A decline in tree growth has occurred in numerous regions over recent decades and is associated with enhanced water deficits driven by climate warming.This phenomenon may be more noticeable at lower latitudes with hig...A decline in tree growth has occurred in numerous regions over recent decades and is associated with enhanced water deficits driven by climate warming.This phenomenon may be more noticeable at lower latitudes with higher temperatures.However,the process by which these elevated temperatures alter growth performance is not well understood.In this study,by combining tree-ring data(including 340 increment cores)and remotely sensed vegetation index data,we investigated the long-term growth performance of Pinus sylvestris var.mongolica Litv.(Mongolian pine),an important species for afforestation in northern China,in response to environmental factors in an area of introduction(lower latitude)and its native range(higher latitude).More notable decreases in both tree-ring width index(RWI)and basal area increment at breast height coincided with lower values and larger variations in the satellite-derived vegetation index in the area of introduction.The RWI showed stronger negative correlations with temperature and positive correlations with the self-calibrating Palmer drought severity index during most months in the introduction area.These results indicate that enhanced drought stress caused by elevated temperatures in lower latitudes might be a key factor for the growth decline in Mongolian pine plantations.The negative impact of increased temperatures on tree growth through exacerbating drought stress at lower latitudes with water deficit highlights the need to reduce water stress in forest management in such areas under climate warming-driven aridification.展开更多
Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited areas.An im...Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited areas.An important species for afforestation in dry environments of northern China,Mongolian pine(Pinus sylvestris var.mongolica Litv.)has recently exhibited growth decline and dieback on many sites,particularly pronounced in old-growth plantations.However,changes in response to drought stress by this species with age as well as the underlying mechanisms are poorly understood.In this study,tree-ring data and remotely sensed vegetation data were combined to investigate variations in growth at individual tree and stand scales for young(9-13 years)and aging(35-52 years)plantations of Mongolian pine in a water-limited area of northern China.A recent decline in tree-ring width in the older plantation also had lower values in satellited-derived normalized difference vegetation indices and normalized difference water indices relative to the younger plantations.In addition,all measured growth-related metrics were strongly correlated with the self-calibrating Palmer drought severity index during the growing season in the older plantation.Sensitivity of growth to drought of the older plantation might be attributed to more severe hydraulic limitations,as reflected by their lower sapwood-and leaf-specific hydraulic conductivities.Our study presents a comprehensive view on changes of growth with age by integrating multiple methods and provides an explanation from the perspective of plant hydraulics for growth decline with age.The results indicate that old-growth Mongolian pine plantations in water-limited environments may face increased growth declines under the context of climate warming and drying.展开更多
Identifying how leaf habit subdivisions link to the fast–slow and avoidance–tolerance trait tradeoffs can provide new insight into divergence in ecophysiological strategies among plant functional groups. Here, we te...Identifying how leaf habit subdivisions link to the fast–slow and avoidance–tolerance trait tradeoffs can provide new insight into divergence in ecophysiological strategies among plant functional groups. Here, we tested a hypothesis that the differentiation across deciduous, semi-deciduous and evergreen woody species contributes to physiological trait tradeoffs in a dry-hot valley savanna. We investigated 11 photosynthetic, morphological and hydraulic traits of 24 species including 8 deciduous, 10 semi-deciduous and 6 evergreen species. Deciduous species were grouped in the fast and avoidance side associated with high values of maximum photosynthetic rates,stomatal conductance and leaf size, while evergreen species were grouped in the slow and tolerance side associated with high photosynthetic water use efficiency, leaf mass per area, sapwood density, Huber value, leaf water potential at turgor loss point and water potential causing 50% loss of stem hydraulic conductance. Semideciduous species generally had intermediate trait values and represented different physiological characteristics when compared to deciduous and evergreen species. The physiological trait tradeoffs showed a close linkage to the differentiation of these three leaf habits. Our findings clearly reveal trait tradeoffs related to fast–slow and avoidance–tolerance strategies among diverse savanna plants, suggesting a syndrome in multiple ecophysiology strategies across different leaf habits.展开更多
