In order to assess the climatical and ecological effect which returned the farmland to pasture or forest, the vegetation and crop in Northwest China with suitable threshold value were classified in this experiment by ...In order to assess the climatical and ecological effect which returned the farmland to pasture or forest, the vegetation and crop in Northwest China with suitable threshold value were classified in this experiment by using multi-temporal SPOT/VEGETATION dada and combing supervised classification with unsupervised classification. Compared with the data from Statistical Department and actual investigation, the precision of the classified result was above 85%.展开更多
Terrestrial ecosystems heavily depend on vegetation,which responds to carbon dioxide(CO_(2))fertilization in hot and humid regions.The subtropical humid karst region is a hot and humid region;whether and to what exten...Terrestrial ecosystems heavily depend on vegetation,which responds to carbon dioxide(CO_(2))fertilization in hot and humid regions.The subtropical humid karst region is a hot and humid region;whether and to what extent CO_(2)fertilization affects vegetation changes in such regions remains unclear.In this study,we investigated the degree to which CO_(2)fertilization influences vegetation changes,along with their spatial and temporal differences,in the subtropical humid karst region using time-lag effect analysis,a random forest model,and multiple regression analysis.Results showed that CO_(2)fertilization plays an important role in vegetation changes,exhibiting clear spatial variations across different geomorphological zones,with its degree of influence ranging mainly between 11%and 25%.The highest contribution of CO_(2)fertilization was observed in the karst basin and non-karstic region,whereas the lowest contribution was found in the karst plateau region.Previous studies have primarily attributed vegetation changes in subtropical humid karst region to ecological engineering,leading to an overestimation of its contribution to these changes.The findings of this study enhance the understanding of the mechanism of vegetation changes in humid karst region and provide theoretical and practical insights for ecological and environmental protection in these regions.展开更多
This research aims to analyse the spatio-temporal changes of vegetation cover in coastal regions of Char Fasson and Galachipa Upazila, Bangladesh for a period of 30 years (1994-2024) based on Landsat satellite imagery...This research aims to analyse the spatio-temporal changes of vegetation cover in coastal regions of Char Fasson and Galachipa Upazila, Bangladesh for a period of 30 years (1994-2024) based on Landsat satellite imagery and NDVI. Through the evaluation of NDVI this paper classifies vegetation as no water/bare vegetation, slightly densed vegetation, moderately densed vegetation, and highly densed vegetation. The findings reveal significant fluctuations in vegetation cover: from 1994 to 2004, there has been an increase in vegetation density implying that afforestation has created more moderate and highly densed vegetation out of density vegetation. However, between 2004 and 2014, vegetation cover decreased because some cyclones, like Sidr and Aila, affected the coastal forest of Bangladesh. Other attempts to afforestation supported improved coverage from vegetation between 2014 and 2024. These findings provide clear evidence of the sustainable benefits of coastal afforestation in the reduction of coastal erosion and storm surges that affect vegetation and coasts. Knowledge gained in this research is highly useful to the environmental planners on recommendations for sustainable land uses and preservation to build up ecological stability in Bangladesh weak coastal areas.展开更多
Understanding the characteristics and driving factors behind changes in vegetation ecosystem resilience is crucial for mitigating both current and future impacts of climate change. Despite recent advances in resilienc...Understanding the characteristics and driving factors behind changes in vegetation ecosystem resilience is crucial for mitigating both current and future impacts of climate change. Despite recent advances in resilience research, significant knowledge gaps remain regarding the drivers of resilience changes. In this study, we investigated the dynamics of ecosystem resilience across China and identified potential driving factors using the kernel normalized difference vegetation index(kNDVI) from 2000 to 2020. Our results indicate that vegetation resilience in China has exhibited an increasing trend over the past two decades, with a notable breakpoint occurring around 2012. We found that precipitation was the dominant driver of changes in ecosystem resilience, accounting for 35.82% of the variation across China, followed by monthly average maximum temperature(Tmax) and vapor pressure deficit(VPD), which explained 28.95% and 28.31% of the variation, respectively. Furthermore, we revealed that daytime and nighttime warming has asymmetric impacts on vegetation resilience, with temperature factors such as Tmin and Tmax becoming more influential, while the importance of precipitation slightly decreases after the resilience change point. Overall, our study highlights the key roles of water availability and temperature in shaping vegetation resilience and underscores the asymmetric effects of daytime and nighttime warming on ecosystem resilience.展开更多
The hydrodynamic response of overland flow to vegetation coverage on convex slopes remains inadequately quantified despite it is critical for soil erosion control in terrains dominated by such topography.This study sy...The hydrodynamic response of overland flow to vegetation coverage on convex slopes remains inadequately quantified despite it is critical for soil erosion control in terrains dominated by such topography.This study systematically investigated the influence of varying vegetation coverage(0%,1.08%,3.24%,4.69%and 9.81%)on the hydrodynamic characteristics of convex slopes through indoor flume experiments under diverse flow discharges(5.5-13.5 m^(3)/h)and slopes(5°-25°).The results revealed three key hydrodynamic mechanisms:(1)Flow retardation and energy dissipation:Increasing vegetation coverage significantly reduced overland flow velocity and promoted higher flow depth,thereby enhancing water retention and energy dissipation.Both stream power(Ω)and unit stream power(ω)declined by 13.9%-30.1%compared to bare slopes.(2)Flow Regime Transition:Froude number(Fr)decreased with increasing vegetation coverage,promoting the transition from supercritical to subcritical flow.The Reynolds number(Re)consistently exceeded 500,indicating the absence of laminar flow.(3)Modification of flow resistance:Vegetation resistance increased nonlinearly with coverage.Maximum bed shear stress was observed at 4.69%coverage(23.5%higher than bare slopes).However,Manning’s(n)and Darcy-Weisbach(f)coefficients did not correlate clearly with Re,indicating that vegetation coverage and slope type feedback significantly change flow resistance mechanisms.展开更多
