Old-growth forests uniquely support biodiversity while serving as some of the planet's most important carbon stocks.The influence of tree and stand age on carbon flux dynamics remains debated—an urgent question a...Old-growth forests uniquely support biodiversity while serving as some of the planet's most important carbon stocks.The influence of tree and stand age on carbon flux dynamics remains debated—an urgent question as climate-driven disturbances may reshape forest age structures and in situ carbon storage.To clarify these relationships in Fagus sylvatica,systems,we examined a unique dataset of 3,503 tree ring series from 190 plots across some of the best preserved old-growth forests from five southern European countries.By employing a dendrochronological approach and integrating key environmental variables,including elevation,slope,temperature,and the presence of large-diameter trees(≥60 cm),we analyzed the complex relationships between tree/stand age within a plot(represented by plot-level mean values,hereafter“stand age”)and aboveground carbon stock across live,standing,and lying deadwood pools.The average stand age was 220 years,with 230 tC⋅ha^(-1) of carbon stored in aboveground biomass and necromass.We found a positive correlation between age and carbon storage at both the individual tree and plot levels.Notably,the presence of large-diameter trees was the strongest indicator of carbon stock,with carbon accumulation peaking at about 30%large-tree stems proportion before stabilising,while younger beech trees(below 100 years old)had a smaller contribution to carbon storage.We found no evidence of a decline in carbon stock with advancing stand age across the studied sites.Despite the ecological importance of old-growth forests,many of them remain unprotected and are disappearing across Europe.Our findings highlight the importance of preserving old-growth forests to maximize their role as long-term ecosystem carbon reservoirs.展开更多
Soil bacteria are integral to ecosystem functioning,significantly contributing to nutrients cycling and organic matter decomposition,and enhancing soil structure.This research considered the composition and dynamics o...Soil bacteria are integral to ecosystem functioning,significantly contributing to nutrients cycling and organic matter decomposition,and enhancing soil structure.This research considered the composition and dynamics of soil bacterial communities under different vegetation types(native Quercus brantii Lindl.and Amygdalus scoparia Spach,and non-native Pinus eldarica Medw.and Cupressus arizonica Greene.)in Zagros mountain area of Iran.This study involved a comparative analysis of soil culturable heterotrophic bacterial communities in spring(wet season)and summer(dry season)to clarify the effects of seasonal changes and vegetation on the dynamics of soil microorganisms.Soil samples were randomly collected under the canopies of various tree species and a control area,yielding a total of 48 composite samples analyzed for bacterial composition.Results indicated that 11 Gram-negative(e.g.,Citrobacter freundii,Enterobacter cloacae,Escherichia coli,Klebsiella oxytoca,Klebsiella pneumoniae,etc.)and 2 Gram-positive(Staphylococcus epidermidis and Staphylococcus aureus)bacteria were identified,showing significant seasonal variation.Specifically,53.85%of bacterial species were common to both seasons,with notable shifts in community composition observed between spring and summer,highlighting a higher abundance of Gram-negative species in spring.Bacterial community structure was significantly influenced by vegetation type,with various tree species shaping distinct microbial assemblages.Moreover,Pearson's correlations revealed that soil properties,particularly pH,phosphorus,and moisture content,were critical drivers of bacterial diversity and abundance.Our findings underscore the dynamic nature of soil bacterial communities in response to seasonal and vegetation changes,emphasizing the importance of repeated temporal sampling for accurate assessments of microbial diversity.Understanding these microbial dynamics is essential for improving soil management strategies and enhancing ecosystem resilience,particularly in arid and semi-arid areas where environmental fluctuations play a pivotal role.This research not only confirms our hypotheses but also enhances our understanding of soil biogeochemical processes and informs future vegetation management practices.展开更多
Extreme climate events(e.g.,heatwaves and droughts)are becoming increasingly frequent due to global climate change,which inevitably affects tree growth and various other ecological processes.While the impacts of droug...Extreme climate events(e.g.,heatwaves and droughts)are becoming increasingly frequent due to global climate change,which inevitably affects tree growth and various other ecological processes.While the impacts of droughts on these processes have been widely evaluated,the effects of heatwaves on tree growth and soil water content(SWC)remain poorly understood,particularly those related to thinning treatment.In this study,we evaluated the impacts of the 2021 Pacific Northwest Heatwave and thinning on forest growth and SWC,as well as assessed how thinning might mitigate the heatwave's impacts in lodgepole pine forests in British Columbia,Canada.We measured meteorological data(air temperature,rainfall,solar radiation(SR),relative humidity(RH),and wind speed(W_(s)),sap flow,SWC,soil temperature(T_(s)),and tree diameters at the breast height(DBH)during the growing season(June–September)in the control(27,000 stems·ha^(-1)),lightly thinned(4,500 stems·ha^(-1)),and heavily thinned(1,100 stems·ha^(-1))experimental plots from 2018 to 2024.We found that thinning persistently and significantly(p<0.05)increased individual tree growth,with the most pronounced effects in the heavily thinned stands.The 2021 Pacific Northwest Heatwave led to an exceptionally hot growing season,significantly(p<0.05)reducing forest growth and SWC across all plots.Forest growth recovered in 2022 in the thinned plots but remained suppressed in the unthinned plots,suggesting that thinning effectively mitigated the impact of the heatwave on forest growth,while the heatwave's impacts were persistent in the unthinned plots.Our study highlights that thinning is a practical management strategy for improving tree growth and supporting climate change adaptation to extreme climate events.展开更多
Frequent droughts pose considerable threat to global forest carbon uptake,but little is known about the response of forest carbon fluxes in climatic transition zones to seasonal drought.In this study,the responses of ...Frequent droughts pose considerable threat to global forest carbon uptake,but little is known about the response of forest carbon fluxes in climatic transition zones to seasonal drought.In this study,the responses of carbon fluxes to seasonal drought in two natural forests(Quercus aliena var.acute serrata Maxim and Pinus tabuliformis Carr.)in the Baotianman Nature Reserve were investigated.The Q.aliena forest exhibited a high resilience with stable gross primary productivity(GPP).However,ecosystem respiration(Re)significantly declined by 18.4%compared with normal years,leading to an increase in net carbon sequestration capacity of 4.1%.This resilience was attributed to its deep root system accessing soil water(SWC_(50cm))to sustain stomatal openness,coupled with the efficient utilization of photosynthetically active radiation to drive photosynthesis.In contrast,the P.tabuliformis forest,which relied on shallow soil moisture(SWC_(20cm)),experienced simultaneous decreases in both GPP and Re during drought,with a sharply greater decrease in GPP,resulting in low net carbon sink capacity.Further analysis revealed that the Q.aliena forest prioritized carbon assimilation through a deep water-stomatal synergy strategy(anisohydric behavior),whereas the P.tabuliformis forest adopted an isohydric strategy favoring water conservation at the expense of carbon fixation efficiency.These findings highlight distinct mechanisms underlying drought adaptation between forest types,providing critical insight into optimizing forest carbon cycle models and selecting drought-resistant species under the influence of climate change.展开更多
Urban forests are essential components of green infrastructure,however,rapid urbanization-induced changes in landscape patterns may affect their ecosystem services through complex ecological processes.A total of 184 s...Urban forests are essential components of green infrastructure,however,rapid urbanization-induced changes in landscape patterns may affect their ecosystem services through complex ecological processes.A total of 184 sample plots in the built-up areas of Nanchang,China,were used as research sites.Urbanization intensities were categorized by the rate of impervious surface area,and forest types were classified into landscape and relaxation forest,attached forest(AF),road forest(RF),and ecological public welfare forest.This study aimed to explore the spatial variations in vegetation characteristics and landscape pattern indices of different forest types under rapid urbanization.The results indicated that the largest patch index(LPI),aggregation index(AI),and percentage of landscape(PLAND)in RF and AF were lower than those in the other forest types(p<0.05).With increasing urbanization intensity,the mean perimeter-area ratio increased by 130.84%,whereas the PLAND,LPI,and AI decreased by 22−86%(p<0.05).Redundancy analysis and variation partitioning suggested that the interpretation rate of landscape pattern indices for variations in vegetation characteristics increased from low to heavy urbanization areas.Especially,the landscape shape index,patch connection index,PLAND,and mean patch size were significantly correlated with vegetation characteristics(e.g.,tree richness,herb coverage,and tree height).In the future,appropriate landscape layout superiority cases should be considered in different urbanization areas and forest types;for instance,increasing the patch connection index will beneficially improve the diversity of trees and herbs in heavy urbanization areas and the RF.This study serves as a reference for maximizing the ecosystem services of urban forests.展开更多
