The influence of climate change on vegetation phenology is a heated issue in current climate change study.We used GIMMS-3g NDVI data to detect the spatio-temporal dynamics of the start of the growing season(SGS) over ...The influence of climate change on vegetation phenology is a heated issue in current climate change study.We used GIMMS-3g NDVI data to detect the spatio-temporal dynamics of the start of the growing season(SGS) over the Tibetan Plateau(TP) from 1982 to 2012 and to analyze its relationship with temperature and precipitation.No significant trend was observed in the SGS at the regional scale during the study period(R^2 = 0.03,P = 0.352).However,there were three time periods(1982-1999,1999-2008 and 2008-2012) with identifiable,distinctly different trends.Regions with a significant advancing trend were mainly scattered throughout the humid and semi-humid areas,whereas the regions with a significant delaying trend were mostly distributed throughout the semi-arid areas.Statistical analysis showed that the response of the SGS to climate change varies spatially.The SGS was significantly correlated with the spring temperature and the start of the thermal growth season(STGS) in the relatively humid area.With increasing aridity,theimportance of the spring temperature for the SGS gradually decreased.However,the influences of precipitation and winter temperature on the SGS were complicated across the plateau.展开更多
Background:The spring phenology and growth strategy of temperate tree species can be strongly linked to their sensitivity to frosts,which deserve more profound investigations under the background of climate warming pa...Background:The spring phenology and growth strategy of temperate tree species can be strongly linked to their sensitivity to frosts,which deserve more profound investigations under the background of climate warming particularly considering the advancement of spring phenology as well as the increase in frequency and intensity of spring cold waves.Methods:Spring phenologies,stem radial growth characteristics,frost sensitivity of leaves and stem hydraulic systems were studied in five diffuse-porous and five ring-porous temperate tree species under a common garden condition.Results:The results showed that the spring leaf phenology of the diffuse-porous species was one to two weeks earlier than that of the ring-porous species.The ring-porous species had significantly higher stem hydraulic conductivity than the diffuse-porous species(1.81 and 0.95 kg·m^(-1)·s^(-1)·MPa^(-1),P<0.05)but were more vulnerable to freeze-thaw induced xylem embolism than the latter.After a simulated freeze-thaw event,the average percentage loss of hydraulic conductivity in the current year shoots increased from 26.0%(native embolism)to 86.7%in the ring-porous species,while it only increased from 21.3%to 38.3%in the diffuse-porous species.The spring phenology was clearly correlated with vulnerability to freeze-thaw induced embolism,with the more vulnerable ring-porous species exhibited substantially delayed phenology to reduce risks of catastrophic hydraulic dysfunction during spring frosts.Nevertheless,ring-porous species can offset the postponed onset of growth and gained even higher annual growth due to significantly higher hydraulic efficiency and leaf gas exchange rates.Conclusions:Contrasts between ring-porous and diffuse-porous species in resistance to freeze-thaw induced embolism suggest that they face different selective pressures from early spring frosts,which may at least be partially responsible for their divergence in spring phenology and growth strategy and can potentially lead to different responses to climate regime shifts.展开更多
Satellite-based remote sensed phenology has been widely used to assess global climate change.However,it is constrained by uncertain linkages with photo-synthesis activity.Two dynamic threshold methods were employed to...Satellite-based remote sensed phenology has been widely used to assess global climate change.However,it is constrained by uncertain linkages with photo-synthesis activity.Two dynamic threshold methods were employed to retrieve spring phenology metrics from four Moderate Resolution Imaging Spectro-radiometer(MODIS)products,including fraction of Absorbed Photosyntheti-cally Active Radiation(fAPAR),Leaf Area Index(LAI),Normalized Difference Vegetation Index(NDVI),and Enhanced Vegetation Index(EVI)for three temperate deciduous broadleaf forests in North America between 2001 and 2009.These MODIS-based spring phenology metrics were subsequently linked to the photosynthetic curves(daily gross primary productivity,GPP)measured by an eddy covariance flux tower.The 20% dynamic threshold spring onset metrics from MODIS products were closer to the photosynthesis onset metrics at the date of 2% GPP increase for NDVI and fAPAR,and closer to the date of 5%and 10% increase of GPP for EVI and LAI,respectively.The 50% dynamic threshold onset metrics were closer to the photosynthesis onset metrics at the date of 10%GPP increase for NDVI,and closer to the date of 20% GPP increase for fAPAR,LAI and EVI,respectively.These results can improve our knowledge on the photosynthesis activity status of remotely sensed spring phenology metrics.展开更多
