclipped treatments.The Rn was lower by 11–21 W m^(-2)(~20–40%of Rn)measured by CNR1 than by Q7.1 at night,while there was only 6 W m^(-2)(~1–2%of Rn)difference during the daytime between these two types of commonly used net radiometers.Conclusions:Overall,the inclusion of the uncertainty in available energy accounted for 65%of the~110 W m^(-2)shortfalls in the lack of closure.Clearly,the unclosed energy balance at these three grassland sites remains significant,with unexplored mechanisms for future research.展开更多
Comprehending the gifts of ecology Stress ecology,climate change,human well-being,and global sustainability are popular items(Naeem et al.2009).Given all the challenges in a developing world where the global populatio...Comprehending the gifts of ecology Stress ecology,climate change,human well-being,and global sustainability are popular items(Naeem et al.2009).Given all the challenges in a developing world where the global population is supposed to reach 9.15 billion in 2050(Pimentel et al.1999.展开更多
Background Pesticide use contributes to national food security.The dissipation pathways and degradation mecha-nisms of pesticides have been widely studied and pesticide residues have remained a focus of public concern...Background Pesticide use contributes to national food security.The dissipation pathways and degradation mecha-nisms of pesticides have been widely studied and pesticide residues have remained a focus of public concern.How-ever,studies on the migration and transformation behaviors of pesticide residues in real-world greenhouse soils are insufficient.Therefore,in this study,we collected greenhouse soil from Shouguang,Shandong Province,and investi-gated the photodegradation and leaching of 17 common pesticides,which leave residues in the soil and are the most frequently used pesticides in Shouguang.The environmental behavior of pesticides in greenhouse soils will provide new information on pesticide residues in the real environment and provide a scientific basis for the prevention and control of pesticide pollution in greenhouse soils.Results The photodegradation of trifloxystrobin followed a first-order kinetic equation,whereas those of emamec-tin benzoate,chlorantraniliprole,buprofezin,difenoconazole,pyraclostrobin,boscalid,tebuconazole,isoprothiolane,metalaxyl,and oxadixyl followed second-order kinetics.The half-lives of 17 pesticides under light and dark conditions ranged from 2.5–104(mean:36.2)and 2.6–110(mean:31.4)days,respectively.The half-lives of emamectin benzoate,pyraclostrobin,and metalaxyl in the light were 86.6%,68.5%,and 94.5%of their half-lives in the dark,respectively.Chlorantraniliprole,metalaxyl,nitenpyram,diethofencarb,acetamiprid,carbendazim,and oxadixyl were leached to≥90%in aqueous solution.Six pesticides,avermectin B1A,emamectin benzoate,trifloxystrobin,difenoconazole,pyraclostrobin,and buprofezin,were difficult to leach from aqueous solutions.Conclusions The degradation rate of some pesticides was higher in the light environment than in the dark.The leaching potential of the leachable pesticides was nitenpyram?metalaxyl>acetamiprid>carbendazim>diethofen-carb≈chlorantraniliprole>isoprothiolane>oxadixyl>boscalid≈tebuconazole>hexaconazole.Pesticides that are easy to leach but not easily degraded,such as chlorantraniliprole and metalaxyl,have a high potential risk of ground-water pollution,and additional degradation technologies should be used to reduce their pollution risk.The study of the photodegradation and vertical migration behavior of various pesticides is conducive to providing references for the agricultural use and pollution control of pesticides.展开更多
Background Algae play important roles in urban river ecosystems and are the cornerstones of most water quality monitoring programs.Thus,a better understanding of algal community dynamics is needed to support sustainab...Background Algae play important roles in urban river ecosystems and are the cornerstones of most water quality monitoring programs.Thus,a better understanding of algal community dynamics is needed to support sustainable management of water resources in urban rivers.Results In this study,we quantifed the seasonal variations in planktonic and periphytic algal community structure in the highly urban Fenhe River and identifed environmental factors afecting algal community structure and diversity.We monitored planktonic(drifting)and periphytic(attached)algal communities in the Taiyuan section of the Fenhe River over one year.The results indicated that Cyanophyta was the dominant phylum in both communities,followed by Bacillariophyta and Chlorophyta.Signifcant diferences were observed in the composition of the planktonic and periphytic algal communities.In particular,the periphytic algal community was more diverse than the planktonic community.Water temperature and pH were the main environmental factors afecting planktonic and periphytic algal community structure,respectively,while nutrients were the most signifcant factor afecting planktonic and periphytic algal diversity.Ecological modeling indicated that the variations in the algal communities of the Fenhe River are mainly driven by stochastic processes.A co-occurrence network developed for the communities displayed positive interactions between the planktonic and periphytic algae.Conclusions These fndings deepen our understanding of the seasonal interaction between planktonic and periphytic algae and the driving factors afecting community structure in the Fenhe River.They also provide a theoretical basis for the managing and protecting water resources in urban river ecosystems.展开更多
