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Encroachment drives facilitation at alpine shrublines

Forest Ecosystems 2024年第1期11卷 62-72页

作者： Yafeng Wang eryuan liang J.Julio Camarero College of Ecology and Environment Nanjing Forestry UniversityNanjing210037China State Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing100101China Instituto Pirenaico de Ecología(IPE-CSIC) Zaragoza50080Spain

Ongoing encroachment is driving recent alpine shrubline dynamics globally,but the role of shrub-shrub interactions in shaping shrublines and their relationships with stem density changes remain poorly ***,the size and age of shrubs from 26 Salix shrubline populations along a 900-km latitudinal gradient(30°-38°N)were measured and mapped across the eastern Tibetan *** pattern analyses were used to quantify the spatial distribution patterns of juveniles and adults,and to assess spatial associations between *** intensity of univariate and bivariate spatial patterns was related to biotic and abiotic *** mark correlation functions with a quantitative mark(shrub height,basal stem diameter,crown width)were also employed to investigate the spatial relationships between shrub traits of juveniles and *** equation models were used to explore the relationships among conspecific interactions,patterns,shrub traits and recruitment dynamics under climate *** shrublines showed clustered patterns,suggesting the existence of conspecific *** patterns of juveniles and conspecific interactions(potentially facilitation)tended to intensify with increasing soil moisture *** warming before 2010 triggered positive effects on population interactions and spatial patterns via increased shrub ***,summer warming after2010 triggered negative effects on interactions through reduced shrub ***,shrub recruitment shifts under rapid climate change could impact spatial patterns,alter conspecific interactions and modify the direction and degree of shrublines responses to *** changes would have profound implications for the stability of alpine woody ecosystems.

关键词： Alpine shrubline Positive interactions Facilitation Spatial clustering Point pattern analyses

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Tree-ring based PDSI reconstruction since AD 1842 in the Ortindag Sand Land,east Inner Mongolia

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Chinese Science Bulletin 2007年第19期52卷 2715-2721页

作者： liang eryuan SHAO XueMei LIU HongYan ECKSTEIN Dieter Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100085 China Institute of Geographic Science and Natural Resource Research Chinese Academy of Sciences Beijing 100101 China College of Environmental Science Peking University Beijing 100871 China Department of Wood Science University of Hamburg Hamburg D-21031 Germany

epartment of Wood Science, University of Hamburg, Hamburg D-21031, GermanyBased on three Chinese pine (Pinus tabulaeformis Carr.) and one Meyer spruce (Picea meyeri Rehd. et Wils.) ring-width chronologies, a 163-year drought history was reconstructed in the eastern Ortindag Sand Land. All tree-ring chronologies show large inter-annual variations and strong common signals and fairly consistent variation between different chronologies, indicating that they are excellent proxy of regional climate. A regional chronology (RC) was established by averaging the four standard chronologies and further employed for the analysis and climatic reconstruction. The analysis revealed that tree growth is primarily limited by low precipitation in February-March and June-July and high temperature in May-July. In addition, RC has high correlations with the monthly Palmer drought severity index (PDSI) prior to and during the growing season because the PDSI considers the accumulation of the droughts. Response function analysis revealed that RC only exhibits significant correlations with the PDSI in June and July (close to the 95% significance level in May). Because May―July is a critical period for tree growth, the average May-July PDSI (PDSI5-7) was reconstructed back to 1842 using RC in the Ortindag Sand Land. The reconstruction can explain 52% of the PDSI variance and the equation was rather stable over time. It agrees well with the variation of the average dryness/wetness indices in North China,and captures the decline process of the East Asian summer monsoon since the mid-1960s. It is worth noting that the Ortindag Sand Land has experienced the most severe drought in the recent 40 years based on the 163-year drought reconstruction. Like summer precipitation in North China the reconstructed PDSI5-7 also displays a 20-year oscillation.

关键词：干旱沙地环境地质

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Strong link between large tropical volcanic eruptions and severe droughts prior to monsoon in the central Himalayas revealed by tree-ring records

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Science Bulletin 2019年第14期64卷 1018-1023页

作者： eryuan liang Binod Dawadi Neil Pederson Shilong Piao Haifeng Zhu Shalik Ram Sigdel Deliang Chen Key Laboratory of Alpine Ecology Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100101 China Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of Sciences Beijing 100101 China Central Department of Hydrology and Meteorology Tribhuvan University Kathmandu Nepal Harvard Forest Harvard University Petersham MA 01366 USA College of Urban and Environmental Sciences Peking University Beijing 100871 China Key Laboratory of Tibetan Environment Changes and Land Surface Processes Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100101 China Regional Climate Group Department of Earth Sciences University of Gothenburg Gothenburg 40530 Sweden

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.

