The Qinba Mountains are climatically and ecologically recognized as the north-south transitional zone of China.Analysis of its phenology is critical for comprehending the response of vegetation to climatic change.We r...The Qinba Mountains are climatically and ecologically recognized as the north-south transitional zone of China.Analysis of its phenology is critical for comprehending the response of vegetation to climatic change.We retrieved the start of spring phenology(SOS)of eight forest communities from the MODIS products and adopted it as an indicator for spring phenology.Trend analysis,partial correlation analysis,and GeoDetector were employed to reveal the spatio-temporal patterns and climatic drivers of SOS.The results indicated that the SOS presented an advance trend from 2001 to 2020,with a mean rate of−0.473 d yr^(−1).The SOS of most forests correlated negatively with air temperature(TEMP)and positively with precipitation(PRE),suggesting that rising TEMP and increasing PRE in spring would forward and delay SOS,respectively.The dominant factors influencing the sensitivity of SOS to climatic variables were altitude,forest type,and latitude,while the effects of slope and aspect were relatively minor.The response of SOS to climatic factors varied significantly in space and among forest communities,partly due to the influence of altitude,slope,and aspect.展开更多
Climate change significantly affects vegetation dynamics.Thus,understanding interactions between vegetation and climatic factors is essential for ecological management.This study used kernel Normalized Difference Vege...Climate change significantly affects vegetation dynamics.Thus,understanding interactions between vegetation and climatic factors is essential for ecological management.This study used kernel Normalized Difference Vegetation Index(kNDVI)and climatic data(temperature,precipitation,humidity,and vapor pressure deficit(VPD))of China from 2000 to 2022,integrating Geographic Convergent Cross Mapping(GCCM)causal modeling,Extreme Gradient Boosting-Shapley Additive Explanations(XGBoost-SHAP)nonlinear threshold identification,and Geographical Simulation and Optimization Systems-Future Land Use Simulation(GeoSOS-FLUS)spatial prediction modeling to investigate vegetation spatiotemporal characteristics,driving mechanisms,nonlinear thresholds,and future spatial patterns.Results indicated that from 2000 to 2022,China's kNDVI showed an overall increasing trend(annual average ranging from 0.29 to 0.33 with distinct spatial differentiation:52.77%of areas locating in agricultural and ecological restoration regions in the central-eastern plain)experienced vegetation improvement,whereas 2.68%of areas locating in the southeastern coastal urbanized regions and the Yangtze River Delta experience vegetation degradation.The coefficient of variation(CV)of kNDVI at 0.30–0.40(accounting for 10.61%)was significantly higher than that of NDVI(accounting for 1.80%).Climate-driven mechanisms exhibited notable library length(L)dependence.At short-term scales(L<50),vegetation-driven transpiration regulated local microclimate,with a causal strength from kNDVI to temperature of 0.04–0.15;at long-term scales(L>100),cumulative temperature effects dominated vegetation dynamics,with a causal strength from temperature to kNDVI of 0.33.Humidity and kNDVI formed bidirectional positive feedback at long-term scales(L=210,causal strength>0.70),whereas the long-term suppressive effect of VPD was particularly pronounced(causal strength=0.21)in arid areas.The optimal threshold intervals identified were temperature at–12.18℃–0.67℃,precipitation at 24.00–159.74 mm,humidity of lower than 22.00%,and VPD of<0.07,0.17–0.24,and>0.30 kPa;notably,the lower precipitation threshold(24.00 mm)represented the minimum water requirements for vegetation recovery in arid areas.Future kNDVI spatial patterns are projected to continue the trend of"southeastern optimization and northwestern delay"from 2025 to 2040:the area proportion of high kNDVI value(>0.50)will rise from 40.43%to 41.85%,concentrated in the Sichuan Basin and the southern hills;meanwhile,the proportion of low-value areas of kNDVI(0.00–0.10)in the arid northwestern areas will decline by only 1.25%,constrained by sustained temperature and VPD stress.This study provides a scientific basis for vegetation dynamic regulation and sustainable development under climate change.展开更多