The quantitative relationship between modern pollen and vegetation provides a critical foundation for reconstructing past vegetation,with relative pollen productivity(RPP)serving as a key calibration parameter.However...The quantitative relationship between modern pollen and vegetation provides a critical foundation for reconstructing past vegetation,with relative pollen productivity(RPP)serving as a key calibration parameter.However,in subtropical evergreen broadleaved forests(SEBFs)in China,RPP studies remain scarce,and the impact of human disturbances on RPP estimates has yet to be adequately assessed,limiting the accuracy of quantitative palaeovegetation reconstructions.This study was conducted in Dinghu Mountain Nature Reserve and its surrounding areas in Zhaoqing,Guangdong Province,and included 31 sampling sites.We performed pollen analysis alongside detailed vegetation surveys and utilized ERV submodel 2 and Prentice’s model to estimate the RPP of 9 common plant taxa in the southern SEBFs.There was a particular focus on evaluating the interference effects of bamboo plantations on the estimation of RPP.The results indicate that bamboo within the family Poaceae contributes minimally to surface soil Poaceae pollen because of its unique flowering characteristics,such as long flowering cycles and monocarpic reproduction.The incorporation of bamboo into the Poaceae vegetation coverage in the analysis led to excessively high RPP values for the other taxa.When bamboo coverage was removed from the Poaceae family,the recalculated RPP values aligned closely with those reported in previous studies.The RPP values,ranked from highest to lowest,were as follows:Castanopsis(12.33±0.03)>Araliaceae(1.60±0.03)>Mallotus(1.53±0.26)>Pinus(1.47±0.03)>Rosaceae(1.07±0.02)>Poaceae(1±0)>Euphorbiaceae(0.44±0.03)>Anacardiaceae(0.26±0.03)>Theaceae(0.15±0).Notably,the RPP values for Mallotus,Araliaceae,Theaceae,and Euphorbiaceae represent the first estimates for China’s subtropical region.Differences between certain RPP estimates and those of previous studies may be attributed to factors such as species composition,vegetation structure,and model selection.The findings of this study highlight that due to the widespread distribution of artificial bamboo forests in China’s subtropical regions,future RPP studies should carefully consider the influence of Poaceae.This consideration is essential for improving the accuracy of the application of fossil pollen for quantitative paleo-vegetation reconstruction in these regions.展开更多
The root-to-shoot(R/S)ratio is a critical indicator of the balance between root biomass and shoot biomass,representing the ecological strategies and adaptive responses of plants to environmental conditions.However,the...The root-to-shoot(R/S)ratio is a critical indicator of the balance between root biomass and shoot biomass,representing the ecological strategies and adaptive responses of plants to environmental conditions.However,the patterns of change in community R/S ratios during forest succession and their response to moisture levels across broad geographic gradients remains unclear.Based on forest biomass data from a national field inventory of 5,825 plots conducted across China between 2011 and 2015,this study looked into allocating biomass shoots and roots at the early,middle,and late stages of growth in plantations and succession in natural forests,and evaluated how moisture availability influences this allocation.The results revealed a significant decline in R/S ratios from early to late stages for both plantations and natural forests.Shoot and root biomass in plantations grew isometrically during the early and middle succession stages but shifted to allometric growth in the late stage,with the slope of the log-transformed shoot-root biomass relationship differing significantly across growth stages.Natural forests,in contrast,maintained isometric growth across successional stages,showing no significant variation in the slope of the log-transformed shoot-root biomass relationship.Environmental factors,particularly moisture levels,strongly influenced R/S ratios.Moisture levels significantly affected size-corrected R/S ratios,particularly in the middle stage of plantations and the early and middle stages of natural forests,supporting the hypothesis of optimal allocation.These findings suggest that in water-limited regions,forest management should prioritize drought-tolerant,deep-rooted native species,encourage mixed-species planting in the early stage,and reduce logging intensity in mature plantations.Conserving natural forests to maintain successional dynamics is essential for long-term ecological resilience.These findings emphasize the importance of balancing productivity with ecological sustainability by adapting practices to specific environments and forest types under climate change.展开更多
Climate change is impacting forests in Central Europe,causing increased mortality and degradation of forest ecosystem services(FES).As global warming intensifies,these effects are likely to worsen,particularly through...Climate change is impacting forests in Central Europe,causing increased mortality and degradation of forest ecosystem services(FES).As global warming intensifies,these effects are likely to worsen,particularly through more severe droughts and increased biotic disturbances.Understanding how forests respond to different levels of warming is essential for adaptation planning.Therefore,this study analyzed changes in forest structure and FES,including timber production,climate change mitigation,recreation,and structural diversity,under three global warming scenarios.Using the LandClim model,we compared warming levels of 1.5,2,and 3℃above preindustrial temperatures,based on 30-year periods from RCP data,to historical climate.Our research focused on Freiburg's forests in southwestern Germany,characterized by diverse tree species and an elevation range of 200–1,250 m a.s.l.A warming of 1.5℃could temporarily increase productivity,but at 2℃,biomass losses of up to 10%would occur below elevations of 450 m due to drought mortality.Under 3℃,losses would intensify below 650 m up to 40%,with even drought-resistant species like pedunculate oak experiencing mortality.At higher elevations,bark beetle outbreaks caused mortality of Norway spruce,while European beech capitalized on the changing ecological conditions.Higher warming levels significantly deteriorated FES,particularly timber production,climate change mitigation,and structural diversity,while recreation was less affected.These findings emphasize the urgency of meeting Paris Agreement targets,as limiting warming below 2℃can reduce severe impacts.If warming exceeds this critical threshold,even species presently considered drought-resistant,such as native sessile and pedunculate oaks and non-native red oak,could face serious threats at lower elevations.This would undermine the effectiveness of current management strategies,as these tree species are key to providing multiple FES.展开更多
Accurately assessing the relationship between tree growth and climatic factors is of great importance in dendrochronology.This study evaluated the consistency between alternative climate datasets(including station and...Accurately assessing the relationship between tree growth and climatic factors is of great importance in dendrochronology.This study evaluated the consistency between alternative climate datasets(including station and gridded data)and actual climate data(fixed-point observations near the sampling sites),in northeastern China’s warm temperate zone and analyzed differences in their correlations with tree-ring width index.The results were:(1)Gridded temperature data,as well as precipitation and relative humidity data from the Huailai meteorological station,was more consistent with the actual climate data;in contrast,gridded soil moisture content data showed significant discrepancies.(2)Horizontal distance had a greater impact on the representativeness of actual climate conditions than vertical elevation differences.(3)Differences in consistency between alternative and actual climate data also affected their correlations with tree-ring width indices.In some growing season months,correlation coefficients,both in magnitude and sign,differed significantly from those based on actual data.The selection of different alternative climate datasets can lead to biased results in assessing forest responses to climate change,which is detrimental to the management of forest ecosystems in harsh environments.Therefore,the scientific and rational selection of alternative climate data is essential for dendroecological and climatological research.展开更多
Forest ecosystems are critical to ecological stability,yet their functionality is increasingly threatened by the growing frequency of drought,particularly in arid and semi-arid regions.While afforestation enhances for...Forest ecosystems are critical to ecological stability,yet their functionality is increasingly threatened by the growing frequency of drought,particularly in arid and semi-arid regions.While afforestation enhances forest cover in these areas,the capacity of planted forests to adapt to climate change is poorly understood.This study examines the drought resistance and adaptive capacity of planted and naturally growing Schrenk spruce(Picea schrenkiana Fisch.&C.A.Mey.)in the Ili River Basin,Xinjiang,China using tree-ring analysis.The results indicate that natural stands have a stronger correlation with meteorological factors than plantations.Over the past 50 years,significant growth declines occurred during 1995-1997,2007-2009,and 2012-2014,with natural forests showing a greater frequency and severity of declines compared to plantations.Planted stands demonstrated greater resistance to drought,whereas natural forests had higher resilience and recovery.Over time,natural forests have shown declining resistance to drought but increased resilience and recovery.Conversely,plantations showed declines in resistance and recovery but an increased capacity for recovery.Older natural forests are more prone to growth decline,while structurally simpler planted forests show stronger drought resistance.However,following periods of drought,natural forests demonstrated a stronger capacity for recovery.These findings provide valuable insights into the response of P.schrenkiana to climate change and offer support for the sustainable management and conservation of forest ecosystems in the Xinjiang region of China.展开更多