Global climate change has been seen to result in marked impacts on forest ecosystems such as accelerated tree mortality worldwide due to incidental hydraulic failure caused by intensified and more frequent occurrence ...Global climate change has been seen to result in marked impacts on forest ecosystems such as accelerated tree mortality worldwide due to incidental hydraulic failure caused by intensified and more frequent occurrence of extreme drought and heat-waves.However,it is well understood how the tree hydrological strategies would adjust to environmental variability brough about by climate changes.Here we investigated the hydraulic adjustment as a mechanism of acclimation to different climate conditions along an altitudinal gradient in Faxon fir(Abies fargesii var.faxoniana)–a tree species that plays a key role in conservation of wildlife and maintenance of ecosystem services in subalpine forests.The hydraulic traits and selective morphological and physiological variables were measured seasonally along an altitudinal gradient from 2,800 to 3,600 m a.s.l.We found that the native percentage loss of conductivity(PLC)increased with altitude across the seasonal measurements.Both the native sapwood-specific hydraulic conductivity(Ks)and native leaf-specific hydraulic conductivity(Kl)significantly decreased with altitude for measurements in July and October,coinciding with the timing for peak growth and pre-dormancy,respectively.The morphological traits varied toward more conservative tree hydrological strategies with increases in altitude,exhibiting trade-offs with hydraulic traits.The total non-structural carbohydrates in both needle(NSCNeedle)and branch(NSCBranch)as well as photosynthetic capacity of current-year leaves played variable roles in maintaining the integrity of the hydraulic functioning and shaping the hydraulic adjustment under prevailing environmental conditions.Our findings indicate that Faxon fir possesses some degree of hydraulic adaptability to water limitation imposed by climate fluctuations in subalpine region through morphological and physiological modifications.展开更多
基金supported by the National Natural Science Foundation of China(grants number 32220103010,32192431,31722013,32101587,32271571)the National Key R&D Program of China(2020YFA0608100)+1 种基金the Major Program of Institute of Applied Ecology,Chinese Academy of Sciences(IAEMP202201)Liaoning Provincial Science and Technology Major Project(2023JH1/10400001).
文摘A decline in tree growth has occurred in numerous regions over recent decades and is associated with enhanced water deficits driven by climate warming.This phenomenon may be more noticeable at lower latitudes with higher temperatures.However,the process by which these elevated temperatures alter growth performance is not well understood.In this study,by combining tree-ring data(including 340 increment cores)and remotely sensed vegetation index data,we investigated the long-term growth performance of Pinus sylvestris var.mongolica Litv.(Mongolian pine),an important species for afforestation in northern China,in response to environmental factors in an area of introduction(lower latitude)and its native range(higher latitude).More notable decreases in both tree-ring width index(RWI)and basal area increment at breast height coincided with lower values and larger variations in the satellite-derived vegetation index in the area of introduction.The RWI showed stronger negative correlations with temperature and positive correlations with the self-calibrating Palmer drought severity index during most months in the introduction area.These results indicate that enhanced drought stress caused by elevated temperatures in lower latitudes might be a key factor for the growth decline in Mongolian pine plantations.The negative impact of increased temperatures on tree growth through exacerbating drought stress at lower latitudes with water deficit highlights the need to reduce water stress in forest management in such areas under climate warming-driven aridification.
基金financially supported by the National Natural Science Foundation of China(31901093,32220103010,32192431,31722013)National Key R&D Program of China(2020YFA0608100,2022YFF1302505)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(ZDBS-LY-DQC019)。
文摘Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited areas.An important species for afforestation in dry environments of northern China,Mongolian pine(Pinus sylvestris var.mongolica Litv.)has recently exhibited growth decline and dieback on many sites,particularly pronounced in old-growth plantations.However,changes in response to drought stress by this species with age as well as the underlying mechanisms are poorly understood.In this study,tree-ring data and remotely sensed vegetation data were combined to investigate variations in growth at individual tree and stand scales for young(9-13 years)and aging(35-52 years)plantations of Mongolian pine in a water-limited area of northern China.A recent decline in tree-ring width in the older plantation also had lower values in satellited-derived normalized difference vegetation indices and normalized difference water indices relative to the younger plantations.In addition,all measured growth-related metrics were strongly correlated with the self-calibrating Palmer drought severity index during the growing season in the older plantation.Sensitivity of growth to drought of the older plantation might be attributed to more severe hydraulic limitations,as reflected by their lower sapwood-and leaf-specific hydraulic conductivities.Our study presents a comprehensive view on changes of growth with age by integrating multiple methods and provides an explanation from the perspective of plant hydraulics for growth decline with age.The results indicate that old-growth Mongolian pine plantations in water-limited environments may face increased growth declines under the context of climate warming and drying.