Mountains are important reservoirs of biodiversity and endemism on a global scale, but little is known about the altitudinal configuration of this diversity and its driving factors in arid mountains. We explored varia...Mountains are important reservoirs of biodiversity and endemism on a global scale, but little is known about the altitudinal configuration of this diversity and its driving factors in arid mountains. We explored variations in composition, diversity, cover,and life forms of vascular plants along a complete altitudinal gradient(1300-4000 m a.s.l) in Sierra de Velasco, an arid mountain in northwestern Argentina.We evaluated the influence of environmental variables on plant diversity and cover. Field sampling was conducted in the northern sector of the Sa. de Velasco,on the western slope in eight 50 m wide altitudinal bands at 400 m elevation intervals. We used rectangular plots(20 × 4 m;n:10/altitudinal band) to register the vascular plants of all the growth forms, and linear transects(20 m long.;n:30/altitudinal band) to quantify the vegetation cover using the point intercept method. Diversity was calculated using hill numbers.Data analysis included non-metric multidimensional scaling(NMDS), indicator species analysis,generalized linear models(GLMs), and variance partitioning analysis. A total of 232 species from 51families and 158 genera were registered. Species composition showed greater similarity at intermediate elevations. Plant diversity and cover exhibited a unimodal distribution, peaking at intermediate elevations(2100-2500 m). In contrast, life forms' distribution showed divergent patterns. Therophytes and succulents predominated at low altitudes,phanerophytes and hemicryptophytes at medium altitudes, and chamaephytes and geophytes at high altitudes. The altitudinal patterns of plant diversity and cover were primarily driven by climatic factors.Conservation efforts in the Sierra de Velasco should focus on the middle and upper zones due to their high biodiversity and vulnerability to climate change.展开更多
The fragmented pattern and the rapidly declining preservation of older glacial features/evidences limits the precision,with which glacial chronologies can be established.The challenge is exacerbated by the scarcity of...The fragmented pattern and the rapidly declining preservation of older glacial features/evidences limits the precision,with which glacial chronologies can be established.The challenge is exacerbated by the scarcity of datable material and limitations of dating methods.Nevertheless,the preserved glacial landforms have been fairly utilized to establish glacial chronologies from different sectors of the Indian Himalayas.The existing Himalayan glacial chrono-stratigraphies have revealed that in a single valley,past glacial advances rarely surpass four stages.Thus,local and regional glacial chronologies must be synthesized to understand glacial dynamics and potential forcing factors.This research presents an overview of glacier responses to climate variations revealed by glacial chrono-stratigraphies in the western Indian Himalayan region over the Quaternary(late).The synthesis demonstrated that,although the glacial advances were sporadic,glaciers in western Himalayas generally advanced during the Marine isotope stage(MIS)-3/4,MIS-2,late glacial,Younger Dryas(YD)and Holocene periods.The Holocene has witnessed multiple glacial advances and the scatter is significant.While previous glacial research revealed that Himalayan glaciers were out of phase with the global last glacial maximum(gLGM),weak Indian Summer Monsoon(ISM)has been implicated(ISM was reduced by roughly 20%).Recent research,however,has shown that gLGM glaciation responded to the global cooling associated with the enhanced mid-latitude westerlies(MLW).Further,the magnitude of gLGM glacier advance varied along and across the Himalayas particularly the transitional valleys located between the ISM and MLW influence.It is also evident that both the ISM and MLW have governed the late Quaternary glacial advances in the western Himalayan region.However,the responses of glaciers to ISM changes are more prominent.The insights gained from this synthesis will help us understand the dynamics of glacier response to climate change,which will be valuable for future climate modelling.展开更多
Launched in 2002, the Beiing–Tianjin Sand Source Control Project (BTSSCP) is an ecological restoration project intended to prevent desertification in China. Evidence from multiple sources has confirmed increases in v...Launched in 2002, the Beiing–Tianjin Sand Source Control Project (BTSSCP) is an ecological restoration project intended to prevent desertification in China. Evidence from multiple sources has confirmed increases in vegetation growth in the BTSSCP region since the initiation of this project. Precipitation and essential climate variable-soil moisture (ECV-SM) conditions are typically considered to be the main drivers of vegetation growth in this region. Although many studies have investigated the inter-annual variations of vegetation growth, few concerns have been focused on the annual and seasonal variations of vegetation growth and their climatic drivers, which are crucial for understanding the relationships among the climate, vegetation, and human activities at the regional scale. Based on the normalized difference vegetation index (NDVI) derived from MODIS and the corresponding climatic data, we explored the responses of vegetation growth to climatic factors at annual and seasonal scales in the BTSSCP region during the period 2000–2014. Over the study region as a whole, NDVI generally increased from 2000 to 2014, at a rate of 0.002/a. Vegetation growth is stimulated mainly by the elevated temperature in spring, whereas precipitation is the leading driver of summer greening. In autumn, positive effects of both temperature and precipitation on vegetation growth were observed. The warming in spring promotes vegetation growth but reduces ECV-SM. Summer greening has a strong cooling effect on land surface temperature. These results indicate that the ecological and environmental consequences of ecological restoration projects should be comprehensively evaluated.展开更多