Conservation and enhancement of old-growth forests are key in forest planning and policies.In order to do so,more knowledge is needed on how the attributes traditionally associated with old-growth forests are distribu...Conservation and enhancement of old-growth forests are key in forest planning and policies.In order to do so,more knowledge is needed on how the attributes traditionally associated with old-growth forests are distributed in space,what differences exist across distinct forest types and what natural or anthropic conditions are affecting the distribution of these old-growthness attributes.Using data from the Third Spanish National Forest Inventory(1997–2007),we calculated six indicators commonly associated with forest old-growthness for the plots in the territory of Peninsular Spain and Balearic Islands,and then combined them into an aggregated index.We then assessed their spatial distribution and the differences across five forest functional types,as well as the effects of ten climate,topographic,landscape,and anthropic variables in their distribution.Relevant geographical patterns were apparent,with climate factors,namely temperature and precipitation,playing a crucial role in the distribution of these attributes.The distribution of the indicators also varied across different forest types,while the effects of recent anthropic impacts were weaker but still relevant.Aridity seemed to be one of the main impediments for the development of old-growthness attributes,coupled with a negative impact of recent human pressure.However,these effects seemed to be mediated by other factors,specially the legacies imposed by the complex history of forest management practices,land use changes and natural disturbances that have shaped the forests of Spain.The results of this exploratory analysis highlight on one hand the importance of climate in the dynamic of forests towards old-growthness,which is relevant in a context of Climate Change,and on the other hand,the need for more insights on the history of our forests in order to understand their present and future.展开更多
Increasing human activity is altering the struc-ture of forests,which affects the composition of communi-ties,including birds.However,little is known about the key forest structure variables that determine the richnes...Increasing human activity is altering the struc-ture of forests,which affects the composition of communi-ties,including birds.However,little is known about the key forest structure variables that determine the richness of bird communities in European temperate oak forests.We,there-fore,aimed to identify key variables in these habitats that could contribute to the design of management strategies for forest conservation by surveying 11 oak-dominated forest sites throughout the mid-mountain range of Hungary at 86 survey points to reveal the role of different compositional and structural variables for forest stands that influence the breeding bird assemblages in the forests at the functional group and individual species levels.Based on decision tree modelling,our results showed that the density of trees larger than 30 cm DBH was an overall important variable,indi-cating that large-diameter trees were essential to provide diverse bird communities.The total abundance of birds,the foliage-gleaners,primary and secondary cavity nest-ers,residents,and five specific bird species were related to the density of high trunk diameter trees.The abundance of shrub nesters was negatively influenced by a high density of trees over 10 cm DBH.The density of the shrub layer positively affected total bird abundance and the abundance of foliage gleaners,secondary cavity nesters and residents.Analysis of the co-dominant tree species showed that the presence of linden,beech,and hornbeam was important in influencing the abundance of various bird species,e.g.,Eur-asian Treecreeper(Certhia familiaris),Marsh Tit(Poecile palustris)and Wood Warbler(Phylloscopus sibilatrix).Our results indicated that large trees,high tree diversity,and dense shrub layer were essential for forest bird communities and are critical targets for protection to maintain diverse and abundant bird communities in oak-dominated forest habitats.展开更多
Temperate forest ecosystems are important habitats for many bat species. However, these habitats are increasingly affected by anthropogenic disturbances, particularly urban development, leading to landscapes with vary...Temperate forest ecosystems are important habitats for many bat species. However, these habitats are increasingly affected by anthropogenic disturbances, particularly urban development, leading to landscapes with varying land cover composition and configuration. Limited research has examined how forest and urban landscape composition and configuration influence bat activity and diversity. Using a multi-year statewide bat acoustic monitoring dataset from North Carolina, USA, we investigated the effects of forest and urban composition and configuration at multiple spatial scales on bat activity and diversity. First, we constructed single-variable landscape index regression models and found that both the composition and configuration of forests and urban developments influenced bat activity and diversity in a species-specific manner. Next, we applied a hierarchical partitioning approach to compare the relative contributions of composition and configuration indices in explaining variance in bat activity. For big brown bats and hoary bats, evergreen forest and urban development composition indices contributed the most to explaining activity variance. In contrast, for eastern red bats, evening bats, and tricolored bats, deciduous forest fragmentation indices describing landscape configuration were the most influential factors. Silver-haired bat activity variance was primarily explained by an evergreen forest fragmentation index. Lastly, urban development configuration indices were the strongest predictors of Mexican free-tailed bat activity and total bat activity. These results suggest that forest and urban landscape configuration should be considered in conservation and management planning for North American temperate forest ecosystems, particularly in regions that have not experienced drastic deforestation in recent decades.展开更多
Old-growth forests are of major importance for biodiversity conservation and climate change mitigation,as well as being a benchmark for the implementation of sustainable forest management.Although dedicated studies ha...Old-growth forests are of major importance for biodiversity conservation and climate change mitigation,as well as being a benchmark for the implementation of sustainable forest management.Although dedicated studies have significantly increased in the last decades,there is still limited knowledge of Mediterranean forests,especially those dominated by Quercus pubescens and related taxa.To fill this knowledge gap,we primarily studied in the field two downy oak forests possessing old-growth traits,localized in Sicily(Mediterranean,Italy).Second,we used a structural heterogeneity index(SHI)to assess their old-growthness level,in comparison with the downy oak stands surveyed in the Regional Forest Inventory(RFI)of Sicily.Third,we tested the effect of different sets of structural parameters on SHI scores,thus assessing whether their choice could affect the final score and the stand assessment.SHI was well proven to discriminate these two stands from the others,both showing,on average,a SHI score just higher than 80,whilst SHI in RFI plots was just under 50,a significantly lower value.The methodological approach used in our study highlights the need to standardize the parameters used to characterize the old-growthness level of Mediterranean forests in order to allow more reliable comparisons.Most of the structural parameters were higher in the two selected stands,except for the attributes related to standing deadwood,suggesting a still limited contribution of standing dead trees and snags in the potential old-growth stands under investigation.The application of a structural index has proven effective for the purpose it was tested for,demonstrating its usefulness in discriminating between two potential old-growth stands from ordinary stands of the same forest type.We believe that both forests deserve primary attention and tailored management measures,as well as inclusion in the recently established Italian Network of old-growth forests.展开更多
The study determined the carbon stocks and litter nutrient concentration in tropical forests along the ecological gradient in Kenya.This could help understand the potential of mitigating climate change using tropical ...The study determined the carbon stocks and litter nutrient concentration in tropical forests along the ecological gradient in Kenya.This could help understand the potential of mitigating climate change using tropical forest ecosystems in different ecological zones,which are being affected by climate change to a level that they are becoming carbon sources instead of sinks.Stratified sampling technique was used to categorize tropical forests into rain,moist deciduous and dry zone forests depending on the average annual rainfall received.Simple random sampling technique was used to select three tropical forests in each category.Modified consistent sampling technique was used to develop 10 main 20 m×100 m plots in each forest,with 202 m×50 m sub-plots in each plot.Systematic random sampling technique was used in selecting 10 sub-plots from each main plot for inventory study.Non-destructive approach based on allometric equations using trees’diameter at breast height(DBH),total height and species’wood specific gravity were used in estimating tree carbon stock in each forest.Soil organic carbon(SOC)and litter nutrient concentration(total phosphorus and nitrogen)were determined in each forest based on standard laboratory procedures.The results indicated that,whilst trees in rain forests recorded a significantly higher(p<0.001)DBH(20.36 cm)and total tree height(12.1 m),trees in dry zone forests recorded a significantly higher(p<0.001)specific gravity(0.67 kg m^(−3)).Dry zone tropical forests stored a significantly lower amount of total tree carbon of 73 Mg ha^(−1),compared to tropical rain forests(439.5 Mg ha^(−1))and moist deciduous tropical forests(449 Mg ha^(−1)).The SOC content was significantly higher in tropical rainforests(3.9%),compared to soils from moist deciduous(2.9%)and dry zone forests(1.8%).While litter from tropical rain forests recorded a significantly higher amount of total nitrogen(3.4%),litter from dry zone forests recorded a significantly higher concentration of total phosphorus(0.27%).In conclusion,ecological gradient that is dictated by the prevailing temperatures and precipitation affects the tropical forests carbon stock potential and litter nutrient concentration.This implies that,the changing climate is having a serious implication on the ecosystem services such as carbon stock and nutrients cycling in tropical forests.展开更多