关键词： Tree ring Drought Tropical volcanic eruptions Central Himalayas

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Critical minimum temperature limits xylogenesis and maintains treelines on the southeastern Tibetan Plateau

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Science Bulletin 2017年第11期62卷 804-812页

作者： Xiaoxia Li eryuan liang Jozica Gricar Sergio Rossi Katarina Cufar Aaron M. Ellison Key Laboratory of Alpine Ecology and Biodiversity Key Laboratory of Tibetan Environment Changes and Land Surface Processes Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100101 China CAS Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101 China Sloven ian Forestry Institute Department of Yield and Silviculture Vecna pot 2 S1-1000 Ljubljana Slovenia University of Quebec in Chicoutimi Departement des Sciences Fondamentales 555 Boulevard de l'Universite Chicoutimi (QC) G7H2B1 Canada Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems Guangdong Provincial Key Laboratory of Applied Botany South China Botanical Garden Chinese Academy of Sciences Guangzhou 510650 China University of Ljubljana Biotechnical Faculty Department of Wood Science and Technology Jamnikarjeva 101 S1-1000 Ljubljana Slovenia Harvard Forest Harvard University 324 North Main St. Petersham MA 01366 USA

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. srnithii） 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 ℃. A process-based modelling chronology of tree-ring formation using this CTmin was consistent with actual tree-ring data. This extremely low CTmin permits Smith fir growing at treeline to complete annual xylem production and maturation and provides both support and a mechanism for treeline formation.

关键词： Cambial activity Critical minimum temperature Timberline Xylem Vaganov-Shashldn model

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Millennial temperature reconstruction based on tree-ring widths of Qilian juniper from Wulan,Qinghai Province,China

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Chinese Science Bulletin 2008年第24期53卷 3914-3920页

作者： ZHU HaiFeng ZHENG YongHong SHAO XueMei LIU XiaoHong XU Yan liang eryuan Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100085 China State Key Laboratory of Cryospheric Sciences Cold and Arid Regions Environment and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China Graduate School of the Chinese Academy of Sciences Beijing 100049 China

The climate of the past 1000 years is an important context for evaluating the recent climate ***,there are few 1000-year-long climate reconstructions with annual resolution in the Qing-hai-Tibet *** this paper,a dendroclimatic analysis was conducted for the radial growth of Qilian juniper from the upper forest limit in Wulan,Qinghai *** results of correlation analysis between the tree-ring widths and the climate variables indicate that the growth of junipers at the upper forest limit is mainly limited by low temperatures of September,November and February of the pregrowth season,and July of the current growth *** is no significant correlation between the tree-ring widths and precipitation.A mean temperature from the previous year's September to the current year's April was reconstructed for the Wulan area since *** reconstruction can explain 40.8% of the instrumental variance in the calibration period(1856―2002).The reconstruction shows that the 20th century is the warmest 100 years,and the 1990s is the warmest decade during the past 1000 years,while the coldest 100 years and decade occur at 1600―1699 and 1642―1651,*** variations are verified well by the temperature reconstruction of the middle Qilian Mountain(QL) and the total organic carbon(TOC) in the Qinghai Lake *** comparison of our reconstruction with the annual temperature reconstruction of extra-tropical Northern Hemisphere suggests that the climate of Wulan during the Medieval Warm Period is of obvious regional specialty,but there was a good response to the climate of hemispheric scales during the recent 400 years.

关键词：西藏高原盆地桧属植物年轮温度记录

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Warming-induced phenological mismatch between trees and shrubs explains high-elevation forest expansion

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National Science Review 2023年第10期10卷 62-71页

作者： Xiaoxia Li eryuan liang J.Julio Camarero Sergio Rossi Jingtian Zhang Haifeng Zhu Yongshuo H.Fu Jian Sun Tao Wang Shilong Piao Josep Pe?uelas State Key Laboratory of Tibetan Plateau Earth System Environment and Resources (TPESER)Institute of Tibetan Plateau ResearchChinese Academy of Sciences Laboratoire sur les écosystèmes terrestres boréaux Département des Sciences FondamentalesUniversité du Québec à Chicoutimi Instituto Pirenaico de Ecología (IPE-CSIC) College of Water Sciences Beijing Normal University CREAF Cerdanyola del Valles CSIC Global Ecology Unit CREAF-CSIC-UAB