Background:The European rabbit(Oryctolagus cuniculus L.1758)was introduced into different regions of the world,generating significant trade‑offs that critically impacted native vegetation.Here,we evaluate the rabbit’...Background:The European rabbit(Oryctolagus cuniculus L.1758)was introduced into different regions of the world,generating significant trade‑offs that critically impacted native vegetation.Here,we evaluate the rabbit’s forage intakes in three vegetation types(forests,shrublands,and grasslands)along the four seasons in a temperate forest landscape in Southern Patagonia and discuss the potential threats over native vegetation.We formulated the following questions:(i)what is the forage offer at each vegetation type?(ii)what is the rabbit’s forage intake and how it varied across the seasons along the year?and(iii)which vegetation types and plant life forms were more used according to the rabbit’s forage intakes?Methods:We censused understory vegetation to characterize the forage offer at each vegetation type and determined seasonal dietary intakes using microhistological analysis of pellets.The plant species identified in the field were grouped according to life form classes(tree regeneration,shrubs,forbs,graminoids,orchids,ferns,bryophytes,and hemiparasites).Data were analysed through uni‑and multi‑variate analyses,determining relationships between forage offer and the rabbit’s forage intakes.Results:Forage intakes revealed changes in plant life form consumption across vegetation types,where intake pressure was considerably different for tree regeneration(p=0.001),graminoids(p=0.001),and hemiparasites(p=0.001).Besides,significant changes in consumption among seasons were detected for shrubs(p=0.001),ferns(p=0.030),and hemiparasites(p=0.002).Although many species play an important role in the rabbit’s forage intake networks(e.g.,Chiliotrichum diffusum,Holcus lanatus),the strongest intake linkages were found in exotic grasses(e.g.,Poa pratensis and Festuca sp.),native hemiparasites(e.g.,Misodendrum sp.),native shrubs(e.g.,Empetrum rubrum),and native trees(e.g.,Nothofagus sp.).The summer and autumn seasons presented higher intake compared to the winter and spring seasons.Furthermore,hemiparasites intake(e.g.,Misodendrum sp.)suggests that rabbits utilize different forage sources depending on the vegetation types.Conclusions:Rabbits regularly inhabit the forest,even though it is not their preferred vegetation type to live.Rabbit management entails isolating regions that are more favourable to intake and emphasizing the year’s season for rabbit control efforts.展开更多
基金supported by the Natural Science Foundation of Hebei Province(No.E2022203011)Zhejiang Provincial Philosophy and Social Sciences Planning Project(project No.24NDJC196YB)+2 种基金Zhejiang Provincial Natural Science Foundation of China under Grant No.LQ20B060004National Natural Science Foundation of China(No.21476190)Zhejiang Shuren University Basic Scientific Research Special Funds(2021XZ016)
文摘Background Intensive and large-scale aquaculture has a high biological density,and a large amount of artificial feed must be provided.As a result,residual feed would be discharged into natural water bodies with water exchange.Due to heavy metal pollution in surface water,residual feed may adsorb heavy metals in the water,affecting the subsequent microbial degradation of feed and the restoration of the water environment.The combined ecological impacts of these two types of pollution urgently need to be explored.Results This study explored the adsorption effect of residual feed on heavy metals and its impact on microbial degradation of residual feed.The results showed that both the insoluble component(mainly fiber,ash,and ether extract,abbreviated as FAE)and soluble component(soluble protein and starch)of the feed had adsorption effects on heavy metals.As the salinity increased,the adsorption capacity of Cu^(2+)and Cd^(2+)decreased,while the adsorption effect on Pb^(2+)was not changed significantly.The adsorption of heavy metals by residual feed could affect the biological degradation of residual feed.The residual feed could adsorb heavy metals and bacterial cells simultaneously,forming FAE-B(bacteria)-S(starch)-Pr(protein)-metal adsorption complex.This adsorption effect could reduce the negative impact of heavy metals on microbial degradation of residual feed.The simulated degradation experiments in actual water bodies also confirmed this.However,the accumulation of heavy metals in residual feed may bring negative effects,such as being consumed by aquatic organisms and entering the food chain.Conclusions The results of this study provide a basis for the collection and centralized treatment of residual feed in aquaculture,as well as the control and remediation of residual feed pollution in natural water bodies.
基金The study had no central budget.The field assistance,including accommodation,vehicle,and field assistants were facilitated by a local NGO(The Corbett Foundation).