Climate change in High Mountain Asia(HMA)is characterized by elevation dependence,which results in vertical zoning of vegetation distribution.However,few studies have been conducted on the distribution patterns of veg...Climate change in High Mountain Asia(HMA)is characterized by elevation dependence,which results in vertical zoning of vegetation distribution.However,few studies have been conducted on the distribution patterns of vegetation,the response of vegetation to climate change,and the key climatic control factors of vegetation along the elevation gradient in this region.In this study,based on the Normalized Difference Vegetation index(NDVI),we investigated the evolution pattern of vegetation in HMA during 2001-2020 using linear trend and Bayesian Estimator of Abrupt change,Seasonality,and Trend(BEAST)methods.Pearson correlation analysis and partial correlation analysis were used to explore the response relationship between vegetation and climatic factors along the elevation gradient.Path analysis was employed to quantitatively reveal the dominant climatic factors affecting vegetation distribution along the elevation gradient.The results showed that NDVI in HMA increased at a rate of 0.011/10a from 2001 to 2020,and the rate of increase abruptly slowed down after 2017.NDVI showed a fluctuating increase at elevation zones 1-2(<2500 m)and then decreased at elevation zones 3-9(2500-6000 m)with the increase of elevation.NDVI was most sensitive to precipitation and temperature at a 1-month lag.With the increase of elevation,the positive response relationship of NDVI with precipitation gradually weakened,while that of NDVI with temperature was the opposite.The total effect coefficient of precipitation(0.95)on vegetation was larger than that of temperature(0.87),indicating that precipitation is the dominant control factor affecting vegetation growth.Spacially,vegetation growth is jointly influenced by precipitation and temperature,but the influence of precipitation on vegetation growth is dominant at each elevation zone.The results of this study contribute to understanding how the elevation gradient effect influences the response of vegetation to climate change in alpine ecosystems.展开更多
This study investigates the impact of vegetation-climate feedback on the global land monsoon system during the Last Interglacial(LIG,127000 years BP)and the mid-Holocene(MH,6000 years BP)using the earth system model E...This study investigates the impact of vegetation-climate feedback on the global land monsoon system during the Last Interglacial(LIG,127000 years BP)and the mid-Holocene(MH,6000 years BP)using the earth system model EC-Earth3.Our findings indicate that vegetation changes significantly influence the global monsoon area and precipitation patterns,especially in the North African and Indian monsoon regions.The North African monsoon region experienced the most substantial increase in vegetation during both the LIG and MH,resulting in significant increases in monsoonal precipitation by 9.8%and 6.0%,respectively.The vegetation feedback also intensified the Saharan Heat Low,strengthened monsoonal flows,and enhanced precipitation over the North African monsoon region.In contrast,the Indian monsoon region exhibited divergent responses to vegetation changes.During the LIG,precipitation in the Indian monsoon region decreased by 2.2%,while it increased by 1.6%during the MH.These differences highlight the complex and region-specific impacts of vegetation feedback on monsoon systems.Overall,this study demonstrates that vegetation feedback exerts distinct influences on the global monsoon during the MH and LIG.These findings highlight the importance of considering vegetation-climate feedback in understanding past monsoon variability and in predicting future climate change impacts on monsoon systems.展开更多
A comprehensive understanding of vegetation responses to climate extremes is essential for predicting ecological risks.The Tianshan Mountains,the world's largest arid mountain system,are ecologically vulnerable to...A comprehensive understanding of vegetation responses to climate extremes is essential for predicting ecological risks.The Tianshan Mountains,the world's largest arid mountain system,are ecologically vulnerable to climate extremes,yet the spatiotemporal heterogeneity of vegetation responses is not well understood.To address this,we assessed changes in vegetation phenophases using the green-up date(GUD)and the monthly maximum vegetation index(MVI).Their relationship with climate extremes across seasons and geographic units was analyzed using Classification and Regression Tree and Principal Component Analysis.Results indicate that GUD advanced by 0.276 days/year,with MVI increasing in spring and decreasing in summer.On a yearly scale,nighttime heatwaves advanced GUD in all vegetation types at lower altitudes with higher snow cover,whereas daytime heatwaves delayed GUD in grasslands.On a monthly scale,early spring heatwaves generally benefitted vegetation,with positive effects decreasing from forests to grasslands:forests benefitted from March to May,forest-grassland from March to April,and grasslands only in March.By late summer,heatwaves were negatively correlated with MVI across all vegetation types.This study highlights the complex responses of vegetation to climate extremes and underscores the vulnerability of high-altitude,low snow-covered grasslands,which is crucial for guiding restoration efforts.展开更多
Tibetan Plateau,as one of the most carbon intensive regions in China,is crucial in the carbon cycle,and accurately estimating its vegetation carbon density(C_(VEG))is essential for assessing regional and national carb...Tibetan Plateau,as one of the most carbon intensive regions in China,is crucial in the carbon cycle,and accurately estimating its vegetation carbon density(C_(VEG))is essential for assessing regional and national carbon balance.However,the spatial distribution of regional C_(VEG)is not available remains highly uncertain due to lack of systematic research,especially for different organs.Here,we investigated the spatial distribution patterns and driving factors of C_(VEG)among different plant organs(leaf,branch,trunk and root)by systematically field grid-sampling 2040 field-plots of plant communities over the Tibetan Plateau from 2019 to 2020.The results showed that the carbon content of plant organs ranged from 255.53 to 515.58 g kg^(-1),with the highest in branches and the lowest in roots.Among the different plant functional groups,the highest C_(VEG)was found in evergreen coniferous forests,and the lowest in desert grasslands,with an average C_(VEG)of 1603.98 g m^(-2).C_(VEG)increased spatially from northwest to southeast over the Tibetan Plateau,with MAP being the dominant factor.Furthermore,the total vegetation carbon stock on the Tibetan Plateau was estimated to be 1965.62 Tg for all vegetation types.Based on the comprehensive field survey dataset,the Random Forest model effectively predicted and mapped the spatial distribution of C_(VEG)(including aboveground,belowground,and the total biomass carbon density)over the Tibetan Plateau with notable accuracy(validation R2 values were 71%,56%,and 64%for C_(AGB),C_(BGB),and C_(VEG),respectively)at a spatial resolution of 1 km×1 km.Our findings can help improve the accuracy of regional carbon stock estimations and provide parameters for carbon cycle model optimization and remote sensing calibration in the future.展开更多