Despite the importance of species interaction in modulating the range shifts of plants,little is known about the responses of coexisting life forms to a warmer ***,we combine long-term monitoring of cambial phenology in sympatric trees and shrubs at two treelines of the Tibetan Plateau,with a meta-analysis of ring-width series from 344 shrubs and 575 trees paired across 11 alpine treelines in the Northern *** a spring warming of +1℃,xylem resumption advances by 2-4 days in trees,but delays by 3-8 days in *** divergent phenological response to warming was due to shrubs being3.2 times more sensitive than trees to chilling *** winters increased the thermal requirement for cambial reactivation in shrubs,leading to a delayed response to warmer *** meta-analysis confirmed such a mechanism across continental *** warming-induced phenological mismatch may give a competitive advantage to trees over shrubs,which would provide a new explanation for increasing alpine treeline shifts under the context of climate change.

关键词： chilling climate warming forcing treeline shift xylogenesis

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Linking leaf elemental traits to biomass across forest biomes in the Himalayas

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Science China Earth Sciences 2024年第5期67卷 1518-1528页

作者： Nita DYOLA eryuan liang Josep PEÑUELAS J.Julio CAMARERO Shalik Ram SIGDEL Sugam ARYAL Wentao LIN Xiang LIU Yongwen LIU Xingliang XU Sergio ROSSI State Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Laboratoire sur lesécosystèmes terrestres boréaux Département des Sciences FondamentalesUniversitédu QuébecàChicoutimi555Boulevard de l′UniversitéChicoutimi(QC)G7H2B1Canada CSIC Global Ecology Unit CREAF-CSIC-UABBellaterraE-08193 CataloniaSpain CREAF Cerdanyola del VallèsE-08193 CataloniaSpain Instituto Pirenaico de Ecología(IPE-CSIC) Avenida Montañana 1005Zaragoza 50059Spain Friedrich-Alexander-Universität Erlangen-Nürnberg Institut für GeographieErlangen 91058Germany State Key Laboratory of Grassland Agro-Ecosystems College of EcologyLanzhou UniversityLanzhou 730000China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China

Plants require a number of essential elements in different proportions for ensuring their growth and *** elemental concentrations in leaves reflect the functions and adaptations of plants under specific environmental ***,less is known about how the spectrum of leaf elements associated with resource acquisition,photosynthesis and growth regulates forest biomass along broad elevational *** 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 *** 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 *** 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 *** promotes biomass at lower elevations,but reduces biomass at higher elevations,demonstrating an interaction between elevation and *** interaction between elevation and mass-ratio effect produces heterogeneous effects on biomass along the elevation *** research indicates that biomass accumulation can be disproportionately affected by elevation due to interactions among trait diversities across vegetation *** higher trait variation enhances the adaptation of species to environmental changes,it reduces

关键词： Ecosystem function Elevational gradient Functional diversity Functional traits Leaf elements Niche complementarity

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干扰对树线生态过程的影响研究进展

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科学通报 2019年第16期64卷 1711-1721页

作者：王亚锋梁尔源南京林业大学生物与环境学院南京210037 中国科学院高寒生态重点实验室中国科学院青藏高原研究所北京100101 中国科学院青藏高原地球科学卓越创新中心北京100101

作为重要的非气候因子之一,干扰与树线之间的关系已成为干扰生态学研究的重要内容之一,开展受干扰树线研究对于实施山区生态保护或修复具有重要意义.当前,关于干扰如何调控树线对气候变化的响应仍缺乏系统的研究.为此,本研究梳理了气候... 详细信息