文摘Background:The habitat resources are structured across different spatial scales in the environment,and thus animals perceive and select habitat resources at different spatial scales.Failure to adopt the scale-dependent framework in species habitat relationships may lead to biased inferences.Multi-scale species distribution models(SDMs)can thus improve the predictive ability as compared to single-scale approaches.This study outlines the importance of multi-scale modeling in assessing the species habitat relationships and may provide a methodological framework using a robust algorithm to model and predict habitat suitability maps(HSMs)for similar multi-species and multi-scale studies.Results:We used a supervised machine learning algorithm,random forest(RF),to assess the habitat relationships of Asiatic wildcat(Felis lybica ornata),jungle cat(Felis chaus),Indian fox(Vulpes bengalensis),and golden-jackal(Canis aureus)at ten spatial scales(500-5000 m)in human-dominated landscapes.We calculated out-of-bag(OOB)error rates of each predictor variable across ten scales to select the most influential spatial scale variables.The scale optimization(OOB rates)indicated that model performance was associated with variables at multiple spatial scales.The species occurrence tended to be related strongest to predictor variables at broader scales(5000 m).Multivariate RF models indicated landscape composition to be strong predictors of the Asiatic wildcat,jungle cat,and Indian fox occurrences.At the same time,topographic and climatic variables were the most important predictors determining the golden jackal distribution.Our models predicted range expansion in all four species under future climatic scenarios.Conclusions:Our results highlight the importance of using multiscale distribution models when predicting the distribution and species habitat relationships.The wide adaptability of meso-carnivores allows them to persist in human-dominated regions and may even thrive in disturbed habitats.These meso-carnivores are among the few species that may benefit from climate change.
文摘Background:Soil erosion is among the foremost causes of declining soil resources in Ethiopia,which in turn affect agricultural productivity.To limit this problem,for the last two decades in Gumara watershed,soil and water conservation measures have been practiced through free labor community mass-mobilization.However,their effect on soil fertility has not been evaluated.This study investigated the impact of implemented soil and water conservation measures on fertility improvement in the Gumara watershed.Both composite and core soil samples were taken from upstream,midstream,and downstream adjacent conserved and non-conserved cultivated and grazing plots.Selected soil fertility indicators were analyzed using standard laboratory procedures.Results:Soil and water conservation practices have resulted in a statistically significantly higher mean values of total nitrogen,exchangeable Na+and Mg2+at p<0.01,and of soil organic carbon and organic matter at p<0.05 in the watershed.The clay content,soil reaction,cation exchange capacity,and exchangeable K+showed nonsignificant,but higher mean values in conserved plots.Furthermore,the effects of conservation practices on soil properties were found more effective in cultivated land uses as compared to that of grazing land uses.This is because conservation treatments had significant effects on organic carbon,total nitrogen,exchangeable Na+and Mg2+in cultivated land uses but only on exchangeable Na+in grazing land uses.The interaction effect of treatments and land uses did not reach a statistically significant result for any of the soil properties considered in this study.Conclusion:Conservation measures have important implications for improving soil fertility in the Gumara watershed.Therefore,proper guidance and follow-up,use of agro-forestry and grass strips,and maintenance are required for the watershed’s sustainability and good soil conditions.
基金All data collection,data analysis,and write-up of the study were supported by Addis Ababa University,African Climate Change Fellowship ProgramDAAD in-country scholarship program.
文摘Introduction:The purpose of this study is to evaluate the associated impact of adoption of adaptation options to climate change and variability on household food security in the Muger sub-basin of the upper Blue-Nile of Ethiopia using a comprehensive data of 442 sampled households from four representative districts’in the sub-basin.The study used a propensity score matching approach to evaluate the impact of adaptation options on household food security.Results:Results show that the decision to adopt adaptation options is found to be positively influenced by male household heads,family size,access to extension service,the size of landholding,and frequency of drought and floods over the past many years.The results further reveal that farmers adopting any of the adaptation options had higher food calorie intake per day per adult equivalent than those who did not.Conclusions:A policy that promotes the adoption of soil and water conservation measures,small-scale irrigation,agronomic practices,and livelihood diversification strategies should be central to food security strategy in the study area.
基金All data collection,data analysis and write-up of the study were financially supported by the College of Horticulture and Forestry,Central Agricultural University,Pasighat,Arunachal Pradesh,India,through intra-mural research project and Rural Horticulture Work Experience(RHWE).
文摘Introduction:Evidence is mounting that traditional knowledge can play a critical role in shaping the biodiversity conservation strategies and maintaining ecosystem services.This study was conducted with Adi community of Arunachal Pradesh(Ar P)state in the Eastern Indian Himalayas to understand as how local systems of forest classification governs conservation tradition and influences subsistence livelihoods.Twenty Adi villages were sampled from East Siang district of Ar P.A total of 197 men and 204 women(total of 401)Adi respondents were selected for this study.A combination of methodologies including in-depth interview,transect walks,focus group discussion,participant observation and informal interactions were combined for data collection.Results:Local forests are classified into 10 different categories based on indicators such as topography,cultural significance,use typology,ownership rights and plant diversity indicators.Local people assign different values(economic,cultural and ecological)to different forest types.Overall,morang followed by regpi and homegardens are perceived to be more valuable to the local needs than other forests with relative ranking of a particular forest reflecting its sustainability.Adis access several diverse services from these community-managed forests.Compared to men(3–35%),the role of women was assessed to be much higher(65 to 100%)in conserving forest biodiversity.Woman-led practices,instrumental in sustainable forest management,included deliberate manipulations of micro-habitats,sustainable harvesting strategies and species domestication.Men were mostly involved in ownership and decision-making roles and in devising social norms to ensure sustainability.Adi celebrate a number of cultural events to sustain biodiversity.Forest-based livelihoods are intrinsically connected to forest resource conservation and are governed by community approaches.Most of the community members gather plants,hunt wild animals and access other ecosystem services from these forests to sustain their livelihoods.Community-owned forests are collectively managed by an indigenous institution‘Kebang’.Conflicts relating to forest land use and resource management are resolved by the customary chief‘Gaon Burha’and his associates using traditional norms.Conclusions:Adi’s system of forest classification,based on ecological,socio-cultural and livelihood indicators,is a location-specific yet comprehensive in nature.Study suggests that integrating the local indicators applied in classifying and strategies applied in managing the local forests can provide valuable insights to the policy makers for the sustainable conservation of forest resources.