基金funded by the National Natural Science Foundation of China (31901285, 32171507, 31870385, 32301308)the CAS“Light of West China”programs to DY and JLZ+3 种基金the Yunnan Fundamental Research Projects (202001AU070128, 202401AT070230)the 14th Five-Year Plan of the Xishuangbanna Tropical Botanical Garden,Chinese Academy of Sciences (XTBG-1450101)German Vargas G. was supported by the NOAA Climate and Global Change Postdoctoral Fellowship Programadministered by UCAR's Cooperative Programs for the Advancement of Earth System Science (CPAESS) under the NOAA Science Collaboration Program award#NA21OAR4310383。
文摘Identifying how leaf habit subdivisions link to the fast–slow and avoidance–tolerance trait tradeoffs can provide new insight into divergence in ecophysiological strategies among plant functional groups. Here, we tested a hypothesis that the differentiation across deciduous, semi-deciduous and evergreen woody species contributes to physiological trait tradeoffs in a dry-hot valley savanna. We investigated 11 photosynthetic, morphological and hydraulic traits of 24 species including 8 deciduous, 10 semi-deciduous and 6 evergreen species. Deciduous species were grouped in the fast and avoidance side associated with high values of maximum photosynthetic rates,stomatal conductance and leaf size, while evergreen species were grouped in the slow and tolerance side associated with high photosynthetic water use efficiency, leaf mass per area, sapwood density, Huber value, leaf water potential at turgor loss point and water potential causing 50% loss of stem hydraulic conductance. Semideciduous species generally had intermediate trait values and represented different physiological characteristics when compared to deciduous and evergreen species. The physiological trait tradeoffs showed a close linkage to the differentiation of these three leaf habits. Our findings clearly reveal trait tradeoffs related to fast–slow and avoidance–tolerance strategies among diverse savanna plants, suggesting a syndrome in multiple ecophysiology strategies across different leaf habits.
基金supported by the National Key Research and Development Program of the Ministry of Science and Technology of China(Grant No.2016YFC0502104).
文摘Global climate change has been seen to result in marked impacts on forest ecosystems such as accelerated tree mortality worldwide due to incidental hydraulic failure caused by intensified and more frequent occurrence of extreme drought and heat-waves.However,it is well understood how the tree hydrological strategies would adjust to environmental variability brough about by climate changes.Here we investigated the hydraulic adjustment as a mechanism of acclimation to different climate conditions along an altitudinal gradient in Faxon fir(Abies fargesii var.faxoniana)–a tree species that plays a key role in conservation of wildlife and maintenance of ecosystem services in subalpine forests.The hydraulic traits and selective morphological and physiological variables were measured seasonally along an altitudinal gradient from 2,800 to 3,600 m a.s.l.We found that the native percentage loss of conductivity(PLC)increased with altitude across the seasonal measurements.Both the native sapwood-specific hydraulic conductivity(Ks)and native leaf-specific hydraulic conductivity(Kl)significantly decreased with altitude for measurements in July and October,coinciding with the timing for peak growth and pre-dormancy,respectively.The morphological traits varied toward more conservative tree hydrological strategies with increases in altitude,exhibiting trade-offs with hydraulic traits.The total non-structural carbohydrates in both needle(NSCNeedle)and branch(NSCBranch)as well as photosynthetic capacity of current-year leaves played variable roles in maintaining the integrity of the hydraulic functioning and shaping the hydraulic adjustment under prevailing environmental conditions.Our findings indicate that Faxon fir possesses some degree of hydraulic adaptability to water limitation imposed by climate fluctuations in subalpine region through morphological and physiological modifications.