In Australia,the proportion of forest area that burns in a typical fire season is less than for other vegetation types.However,the 2019-2020 austral spring-summer was an exception,with over four times the previous max...In Australia,the proportion of forest area that burns in a typical fire season is less than for other vegetation types.However,the 2019-2020 austral spring-summer was an exception,with over four times the previous maximum area burnt in southeast Australian temperate forests.Temperate forest fires have extensive socio-economic,human health,greenhouse gas emissions,and biodiversity impacts due to high fire intensities.A robust model that identifies driving factors of forest fires and relates impact thresholds to fire activity at regional scales would help land managers and fire-fighting agencies prepare for potentially hazardous fire in Australia.Here,we developed a machine-learning diagnostic model to quantify nonlinear relationships between monthly burnt area and biophysical factors in southeast Australian forests for 2001-2020 on a 0.25°grid based on several biophysical parameters,notably fire weather and vegetation productivity.Our model explained over 80%of the variation in the burnt area.We identified that burnt area dynamics in southeast Australian forest were primarily controlled by extreme fire weather,which mainly linked to fluctuations in the Southern Annular Mode(SAM)and Indian Ocean Dipole(IOD),with a relatively smaller contribution from the central Pacific El Niño Southern Oscillation(ENSO).Our fire diagnostic model and the non-linear relationships between burnt area and environmental covariates can provide useful guidance to decision-makers who manage preparations for an upcoming fire season,and model developers working on improved early warning systems for forest fires.展开更多
Relationships among productivity,leaf phenology,and seasonal variation in moisture and light availability are poorly understood for evergreen broadleaved tropical/subtropical forests,which contribute 25% of terrestria...Relationships among productivity,leaf phenology,and seasonal variation in moisture and light availability are poorly understood for evergreen broadleaved tropical/subtropical forests,which contribute 25% of terrestrial productivity.On the one hand,as moisture availability declines,trees shed leaves to reduce transpiration and the risk of hydraulic failure.On the other hand,increases in light availability promote the replacement of senescent leaves to increase productivity.Here,we provide a comprehensive framework that relates the seasonality of climate,leaf abscission,and leaf productivity across the evergreen broadleaved tropical/subtropical forest biome.The seasonal correlation between rainfall and light availability varies from strongly negative to strongly positive across the tropics and maps onto the seasonal correlation between litterfall mass and productivity for 68 forests.Where rainfall and light covary positively,litterfall and productivity also covary positively and are always greater in the wetter sunnier season.Where rainfall and light covary negatively,litterfall and productivity are always greater in the drier and sunnier season if moisture supplies remain adequate;otherwise productivity is smaller in the drier sunnier season.This framework will improve the representation of tropical/subtropical forests in Earth system models and suggests how phenology and productivity will change as climate change alters the seasonality of cloud cover and rainfall across tropical/subtropical forests.展开更多
基金National Key Research and Development Program of China,No.2023YFE0208100,No.2021YFC3000201Natural Science Foundation of Henan Province,No.232300420165。
文摘The Qinba Mountains are climatically and ecologically recognized as the north-south transitional zone of China.Analysis of its phenology is critical for comprehending the response of vegetation to climatic change.We retrieved the start of spring phenology(SOS)of eight forest communities from the MODIS products and adopted it as an indicator for spring phenology.Trend analysis,partial correlation analysis,and GeoDetector were employed to reveal the spatio-temporal patterns and climatic drivers of SOS.The results indicated that the SOS presented an advance trend from 2001 to 2020,with a mean rate of−0.473 d yr^(−1).The SOS of most forests correlated negatively with air temperature(TEMP)and positively with precipitation(PRE),suggesting that rising TEMP and increasing PRE in spring would forward and delay SOS,respectively.The dominant factors influencing the sensitivity of SOS to climatic variables were altitude,forest type,and latitude,while the effects of slope and aspect were relatively minor.The response of SOS to climatic factors varied significantly in space and among forest communities,partly due to the influence of altitude,slope,and aspect.