基金the Dean's Research Fund of the University of Hartford College of Arts and Sciencesthe University of Hartford Women's Advancement lnitiative Fund.
文摘Introduction:Construction activities in and along urban streams increase the sediment input into surface waters,causing an overall decline in water quality and aquatic ecosystems.In this case study,we investigate the water quality impacts of local hydromodification in an urban stream(discharge 0.4 m^(3)/s).At the site of interest,workers removed a stream crossing consisting of an embankment with culverts and replaced it with a small bridge(single span of 25 m)in an effort to improve flow capacity.Methods:Water samples were taken at four sites along the North Branch Park River in Connecticut,Northeastern United States.Turbidity and dissolved oxygen(DO)were measured in situ,and nitrate and total phosphorus(TP)were measured in the laboratory.Benthic macroinvertebrate samples were also collected and analyzed for taxon richness and Shannon-Weaver species diversity.Data were compared between upstream and downstream sites and before,during,and after hydromodification.We used one-way ANOVA combined with the post hoc Turkey test to derive statistical significance.Results:During construction,turbidity increased temporarily by 60.9%[from 2.48 Nephelometric Turbidity Units(NTU)over ambient to 4.00 NTU].Once construction was completed,DO increased locally from 11.0 to 13.0 mg/L.Benthic macroinvertebrate taxon richness and species diversity declined by 61.6 and 32.6%respectively,with no recovery observed in the year following construction.Water quality was only affected within 50 m downstream.Nitrate and TP concentrations were unaffected.Conclusions:Small-scale hydromodification temporarily increased the turbidity as a result of increased sediment input,approaching the maximum level for clean water(5 NTU).Benthic macroinvertebrate communities declined in the immediate downstream vicinity of construction but are expected to recover soon given that turbidity recovered to pre-construction levels,and DO increased.These outcomes emphasize that environmental assessment is important not only for large-scale hydromodification but also for smaller scale stream modifications.
基金This study was funded by the Dirección de Estudios de Posgrado e Investigación,Instituto Politécnico Nacional(SIP grant 20082265)A.M.L.,D.E.U.,and B.G.A.are COFAA-IPN and EDI-IPN fellows of the Instituto Politécnico Nacional of Mexico.C.H.S.received fellowships from PIFI-IPN and Consejo Nacional de Ciencia y Tecnología(CONACYT).
文摘Introduction:The lagoon is a component of coastal zones,whose populations of autotrophic picoplankton(APP)remain largely unstudied.These lagoons display high-nutrient productivity and additionally may also be subjected to anthropogenic activities.This study selected Laguna Macapule,located on the eastern shore in the mid-region of the Gulf of California,due to the fact that a drainage network servicing the surrounding agricultural region(>230,000 hectares under cultivation)directs irrigation runoff,shrimp farm effluents,and urban wastewater containing large quantities of nutrients to be discharged into this lagoon.We propose to identify the APP’s response to various types of environmental and anthropogenic influence in this highly impacted coastal lagoon.Methods:Two sites(separated by 2.7 km)were monitored from December 2007 to December 2008.One,located at the entrance to Laguna Macapule(oceanic influence)and the other a discharge canal(eutrophic conditions)inside the lagoon at El Tortugón.Results:APP was the numerically dominant phytoplankton fraction(15×106 to 620×106 cells L−1)with coccoidal cyanobacteria as the dominant fraction throughout the year.Peak levels were reached in spring-early autumn and they were the second largest contributor to biomass.Abundance of APP cells corresponds to the lagoon’s eutrophic status.Maximum numbers and a higher average of APP were recorded at the El Tortugón channel during the warm season(months with SST higher than 24°C).The general positive relationship of the APP’s annual cycle at both sites as well as a negative relationship with heterotrophic nanoflagellates(HNF)abundance,supports the idea that natural forcing,in particular sea surface temperature(SST)is the predominant influences on APP’s seasonal variability.Conclusions:Distinguishable significant differences in APP abundances and nutrients were recognizable between the two sites.The interplay of these variables contributed to lower densities of APP in winter and high densities in springearly autumn.N:P=~4 suggests that spring-early autumn abundance of the APP autotrophic component was sustained by urea from shrimp farm discharge water.Thus,a total nutrient-based approach is likely the most suitable tool for establishing nitrogen limitation of biological production in Laguna Macapule and similarly impacted ecosystems around the world.