Investigating the spatial distribution of vegetation in monsoonal-climate-dominated high mountain area and detecting its changes that occurred in paraglacial areas is crucial for understanding the cascading environmen...Investigating the spatial distribution of vegetation in monsoonal-climate-dominated high mountain area and detecting its changes that occurred in paraglacial areas is crucial for understanding the cascading environmental effects of shrinking glaciers.We used Landsat images from 1994 to 2022,obtained landscape distribution patterns of glaciers and vegetation in Mt.Gongga,and detected paraglacial vegetation changes under deglaciating environments.We observed there is a pronounced difference in glacier and vegetation coverage between the eastern and western slopes in Mt.Gongga,the eastern slope occupies 78.68% of vegetation area and 61.02% of glacier area,whilst the western slope occupies lower area.Exaggerate warming accelerated glacier retreat,and proglacial areas are generally characterized by very fast primary succession,resulting in an increase of 0.32 km^(2)in vegetation area within two typical glacier forefields on the eastern slope.The phenomenon of paraglacial slope failure following glacier thinning is widespread in Mt.Gongga,resulting in vegetation area decreased by 0.34 km^(2).Concurrently,the fast retreat of glaciers and changes in ice surface geomorphology have caused rapid dynamics in supraglacial vegetation developed on its lower debris-covered sections.We suggested that rapid changes of temperate glaciers can significantly influence paraglacial landform,leading to rapid dynamic changes of vegetation in a balance between colonization and destruction.展开更多
Numerous steep slopes resulting from infrastructure construction drastically affect ecological landscapes.The vegetation concrete(VC)ecological slope protection method efficiently rehabilitates slope ecosystems.Despit...Numerous steep slopes resulting from infrastructure construction drastically affect ecological landscapes.The vegetation concrete(VC)ecological slope protection method efficiently rehabilitates slope ecosystems.Despite advancements in the construction process,the standard irrigation maintenance method for slope vegetation remains unspecified.Three principal factors affecting VC water diffusion from production to application are:site conditions,irrigation design parameters,and substrate preparation standards.This study employed an energy-efficient porous ceramic emitter in buried irrigation equipment to investigate the effect of slope,water head,and bulk density on water diffusion patterns,analyzing both apparent and fine-scale dynamics through laboratory experiments and numerical simulations.The results demonstrated a positive correlation between slope and water head with the distance of wetted front.However,bulk density showed a negative correlation.The power function exhibited optimal fitting for wetted front advancement over time,with the'power0-type'function most precisely representing the VC wetted front movement(R2>0.99).The water content,utilized to assess the precision of the HYDRUS simulation grounded in the van Genuchten model and the centrifuge method(p<0.05),exhibited discrepancies with the wetted front while revealing a robust logistic correlation with irrigation duration.The root-mean-square error,mean absolute error,and percent bias between the observed and simulated water contents were 0.85%,0.74%,and-3.50%,respectively.The VC soil hydrodynamic parameters,specifically the inverse of the intake suction,the pore-size distribution exponent,and the shape factor,were quantified as 0.019,1.329,and 0.248,respectively.Water head significantly influenced water transport more than slope;yet,irrespective of their combination,extended irrigation generally intensified the'instability'of water diffusion.To regulate slope substrate moisture through water diffusion in practical conditions,it is advisable to prioritize the modification of VC preparations,followed by the design of an appropriate irrigation pressure,and finally the selection of an optimal location for the irrigator's deployment.The findings of water diffusion through a semi-rigid composite substrate broaden the applicability of soil hydrodynamics theory to composite soils and enhance its implications through conceptual and practical advice.展开更多
In a warming world,climate extremes tend to be more frequent and intense.The exceptional response of ecosystems triggered by extreme climate events under a warmer and wetter climate in northwest China(NWC)has aroused ...In a warming world,climate extremes tend to be more frequent and intense.The exceptional response of ecosystems triggered by extreme climate events under a warmer and wetter climate in northwest China(NWC)has aroused growing concern.However,understanding the responses of vegetation to climate extremes from the compound events perspective remains challenging.In this study,we identify the climate dynamics in NWC during 1971–2020 based on daily meteorological observations,focusing on the changes in compound hot-dry events(CHDEs)during the warmer and wetter period.We further explore the effects of CHDEs on vegetation by examining vegetation anomalies and recovery time using daily gross primary productivity(GPP)data.The results show a clear warmer and wetter period in NWC during 2000–2020.No signs of a hiatus in CHDEs increase are observed during this period,and even the duration of CHDEs in western NWC keeps showing an increasing tendency.Vegetation in eastern NWC,with a lower probability of GPP anomalies,exhibits stronger resistance of ecosystems to CHDEs than in western NWC.In NWC,vegetation typically returns to its normal state in 5.50 days on average,but exhibits greater resilience in the western region,where it takes less recovery time(4.82 days).Vegetation in the central region shows the lowest probability of GPP anomalies and relatively longer recovery time,likely due to its higher altitudes.Our research underscores the imperative to address the considerable impacts of CHDEs on vegetation growth even as the regional climate becomes increasingly warmer and wetter.展开更多
Accurate and timely estimation of above-ground biomass is crucial for understanding crop growth dynamics,optimizing agricultural input management,and assessing productivity in sustainable farming practices.However,con...Accurate and timely estimation of above-ground biomass is crucial for understanding crop growth dynamics,optimizing agricultural input management,and assessing productivity in sustainable farming practices.However,conventional biomass assessments are destructive and resource-intensive.In contrast,remote sensing techniques,particularly those utilizing low-altitude unmanned aerial vehicles,provide a non-destructive approach to collect imagery data on plant canopy features,including spectral reflectance and structural details at any stage of the crop life cycle.This study explores the potential visible-light-derived vegetative indices to improve biomass prediction during the flowering period of buckwheat(Fagopyrum tataricum).Red,green,and blue(RGB)images of buckwheat were acquired during peak flowering,using a DJI P4 multispectral Drone.From the analysis of those images,four vegetative indices were calculated.Aboveground fresh biomass was harvested and measured on 14 September 2024.The results showed negative correlations between the green-band based excess green(ExG),excess green minus excess red(ExGR),and green leaf index(GLI)indices and the fresh above-ground biomass of buckwheat,while the red band-based excess red(ExR)index showed an insignificant positive correlation at p<0.10.An investigation into greenband-based vegetation indices(VIs)for estimating fresh biomass revealed significant negative correlations during the experimental period.This unexpected inverse relationship is attributed to spectral interference from abundant white flowers during the flowering stage,where the high reflectance of white petals masked the green vegetation signal.Consequently,these green-band VIs demonstrated limited predictive power for biomass under such conditions,indicating that their utility is compromised when floral reflectance is dominant.Therefore,we suggest that further experiments are required to validate this relationship and improve the estimation of fresh above-ground biomass in white-flowered buckwheat plants.展开更多