Temperate forests exert significant biogeophysical influences on local and regional climates through modulating the energy and moisture exchanges between the land surface and the atmosphere,thereby serving as crucial ...Temperate forests exert significant biogeophysical influences on local and regional climates through modulating the energy and moisture exchanges between the land surface and the atmosphere,thereby serving as crucial barriers with significant buffering impacts on the productivity of adjacent agricultural ecosystems.However,the extent and underlying mechanisms of these biogeophysical and buffering effects of temperate forest barriers remains insufficiently understood.In this study,we integrated the dynamic crop model Noah-MP-Crop with the Weather Research and Forecasting(WRF)model to investigate the biogeophysical climate regulation of temperate forests and its buffering effects on crop yields in adjacent agricultural lands across Northeast China.Our findings revealed that temperate forest barriers induced significant local climate effects by cooling air and surface temperatures and reducing wind speeds within forested areas during the growing season,while also regulating non-local climate,particularly by altering regional precipitation patterns,2 m water vapor mixing ratio(Q2),and soil moisture,predominantly in adjacent cropland areas.Furthermore,these forest barriers were found to modulate climate extremes,through affecting maximum temperature and wind speed on a local scale,as well as both maximum and minimum Q2 in non-local croplands.Our study also observed that temperate forest barriers,through biogeophysical climate regulation,enhanced GPP,NPP,and grain yields across most cropland areas.This productivity boost was especially pronounced,with yield increases up to 20%in certain regions during the extreme drought conditions of 2017,underscoring the critical role of temperate forest barriers in sustaining and enhancing crop yields under severe climatic stress.Our findings underscore the significant buffering effects of temperate forest barriers on regional agricultural production,having important implications for climate adaptation strategies aimed at bolstering agricultural resilience in the face of increasing climate variability and extremes.展开更多
Evergreen broad-leaved forests(EBLFs) are widely distributed in East Asia and play a vital role in ecosystem stability. The occurrence of these forests in East Asia has been a subject of debate across various discipli...Evergreen broad-leaved forests(EBLFs) are widely distributed in East Asia and play a vital role in ecosystem stability. The occurrence of these forests in East Asia has been a subject of debate across various disciplines. In this study, we explored the occurrence of East Asian EBLFs from a paleobotanical perspective. By collecting plant fossils from four regions in East Asia, we have established the evolutionary history of EBLFs. Through floral similarity analysis and paleoclimatic reconstruction, we have revealed a diverse spatio-temporal pattern for the occurrence of EBLFs in East Asia. The earliest occurrence of EBLFs in southern China can be traced back to the middle Eocene, followed by southwestern China during the late Eocene-early Oligocene. Subsequently, EBLFs emerged in Japan during the early Oligocene and eventually appeared in central-eastern China around the Miocene. Paleoclimate simulation results suggest that the precipitation of wettest quarter(PWet Q, mm) exceeding 600 mm is crucial for the occurrence of EBLFs. Furthermore, the heterogeneous occurrence of EBLFs in East Asia is closely associated with the evolution of the Asian Monsoon. This study provides new insights into the occurrence of EBLFs in East Asia.展开更多
This paper explores the synergistic effect of a model combining Elastic Net and Random Forest in online fraud detection.The study selects a public network dataset containing 1781 data records,divides the dataset by 70...This paper explores the synergistic effect of a model combining Elastic Net and Random Forest in online fraud detection.The study selects a public network dataset containing 1781 data records,divides the dataset by 70%for training and 30%for validation,and analyses the correlation between features using a correlation matrix.The experimental results show that the Elastic Net feature selection method generally outperforms PCA in all models,especially when combined with the Random Forest and XGBoost models,and the ElasticNet+Random Forest model achieves the highest accuracy of 0.968 and AUC value of 0.983,while the Kappa and MCC also reached 0.839 and 0.844 respectively,showing extremely high consistency and correlation.This indicates that combining Elastic Net feature selection and Random Forest model has significant performance advantages in online fraud detection.展开更多
Sacred forests play a valuable role in the conservation of local biodiversity and provide numerous ecosystem services in Cameroon. The aim of this study was to estimate floristic diversity, stand structures and carbon...Sacred forests play a valuable role in the conservation of local biodiversity and provide numerous ecosystem services in Cameroon. The aim of this study was to estimate floristic diversity, stand structures and carbon stocks in the sacred forests of Bandrefam and Batoufam (western Cameroon). The floristic inventory and the stand structures were carried out in 25 m × 25 m plots for individuals with diameters greater than 10 cm;5 m × 5 m for individuals with diameters less than 10 cm. Carbon stocks were estimated using the non-destructive method and allometric equations. The floristic inventory identified 65 species divided into 57 genera and 30 families in the Bandrefam sacred forest and 45 species divided into 42 genera and 27 families in the Batoufam sacred forest. In the Bandrefam, the most important families are Phyllanthaceae (53.98%), Moraceae (21.69%), Lamiaceae (20.15%). At Batoufam, the most important families are Phyllanthaceae (39.73%), Fabaceae (28.47%), Araliaceae (23.77%). Malacantha alnifolia (55.14%), Vitex grandifolia (18.43%), Bosqueia angolensis (15.06%) were the most important species in Bandrefam. Otherwise, Malacantha alnifolia (28%), Polyscias fulva (22.73%), Psychotria sp. (21.28%) were the most important in Batoufam. The Bandrefam sacred forest has the highest tree density (2669 stems/ha). Total carbon stock is 484.88 ± 2.28 tC/ha at Batoufam and 313.95 ± 0.93 tC/ha at Bandrefam. The economic value varies between 5858.04 ± 27.62 USD/ha in Batoufam sacred forest and 3788.51 ± 11.26 USD/ha in Bandrefam sacred forest. The number of individuals and small-diameter trees has little influence on the carbon stocks in the trees. Medium-diameter trees store the most carbon, and very large-diameter trees, which are very poorly represented, store less carbon. In another way, wood density and the basal areas influence the carbon storage of the trees.展开更多
基金supported by the Czech University of Life Sciences(Internal Grant Agency:A_12_24,43110/1312/3103,the Czech Science Foundation(Grant GACR No.21-27454S)Technology Agency of the Czech Republic(TACR No.SS06010420)+2 种基金provided by the CLIMB-FOREST project(No.101060554)project FORbEST(No.101181878)funded under the Horizon Europe Framework Programme。
文摘Old-growth forests uniquely support biodiversity while serving as some of the planet's most important carbon stocks.The influence of tree and stand age on carbon flux dynamics remains debated—an urgent question as climate-driven disturbances may reshape forest age structures and in situ carbon storage.To clarify these relationships in Fagus sylvatica,systems,we examined a unique dataset of 3,503 tree ring series from 190 plots across some of the best preserved old-growth forests from five southern European countries.By employing a dendrochronological approach and integrating key environmental variables,including elevation,slope,temperature,and the presence of large-diameter trees(≥60 cm),we analyzed the complex relationships between tree/stand age within a plot(represented by plot-level mean values,hereafter“stand age”)and aboveground carbon stock across live,standing,and lying deadwood pools.The average stand age was 220 years,with 230 tC⋅ha^(-1) of carbon stored in aboveground biomass and necromass.We found a positive correlation between age and carbon storage at both the individual tree and plot levels.Notably,the presence of large-diameter trees was the strongest indicator of carbon stock,with carbon accumulation peaking at about 30%large-tree stems proportion before stabilising,while younger beech trees(below 100 years old)had a smaller contribution to carbon storage.We found no evidence of a decline in carbon stock with advancing stand age across the studied sites.Despite the ecological importance of old-growth forests,many of them remain unprotected and are disappearing across Europe.Our findings highlight the importance of preserving old-growth forests to maximize their role as long-term ecosystem carbon reservoirs.