基金a copy of Network3D,Sonia Kéfi and Dominique Gravel for discussions and comments on the results,Claire Gougat-Barbera for help with the molecular biology experiments,and Joshua S.Weitz and Cesar Flores for discussions about bacteria-phage networks.TP thanks the Canadian Research Chair on Continental Ecosystems Ecology for computational support.MEH thanks the Agence National de la Recherche Scientifique[EvolStress(ANR-09-BLAN-099-01)]the McDonnell Foundation(JSMF 220020294/SCS-Research Award)for financial support.
文摘Introduction:The persistence of generalists and specialists is a topical question in community ecology and results from both ecological and evolutionary processes.At fine taxonomical scales,ecological specialisation,i.e.organisms preferentially exploiting a subset of available habitats,is thought to be a driver promoting niche diversity.It is not clear,however,how different mechanisms interact to shape specialist-generalist coexistence.Methods:We reconstruct the structure of five bacteria-phage networks from soil isolates,and perform an analysis of the relationships between host phylogenetic diversity,parasite specialism,and parasite performance.Results:We show that the co-occurrence of species on a continuum of specialism/generalism is influenced by niche overlap,phage impact on bacterial hosts,and host phylogenetic structure.In addition,using a null-model analysis we show that infection strategies of the phages have more explanatory power than bacterial defenses on key structural features of these antagonistic communities.Conclusions:We report that generalists have more impact on their hosts than specialists,even when the phylogenetic heterogeneity of hosts is controlled for.We discuss our results in the light of their implications for the evolution of biotic interactions.
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funded by the grant PIP 2021–2023 N°0871“Resilience of managed Nothofagus pumilioforests against harvesting,climate change and extreme events in Tierra del Fuego”of CONICET(Argentina)
文摘Background Forest ecosystems undergo significant transformations due to harvesting and climate fluctuations,emphasizing the critical role of seeding in natural regeneration and long-term structural preservation.Climate change further amplifies these dynamics,affecting phenology across species and regions.In Tierra del Fuego(Argentina),Nothofagus pumilio(lenga)forests represent the most important timber resource,and it is managed through different silvicultural strategies.This species demonstrates notable post-disturbance regeneration,yet seed fall exhibits signifi-cant variability,leading to variations in seed quality(e.g.,viability).This study aims to assess fluctuations in N.pumilio seed quality,determine how it varies concerning forest management strategies,annual productivity,and the co-occurrence of climatic phenomena including El Ni?o-Southern Oscillation(ENSO)and the Southern Annular Mode(SAM).Results Viable seeds represented 18.4%of the total,notably higher in unharvested than in managed areas.Con-versely,empty seeds were more prevalent in harvested areas(>75%).Seed quality exhibited significant differences across silvicultural treatments,except for insect-predated seeds,which had similar proportions across all areas,though dispersed retention showed higher predation.When considering years with varying production levels,high-production years favoured full and viable seeds,particularly in unharvested forests and aggregated retention,while low-production years saw reduced viability across all treatments.Quadratic models revealed that viability increased with seed production,where unharvested forests achieved the highest values.Climate variability influenced seed proportions,where ENSO+/SAM+promoting more full and viable seeds,while ENSO–/SAM+favoured non-predated seeds,especially in unharvested stands.Conclusions Seed quality varies among treatments and years with different levels of seeding.Variations in seed qual-ity,linked to climatic events,influence seed viability.Seed quality plays a critical role in forest regeneration,ensuring a seedling bank for harvested stands to face climate variability.These findings are relevant for forest management and ecosystem services,considering the increasing climate variability and extreme events.Understanding these influ-ences is crucial for Nothofagus pumilio forests'sustainability and global forest adaptation strategies.
基金Funded by the A Starker Leopold Chair of Wildlife Ecology at UC Berkeley.
文摘This paper lays out a hierarchical,appropriate-complexity framework for conceptualizing movement-path segments at different spatiotemporal scales in a way that facilitates comparative analyses and bridges behavior and mathematical concepts.It then outlines a process for generating a multimode,multiscale stochastic simulation model that can be used to test animal movement hypotheses and make predictions of movement responses to management and global change.Many methods for analyzing movement data begin by generating step-length(SL)and turning-angle(TA)distributions from relocation time-series data,some of which are linked to ecological,landscape,and environmental covariates.The frequency at which these data are collected may vary from sub-seconds to several hours.The kinds of questions that may be asked of these data,however,are very much scale dependent.The hierarchical path-segmentation(HPS)framework presented here clarifies how the scale at which SL and TA data are collected relates to other sub-and super-diel scales.Difficulties arise because the information contained in SL and TA time series are often not directly relatable to the physiological,ecological,and sociological factors that drive the structure of movement paths at longer scales.These difficulties are overcome by anchoring the classification of movement types around the concept of fixed-period(24 h)diel activity routines and providing a bridge between behavioral/ecological and stochastic-walk concepts(means,variances,correlations,individual-state and local environmental covariates).This bridge is achieved through the generation of relatively short segments conceived as characteristic sequences of fundamental movement elements.These short segments are then used to characterize longer canonical-activity-mode segments that emerge through movement at behaviorally relevant sub-diel scales.HPS thus provides a novel system for integrating sub-minute movement sequences into canonical activity modes(CAMs)that,in turn,can be strung together into various types of diel activity routines(DARs).These DARs both vary among individuals within a given day,and for any given individual across time and under the influence of landscape factors.An understanding of how DARs are influenced by environmental inputs will help us predict the response of supra-diel lifetime movement phases(LiMPs)of individuals,as well as their complete lifetime tracks(LiTs),to anthropogenically induced global change.