Various types of vegetative cover,predominantly woodlands,shrublands,and grasslands,provide a range of habitats for urban organisms and are the main contributors to urban ecosystem services.The goal of this study was ...Various types of vegetative cover,predominantly woodlands,shrublands,and grasslands,provide a range of habitats for urban organisms and are the main contributors to urban ecosystem services.The goal of this study was to assess the potential of different vegetation types in maintaining and enhancing bryophyte diversity in urban areas.Bryophytes,small non-vascular plants,in woodlands,shrublands,and grasslands in Hefei city(eastern China)were investigated,and their species richness,abundance,community composition and relationships with habitat characteristics were analysed.The results show that urban woodlands had the highest species richness and abundance of bryophytes and a distinct community composition compared with the other vegetation types.Relative light intensity had a positive effect on species richness in urban woodlands,whereas litter cover had a negative effect on abundance.Shrub,grass and litter covers,and relative air humidity were the main factors driving the differences in bryophyte species composition between woodlands and other vegetation types.Therefore,owing to their high potential to maintain bryophyte diversity,woodlands should receive increased attention during the construction of urban green spaces.In addition,promoting structural heterogeneity and increasing light availability would be beneficial to bryophyte species diversity.展开更多
The Monte Desert is characterized by a great diversity of landforms created with fluvial,alluvial which the vegetation patterns are related to.The present work has the following objectives:(1) determine whether topogr...The Monte Desert is characterized by a great diversity of landforms created with fluvial,alluvial which the vegetation patterns are related to.The present work has the following objectives:(1) determine whether topographical attributes,surface characteristics,soil properties and vegetation patterns vary between alluvial landforms,and(2) define whether morphometric,soil and surface properties influence vegetation patterns along alluvial landscape.Morphometric data were obtained by processing a 5 m digital elevation model.The coverage of rock fragments,fine sediments and mulch was quantified.Observations and descriptions of the soil profiles were restricted to the uppermost 50 cm.Vegetation properties were calculated using a Point Quadrat Method.The relationship between variables was evaluated through multivariate statistical analysis.The main results show the presence of 45 plant species distributed in 19 families,where shrubs are dominant.The wind effect,topographic wetness and dissection of the landscape are limiting factors of diversity.The coverage of superficial rock fragments influence vegetation coverage through the distribution and availability of rainwater.Furthermore,the different soil textures reveal that the silt content favors an increase in vegetation coverage.The presence of V horizon could condition the installation and development of vegetation in the early stages of growth.展开更多
The Loess Plateau region in China is characterized by a fragile environment,where vegetation is susceptible to both natural variations and anthropogenic influences.Previous research has indicated a greening trend in v...The Loess Plateau region in China is characterized by a fragile environment,where vegetation is susceptible to both natural variations and anthropogenic influences.Previous research has indicated a greening trend in vegetation across the Loess Plateau over the past two decades.However,the specific contributions of natural and anthropogenic drivers,both individually and interactively,to vegetation distribution remain unclear.To address this gap,we conducted a study using Shaanxi Province as a case area.Utilizing multisource data,we employed the Geographical Detector Model(GDM)to analyze the impacts of natural and human related factors on vegetation distribution.Our analysis revealed that the average NDVI(Normalized Difference Vegetation Index)increased at a rate of 0.006 per year from 2000 to 2021.Notably,88.8%of the region experienced vegetation greening,while 4.5%showed significant declines in NDVI,particularly in areas,such as Xi'an,Weinan,Baoji,Hanzhong,and Ankang.Furthermore,NDVI trend projections suggest that the area undergoing vegetation degradation may surpass the area showing improvement in the future.The study identified that vegetation distribution was influenced by both natural and anthropogenic factors for the whole study area.Precipitation,surface types and land use type were the primary factors with q values above 0.5.During the study period,impacts of GDP,nighttime lights and population density among anthropogenic factors on vegetation distribution increased by 130%,125%and 41%,respectively.Conversely,except for slope and aspect,natural factors'influence on vegetation distribution declined by 5%to 26%.The impact of driving factors on NDVI distribution varied across ecological regions.In Fenwei Basin Agro-Ecoregion(EcoregionⅢ),the influence of anthropogenic factors on vegetation distribution was greater than that in the other three ecoregions.Precipitation primarily affected the vegetation distribution in Loess Plateau Agricultural and Grassland Ecoregion(EcoregionⅡ).Additionally,the combined interactive effects of factors had a stronger influence on NDVI distribution than any single factor.These findings provide valuable insights for local governments in Shaanxi Province to develop targeted ecological restoration and environmental management policies.展开更多
基金Supported by the National Natural Science Foundation of China(No.40675071)~~
文摘In order to assess the climatical and ecological effect which returned the farmland to pasture or forest, the vegetation and crop in Northwest China with suitable threshold value were classified in this experiment by using multi-temporal SPOT/VEGETATION dada and combing supervised classification with unsupervised classification. Compared with the data from Statistical Department and actual investigation, the precision of the classified result was above 85%.