Global climate change has caused phenology change of vegetation.This is especially obvious in urban area.This paper reveals response mechanism of spring phenology of main gymnosperm in Harbin City proper to climate ch...Global climate change has caused phenology change of vegetation.This is especially obvious in urban area.This paper reveals response mechanism of spring phenology of main gymnosperm in Harbin City proper to climate change based on relationship study between two typical phenophases(beginning of bud burst and beginning of leaf expansion) of Korean pine(Pinus koraiensis),Koyama spruce(Picea koraiensis Nakai),needle fir(Abies nephrolepis) and Pinus sylvestnis var.mongolica Litv.and the temperature of every ten days in winter and spring through the phenology observation in Harbin proper from 1963 to 2008 and meteorological observation data from 1951 to 2008.Study conclusion shows the advancing trend of the beginning date of accumulated temperature that meets plant germination in Harbin City.The beginning of bud burst of P.koraiensis is mainly subject to temperature in middle and late February and the beginning pf leaf expansion is subject to temperature in middle and late March.The beginning of bud burst of P.koraiensis Nakai is mainly subject to temperature from late January to middle of February and leaf expansion is subject to temperature mainly in March and April.The beginning of bud burst of A.nephrolepis is mainly subject to temperature from January to March and leaf expansion time is subject to temperature in May.The beginning of bud burst of P.sylvestnis var.mongolica Litv.is mainly subject to the middle of March and the middle of April.The spring phenology of all these 4 selected species showed tremendous advancement.However the advancing trend of different species is varied.The impact level of temperature in each phase to spring phenology of different species is different.The spring phenology of all 4 selected species is prominently relevant to the temperature in earlier period before occurrence of phenology.Low temperature is a favor for breaking dormancy of plants.Suitable lower temperature is good for advancing spring phenology of plants.Temperature in Harbin is relatively lower in winter.Increase of temperature in winter is propitious to advancing of spring phenology of plants.展开更多
Phenological research is engaged in monitoring the infuence of climate change on the natural environment.The International Phenological Gardens(IPG)network provides a valuable dataset of standardized tree phenology re...Phenological research is engaged in monitoring the infuence of climate change on the natural environment.The International Phenological Gardens(IPG)network provides a valuable dataset of standardized tree phenology records dating back to the mid-20th century.To make best use of this actively growing record,it is important to investigate how network data can be applied to predict the timing of phenological events in natural populations.This study compared clonally propagated IPG downy birch(Betula pubescens Ehrh.)and hazel(Corylus avellana L.)specimens of central European provenance to nearby wild populations at the western-most margin of the IPG network,in the south-west of Ireland.In addition to monitoring by trained scientists,observations by citizen scientists were included.The order of the timing of phenological events among sites was consistent across 2 years,confrming reproducibility of the results.IPG trees had the earliest B.pubescens leaf unfolding and C.avellana fowering dates of the sites studied.In addition,leaf unfolding occurred later in the wild populations than expected from the temperature responses of the B.pubescens and C.avellana IPG clones.Natural variation in phenology also exceeded the historical change observed at the IPG site,suggesting a potential genetic basis for climate adaptation.Trunk circumference,refecting the age-dependent increase in tree size,was found to infuence C.avellana phenology,with earlier timing of phenological events in larger trees.This fnding highlights tree size as an important consideration in the management of phenological gardens and tree phenology research in general.展开更多
The timing of flowering(FL)and leaf unfolding(LU)determine plants’reproduction and vegetative growth.Global warming has substantially advanced FL and LU of temperate and boreal plants,but their responses to warming d...The timing of flowering(FL)and leaf unfolding(LU)determine plants’reproduction and vegetative growth.Global warming has substantially advanced FL and LU of temperate and boreal plants,but their responses to warming differ,which may influence the time interval between FL and LU(ΔLU-FL),thereby impacting plant fitness and intraspecific physiological processes.Based on twigs collected from two flowering-first tree species,Populus tomentosa and Amygdalus triloba,we conducted a manipulative experiment to investigate the effects of winter chilling,spring warming and photoperiod on theΔLU-FL.We found that photoperiod did not affect theΔLU-FL of Amygdalus triloba,but shortenedΔLU-FL by 5.1 d of Populus tomentosa.Interestingly,spring warming and winter chilling oppositely affected theΔLU-FL of both species.Specifically,low chilling accumulation extended theΔLU-FL by 3.8 and 9.4 d for Populus tomentosa and Amygdalus triloba,but spring warming shortened theΔLU-FL by 4.1 and 0.2 d℃^(-1).Our results indicate that climate warming will decrease or increase theΔLU-FL depending on the warming periods,i.e.,spring or winter.The shifted time interval between flowering and leaf unfolding may have ecological effects including affecting pollen transfer efficiency and alter the structure and functioning of terrestrial ecosystem.展开更多