文摘Soil bacteria are integral to ecosystem functioning,significantly contributing to nutrients cycling and organic matter decomposition,and enhancing soil structure.This research considered the composition and dynamics of soil bacterial communities under different vegetation types(native Quercus brantii Lindl.and Amygdalus scoparia Spach,and non-native Pinus eldarica Medw.and Cupressus arizonica Greene.)in Zagros mountain area of Iran.This study involved a comparative analysis of soil culturable heterotrophic bacterial communities in spring(wet season)and summer(dry season)to clarify the effects of seasonal changes and vegetation on the dynamics of soil microorganisms.Soil samples were randomly collected under the canopies of various tree species and a control area,yielding a total of 48 composite samples analyzed for bacterial composition.Results indicated that 11 Gram-negative(e.g.,Citrobacter freundii,Enterobacter cloacae,Escherichia coli,Klebsiella oxytoca,Klebsiella pneumoniae,etc.)and 2 Gram-positive(Staphylococcus epidermidis and Staphylococcus aureus)bacteria were identified,showing significant seasonal variation.Specifically,53.85%of bacterial species were common to both seasons,with notable shifts in community composition observed between spring and summer,highlighting a higher abundance of Gram-negative species in spring.Bacterial community structure was significantly influenced by vegetation type,with various tree species shaping distinct microbial assemblages.Moreover,Pearson's correlations revealed that soil properties,particularly pH,phosphorus,and moisture content,were critical drivers of bacterial diversity and abundance.Our findings underscore the dynamic nature of soil bacterial communities in response to seasonal and vegetation changes,emphasizing the importance of repeated temporal sampling for accurate assessments of microbial diversity.Understanding these microbial dynamics is essential for improving soil management strategies and enhancing ecosystem resilience,particularly in arid and semi-arid areas where environmental fluctuations play a pivotal role.This research not only confirms our hypotheses but also enhances our understanding of soil biogeochemical processes and informs future vegetation management practices.
基金supported by the British Columbia Ministry of Forces through long-term annual contracts with University of British Columbia(Okanagan)(No.RE25SIR242)the Natural Sciences and Engineering Research Council of Canada(NSERC),Discovery Grants Program(No.RGPIN-2021-02628)+1 种基金supported by the China Postdoctoral Science Foundation(No.2024M760387)Heilongjiang Postdoctoral Financial Assistance(No.LBH-Z24062)。
文摘Extreme climate events(e.g.,heatwaves and droughts)are becoming increasingly frequent due to global climate change,which inevitably affects tree growth and various other ecological processes.While the impacts of droughts on these processes have been widely evaluated,the effects of heatwaves on tree growth and soil water content(SWC)remain poorly understood,particularly those related to thinning treatment.In this study,we evaluated the impacts of the 2021 Pacific Northwest Heatwave and thinning on forest growth and SWC,as well as assessed how thinning might mitigate the heatwave's impacts in lodgepole pine forests in British Columbia,Canada.We measured meteorological data(air temperature,rainfall,solar radiation(SR),relative humidity(RH),and wind speed(W_(s)),sap flow,SWC,soil temperature(T_(s)),and tree diameters at the breast height(DBH)during the growing season(June–September)in the control(27,000 stems·ha^(-1)),lightly thinned(4,500 stems·ha^(-1)),and heavily thinned(1,100 stems·ha^(-1))experimental plots from 2018 to 2024.We found that thinning persistently and significantly(p<0.05)increased individual tree growth,with the most pronounced effects in the heavily thinned stands.The 2021 Pacific Northwest Heatwave led to an exceptionally hot growing season,significantly(p<0.05)reducing forest growth and SWC across all plots.Forest growth recovered in 2022 in the thinned plots but remained suppressed in the unthinned plots,suggesting that thinning effectively mitigated the impact of the heatwave on forest growth,while the heatwave's impacts were persistent in the unthinned plots.Our study highlights that thinning is a practical management strategy for improving tree growth and supporting climate change adaptation to extreme climate events.
基金financially supported by the National Key Research and Development Program of China(2021YFD2200405)the National Natural Science Foundation of China(31930078)special funds for Baotianman Forest Ecosystem Research Station from Chinese Academy of Forestry and Ministry of Science and Technology of China。
文摘Frequent droughts pose considerable threat to global forest carbon uptake,but little is known about the response of forest carbon fluxes in climatic transition zones to seasonal drought.In this study,the responses of carbon fluxes to seasonal drought in two natural forests(Quercus aliena var.acute serrata Maxim and Pinus tabuliformis Carr.)in the Baotianman Nature Reserve were investigated.The Q.aliena forest exhibited a high resilience with stable gross primary productivity(GPP).However,ecosystem respiration(Re)significantly declined by 18.4%compared with normal years,leading to an increase in net carbon sequestration capacity of 4.1%.This resilience was attributed to its deep root system accessing soil water(SWC_(50cm))to sustain stomatal openness,coupled with the efficient utilization of photosynthetically active radiation to drive photosynthesis.In contrast,the P.tabuliformis forest,which relied on shallow soil moisture(SWC_(20cm)),experienced simultaneous decreases in both GPP and Re during drought,with a sharply greater decrease in GPP,resulting in low net carbon sink capacity.Further analysis revealed that the Q.aliena forest prioritized carbon assimilation through a deep water-stomatal synergy strategy(anisohydric behavior),whereas the P.tabuliformis forest adopted an isohydric strategy favoring water conservation at the expense of carbon fixation efficiency.These findings highlight distinct mechanisms underlying drought adaptation between forest types,providing critical insight into optimizing forest carbon cycle models and selecting drought-resistant species under the influence of climate change.
基金supported by the National Natural Science Foundation of China(32460380,42007042)State Key Laboratory of Subtropical Silviculture(SKLSSKF2023-06)+2 种基金Natural Science Foundation of Jiangxi Province(20242BAB25389)National Undergraduate Innovation and Entrepreneurship Training Program(202410410029X)Jiangxi Province Graduate Student Innovation Special Fund Project(YC2024-S330).
文摘Urban forests are essential components of green infrastructure,however,rapid urbanization-induced changes in landscape patterns may affect their ecosystem services through complex ecological processes.A total of 184 sample plots in the built-up areas of Nanchang,China,were used as research sites.Urbanization intensities were categorized by the rate of impervious surface area,and forest types were classified into landscape and relaxation forest,attached forest(AF),road forest(RF),and ecological public welfare forest.This study aimed to explore the spatial variations in vegetation characteristics and landscape pattern indices of different forest types under rapid urbanization.The results indicated that the largest patch index(LPI),aggregation index(AI),and percentage of landscape(PLAND)in RF and AF were lower than those in the other forest types(p<0.05).With increasing urbanization intensity,the mean perimeter-area ratio increased by 130.84%,whereas the PLAND,LPI,and AI decreased by 22−86%(p<0.05).Redundancy analysis and variation partitioning suggested that the interpretation rate of landscape pattern indices for variations in vegetation characteristics increased from low to heavy urbanization areas.Especially,the landscape shape index,patch connection index,PLAND,and mean patch size were significantly correlated with vegetation characteristics(e.g.,tree richness,herb coverage,and tree height).In the future,appropriate landscape layout superiority cases should be considered in different urbanization areas and forest types;for instance,increasing the patch connection index will beneficially improve the diversity of trees and herbs in heavy urbanization areas and the RF.This study serves as a reference for maximizing the ecosystem services of urban forests.