基金funded by the Key Science and Technology Research Projects of Henan Province(252102320172).
文摘Climate change significantly affects vegetation dynamics.Thus,understanding interactions between vegetation and climatic factors is essential for ecological management.This study used kernel Normalized Difference Vegetation Index(kNDVI)and climatic data(temperature,precipitation,humidity,and vapor pressure deficit(VPD))of China from 2000 to 2022,integrating Geographic Convergent Cross Mapping(GCCM)causal modeling,Extreme Gradient Boosting-Shapley Additive Explanations(XGBoost-SHAP)nonlinear threshold identification,and Geographical Simulation and Optimization Systems-Future Land Use Simulation(GeoSOS-FLUS)spatial prediction modeling to investigate vegetation spatiotemporal characteristics,driving mechanisms,nonlinear thresholds,and future spatial patterns.Results indicated that from 2000 to 2022,China's kNDVI showed an overall increasing trend(annual average ranging from 0.29 to 0.33 with distinct spatial differentiation:52.77%of areas locating in agricultural and ecological restoration regions in the central-eastern plain)experienced vegetation improvement,whereas 2.68%of areas locating in the southeastern coastal urbanized regions and the Yangtze River Delta experience vegetation degradation.The coefficient of variation(CV)of kNDVI at 0.30–0.40(accounting for 10.61%)was significantly higher than that of NDVI(accounting for 1.80%).Climate-driven mechanisms exhibited notable library length(L)dependence.At short-term scales(L<50),vegetation-driven transpiration regulated local microclimate,with a causal strength from kNDVI to temperature of 0.04–0.15;at long-term scales(L>100),cumulative temperature effects dominated vegetation dynamics,with a causal strength from temperature to kNDVI of 0.33.Humidity and kNDVI formed bidirectional positive feedback at long-term scales(L=210,causal strength>0.70),whereas the long-term suppressive effect of VPD was particularly pronounced(causal strength=0.21)in arid areas.The optimal threshold intervals identified were temperature at–12.18℃–0.67℃,precipitation at 24.00–159.74 mm,humidity of lower than 22.00%,and VPD of<0.07,0.17–0.24,and>0.30 kPa;notably,the lower precipitation threshold(24.00 mm)represented the minimum water requirements for vegetation recovery in arid areas.Future kNDVI spatial patterns are projected to continue the trend of"southeastern optimization and northwestern delay"from 2025 to 2040:the area proportion of high kNDVI value(>0.50)will rise from 40.43%to 41.85%,concentrated in the Sichuan Basin and the southern hills;meanwhile,the proportion of low-value areas of kNDVI(0.00–0.10)in the arid northwestern areas will decline by only 1.25%,constrained by sustained temperature and VPD stress.This study provides a scientific basis for vegetation dynamic regulation and sustainable development under climate change.