基金The International Foundation for Science had funded this research(IFS)(Grant No.W_6250-1,January 2019)and Bahir Dar University。
文摘Background:Soil erosion is one of the major threats in the Ethiopian highlands.In this study,soil erosion in the Muga watershed of the Upper Blue Nile Basin(Abay)under historical and future climate and land use/land cover(LULC)change was assessed.Future LULC was predicted based on LULC map of 1985,2002,and 2017.LULC maps of the historical periods were delineated from Landsat images,and future LULC was predicted using the CA–Markov chain model.Precipitation for the future period was projected from six regional circulation models.The RUSLE model was used to estimate the current and future soil erosion rate in Muga watershed.Results:The average annual rate of soil erosion in the study area was increased from about 15 t ha^(−1) year^(−1) in 1985 to 19 t ha^(−1) year^(−1) in 2002,and 19.7 t ha^(−1) year^(−1) in 2017.Expansion of crop cultivation and loss of vegetation caused an increase in soil erosion.Unless proper measure is taken against the LULC changes,the rate of soil loss is expected to increase and reach about 20.7 t ha^(−1) year^(−1) in 2033.In the 2050s,soil loss is projected to increase by 9.6%and 11.3%under RCP4.5 and RCP8.5,respectively,compared with the baseline period.Thus,the soil loss rate is expected to increase under both scenarios due to the higher erosive power of the future intense rainfall.When both LULC and climate changes act together,the mean annual soil loss rate shows a rise of 13.2%and 15.7%in the future under RCP4.5 and RCP8.5,respectively,which is due to synergistic efects.Conclusions:The results of this study can be useful for formulating proper land use planning and investments to mitigate the adverse efect of LULC on soil loss.Furthermore,climate change will exacerbate the existing soil erosion problem and would need for vigorous proper conservation policies and investments to mitigate the negative impacts of climate change on soil loss.
文摘Background:Current forests of the eastern USA have the potential to succeed in composition to more shade-tolerant species.However,long-term processes of transition from fire-tolerant tree species to fire-sensitive species and effects of current land use on forests may interfere with successional progression.Methods:I examined if forests in three regions have increased in shade tolerance and if life history strategy groups that represent response to disturbance(i.e.,fire-tolerance,early-successional species based on low shade tolerance,mid-successional species,late-successional species,and trees valued for traits related to short harvest rotations)have changed,using Forest Inventory and Analysis surveys,adjusted for comparison,and generalized linear mixed models to assess approximately 30 year trends,with adjustments to equalize different survey methods.Results:Although statistically significant,a slight increase of 2 to 4%in regional mean shade tolerance may not be ecologically significant.In the central East,mid-successional species replaced early-successional species and early-successional species replaced fire-tolerant oaks,resulting in an overall shift from fire-tolerant oaks to mid-successional species.Decreased fire-tolerant pine species and increased planted pine species were the major changes in the northern Southeast and Coastal Plain.Conclusions:The successional process of increased composition by shade-tolerant species over time was overshadowed by land use changes that resulted in decreased fire-tolerant species and increased planted pine.Furthermore,frequent land use disturbance may continue to prevent the slow progress of compositional succession to very shade-tolerant species.
文摘Water is essential to life on Earth.Ecohydrology,the study of interactions between ecological and hydrological processes,is fundamental to our understanding and quantification of services provided by ecosystems.Our knowledge of ecohydrology is incomplete due to the complex nature of ecosystems,which are constantly changing under multiple stresses from air pollution to climate change,from deforestation to urbanization,and from soil erosion to soil pollution.Ecosystem services,the goods and services that ecosystems provide for human wellbeing,are increasingly adopted as a framework worldwide for ecological restoration and conservation,watershed management,and sustainable development policy making.