基金National Natural Science Foundation of China,No.41761003The Karst Science Research Center of Guizhou Province,No.U1812401。
文摘Terrestrial ecosystems heavily depend on vegetation,which responds to carbon dioxide(CO_(2))fertilization in hot and humid regions.The subtropical humid karst region is a hot and humid region;whether and to what extent CO_(2)fertilization affects vegetation changes in such regions remains unclear.In this study,we investigated the degree to which CO_(2)fertilization influences vegetation changes,along with their spatial and temporal differences,in the subtropical humid karst region using time-lag effect analysis,a random forest model,and multiple regression analysis.Results showed that CO_(2)fertilization plays an important role in vegetation changes,exhibiting clear spatial variations across different geomorphological zones,with its degree of influence ranging mainly between 11%and 25%.The highest contribution of CO_(2)fertilization was observed in the karst basin and non-karstic region,whereas the lowest contribution was found in the karst plateau region.Previous studies have primarily attributed vegetation changes in subtropical humid karst region to ecological engineering,leading to an overestimation of its contribution to these changes.The findings of this study enhance the understanding of the mechanism of vegetation changes in humid karst region and provide theoretical and practical insights for ecological and environmental protection in these regions.
文摘This research aims to analyse the spatio-temporal changes of vegetation cover in coastal regions of Char Fasson and Galachipa Upazila, Bangladesh for a period of 30 years (1994-2024) based on Landsat satellite imagery and NDVI. Through the evaluation of NDVI this paper classifies vegetation as no water/bare vegetation, slightly densed vegetation, moderately densed vegetation, and highly densed vegetation. The findings reveal significant fluctuations in vegetation cover: from 1994 to 2004, there has been an increase in vegetation density implying that afforestation has created more moderate and highly densed vegetation out of density vegetation. However, between 2004 and 2014, vegetation cover decreased because some cyclones, like Sidr and Aila, affected the coastal forest of Bangladesh. Other attempts to afforestation supported improved coverage from vegetation between 2014 and 2024. These findings provide clear evidence of the sustainable benefits of coastal afforestation in the reduction of coastal erosion and storm surges that affect vegetation and coasts. Knowledge gained in this research is highly useful to the environmental planners on recommendations for sustainable land uses and preservation to build up ecological stability in Bangladesh weak coastal areas.
基金National Key Research and Development Program,No.2021xjkk0303。
文摘Understanding the characteristics and driving factors behind changes in vegetation ecosystem resilience is crucial for mitigating both current and future impacts of climate change. Despite recent advances in resilience research, significant knowledge gaps remain regarding the drivers of resilience changes. In this study, we investigated the dynamics of ecosystem resilience across China and identified potential driving factors using the kernel normalized difference vegetation index(kNDVI) from 2000 to 2020. Our results indicate that vegetation resilience in China has exhibited an increasing trend over the past two decades, with a notable breakpoint occurring around 2012. We found that precipitation was the dominant driver of changes in ecosystem resilience, accounting for 35.82% of the variation across China, followed by monthly average maximum temperature(Tmax) and vapor pressure deficit(VPD), which explained 28.95% and 28.31% of the variation, respectively. Furthermore, we revealed that daytime and nighttime warming has asymmetric impacts on vegetation resilience, with temperature factors such as Tmin and Tmax becoming more influential, while the importance of precipitation slightly decreases after the resilience change point. Overall, our study highlights the key roles of water availability and temperature in shaping vegetation resilience and underscores the asymmetric effects of daytime and nighttime warming on ecosystem resilience.
基金financially supported by the National Natural Science Foundation of China(Grant NO.52279056)Inner Mongolia open list project(Grant NO.2024JBGS0023)。
文摘The hydrodynamic response of overland flow to vegetation coverage on convex slopes remains inadequately quantified despite it is critical for soil erosion control in terrains dominated by such topography.This study systematically investigated the influence of varying vegetation coverage(0%,1.08%,3.24%,4.69%and 9.81%)on the hydrodynamic characteristics of convex slopes through indoor flume experiments under diverse flow discharges(5.5-13.5 m^(3)/h)and slopes(5°-25°).The results revealed three key hydrodynamic mechanisms:(1)Flow retardation and energy dissipation:Increasing vegetation coverage significantly reduced overland flow velocity and promoted higher flow depth,thereby enhancing water retention and energy dissipation.Both stream power(Ω)and unit stream power(ω)declined by 13.9%-30.1%compared to bare slopes.(2)Flow Regime Transition:Froude number(Fr)decreased with increasing vegetation coverage,promoting the transition from supercritical to subcritical flow.The Reynolds number(Re)consistently exceeded 500,indicating the absence of laminar flow.(3)Modification of flow resistance:Vegetation resistance increased nonlinearly with coverage.Maximum bed shear stress was observed at 4.69%coverage(23.5%higher than bare slopes).However,Manning’s(n)and Darcy-Weisbach(f)coefficients did not correlate clearly with Re,indicating that vegetation coverage and slope type feedback significantly change flow resistance mechanisms.
基金supported by the Xinjiang Uygur Autonomous Region Major Scientific and Technological Special Project Research and Demonstration on the Development Model of Ecological Agriculture and Efficient Utilization of Soil and Water Resources in Modern Irrigation Areas(2023A02002-1).