文摘Mountains are important reservoirs of biodiversity and endemism on a global scale, but little is known about the altitudinal configuration of this diversity and its driving factors in arid mountains. We explored variations in composition, diversity, cover,and life forms of vascular plants along a complete altitudinal gradient(1300-4000 m a.s.l) in Sierra de Velasco, an arid mountain in northwestern Argentina.We evaluated the influence of environmental variables on plant diversity and cover. Field sampling was conducted in the northern sector of the Sa. de Velasco,on the western slope in eight 50 m wide altitudinal bands at 400 m elevation intervals. We used rectangular plots(20 × 4 m;n:10/altitudinal band) to register the vascular plants of all the growth forms, and linear transects(20 m long.;n:30/altitudinal band) to quantify the vegetation cover using the point intercept method. Diversity was calculated using hill numbers.Data analysis included non-metric multidimensional scaling(NMDS), indicator species analysis,generalized linear models(GLMs), and variance partitioning analysis. A total of 232 species from 51families and 158 genera were registered. Species composition showed greater similarity at intermediate elevations. Plant diversity and cover exhibited a unimodal distribution, peaking at intermediate elevations(2100-2500 m). In contrast, life forms' distribution showed divergent patterns. Therophytes and succulents predominated at low altitudes,phanerophytes and hemicryptophytes at medium altitudes, and chamaephytes and geophytes at high altitudes. The altitudinal patterns of plant diversity and cover were primarily driven by climatic factors.Conservation efforts in the Sierra de Velasco should focus on the middle and upper zones due to their high biodiversity and vulnerability to climate change.
基金The authors are thankful to the Director,Birbal Sahni Institute of Palaeosciences,Lucknow for constant support and providing infrastructural facilities.
文摘The fragmented pattern and the rapidly declining preservation of older glacial features/evidences limits the precision,with which glacial chronologies can be established.The challenge is exacerbated by the scarcity of datable material and limitations of dating methods.Nevertheless,the preserved glacial landforms have been fairly utilized to establish glacial chronologies from different sectors of the Indian Himalayas.The existing Himalayan glacial chrono-stratigraphies have revealed that in a single valley,past glacial advances rarely surpass four stages.Thus,local and regional glacial chronologies must be synthesized to understand glacial dynamics and potential forcing factors.This research presents an overview of glacier responses to climate variations revealed by glacial chrono-stratigraphies in the western Indian Himalayan region over the Quaternary(late).The synthesis demonstrated that,although the glacial advances were sporadic,glaciers in western Himalayas generally advanced during the Marine isotope stage(MIS)-3/4,MIS-2,late glacial,Younger Dryas(YD)and Holocene periods.The Holocene has witnessed multiple glacial advances and the scatter is significant.While previous glacial research revealed that Himalayan glaciers were out of phase with the global last glacial maximum(gLGM),weak Indian Summer Monsoon(ISM)has been implicated(ISM was reduced by roughly 20%).Recent research,however,has shown that gLGM glaciation responded to the global cooling associated with the enhanced mid-latitude westerlies(MLW).Further,the magnitude of gLGM glacier advance varied along and across the Himalayas particularly the transitional valleys located between the ISM and MLW influence.It is also evident that both the ISM and MLW have governed the late Quaternary glacial advances in the western Himalayan region.However,the responses of glaciers to ISM changes are more prominent.The insights gained from this synthesis will help us understand the dynamics of glacier response to climate change,which will be valuable for future climate modelling.
基金financially supported by the National Natural Science Foundation of China (31560135, 41361100)the Discipline Construction Fund Project of Gansu Agricultural University (GAU-XKJS-2018-104, GAU-XKJS-2018-108)the Gansu Science and Technology Support Program (1604FKCA088)
文摘Launched in 2002, the Beiing–Tianjin Sand Source Control Project (BTSSCP) is an ecological restoration project intended to prevent desertification in China. Evidence from multiple sources has confirmed increases in vegetation growth in the BTSSCP region since the initiation of this project. Precipitation and essential climate variable-soil moisture (ECV-SM) conditions are typically considered to be the main drivers of vegetation growth in this region. Although many studies have investigated the inter-annual variations of vegetation growth, few concerns have been focused on the annual and seasonal variations of vegetation growth and their climatic drivers, which are crucial for understanding the relationships among the climate, vegetation, and human activities at the regional scale. Based on the normalized difference vegetation index (NDVI) derived from MODIS and the corresponding climatic data, we explored the responses of vegetation growth to climatic factors at annual and seasonal scales in the BTSSCP region during the period 2000–2014. Over the study region as a whole, NDVI generally increased from 2000 to 2014, at a rate of 0.002/a. Vegetation growth is stimulated mainly by the elevated temperature in spring, whereas precipitation is the leading driver of summer greening. In autumn, positive effects of both temperature and precipitation on vegetation growth were observed. The warming in spring promotes vegetation growth but reduces ECV-SM. Summer greening has a strong cooling effect on land surface temperature. These results indicate that the ecological and environmental consequences of ecological restoration projects should be comprehensively evaluated.
