The Himalayas are characterized by a broad gradient of bioclimatic zones along their elevation.However,less is known how forest growth responds to climatic change along elevation.In this study,four standard treering w...The Himalayas are characterized by a broad gradient of bioclimatic zones along their elevation.However,less is known how forest growth responds to climatic change along elevation.In this study,four standard treering width chronologies of Himalayan fir(Abies spectabilis)were developed,spanning 142–649 years along an elevation gradient of 3076–3900 m a.s.l.Principal component analysis classified the four chronologies into two groups;the ones at lower elevations(M1 and M2)and higher elevations(M3 and M4)show two distinct growth trends.Radial growth is limited by summer(June–August)precipitation at M3,and by precipitation during spring(March–May)and summer at M4.It is limited by spring temperatures and winter precipitation(December–February)at M1.Tree-ring width chronologies also significantly correlate with winter and spring Palmer Drought Severity Index(PDSI)at M1,and with summer PDSI at M3 and M4.Thus,Himalayan fir growth at high elevations is mainly limited by moisture stress rather than by low temperatures.Furthermore,the occurrence of missing rings coincides with dry periods,providing additional evidence for moisture limitation of Himalayan fir growth.展开更多
Plants require a number of essential elements in different proportions for ensuring their growth and development.The elemental concentrations in leaves reflect the functions and adaptations of plants under specific en...Plants require a number of essential elements in different proportions for ensuring their growth and development.The elemental concentrations in leaves reflect the functions and adaptations of plants under specific environmental conditions.However,less is known about how the spectrum of leaf elements associated with resource acquisition,photosynthesis and growth regulates forest biomass along broad elevational gradients.We examined the influence of leaf element distribution and diversity on forest biomass by analyzing ten elements(C,N,P,K,Ca,Mg,Zn,Fe,Cu,and Mn)in tree communities situated every 100 meters along an extensive elevation gradient,ranging from the tropical forest(80 meters above sea level)to the alpine treeline(4200 meters above sea level)in the Kangchenjunga Landscape in eastern Nepal Himalayas.We calculated communityweighted averages(reflecting dominant traits governing biomass,i.e.,mass-ratio effect)and functional divergence(reflecting increased trait variety,i.e.,complementarity effect)for leaf elements in a total of 1,859 trees representing 116 species.An increasing mass-ratio effect and decreasing complementarity in leaf elements enhance forest biomass accumulation.A combination of elements together with elevation explains biomass(52.2%of the variance)better than individual elemental trait diversity(0.05%to 21%of the variance).Elevation modulates trait diversity among plant species in biomass accumulation.Complementarity promotes biomass at lower elevations,but reduces biomass at higher elevations,demonstrating an interaction between elevation and complementarity.The interaction between elevation and mass-ratio effect produces heterogeneous effects on biomass along the elevation gradient.Our research indicates that biomass accumulation can be disproportionately affected by elevation due to interactions among trait diversities across vegetation zones.While higher trait variation enhances the adaptation of species to environmental changes,it reduces biomass accumulation,especially at higher elevations.展开更多
Large tropical volcanic eruptions can cause short-term global cooling. However, little is known whether large tropical volcanic eruptions, like the one in Tambora/Indonesia in 1815, cause regional hydroclimatic anomal...Large tropical volcanic eruptions can cause short-term global cooling. However, little is known whether large tropical volcanic eruptions, like the one in Tambora/Indonesia in 1815, cause regional hydroclimatic anomalies. Using a tree-ring network of precisely dated Himalayan birch in the central Himalayas, we reconstructed variations in the regional pre-monsoon precipitation back to 1650 CE. A superposed epoch analysis indicates that the pre-monsoon regional droughts are associated with large tropical volcanic eruptions, appearing to have a strong influence on hydroclimatic conditions in the central Himalayas. In fact, the most severe drought since 1650 CE occurred after the Tambora eruption. These results suggest that dry conditions prior to monsoon in the central Himalayas were associated with explosive tropical volcanism. Prolonged La Ni?a events also correspond with persistent pre-monsoon droughts in the central Himalayas. Our results provide evidence that large tropical volcanic eruptions most likely induced severe droughts prior to monsoon in the central Himalayas.展开更多
基金We thank the Kathmandu Center for Research and Education,CAS-TU,for help during the fieldwork。
文摘The Himalayas are characterized by a broad gradient of bioclimatic zones along their elevation.However,less is known how forest growth responds to climatic change along elevation.In this study,four standard treering width chronologies of Himalayan fir(Abies spectabilis)were developed,spanning 142–649 years along an elevation gradient of 3076–3900 m a.s.l.Principal component analysis classified the four chronologies into two groups;the ones at lower elevations(M1 and M2)and higher elevations(M3 and M4)show two distinct growth trends.Radial growth is limited by summer(June–August)precipitation at M3,and by precipitation during spring(March–May)and summer at M4.It is limited by spring temperatures and winter precipitation(December–February)at M1.Tree-ring width chronologies also significantly correlate with winter and spring Palmer Drought Severity Index(PDSI)at M1,and with summer PDSI at M3 and M4.Thus,Himalayan fir growth at high elevations is mainly limited by moisture stress rather than by low temperatures.Furthermore,the occurrence of missing rings coincides with dry periods,providing additional evidence for moisture limitation of Himalayan fir growth.
