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
Physiological and ecological mechanisms that define treelines are still debated.It has been suggested that the absence of trees above the treeline is caused by low temperatures that limit growth.Thus,we hypothesized t...Physiological and ecological mechanisms that define treelines are still debated.It has been suggested that the absence of trees above the treeline is caused by low temperatures that limit growth.Thus,we hypothesized that there is a critical minimum temperature(CTmin) preventing xylogenesis at treeline.We tested this hypothesis by examining weekly xylogenesis across three and four growing seasons in two natural Smith fir(Abies georgei var.smithii) treeline sites on the southeastern Tibetan Plateau.Despite differences in the timing of cell differentiation among years,minimum air temperature was the dominant climatic variable associated with xylem growth;the critical minimum temperature(CTmin) for the onset and end of xylogenesis occurred at 0.7 ± 0.4 °C.A process-based modelling chronology of tree-ring formation using this CTminwas consistent with actual tree-ring data.This extremely low CTminpermits Smith fir growing at treeline to complete annual xylem production and maturation and provides both support and a mechanism for treeline formation.展开更多
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supported by the National Natural Science Foundations of China(41525001,41661144040,41601204)supported by the Bilateral Project between China and Slovenia(BI-CN/09–11-012)+1 种基金COST Action(FP1106,STRe ESS)supported by the Chinese Academy of Sciences President International Fellowship Initiative for Visiting Scientists(2016VBA074)
文摘Physiological and ecological mechanisms that define treelines are still debated.It has been suggested that the absence of trees above the treeline is caused by low temperatures that limit growth.Thus,we hypothesized that there is a critical minimum temperature(CTmin) preventing xylogenesis at treeline.We tested this hypothesis by examining weekly xylogenesis across three and four growing seasons in two natural Smith fir(Abies georgei var.smithii) treeline sites on the southeastern Tibetan Plateau.Despite differences in the timing of cell differentiation among years,minimum air temperature was the dominant climatic variable associated with xylem growth;the critical minimum temperature(CTmin) for the onset and end of xylogenesis occurred at 0.7 ± 0.4 °C.A process-based modelling chronology of tree-ring formation using this CTminwas consistent with actual tree-ring data.This extremely low CTminpermits Smith fir growing at treeline to complete annual xylem production and maturation and provides both support and a mechanism for treeline formation.