基金funded by projects of special Funding for Research of National Oceanic Public Service Industry(201505028)Zhejiang Provincial Natural Science Foundation(LQ13C030002)+1 种基金Science and Technology Plan Zhejiang Province(2012C12017-3,2013C25096,2014F50003)Zhejiang Province pelagic fishery(2015)“Cooperation and exchange of aquaculture technology between China and Israel based on the level of ecological system,”and Wenzhou Municipal Science。
文摘Introduction:Understanding how mangroves respond to rare cold events has implications for both restoration and conservation under climate change scenarios.This study investigated the responses of photosynthesis and activities of key enzymes involving carbon and nitrogen metabolism at different ages of Kandelia obovata to a rare cold event in the winter of 2010.Methods:This study took place on Ximen Island,Zhejiang Province,China.We measured the physiological recovery of 2-3-,5-6-,9-10-and 54-55-year-old K.obovata trees after freezing injury in February and March in 2011 and 2012,respectively.Results:Chilling injury index and electrolyte leakage of K.obovata increased with increasing tree age in the winter of 2010,and electrolyte leakage in K.obovata at different ages in the winter of 2010 was far higher than that in the winter of 2011.The rare cold events significantly changed the recoveries of the leaf net photosynthetic rate(Pn)and stomatal conductance(Gs);ratios of chlorophyll a/chlorophyll b(Chl a/Chl b);contents of total soluble sugar(TSS),sucrose,free amino acid(FAA),and soluble protein;and activities of sucrose phosphate synthase(SPS),endopeptidase,and carboxypeptidase in K.obovata at different ages.These effects were mainly due to changes in the physiological mechanism in the 2-year-old trees.A clear decrease in Pn of the 2-year-old trees was observed in February 2011,as exemplified by reductions in ratios of Chl a/Chl b and chlorophyll/carotenoid(Chl/Car),as well as inhibition of the levels of TSS and FAA(osmotic substances).During recovery in 2011 and 2012,the activities of SPS and sucrose synthase(SS)were responsible for sucrose synthesis after the rare cold events in 2011,but only SPS activity was one of the main factors contributing to the metabolism of stachyose to sucrose without cold damage in 2012.Carboxypeptidase played a more important role than endopeptidase during protein hydrolysis after the rare cold events.Conclusions:The results suggest that the recovery of photosynthetic capacity in K.obovata was changed after a rare cold event,which is associated with pigment components and activities of SS,SPS,and carboxypeptidase,especially the seedlings.
基金This study was supported by the Natural Science Foundation of China(31170454,31229001,31130202)the State Key Basic Research Development Program of China(2013CB956600)the NASA-NEWS Program(NN-H-04-Z-YS-005-N),and the USCCC。
文摘Introduction:Low energy balance closure(EBC)at a particular eddy-covariance flux site has increased the uncertainties of carbon,water,and energy measurements and has thus hampered the urgent research of scaling up and modeling analyses through site combinations in regional or global flux networks.Methods:A series of manipulative experiments were conducted in this study to explore the role of net radiation(Rn)in the EBC in relation to spatial variability of vegetation characteristics,source area,and sensor type in three sites of the Inner Mongolian grassland of northern China.Results:At all three sites,the residual fluxes of EBC peaked consistently at 110 W m^(-2).The spatial variability in net radiation was 19 W m^(-2)(5%of R_(n))during the day and 7 W m^(-2)(16%)at night,with an average of 13 W m^(-2)(11%)from eight plot measurements across the three sites.Large area measurements of Rn significantly increased by 9 W m^(-2)during the day and decreased by 4 W m^(-2)at night in the unclipped treatments.Net radiation decreased by 25 W m^(-2)(6%of Rn)at midday and 81 MJ m^(-2)(6%)during a growing season with heavier regular clipping than that in unclipped treatments.The Rn was lower by 11–21 W m^(-2)(~20–40%of Rn)measured by CNR1 than by Q7.1 at night,while there was only 6 W m^(-2)(~1–2%of Rn)difference during the daytime between these two types of commonly used net radiometers.Conclusions:Overall,the inclusion of the uncertainty in available energy accounted for 65%of the~110 W m^(-2)shortfalls in the lack of closure.Clearly,the unclosed energy balance at these three grassland sites remains significant,with unexplored mechanisms for future research.
文摘Comprehending the gifts of ecology Stress ecology,climate change,human well-being,and global sustainability are popular items(Naeem et al.2009).Given all the challenges in a developing world where the global population is supposed to reach 9.15 billion in 2050(Pimentel et al.1999.