The mechanisms regulating spring phenology have been extensively studied in angiosperm species.However,given that gymnosperms and angiosperms diverged 300 million years ago,phenology may be triggered by different cues...The mechanisms regulating spring phenology have been extensively studied in angiosperm species.However,given that gymnosperms and angiosperms diverged 300 million years ago,phenology may be triggered by different cues in gymnosperm species.The regulatory mechanisms of phenology in subtropical regions remain largely unknown.In combination,it remains untested whether subtropical gymnosperm species have chilling requirements and are photosensitive.We conducted a climate chamber experiment with three chilling and three photoperiod treatments to investigate budburst during an 8-week forcing period.We tested whether budburst of eight gymnosperms species(Cryptomeria japonica,Cunninghamia lanceolata,Cupressus funebris,Ginkgo biloba,Metasequoia glyptostroboides,Pinus massoniana,Pseudolarix amabilis and Podocarpus macrophyllus)was photoperiod sensitive or has strong chilling requirements and whether photoperiod or chilling was more important for advancing budburst.Chilling advanced budburst and increased the percentage of budburst for gymnosperm species.Gymnosperm species required moderate chilling days to advance budburst.Interestingly,the forcing requirement for gymnosperm species was higher than that for angiosperms in the same forest,suggesting that gymnosperms may need more cumulative forcing to initiate budburst than do angiosperms.Compared with temperate gymnosperm species in Germany(194-600℃days),the subtropical species studied here had a much higher forcing requirement(814-1150℃days).The effects of photoperiod were minor,suggesting that chilling outweighs photoperiod in advancing budburst of gymnosperm species in this subtropical region.These results reveal that increased winter temperatures with continued global warming may impact not only angiosperms but also gymnosperms,leading to their delayed spring budburst.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB03030500)National Natural Science Foundation of China(Grant Nos.41201095,41171080,41371120)
文摘The influence of climate change on vegetation phenology is a heated issue in current climate change study.We used GIMMS-3g NDVI data to detect the spatio-temporal dynamics of the start of the growing season(SGS) over the Tibetan Plateau(TP) from 1982 to 2012 and to analyze its relationship with temperature and precipitation.No significant trend was observed in the SGS at the regional scale during the study period(R^2 = 0.03,P = 0.352).However,there were three time periods(1982-1999,1999-2008 and 2008-2012) with identifiable,distinctly different trends.Regions with a significant advancing trend were mainly scattered throughout the humid and semi-humid areas,whereas the regions with a significant delaying trend were mostly distributed throughout the semi-arid areas.Statistical analysis showed that the response of the SGS to climate change varies spatially.The SGS was significantly correlated with the spring temperature and the start of the thermal growth season(STGS) in the relatively humid area.With increasing aridity,theimportance of the spring temperature for the SGS gradually decreased.However,the influences of precipitation and winter temperature on the SGS were complicated across the plateau.
基金supported by the National Natural Science Foundation of China(Nos.31901284,31870593,31722013,32192431)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(No.ZDBS-LY-DQC019)National Key R&D Program of China(No.2020YFA0608100)。
文摘Background:The spring phenology and growth strategy of temperate tree species can be strongly linked to their sensitivity to frosts,which deserve more profound investigations under the background of climate warming particularly considering the advancement of spring phenology as well as the increase in frequency and intensity of spring cold waves.Methods:Spring phenologies,stem radial growth characteristics,frost sensitivity of leaves and stem hydraulic systems were studied in five diffuse-porous and five ring-porous temperate tree species under a common garden condition.Results:The results showed that the spring leaf phenology of the diffuse-porous species was one to two weeks earlier than that of the ring-porous species.The ring-porous species had significantly higher stem hydraulic conductivity than the diffuse-porous species(1.81 and 0.95 kg·m^(-1)·s^(-1)·MPa^(-1),P<0.05)but were more vulnerable to freeze-thaw induced xylem embolism than the latter.After a simulated freeze-thaw event,the average percentage loss of hydraulic conductivity in the current year shoots increased from 26.0%(native embolism)to 86.7%in the ring-porous species,while it only increased from 21.3%to 38.3%in the diffuse-porous species.The spring phenology was clearly correlated with vulnerability to freeze-thaw induced embolism,with the more vulnerable ring-porous species exhibited substantially delayed phenology to reduce risks of catastrophic hydraulic dysfunction during spring frosts.Nevertheless,ring-porous species can offset the postponed onset of growth and gained even higher annual growth due to significantly higher hydraulic efficiency and leaf gas exchange rates.Conclusions:Contrasts between ring-porous and diffuse-porous species in resistance to freeze-thaw induced embolism suggest that they face different selective pressures from early spring frosts,which may at least be partially responsible for their divergence in spring phenology and growth strategy and can potentially lead to different responses to climate regime shifts.