文摘Climate change in High Mountain Asia(HMA)is characterized by elevation dependence,which results in vertical zoning of vegetation distribution.However,few studies have been conducted on the distribution patterns of vegetation,the response of vegetation to climate change,and the key climatic control factors of vegetation along the elevation gradient in this region.In this study,based on the Normalized Difference Vegetation index(NDVI),we investigated the evolution pattern of vegetation in HMA during 2001-2020 using linear trend and Bayesian Estimator of Abrupt change,Seasonality,and Trend(BEAST)methods.Pearson correlation analysis and partial correlation analysis were used to explore the response relationship between vegetation and climatic factors along the elevation gradient.Path analysis was employed to quantitatively reveal the dominant climatic factors affecting vegetation distribution along the elevation gradient.The results showed that NDVI in HMA increased at a rate of 0.011/10a from 2001 to 2020,and the rate of increase abruptly slowed down after 2017.NDVI showed a fluctuating increase at elevation zones 1-2(<2500 m)and then decreased at elevation zones 3-9(2500-6000 m)with the increase of elevation.NDVI was most sensitive to precipitation and temperature at a 1-month lag.With the increase of elevation,the positive response relationship of NDVI with precipitation gradually weakened,while that of NDVI with temperature was the opposite.The total effect coefficient of precipitation(0.95)on vegetation was larger than that of temperature(0.87),indicating that precipitation is the dominant control factor affecting vegetation growth.Spacially,vegetation growth is jointly influenced by precipitation and temperature,but the influence of precipitation on vegetation growth is dominant at each elevation zone.The results of this study contribute to understanding how the elevation gradient effect influences the response of vegetation to climate change in alpine ecosystems.
基金supported by the Swedish Research Council(Vetenskapsradet,Grant No.202203129)the Project of Youth Science and Technology Fund of Gansu Province(Grant No.24JRRA439)partially funded by the Swedish Research Council(Vetenskapsradet,Grant No.2022-06725)。
文摘This study investigates the impact of vegetation-climate feedback on the global land monsoon system during the Last Interglacial(LIG,127000 years BP)and the mid-Holocene(MH,6000 years BP)using the earth system model EC-Earth3.Our findings indicate that vegetation changes significantly influence the global monsoon area and precipitation patterns,especially in the North African and Indian monsoon regions.The North African monsoon region experienced the most substantial increase in vegetation during both the LIG and MH,resulting in significant increases in monsoonal precipitation by 9.8%and 6.0%,respectively.The vegetation feedback also intensified the Saharan Heat Low,strengthened monsoonal flows,and enhanced precipitation over the North African monsoon region.In contrast,the Indian monsoon region exhibited divergent responses to vegetation changes.During the LIG,precipitation in the Indian monsoon region decreased by 2.2%,while it increased by 1.6%during the MH.These differences highlight the complex and region-specific impacts of vegetation feedback on monsoon systems.Overall,this study demonstrates that vegetation feedback exerts distinct influences on the global monsoon during the MH and LIG.These findings highlight the importance of considering vegetation-climate feedback in understanding past monsoon variability and in predicting future climate change impacts on monsoon systems.
基金National Natural Science Foundation of China,No.41871025The Third Xinjiang Scientific Expedition Program,No.2022xjkk0100+1 种基金The Natural Science Foundation of Shanghai,No.24ZR1440400The Young Talent Development Program in the Humanities at Shanghai Jiao Tong University,No.2025QN034。
文摘A comprehensive understanding of vegetation responses to climate extremes is essential for predicting ecological risks.The Tianshan Mountains,the world's largest arid mountain system,are ecologically vulnerable to climate extremes,yet the spatiotemporal heterogeneity of vegetation responses is not well understood.To address this,we assessed changes in vegetation phenophases using the green-up date(GUD)and the monthly maximum vegetation index(MVI).Their relationship with climate extremes across seasons and geographic units was analyzed using Classification and Regression Tree and Principal Component Analysis.Results indicate that GUD advanced by 0.276 days/year,with MVI increasing in spring and decreasing in summer.On a yearly scale,nighttime heatwaves advanced GUD in all vegetation types at lower altitudes with higher snow cover,whereas daytime heatwaves delayed GUD in grasslands.On a monthly scale,early spring heatwaves generally benefitted vegetation,with positive effects decreasing from forests to grasslands:forests benefitted from March to May,forest-grassland from March to April,and grasslands only in March.By late summer,heatwaves were negatively correlated with MVI across all vegetation types.This study highlights the complex responses of vegetation to climate extremes and underscores the vulnerability of high-altitude,low snow-covered grasslands,which is crucial for guiding restoration efforts.
基金supported by CAS Project for Young Scientists in Basic Research(YSBR-037)the National Natural Science Foundation of China(42141004,32430067)by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP,2019QZKK060602).
文摘Tibetan Plateau,as one of the most carbon intensive regions in China,is crucial in the carbon cycle,and accurately estimating its vegetation carbon density(C_(VEG))is essential for assessing regional and national carbon balance.However,the spatial distribution of regional C_(VEG)is not available remains highly uncertain due to lack of systematic research,especially for different organs.Here,we investigated the spatial distribution patterns and driving factors of C_(VEG)among different plant organs(leaf,branch,trunk and root)by systematically field grid-sampling 2040 field-plots of plant communities over the Tibetan Plateau from 2019 to 2020.The results showed that the carbon content of plant organs ranged from 255.53 to 515.58 g kg^(-1),with the highest in branches and the lowest in roots.Among the different plant functional groups,the highest C_(VEG)was found in evergreen coniferous forests,and the lowest in desert grasslands,with an average C_(VEG)of 1603.98 g m^(-2).C_(VEG)increased spatially from northwest to southeast over the Tibetan Plateau,with MAP being the dominant factor.Furthermore,the total vegetation carbon stock on the Tibetan Plateau was estimated to be 1965.62 Tg for all vegetation types.Based on the comprehensive field survey dataset,the Random Forest model effectively predicted and mapped the spatial distribution of C_(VEG)(including aboveground,belowground,and the total biomass carbon density)over the Tibetan Plateau with notable accuracy(validation R2 values were 71%,56%,and 64%for C_(AGB),C_(BGB),and C_(VEG),respectively)at a spatial resolution of 1 km×1 km.Our findings can help improve the accuracy of regional carbon stock estimations and provide parameters for carbon cycle model optimization and remote sensing calibration in the future.