基金supported by the National Natural Science Foundation of China(42088101 and 42030605)support from the research project:Towards an Operational Fire Early Warning System for Indonesia(TOFEWSI)+1 种基金The TOFEWSI project was funded from October 2017-October 2021 through the UK’s National Environment Research Council/Newton Fund on behalf of the UK Research&Innovation(NE/P014801/1)(UK Principal InvestigatorAllan Spessa)(https//tofewsi.github.io/)financial support from the Natural Science Foundation of Qinghai(2021-HZ-811)。
文摘In Australia,the proportion of forest area that burns in a typical fire season is less than for other vegetation types.However,the 2019-2020 austral spring-summer was an exception,with over four times the previous maximum area burnt in southeast Australian temperate forests.Temperate forest fires have extensive socio-economic,human health,greenhouse gas emissions,and biodiversity impacts due to high fire intensities.A robust model that identifies driving factors of forest fires and relates impact thresholds to fire activity at regional scales would help land managers and fire-fighting agencies prepare for potentially hazardous fire in Australia.Here,we developed a machine-learning diagnostic model to quantify nonlinear relationships between monthly burnt area and biophysical factors in southeast Australian forests for 2001-2020 on a 0.25°grid based on several biophysical parameters,notably fire weather and vegetation productivity.Our model explained over 80%of the variation in the burnt area.We identified that burnt area dynamics in southeast Australian forest were primarily controlled by extreme fire weather,which mainly linked to fluctuations in the Southern Annular Mode(SAM)and Indian Ocean Dipole(IOD),with a relatively smaller contribution from the central Pacific El Niño Southern Oscillation(ENSO).Our fire diagnostic model and the non-linear relationships between burnt area and environmental covariates can provide useful guidance to decision-makers who manage preparations for an upcoming fire season,and model developers working on improved early warning systems for forest fires.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(grant number 2020B0301030004)the National Natural Science Foundation of China(grant numbers 31971458,41971275)+3 种基金the Special highlevel plan project of Guangdong Province(grant number 2016TQ03Z354)Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(grant number 311021009)the Guangdong Basic and Applied Basic Research Foundation(grant number 2020A151501091)GDAS Special Project of Science and Technology Development(grant number 2020GDASYL-20200102002).
文摘Relationships among productivity,leaf phenology,and seasonal variation in moisture and light availability are poorly understood for evergreen broadleaved tropical/subtropical forests,which contribute 25% of terrestrial productivity.On the one hand,as moisture availability declines,trees shed leaves to reduce transpiration and the risk of hydraulic failure.On the other hand,increases in light availability promote the replacement of senescent leaves to increase productivity.Here,we provide a comprehensive framework that relates the seasonality of climate,leaf abscission,and leaf productivity across the evergreen broadleaved tropical/subtropical forest biome.The seasonal correlation between rainfall and light availability varies from strongly negative to strongly positive across the tropics and maps onto the seasonal correlation between litterfall mass and productivity for 68 forests.Where rainfall and light covary positively,litterfall and productivity also covary positively and are always greater in the wetter sunnier season.Where rainfall and light covary negatively,litterfall and productivity are always greater in the drier and sunnier season if moisture supplies remain adequate;otherwise productivity is smaller in the drier sunnier season.This framework will improve the representation of tropical/subtropical forests in Earth system models and suggests how phenology and productivity will change as climate change alters the seasonality of cloud cover and rainfall across tropical/subtropical forests.