基金The authors gratefully acknowledge financial support provided for this research by the National Natural Science Foundation of China(41222008,91125003)the External Cooperation Program of the Chinese Academy of Sciences(GJH21123).
文摘Satellite-based remote sensed phenology has been widely used to assess global climate change.However,it is constrained by uncertain linkages with photo-synthesis activity.Two dynamic threshold methods were employed to retrieve spring phenology metrics from four Moderate Resolution Imaging Spectro-radiometer(MODIS)products,including fraction of Absorbed Photosyntheti-cally Active Radiation(fAPAR),Leaf Area Index(LAI),Normalized Difference Vegetation Index(NDVI),and Enhanced Vegetation Index(EVI)for three temperate deciduous broadleaf forests in North America between 2001 and 2009.These MODIS-based spring phenology metrics were subsequently linked to the photosynthetic curves(daily gross primary productivity,GPP)measured by an eddy covariance flux tower.The 20% dynamic threshold spring onset metrics from MODIS products were closer to the photosynthesis onset metrics at the date of 2% GPP increase for NDVI and fAPAR,and closer to the date of 5%and 10% increase of GPP for EVI and LAI,respectively.The 50% dynamic threshold onset metrics were closer to the photosynthesis onset metrics at the date of 10%GPP increase for NDVI,and closer to the date of 20% GPP increase for fAPAR,LAI and EVI,respectively.These results can improve our knowledge on the photosynthesis activity status of remotely sensed spring phenology metrics.
文摘Global climate change has caused phenology change of vegetation.This is especially obvious in urban area.This paper reveals response mechanism of spring phenology of main gymnosperm in Harbin City proper to climate change based on relationship study between two typical phenophases(beginning of bud burst and beginning of leaf expansion) of Korean pine(Pinus koraiensis),Koyama spruce(Picea koraiensis Nakai),needle fir(Abies nephrolepis) and Pinus sylvestnis var.mongolica Litv.and the temperature of every ten days in winter and spring through the phenology observation in Harbin proper from 1963 to 2008 and meteorological observation data from 1951 to 2008.Study conclusion shows the advancing trend of the beginning date of accumulated temperature that meets plant germination in Harbin City.The beginning of bud burst of P.koraiensis is mainly subject to temperature in middle and late February and the beginning pf leaf expansion is subject to temperature in middle and late March.The beginning of bud burst of P.koraiensis Nakai is mainly subject to temperature from late January to middle of February and leaf expansion is subject to temperature mainly in March and April.The beginning of bud burst of A.nephrolepis is mainly subject to temperature from January to March and leaf expansion time is subject to temperature in May.The beginning of bud burst of P.sylvestnis var.mongolica Litv.is mainly subject to the middle of March and the middle of April.The spring phenology of all these 4 selected species showed tremendous advancement.However the advancing trend of different species is varied.The impact level of temperature in each phase to spring phenology of different species is different.The spring phenology of all 4 selected species is prominently relevant to the temperature in earlier period before occurrence of phenology.Low temperature is a favor for breaking dormancy of plants.Suitable lower temperature is good for advancing spring phenology of plants.Temperature in Harbin is relatively lower in winter.Increase of temperature in winter is propitious to advancing of spring phenology of plants.
基金carried out as part of the LIVE Project(www.ecomuseumlive.eu),which received funding from the European Regional Development Fund through its Ireland Wales Cooperation Programme 2014-2020(contract number C81315).