基金Science and Technology Research Program of Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,No.IMHE-CXTD-02,No.IMHE-ZDRW-06。
文摘Investigating the spatial distribution of vegetation in monsoonal-climate-dominated high mountain area and detecting its changes that occurred in paraglacial areas is crucial for understanding the cascading environmental effects of shrinking glaciers.We used Landsat images from 1994 to 2022,obtained landscape distribution patterns of glaciers and vegetation in Mt.Gongga,and detected paraglacial vegetation changes under deglaciating environments.We observed there is a pronounced difference in glacier and vegetation coverage between the eastern and western slopes in Mt.Gongga,the eastern slope occupies 78.68% of vegetation area and 61.02% of glacier area,whilst the western slope occupies lower area.Exaggerate warming accelerated glacier retreat,and proglacial areas are generally characterized by very fast primary succession,resulting in an increase of 0.32 km^(2)in vegetation area within two typical glacier forefields on the eastern slope.The phenomenon of paraglacial slope failure following glacier thinning is widespread in Mt.Gongga,resulting in vegetation area decreased by 0.34 km^(2).Concurrently,the fast retreat of glaciers and changes in ice surface geomorphology have caused rapid dynamics in supraglacial vegetation developed on its lower debris-covered sections.We suggested that rapid changes of temperate glaciers can significantly influence paraglacial landform,leading to rapid dynamic changes of vegetation in a balance between colonization and destruction.
基金supported by the National Natural Science Foundation of China(Grant No.41925030)the Nyingchi National Sustainable Development Experimental Zone Project(2023-SYQ-007)the Science and Technology Research Program of Institute of Mountain Hazards and Environment,Chinese Academy of Sciences(Grant No.IMHE-ZDRW-02)。
文摘Numerous steep slopes resulting from infrastructure construction drastically affect ecological landscapes.The vegetation concrete(VC)ecological slope protection method efficiently rehabilitates slope ecosystems.Despite advancements in the construction process,the standard irrigation maintenance method for slope vegetation remains unspecified.Three principal factors affecting VC water diffusion from production to application are:site conditions,irrigation design parameters,and substrate preparation standards.This study employed an energy-efficient porous ceramic emitter in buried irrigation equipment to investigate the effect of slope,water head,and bulk density on water diffusion patterns,analyzing both apparent and fine-scale dynamics through laboratory experiments and numerical simulations.The results demonstrated a positive correlation between slope and water head with the distance of wetted front.However,bulk density showed a negative correlation.The power function exhibited optimal fitting for wetted front advancement over time,with the'power0-type'function most precisely representing the VC wetted front movement(R2>0.99).The water content,utilized to assess the precision of the HYDRUS simulation grounded in the van Genuchten model and the centrifuge method(p<0.05),exhibited discrepancies with the wetted front while revealing a robust logistic correlation with irrigation duration.The root-mean-square error,mean absolute error,and percent bias between the observed and simulated water contents were 0.85%,0.74%,and-3.50%,respectively.The VC soil hydrodynamic parameters,specifically the inverse of the intake suction,the pore-size distribution exponent,and the shape factor,were quantified as 0.019,1.329,and 0.248,respectively.Water head significantly influenced water transport more than slope;yet,irrespective of their combination,extended irrigation generally intensified the'instability'of water diffusion.To regulate slope substrate moisture through water diffusion in practical conditions,it is advisable to prioritize the modification of VC preparations,followed by the design of an appropriate irrigation pressure,and finally the selection of an optimal location for the irrigator's deployment.The findings of water diffusion through a semi-rigid composite substrate broaden the applicability of soil hydrodynamics theory to composite soils and enhance its implications through conceptual and practical advice.
基金supported by the National Natural Science Foundation of China(Grant No.42371423)the Fundamental Research Funds for the Central Universities(Grant No.2042023kfyq04)+1 种基金the China Postdoctoral Science Foundation(Grant No.2023M742682)the Postdoctoral Fellowship Program of CPSF(Grant No.GZB20230539).
文摘In a warming world,climate extremes tend to be more frequent and intense.The exceptional response of ecosystems triggered by extreme climate events under a warmer and wetter climate in northwest China(NWC)has aroused growing concern.However,understanding the responses of vegetation to climate extremes from the compound events perspective remains challenging.In this study,we identify the climate dynamics in NWC during 1971–2020 based on daily meteorological observations,focusing on the changes in compound hot-dry events(CHDEs)during the warmer and wetter period.We further explore the effects of CHDEs on vegetation by examining vegetation anomalies and recovery time using daily gross primary productivity(GPP)data.The results show a clear warmer and wetter period in NWC during 2000–2020.No signs of a hiatus in CHDEs increase are observed during this period,and even the duration of CHDEs in western NWC keeps showing an increasing tendency.Vegetation in eastern NWC,with a lower probability of GPP anomalies,exhibits stronger resistance of ecosystems to CHDEs than in western NWC.In NWC,vegetation typically returns to its normal state in 5.50 days on average,but exhibits greater resilience in the western region,where it takes less recovery time(4.82 days).Vegetation in the central region shows the lowest probability of GPP anomalies and relatively longer recovery time,likely due to its higher altitudes.Our research underscores the imperative to address the considerable impacts of CHDEs on vegetation growth even as the regional climate becomes increasingly warmer and wetter.
基金supported by the 2025 scientific promotion program funded by Jeju National University.