基金supported by the National Natural Science Foundation of China(Grant No.42030508)the Second Tibetan Plateau Scientific Expedition and Research Program(Grant No.2019QZKK0301)+3 种基金supported by CAS-TWAS President’s Fellowship Program for International Ph.D.studentssupported by Spanish Government(Grant Nos.PID2019-110521GB-I00 and TED2021-132627B-I00)the Catalan Government(Grant No.SGR 2017-1005)and the Fundación“Ramón Areces”(Grant No.CIVP20A6621)supported by the Spanish Government(Grant No.RTI2018-096884-B-C31)。
文摘Plants require a number of essential elements in different proportions for ensuring their growth and development.The elemental concentrations in leaves reflect the functions and adaptations of plants under specific environmental conditions.However,less is known about how the spectrum of leaf elements associated with resource acquisition,photosynthesis and growth regulates forest biomass along broad elevational gradients.We examined the influence of leaf element distribution and diversity on forest biomass by analyzing ten elements(C,N,P,K,Ca,Mg,Zn,Fe,Cu,and Mn)in tree communities situated every 100 meters along an extensive elevation gradient,ranging from the tropical forest(80 meters above sea level)to the alpine treeline(4200 meters above sea level)in the Kangchenjunga Landscape in eastern Nepal Himalayas.We calculated communityweighted averages(reflecting dominant traits governing biomass,i.e.,mass-ratio effect)and functional divergence(reflecting increased trait variety,i.e.,complementarity effect)for leaf elements in a total of 1,859 trees representing 116 species.An increasing mass-ratio effect and decreasing complementarity in leaf elements enhance forest biomass accumulation.A combination of elements together with elevation explains biomass(52.2%of the variance)better than individual elemental trait diversity(0.05%to 21%of the variance).Elevation modulates trait diversity among plant species in biomass accumulation.Complementarity promotes biomass at lower elevations,but reduces biomass at higher elevations,demonstrating an interaction between elevation and complementarity.The interaction between elevation and mass-ratio effect produces heterogeneous effects on biomass along the elevation gradient.Our research indicates that biomass accumulation can be disproportionately affected by elevation due to interactions among trait diversities across vegetation zones.While higher trait variation enhances the adaptation of species to environmental changes,it reduces biomass accumulation,especially at higher elevations.
基金the National Natural Science Foundation of China(42030508)the Science and Technology Major Project of Tibetan Autonomous Region of China(XZ202201ZD0005G02)the Long-Term Ecological Observation Study of Alpine Pine in Southeast Tibet(Science and Technology Innovation Base)(XZ202301JD0001G).
基金supported by the National Natural Science Foundation of China(42030508,41988101)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(2019QZKK0301)+1 种基金funding from the European Research Council(ERC-SyG-2013-610028 IMBALANCE-P)funding from the project “Inside out”(#POIR.04.04.00-00-5F85/18-00)funded by the HOMING programme of the Foundation for Polish Science co-financed by the European Union under the European Regional Development Fund。
基金supported by the National Natural Science Foundation of China (41661144040)the Strategic Priority Research Program of Chinese Academy of Sciences (XDA20050101, XDA2006040103)+1 种基金Youth Innovation Promotion Association of Chinese Academy of Sciences, and the Open Research Fund of Key Laboratory of Tibetan Environmental Changes and Land Surface Processes, Chinese Academy of Sciencessupported by the Chinese Academy of Sciences President’s International Fellowship Initiative (2018PC0040)
文摘Large tropical volcanic eruptions can cause short-term global cooling. However, little is known whether large tropical volcanic eruptions, like the one in Tambora/Indonesia in 1815, cause regional hydroclimatic anomalies. Using a tree-ring network of precisely dated Himalayan birch in the central Himalayas, we reconstructed variations in the regional pre-monsoon precipitation back to 1650 CE. A superposed epoch analysis indicates that the pre-monsoon regional droughts are associated with large tropical volcanic eruptions, appearing to have a strong influence on hydroclimatic conditions in the central Himalayas. In fact, the most severe drought since 1650 CE occurred after the Tambora eruption. These results suggest that dry conditions prior to monsoon in the central Himalayas were associated with explosive tropical volcanism. Prolonged La Ni?a events also correspond with persistent pre-monsoon droughts in the central Himalayas. Our results provide evidence that large tropical volcanic eruptions most likely induced severe droughts prior to monsoon in the central Himalayas.