基金supported by the National Natural Science Foundation of China(Grant Nos.42407595&41630753)the National Key Research and Development Program of China(Grant No.2022YFF0801501).
文摘The quantitative relationship between modern pollen and vegetation provides a critical foundation for reconstructing past vegetation,with relative pollen productivity(RPP)serving as a key calibration parameter.However,in subtropical evergreen broadleaved forests(SEBFs)in China,RPP studies remain scarce,and the impact of human disturbances on RPP estimates has yet to be adequately assessed,limiting the accuracy of quantitative palaeovegetation reconstructions.This study was conducted in Dinghu Mountain Nature Reserve and its surrounding areas in Zhaoqing,Guangdong Province,and included 31 sampling sites.We performed pollen analysis alongside detailed vegetation surveys and utilized ERV submodel 2 and Prentice’s model to estimate the RPP of 9 common plant taxa in the southern SEBFs.There was a particular focus on evaluating the interference effects of bamboo plantations on the estimation of RPP.The results indicate that bamboo within the family Poaceae contributes minimally to surface soil Poaceae pollen because of its unique flowering characteristics,such as long flowering cycles and monocarpic reproduction.The incorporation of bamboo into the Poaceae vegetation coverage in the analysis led to excessively high RPP values for the other taxa.When bamboo coverage was removed from the Poaceae family,the recalculated RPP values aligned closely with those reported in previous studies.The RPP values,ranked from highest to lowest,were as follows:Castanopsis(12.33±0.03)>Araliaceae(1.60±0.03)>Mallotus(1.53±0.26)>Pinus(1.47±0.03)>Rosaceae(1.07±0.02)>Poaceae(1±0)>Euphorbiaceae(0.44±0.03)>Anacardiaceae(0.26±0.03)>Theaceae(0.15±0).Notably,the RPP values for Mallotus,Araliaceae,Theaceae,and Euphorbiaceae represent the first estimates for China’s subtropical region.Differences between certain RPP estimates and those of previous studies may be attributed to factors such as species composition,vegetation structure,and model selection.The findings of this study highlight that due to the widespread distribution of artificial bamboo forests in China’s subtropical regions,future RPP studies should carefully consider the influence of Poaceae.This consideration is essential for improving the accuracy of the application of fossil pollen for quantitative paleo-vegetation reconstruction in these regions.
基金supported by the China National Science Foundation(No.42130506,42071031)the Special Technology Innovation Fund of Carbon Peak and Carbon Neutrality in Jiangsu Province(BK20231515)+1 种基金the Spanish Government grant PID2022-140808NB-I00 funded by MICIU/AEI/https://doi.org/10.13039/501100011033the Catalan Government grants SGR 2021-1333 and AGAUR2023 CLIMA 00118.
文摘The root-to-shoot(R/S)ratio is a critical indicator of the balance between root biomass and shoot biomass,representing the ecological strategies and adaptive responses of plants to environmental conditions.However,the patterns of change in community R/S ratios during forest succession and their response to moisture levels across broad geographic gradients remains unclear.Based on forest biomass data from a national field inventory of 5,825 plots conducted across China between 2011 and 2015,this study looked into allocating biomass shoots and roots at the early,middle,and late stages of growth in plantations and succession in natural forests,and evaluated how moisture availability influences this allocation.The results revealed a significant decline in R/S ratios from early to late stages for both plantations and natural forests.Shoot and root biomass in plantations grew isometrically during the early and middle succession stages but shifted to allometric growth in the late stage,with the slope of the log-transformed shoot-root biomass relationship differing significantly across growth stages.Natural forests,in contrast,maintained isometric growth across successional stages,showing no significant variation in the slope of the log-transformed shoot-root biomass relationship.Environmental factors,particularly moisture levels,strongly influenced R/S ratios.Moisture levels significantly affected size-corrected R/S ratios,particularly in the middle stage of plantations and the early and middle stages of natural forests,supporting the hypothesis of optimal allocation.These findings suggest that in water-limited regions,forest management should prioritize drought-tolerant,deep-rooted native species,encourage mixed-species planting in the early stage,and reduce logging intensity in mature plantations.Conserving natural forests to maintain successional dynamics is essential for long-term ecological resilience.These findings emphasize the importance of balancing productivity with ecological sustainability by adapting practices to specific environments and forest types under climate change.
基金funded by the HORIZON EUROPE's project"eco2adapt"(Ecosystem-based Adaptation and Changemaking to Shape,Project,and Sustain the Resilience of Tomorrow's Forests,Grant no:101059498)。
文摘Climate change is impacting forests in Central Europe,causing increased mortality and degradation of forest ecosystem services(FES).As global warming intensifies,these effects are likely to worsen,particularly through more severe droughts and increased biotic disturbances.Understanding how forests respond to different levels of warming is essential for adaptation planning.Therefore,this study analyzed changes in forest structure and FES,including timber production,climate change mitigation,recreation,and structural diversity,under three global warming scenarios.Using the LandClim model,we compared warming levels of 1.5,2,and 3℃above preindustrial temperatures,based on 30-year periods from RCP data,to historical climate.Our research focused on Freiburg's forests in southwestern Germany,characterized by diverse tree species and an elevation range of 200–1,250 m a.s.l.A warming of 1.5℃could temporarily increase productivity,but at 2℃,biomass losses of up to 10%would occur below elevations of 450 m due to drought mortality.Under 3℃,losses would intensify below 650 m up to 40%,with even drought-resistant species like pedunculate oak experiencing mortality.At higher elevations,bark beetle outbreaks caused mortality of Norway spruce,while European beech capitalized on the changing ecological conditions.Higher warming levels significantly deteriorated FES,particularly timber production,climate change mitigation,and structural diversity,while recreation was less affected.These findings emphasize the urgency of meeting Paris Agreement targets,as limiting warming below 2℃can reduce severe impacts.If warming exceeds this critical threshold,even species presently considered drought-resistant,such as native sessile and pedunculate oaks and non-native red oak,could face serious threats at lower elevations.This would undermine the effectiveness of current management strategies,as these tree species are key to providing multiple FES.
基金supported by the International Partnership program of the Chinese Academy of Sciences(170GJHZ2023074GC)National Natural Science Foundation of China(42425706 and 42488201)+1 种基金National Key Research and Development Program of China(2024YFF0807902)Beijing Natural Science Foundation(8242041),and China Postdoctoral Science Foundation(2025M770353).
文摘Accurately assessing the relationship between tree growth and climatic factors is of great importance in dendrochronology.This study evaluated the consistency between alternative climate datasets(including station and gridded data)and actual climate data(fixed-point observations near the sampling sites),in northeastern China’s warm temperate zone and analyzed differences in their correlations with tree-ring width index.The results were:(1)Gridded temperature data,as well as precipitation and relative humidity data from the Huailai meteorological station,was more consistent with the actual climate data;in contrast,gridded soil moisture content data showed significant discrepancies.(2)Horizontal distance had a greater impact on the representativeness of actual climate conditions than vertical elevation differences.(3)Differences in consistency between alternative and actual climate data also affected their correlations with tree-ring width indices.In some growing season months,correlation coefficients,both in magnitude and sign,differed significantly from those based on actual data.The selection of different alternative climate datasets can lead to biased results in assessing forest responses to climate change,which is detrimental to the management of forest ecosystems in harsh environments.Therefore,the scientific and rational selection of alternative climate data is essential for dendroecological and climatological research.