文摘Accurate and timely estimation of above-ground biomass is crucial for understanding crop growth dynamics,optimizing agricultural input management,and assessing productivity in sustainable farming practices.However,conventional biomass assessments are destructive and resource-intensive.In contrast,remote sensing techniques,particularly those utilizing low-altitude unmanned aerial vehicles,provide a non-destructive approach to collect imagery data on plant canopy features,including spectral reflectance and structural details at any stage of the crop life cycle.This study explores the potential visible-light-derived vegetative indices to improve biomass prediction during the flowering period of buckwheat(Fagopyrum tataricum).Red,green,and blue(RGB)images of buckwheat were acquired during peak flowering,using a DJI P4 multispectral Drone.From the analysis of those images,four vegetative indices were calculated.Aboveground fresh biomass was harvested and measured on 14 September 2024.The results showed negative correlations between the green-band based excess green(ExG),excess green minus excess red(ExGR),and green leaf index(GLI)indices and the fresh above-ground biomass of buckwheat,while the red band-based excess red(ExR)index showed an insignificant positive correlation at p<0.10.An investigation into greenband-based vegetation indices(VIs)for estimating fresh biomass revealed significant negative correlations during the experimental period.This unexpected inverse relationship is attributed to spectral interference from abundant white flowers during the flowering stage,where the high reflectance of white petals masked the green vegetation signal.Consequently,these green-band VIs demonstrated limited predictive power for biomass under such conditions,indicating that their utility is compromised when floral reflectance is dominant.Therefore,we suggest that further experiments are required to validate this relationship and improve the estimation of fresh above-ground biomass in white-flowered buckwheat plants.
基金funded by the Scientific Research Project of Anhui Higher Education Institutions(2022AH050915)the Anhui Agricultural University Natural Science Foundation Youth Project(K2137004)the Anhui Agricultural University Introducing and Stabilizing Talent Project(rc372103).
文摘Various types of vegetative cover,predominantly woodlands,shrublands,and grasslands,provide a range of habitats for urban organisms and are the main contributors to urban ecosystem services.The goal of this study was to assess the potential of different vegetation types in maintaining and enhancing bryophyte diversity in urban areas.Bryophytes,small non-vascular plants,in woodlands,shrublands,and grasslands in Hefei city(eastern China)were investigated,and their species richness,abundance,community composition and relationships with habitat characteristics were analysed.The results show that urban woodlands had the highest species richness and abundance of bryophytes and a distinct community composition compared with the other vegetation types.Relative light intensity had a positive effect on species richness in urban woodlands,whereas litter cover had a negative effect on abundance.Shrub,grass and litter covers,and relative air humidity were the main factors driving the differences in bryophyte species composition between woodlands and other vegetation types.Therefore,owing to their high potential to maintain bryophyte diversity,woodlands should receive increased attention during the construction of urban green spaces.In addition,promoting structural heterogeneity and increasing light availability would be beneficial to bryophyte species diversity.
文摘The Monte Desert is characterized by a great diversity of landforms created with fluvial,alluvial which the vegetation patterns are related to.The present work has the following objectives:(1) determine whether topographical attributes,surface characteristics,soil properties and vegetation patterns vary between alluvial landforms,and(2) define whether morphometric,soil and surface properties influence vegetation patterns along alluvial landscape.Morphometric data were obtained by processing a 5 m digital elevation model.The coverage of rock fragments,fine sediments and mulch was quantified.Observations and descriptions of the soil profiles were restricted to the uppermost 50 cm.Vegetation properties were calculated using a Point Quadrat Method.The relationship between variables was evaluated through multivariate statistical analysis.The main results show the presence of 45 plant species distributed in 19 families,where shrubs are dominant.The wind effect,topographic wetness and dissection of the landscape are limiting factors of diversity.The coverage of superficial rock fragments influence vegetation coverage through the distribution and availability of rainwater.Furthermore,the different soil textures reveal that the silt content favors an increase in vegetation coverage.The presence of V horizon could condition the installation and development of vegetation in the early stages of growth.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFF0801304)Philosophy and Social Science Foundation of China(Grant No.23BRK011,24CTJ021)+3 种基金the Humanities and Social Sciences Research Planning Fund of the Ministry of Education,China(Grant No.22YJAZH020)Shaanxi Provincial Social Science Foundation(Grant No.2024D041)Graduate Innovation Funds of Xi’an University of Finance and Economics(Grant No.23YC011)the Youth Innovation Team of Shaanxi Universities,China。
文摘The Loess Plateau region in China is characterized by a fragile environment,where vegetation is susceptible to both natural variations and anthropogenic influences.Previous research has indicated a greening trend in vegetation across the Loess Plateau over the past two decades.However,the specific contributions of natural and anthropogenic drivers,both individually and interactively,to vegetation distribution remain unclear.To address this gap,we conducted a study using Shaanxi Province as a case area.Utilizing multisource data,we employed the Geographical Detector Model(GDM)to analyze the impacts of natural and human related factors on vegetation distribution.Our analysis revealed that the average NDVI(Normalized Difference Vegetation Index)increased at a rate of 0.006 per year from 2000 to 2021.Notably,88.8%of the region experienced vegetation greening,while 4.5%showed significant declines in NDVI,particularly in areas,such as Xi'an,Weinan,Baoji,Hanzhong,and Ankang.Furthermore,NDVI trend projections suggest that the area undergoing vegetation degradation may surpass the area showing improvement in the future.The study identified that vegetation distribution was influenced by both natural and anthropogenic factors for the whole study area.Precipitation,surface types and land use type were the primary factors with q values above 0.5.During the study period,impacts of GDP,nighttime lights and population density among anthropogenic factors on vegetation distribution increased by 130%,125%and 41%,respectively.Conversely,except for slope and aspect,natural factors'influence on vegetation distribution declined by 5%to 26%.The impact of driving factors on NDVI distribution varied across ecological regions.In Fenwei Basin Agro-Ecoregion(EcoregionⅢ),the influence of anthropogenic factors on vegetation distribution was greater than that in the other three ecoregions.Precipitation primarily affected the vegetation distribution in Loess Plateau Agricultural and Grassland Ecoregion(EcoregionⅡ).Additionally,the combined interactive effects of factors had a stronger influence on NDVI distribution than any single factor.These findings provide valuable insights for local governments in Shaanxi Province to develop targeted ecological restoration and environmental management policies.