文摘Phenological research is engaged in monitoring the infuence of climate change on the natural environment.The International Phenological Gardens(IPG)network provides a valuable dataset of standardized tree phenology records dating back to the mid-20th century.To make best use of this actively growing record,it is important to investigate how network data can be applied to predict the timing of phenological events in natural populations.This study compared clonally propagated IPG downy birch(Betula pubescens Ehrh.)and hazel(Corylus avellana L.)specimens of central European provenance to nearby wild populations at the western-most margin of the IPG network,in the south-west of Ireland.In addition to monitoring by trained scientists,observations by citizen scientists were included.The order of the timing of phenological events among sites was consistent across 2 years,confrming reproducibility of the results.IPG trees had the earliest B.pubescens leaf unfolding and C.avellana fowering dates of the sites studied.In addition,leaf unfolding occurred later in the wild populations than expected from the temperature responses of the B.pubescens and C.avellana IPG clones.Natural variation in phenology also exceeded the historical change observed at the IPG site,suggesting a potential genetic basis for climate adaptation.Trunk circumference,refecting the age-dependent increase in tree size,was found to infuence C.avellana phenology,with earlier timing of phenological events in larger trees.This fnding highlights tree size as an important consideration in the management of phenological gardens and tree phenology research in general.
基金the National Funds for Distinguished Young Scholar(42025101)the International Cooperation and Exchanges NSFC-FWO(32111530083)the 111 Project(B18006)。
文摘The timing of flowering(FL)and leaf unfolding(LU)determine plants’reproduction and vegetative growth.Global warming has substantially advanced FL and LU of temperate and boreal plants,but their responses to warming differ,which may influence the time interval between FL and LU(ΔLU-FL),thereby impacting plant fitness and intraspecific physiological processes.Based on twigs collected from two flowering-first tree species,Populus tomentosa and Amygdalus triloba,we conducted a manipulative experiment to investigate the effects of winter chilling,spring warming and photoperiod on theΔLU-FL.We found that photoperiod did not affect theΔLU-FL of Amygdalus triloba,but shortenedΔLU-FL by 5.1 d of Populus tomentosa.Interestingly,spring warming and winter chilling oppositely affected theΔLU-FL of both species.Specifically,low chilling accumulation extended theΔLU-FL by 3.8 and 9.4 d for Populus tomentosa and Amygdalus triloba,but spring warming shortened theΔLU-FL by 4.1 and 0.2 d℃^(-1).Our results indicate that climate warming will decrease or increase theΔLU-FL depending on the warming periods,i.e.,spring or winter.The shifted time interval between flowering and leaf unfolding may have ecological effects including affecting pollen transfer efficiency and alter the structure and functioning of terrestrial ecosystem.
基金supported by the Innovative Research Team Program of Hainan Natural Science Fund(2018CXTD331)the Natural Science Foundation of Hainan Province(320RC504)Hainan University(KYQD(ZR)1979).
文摘The mechanisms regulating spring phenology have been extensively studied in angiosperm species.However,given that gymnosperms and angiosperms diverged 300 million years ago,phenology may be triggered by different cues in gymnosperm species.The regulatory mechanisms of phenology in subtropical regions remain largely unknown.In combination,it remains untested whether subtropical gymnosperm species have chilling requirements and are photosensitive.We conducted a climate chamber experiment with three chilling and three photoperiod treatments to investigate budburst during an 8-week forcing period.We tested whether budburst of eight gymnosperms species(Cryptomeria japonica,Cunninghamia lanceolata,Cupressus funebris,Ginkgo biloba,Metasequoia glyptostroboides,Pinus massoniana,Pseudolarix amabilis and Podocarpus macrophyllus)was photoperiod sensitive or has strong chilling requirements and whether photoperiod or chilling was more important for advancing budburst.Chilling advanced budburst and increased the percentage of budburst for gymnosperm species.Gymnosperm species required moderate chilling days to advance budburst.Interestingly,the forcing requirement for gymnosperm species was higher than that for angiosperms in the same forest,suggesting that gymnosperms may need more cumulative forcing to initiate budburst than do angiosperms.Compared with temperate gymnosperm species in Germany(194-600℃days),the subtropical species studied here had a much higher forcing requirement(814-1150℃days).The effects of photoperiod were minor,suggesting that chilling outweighs photoperiod in advancing budburst of gymnosperm species in this subtropical region.These results reveal that increased winter temperatures with continued global warming may impact not only angiosperms but also gymnosperms,leading to their delayed spring budburst.