基金supported by the Tianshan Talent Program of Xinjiang(2022TSYCCX0003,2024TSYCCX0041)the National Natural Science Foundation of China(42375054)+1 种基金the Desert Meteorological Science Research Foundation of China(Sqj2021018)the Young Meteorological Talent Program of China Meteorological Administration and Youth Innovation Team of China Meteorological Administration(CMA2023QN08)。
文摘Forest ecosystems are critical to ecological stability,yet their functionality is increasingly threatened by the growing frequency of drought,particularly in arid and semi-arid regions.While afforestation enhances forest cover in these areas,the capacity of planted forests to adapt to climate change is poorly understood.This study examines the drought resistance and adaptive capacity of planted and naturally growing Schrenk spruce(Picea schrenkiana Fisch.&C.A.Mey.)in the Ili River Basin,Xinjiang,China using tree-ring analysis.The results indicate that natural stands have a stronger correlation with meteorological factors than plantations.Over the past 50 years,significant growth declines occurred during 1995-1997,2007-2009,and 2012-2014,with natural forests showing a greater frequency and severity of declines compared to plantations.Planted stands demonstrated greater resistance to drought,whereas natural forests had higher resilience and recovery.Over time,natural forests have shown declining resistance to drought but increased resilience and recovery.Conversely,plantations showed declines in resistance and recovery but an increased capacity for recovery.Older natural forests are more prone to growth decline,while structurally simpler planted forests show stronger drought resistance.However,following periods of drought,natural forests demonstrated a stronger capacity for recovery.These findings provide valuable insights into the response of P.schrenkiana to climate change and offer support for the sustainable management and conservation of forest ecosystems in the Xinjiang region of China.
基金supported by the Spanish Ministry of Science and Innovation project GREEN-RISK(Evaluation of past changes in ecosystem services and biodiversity in forests and restoration priorities under global change impacts-PID2020-119933RB-C21)A.C.received a pre-doctoral fellowship funded by the Spanish Ministry of Science and Innovation(PRE2021-099642).
文摘Conservation and enhancement of old-growth forests are key in forest planning and policies.In order to do so,more knowledge is needed on how the attributes traditionally associated with old-growth forests are distributed in space,what differences exist across distinct forest types and what natural or anthropic conditions are affecting the distribution of these old-growthness attributes.Using data from the Third Spanish National Forest Inventory(1997–2007),we calculated six indicators commonly associated with forest old-growthness for the plots in the territory of Peninsular Spain and Balearic Islands,and then combined them into an aggregated index.We then assessed their spatial distribution and the differences across five forest functional types,as well as the effects of ten climate,topographic,landscape,and anthropic variables in their distribution.Relevant geographical patterns were apparent,with climate factors,namely temperature and precipitation,playing a crucial role in the distribution of these attributes.The distribution of the indicators also varied across different forest types,while the effects of recent anthropic impacts were weaker but still relevant.Aridity seemed to be one of the main impediments for the development of old-growthness attributes,coupled with a negative impact of recent human pressure.However,these effects seemed to be mediated by other factors,specially the legacies imposed by the complex history of forest management practices,land use changes and natural disturbances that have shaped the forests of Spain.The results of this exploratory analysis highlight on one hand the importance of climate in the dynamic of forests towards old-growthness,which is relevant in a context of Climate Change,and on the other hand,the need for more insights on the history of our forests in order to understand their present and future.
基金supported part ia l l y by LIFE4Oak Forests Project LIFE16NAT/IT/000245)the RRF 2.3.121202200008 projectthe MERLiN project funded under the European Commission H2020 Programme(101036337 MERLiN H2020 LC GD 2020)。
文摘Increasing human activity is altering the struc-ture of forests,which affects the composition of communi-ties,including birds.However,little is known about the key forest structure variables that determine the richness of bird communities in European temperate oak forests.We,there-fore,aimed to identify key variables in these habitats that could contribute to the design of management strategies for forest conservation by surveying 11 oak-dominated forest sites throughout the mid-mountain range of Hungary at 86 survey points to reveal the role of different compositional and structural variables for forest stands that influence the breeding bird assemblages in the forests at the functional group and individual species levels.Based on decision tree modelling,our results showed that the density of trees larger than 30 cm DBH was an overall important variable,indi-cating that large-diameter trees were essential to provide diverse bird communities.The total abundance of birds,the foliage-gleaners,primary and secondary cavity nest-ers,residents,and five specific bird species were related to the density of high trunk diameter trees.The abundance of shrub nesters was negatively influenced by a high density of trees over 10 cm DBH.The density of the shrub layer positively affected total bird abundance and the abundance of foliage gleaners,secondary cavity nesters and residents.Analysis of the co-dominant tree species showed that the presence of linden,beech,and hornbeam was important in influencing the abundance of various bird species,e.g.,Eur-asian Treecreeper(Certhia familiaris),Marsh Tit(Poecile palustris)and Wood Warbler(Phylloscopus sibilatrix).Our results indicated that large trees,high tree diversity,and dense shrub layer were essential for forest bird communities and are critical targets for protection to maintain diverse and abundant bird communities in oak-dominated forest habitats.
基金funding support from the United States Fish and Wildlife Service,the North Carolina Wildlife Resources Commission,and the University of North Carolina at Greensboro,as part of a collective effort for the North American Bat Monitoring Program(NABat).
文摘Temperate forest ecosystems are important habitats for many bat species. However, these habitats are increasingly affected by anthropogenic disturbances, particularly urban development, leading to landscapes with varying land cover composition and configuration. Limited research has examined how forest and urban landscape composition and configuration influence bat activity and diversity. Using a multi-year statewide bat acoustic monitoring dataset from North Carolina, USA, we investigated the effects of forest and urban composition and configuration at multiple spatial scales on bat activity and diversity. First, we constructed single-variable landscape index regression models and found that both the composition and configuration of forests and urban developments influenced bat activity and diversity in a species-specific manner. Next, we applied a hierarchical partitioning approach to compare the relative contributions of composition and configuration indices in explaining variance in bat activity. For big brown bats and hoary bats, evergreen forest and urban development composition indices contributed the most to explaining activity variance. In contrast, for eastern red bats, evening bats, and tricolored bats, deciduous forest fragmentation indices describing landscape configuration were the most influential factors. Silver-haired bat activity variance was primarily explained by an evergreen forest fragmentation index. Lastly, urban development configuration indices were the strongest predictors of Mexican free-tailed bat activity and total bat activity. These results suggest that forest and urban landscape configuration should be considered in conservation and management planning for North American temperate forest ecosystems, particularly in regions that have not experienced drastic deforestation in recent decades.
基金Field surveys were carried out within the forest monitoring activities of Action A1.3 of the Project LIFE4OAKFORESTS(LIFE16NAT/IT/000245),in collaboration with“Ente di Gestione per i Parchi e la Biodiversità-Romagna”.
文摘Old-growth forests are of major importance for biodiversity conservation and climate change mitigation,as well as being a benchmark for the implementation of sustainable forest management.Although dedicated studies have significantly increased in the last decades,there is still limited knowledge of Mediterranean forests,especially those dominated by Quercus pubescens and related taxa.To fill this knowledge gap,we primarily studied in the field two downy oak forests possessing old-growth traits,localized in Sicily(Mediterranean,Italy).Second,we used a structural heterogeneity index(SHI)to assess their old-growthness level,in comparison with the downy oak stands surveyed in the Regional Forest Inventory(RFI)of Sicily.Third,we tested the effect of different sets of structural parameters on SHI scores,thus assessing whether their choice could affect the final score and the stand assessment.SHI was well proven to discriminate these two stands from the others,both showing,on average,a SHI score just higher than 80,whilst SHI in RFI plots was just under 50,a significantly lower value.The methodological approach used in our study highlights the need to standardize the parameters used to characterize the old-growthness level of Mediterranean forests in order to allow more reliable comparisons.Most of the structural parameters were higher in the two selected stands,except for the attributes related to standing deadwood,suggesting a still limited contribution of standing dead trees and snags in the potential old-growth stands under investigation.The application of a structural index has proven effective for the purpose it was tested for,demonstrating its usefulness in discriminating between two potential old-growth stands from ordinary stands of the same forest type.We believe that both forests deserve primary attention and tailored management measures,as well as inclusion in the recently established Italian Network of old-growth forests.
基金funded by the Kenya National Research Fund(NRF-Kenya,2018).