基金funded by the National Key Research and Development Plan of China(2016YFD0201204)the National Natural Science Foundation of China–Shandong United Fund(U2006214)
文摘Background Pesticide use contributes to national food security.The dissipation pathways and degradation mecha-nisms of pesticides have been widely studied and pesticide residues have remained a focus of public concern.How-ever,studies on the migration and transformation behaviors of pesticide residues in real-world greenhouse soils are insufficient.Therefore,in this study,we collected greenhouse soil from Shouguang,Shandong Province,and investi-gated the photodegradation and leaching of 17 common pesticides,which leave residues in the soil and are the most frequently used pesticides in Shouguang.The environmental behavior of pesticides in greenhouse soils will provide new information on pesticide residues in the real environment and provide a scientific basis for the prevention and control of pesticide pollution in greenhouse soils.Results The photodegradation of trifloxystrobin followed a first-order kinetic equation,whereas those of emamec-tin benzoate,chlorantraniliprole,buprofezin,difenoconazole,pyraclostrobin,boscalid,tebuconazole,isoprothiolane,metalaxyl,and oxadixyl followed second-order kinetics.The half-lives of 17 pesticides under light and dark conditions ranged from 2.5–104(mean:36.2)and 2.6–110(mean:31.4)days,respectively.The half-lives of emamectin benzoate,pyraclostrobin,and metalaxyl in the light were 86.6%,68.5%,and 94.5%of their half-lives in the dark,respectively.Chlorantraniliprole,metalaxyl,nitenpyram,diethofencarb,acetamiprid,carbendazim,and oxadixyl were leached to≥90%in aqueous solution.Six pesticides,avermectin B1A,emamectin benzoate,trifloxystrobin,difenoconazole,pyraclostrobin,and buprofezin,were difficult to leach from aqueous solutions.Conclusions The degradation rate of some pesticides was higher in the light environment than in the dark.The leaching potential of the leachable pesticides was nitenpyram?metalaxyl>acetamiprid>carbendazim>diethofen-carb≈chlorantraniliprole>isoprothiolane>oxadixyl>boscalid≈tebuconazole>hexaconazole.Pesticides that are easy to leach but not easily degraded,such as chlorantraniliprole and metalaxyl,have a high potential risk of ground-water pollution,and additional degradation technologies should be used to reduce their pollution risk.The study of the photodegradation and vertical migration behavior of various pesticides is conducive to providing references for the agricultural use and pollution control of pesticides.
基金funded by the National Nature Science Foundation of China(Nos.32270220 and U22A20445 to Jia Feng)the Excellent Achievement Cultivation Project of Higher education in Shanxi(No.2020KJ029)the Nature Science Foundation of Shanxi Province(No.202203021211313).
文摘Background Algae play important roles in urban river ecosystems and are the cornerstones of most water quality monitoring programs.Thus,a better understanding of algal community dynamics is needed to support sustainable management of water resources in urban rivers.Results In this study,we quantifed the seasonal variations in planktonic and periphytic algal community structure in the highly urban Fenhe River and identifed environmental factors afecting algal community structure and diversity.We monitored planktonic(drifting)and periphytic(attached)algal communities in the Taiyuan section of the Fenhe River over one year.The results indicated that Cyanophyta was the dominant phylum in both communities,followed by Bacillariophyta and Chlorophyta.Signifcant diferences were observed in the composition of the planktonic and periphytic algal communities.In particular,the periphytic algal community was more diverse than the planktonic community.Water temperature and pH were the main environmental factors afecting planktonic and periphytic algal community structure,respectively,while nutrients were the most signifcant factor afecting planktonic and periphytic algal diversity.Ecological modeling indicated that the variations in the algal communities of the Fenhe River are mainly driven by stochastic processes.A co-occurrence network developed for the communities displayed positive interactions between the planktonic and periphytic algae.Conclusions These fndings deepen our understanding of the seasonal interaction between planktonic and periphytic algae and the driving factors afecting community structure in the Fenhe River.They also provide a theoretical basis for the managing and protecting water resources in urban river ecosystems.
文摘Background:The European rabbit(Oryctolagus cuniculus L.1758)was introduced into different regions of the world,generating significant trade‑offs that critically impacted native vegetation.Here,we evaluate the rabbit’s forage intakes in three vegetation types(forests,shrublands,and grasslands)along the four seasons in a temperate forest landscape in Southern Patagonia and discuss the potential threats over native vegetation.We formulated the following questions:(i)what is the forage offer at each vegetation type?(ii)what is the rabbit’s forage intake and how it varied across the seasons along the year?and(iii)which vegetation types and plant life forms were more used according to the rabbit’s forage intakes?Methods:We censused understory vegetation to characterize the forage offer at each vegetation type and determined seasonal dietary intakes using microhistological analysis of pellets.The plant species identified in the field were grouped according to life form classes(tree regeneration,shrubs,forbs,graminoids,orchids,ferns,bryophytes,and hemiparasites).Data were analysed through uni‑and multi‑variate analyses,determining relationships between forage offer and the rabbit’s forage intakes.Results:Forage intakes revealed changes in plant life form consumption across vegetation types,where intake pressure was considerably different for tree regeneration(p=0.001),graminoids(p=0.001),and hemiparasites(p=0.001).Besides,significant changes in consumption among seasons were detected for shrubs(p=0.001),ferns(p=0.030),and hemiparasites(p=0.002).Although many species play an important role in the rabbit’s forage intake networks(e.g.,Chiliotrichum diffusum,Holcus lanatus),the strongest intake linkages were found in exotic grasses(e.g.,Poa pratensis and Festuca sp.),native hemiparasites(e.g.,Misodendrum sp.),native shrubs(e.g.,Empetrum rubrum),and native trees(e.g.,Nothofagus sp.).The summer and autumn seasons presented higher intake compared to the winter and spring seasons.Furthermore,hemiparasites intake(e.g.,Misodendrum sp.)suggests that rabbits utilize different forage sources depending on the vegetation types.Conclusions:Rabbits regularly inhabit the forest,even though it is not their preferred vegetation type to live.Rabbit management entails isolating regions that are more favourable to intake and emphasizing the year’s season for rabbit control efforts.