文摘The study determined the carbon stocks and litter nutrient concentration in tropical forests along the ecological gradient in Kenya.This could help understand the potential of mitigating climate change using tropical forest ecosystems in different ecological zones,which are being affected by climate change to a level that they are becoming carbon sources instead of sinks.Stratified sampling technique was used to categorize tropical forests into rain,moist deciduous and dry zone forests depending on the average annual rainfall received.Simple random sampling technique was used to select three tropical forests in each category.Modified consistent sampling technique was used to develop 10 main 20 m×100 m plots in each forest,with 202 m×50 m sub-plots in each plot.Systematic random sampling technique was used in selecting 10 sub-plots from each main plot for inventory study.Non-destructive approach based on allometric equations using trees’diameter at breast height(DBH),total height and species’wood specific gravity were used in estimating tree carbon stock in each forest.Soil organic carbon(SOC)and litter nutrient concentration(total phosphorus and nitrogen)were determined in each forest based on standard laboratory procedures.The results indicated that,whilst trees in rain forests recorded a significantly higher(p<0.001)DBH(20.36 cm)and total tree height(12.1 m),trees in dry zone forests recorded a significantly higher(p<0.001)specific gravity(0.67 kg m^(−3)).Dry zone tropical forests stored a significantly lower amount of total tree carbon of 73 Mg ha^(−1),compared to tropical rain forests(439.5 Mg ha^(−1))and moist deciduous tropical forests(449 Mg ha^(−1)).The SOC content was significantly higher in tropical rainforests(3.9%),compared to soils from moist deciduous(2.9%)and dry zone forests(1.8%).While litter from tropical rain forests recorded a significantly higher amount of total nitrogen(3.4%),litter from dry zone forests recorded a significantly higher concentration of total phosphorus(0.27%).In conclusion,ecological gradient that is dictated by the prevailing temperatures and precipitation affects the tropical forests carbon stock potential and litter nutrient concentration.This implies that,the changing climate is having a serious implication on the ecosystem services such as carbon stock and nutrients cycling in tropical forests.
基金supported by National Key R&D Program of China(Grant No.2024YFD1501600)the National Natural Science Foundation of China(Grants No.42071025,42371075)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2023240).
文摘Temperate forests exert significant biogeophysical influences on local and regional climates through modulating the energy and moisture exchanges between the land surface and the atmosphere,thereby serving as crucial barriers with significant buffering impacts on the productivity of adjacent agricultural ecosystems.However,the extent and underlying mechanisms of these biogeophysical and buffering effects of temperate forest barriers remains insufficiently understood.In this study,we integrated the dynamic crop model Noah-MP-Crop with the Weather Research and Forecasting(WRF)model to investigate the biogeophysical climate regulation of temperate forests and its buffering effects on crop yields in adjacent agricultural lands across Northeast China.Our findings revealed that temperate forest barriers induced significant local climate effects by cooling air and surface temperatures and reducing wind speeds within forested areas during the growing season,while also regulating non-local climate,particularly by altering regional precipitation patterns,2 m water vapor mixing ratio(Q2),and soil moisture,predominantly in adjacent cropland areas.Furthermore,these forest barriers were found to modulate climate extremes,through affecting maximum temperature and wind speed on a local scale,as well as both maximum and minimum Q2 in non-local croplands.Our study also observed that temperate forest barriers,through biogeophysical climate regulation,enhanced GPP,NPP,and grain yields across most cropland areas.This productivity boost was especially pronounced,with yield increases up to 20%in certain regions during the extreme drought conditions of 2017,underscoring the critical role of temperate forest barriers in sustaining and enhancing crop yields under severe climatic stress.Our findings underscore the significant buffering effects of temperate forest barriers on regional agricultural production,having important implications for climate adaptation strategies aimed at bolstering agricultural resilience in the face of increasing climate variability and extremes.
基金supported by National Key R&D Program of China(No.2022YFF0800800)National Science Fund for Distinguished Young Scholars(No.32225005)+3 种基金National Natural Science Foundation of China(NSFC)(Nos.42072024,42320104005,42372033)the Young and Middle-aged Academic and Technical Leaders of Yunnan(No.202305AC160051)Basic Research Project of Yunnan Province(No.202401AT070222)the 14th Five-Year Plan of the Xishuangbanna Tropical Botanical Garden,Chinese Academy of Sciences(Nos.XTBG-1450101,E3ZKFF7B).
文摘Evergreen broad-leaved forests(EBLFs) are widely distributed in East Asia and play a vital role in ecosystem stability. The occurrence of these forests in East Asia has been a subject of debate across various disciplines. In this study, we explored the occurrence of East Asian EBLFs from a paleobotanical perspective. By collecting plant fossils from four regions in East Asia, we have established the evolutionary history of EBLFs. Through floral similarity analysis and paleoclimatic reconstruction, we have revealed a diverse spatio-temporal pattern for the occurrence of EBLFs in East Asia. The earliest occurrence of EBLFs in southern China can be traced back to the middle Eocene, followed by southwestern China during the late Eocene-early Oligocene. Subsequently, EBLFs emerged in Japan during the early Oligocene and eventually appeared in central-eastern China around the Miocene. Paleoclimate simulation results suggest that the precipitation of wettest quarter(PWet Q, mm) exceeding 600 mm is crucial for the occurrence of EBLFs. Furthermore, the heterogeneous occurrence of EBLFs in East Asia is closely associated with the evolution of the Asian Monsoon. This study provides new insights into the occurrence of EBLFs in East Asia.
基金Guangdong Innovation and Entrepreneurship Training Programme for Undergraduates“Automatic Classification and Identification of Fraudulent Websites Based on Machine Learning”(Project No.:DC2023125)。
文摘This paper explores the synergistic effect of a model combining Elastic Net and Random Forest in online fraud detection.The study selects a public network dataset containing 1781 data records,divides the dataset by 70%for training and 30%for validation,and analyses the correlation between features using a correlation matrix.The experimental results show that the Elastic Net feature selection method generally outperforms PCA in all models,especially when combined with the Random Forest and XGBoost models,and the ElasticNet+Random Forest model achieves the highest accuracy of 0.968 and AUC value of 0.983,while the Kappa and MCC also reached 0.839 and 0.844 respectively,showing extremely high consistency and correlation.This indicates that combining Elastic Net feature selection and Random Forest model has significant performance advantages in online fraud detection.
文摘Sacred forests play a valuable role in the conservation of local biodiversity and provide numerous ecosystem services in Cameroon. The aim of this study was to estimate floristic diversity, stand structures and carbon stocks in the sacred forests of Bandrefam and Batoufam (western Cameroon). The floristic inventory and the stand structures were carried out in 25 m × 25 m plots for individuals with diameters greater than 10 cm;5 m × 5 m for individuals with diameters less than 10 cm. Carbon stocks were estimated using the non-destructive method and allometric equations. The floristic inventory identified 65 species divided into 57 genera and 30 families in the Bandrefam sacred forest and 45 species divided into 42 genera and 27 families in the Batoufam sacred forest. In the Bandrefam, the most important families are Phyllanthaceae (53.98%), Moraceae (21.69%), Lamiaceae (20.15%). At Batoufam, the most important families are Phyllanthaceae (39.73%), Fabaceae (28.47%), Araliaceae (23.77%). Malacantha alnifolia (55.14%), Vitex grandifolia (18.43%), Bosqueia angolensis (15.06%) were the most important species in Bandrefam. Otherwise, Malacantha alnifolia (28%), Polyscias fulva (22.73%), Psychotria sp. (21.28%) were the most important in Batoufam. The Bandrefam sacred forest has the highest tree density (2669 stems/ha). Total carbon stock is 484.88 ± 2.28 tC/ha at Batoufam and 313.95 ± 0.93 tC/ha at Bandrefam. The economic value varies between 5858.04 ± 27.62 USD/ha in Batoufam sacred forest and 3788.51 ± 11.26 USD/ha in Bandrefam sacred forest. The number of individuals and small-diameter trees has little influence on the carbon stocks in the trees. Medium-diameter trees store the most carbon, and very large-diameter trees, which are very poorly represented, store less carbon. In another way, wood density and the basal areas influence the carbon storage of the trees.