作为重要的非气候因子之一,干扰与树线之间的关系已成为干扰生态学研究的重要内容之一,开展受干扰树线研究对于实施山区生态保护或修复具有重要意义.当前,关于干扰如何调控树线对气候变化的响应仍缺乏系统的研究.为此,本研究梳理了气候变化背景下多种干扰因子对树线生态过程的影响.已有的树线研究中涉及的自然干扰主要包括:火山喷发、冰川进退、野火、雪崩、生物活动、极端低温、强风等;人为干扰包括:森林砍伐、放牧、人为用火、开矿、农耕、药草采集、旅游等.在多数情况下,由于在强度、频率、持续时间上的差异,不同干扰因子对树线生态过程具有不同的效应.在干扰迹地上,根据土壤生境状况,树线变化将经历由多种环境因素驱动的原生或次生演替过程以及由气候驱动的林分变化两个主要阶段.当前研究中缺少对常见干扰因子的连续观测资料,且未能很好地区分干扰历史和气候变化对树线生态过程影响的相对贡献.相关研究需同时关注干扰因子对树线的破坏性和增益性影响,尤其加强后者研究可避免对树线干扰因子的片面认识.今后亟待开展干扰状况下的树线模拟研究.基于多种研究手段,围绕关键生态过程,针对树线人为干扰因子进行长期跟踪调查是值得尝试的研究思路.值得提出的是,青藏高原既拥有北半球最高海拔的天然树线,也分布着不同类型的受干扰树线,是开展天然树线与受干扰树线对比研究的理想区域.

关键词：树线干扰树轮生态学气候变化青藏高原

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灌木年轮学研究进展

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生态学报 2013年第5期33卷 1367-1374页

作者：芦晓明梁尔源中国科学院环境变化与地表过程重点实验室中国科学院青藏高原研究所北京100101 中国科学院大学北京100049

灌木往往分布在树线以上或以北的高海拔和高纬度地区以及干旱、半干旱区,是把传统上以乔木为主的树轮研究扩展至森林分布界限以外的唯一选择。尽管灌木具有以上研究潜力,迄今用于树木年代学研究的灌木种类仅有30种左右。介绍了灌木年轮... 详细信息

灌木往往分布在树线以上或以北的高海拔和高纬度地区以及干旱、半干旱区,是把传统上以乔木为主的树轮研究扩展至森林分布界限以外的唯一选择。尽管灌木具有以上研究潜力,迄今用于树木年代学研究的灌木种类仅有30种左右。介绍了灌木年轮研究方法,综述了过去几十年来环北极高纬度地区,干旱、半干旱区以及高海拔地区的灌木年轮研究的主要进展。主要研究进展如下:(1)发掘一些灌木的树木年代学潜力;(2)揭示限制灌木生长的主要环境因子,并尝试利用灌木年轮宽度等指标重建过去区域气候变化历史;(3)探讨全球变暖的背景下,灌木的生长或分布范围的变化;(4)通过人为控制增温来揭示变暖对灌木生理特征和生长的影响。这些研究展示了灌木在扩展传统乔木树轮研究网络方面的潜力,也是树木年代学研究中最有前景的研究方向之一。目前的灌木年轮学研究多集中于环北极苔原带。作为地球的第三极,青藏高原具有广泛的高山灌木分布,具有把青藏高原边缘区以乔木为主的树木年轮网络扩展至更高海拔和高原内部的潜力。青藏高原高山灌木的年轮学研究并没有引起足够的重视。青藏高原高山灌木的生长是如何适应极端环境条件的,全球变暖的背景下,青藏高原高山灌木的分布和生长正在发生哪些变化等,都有待深入研究。

关键词：灌木年轮气候变化树木年代学青藏高原

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火山喷发对陆地植被与碳循环影响的研究进展

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科学通报 2024年第2期69卷 160-168页

作者：张原梁尔源汪涛朴世龙中国科学院青藏高原研究所高寒生态重点实验室北京100101 Laboratory for Sciences of Climate and Environment Institute Pierre-Simon LaplaceFrench Alternative Energies and Atomic Energy Commission/French National Centre for Scientific Research/Versailles-St-Quentin UniversityGif sur Yvette 91191France 中国科学院青藏高原地球科学卓越创新中心北京100101 北京大学城市与环境学院北京100871

1991年,Pinatubo火山喷发导致全球大气二氧化碳浓度上升态势出现停滞,这一现象揭示了地球内部系统可以通过火山活动对地表生物地球化学循环产生重大影响.近些年,火山喷发对陆地生态系统的影响及其驱动机制引起科学界的广泛讨论.本文系... 详细信息

1991年,Pinatubo火山喷发导致全球大气二氧化碳浓度上升态势出现停滞,这一现象揭示了地球内部系统可以通过火山活动对地表生物地球化学循环产生重大影响.近些年,火山喷发对陆地生态系统的影响及其驱动机制引起科学界的广泛讨论.本文系统梳理了火山喷发对陆地生态系统影响的研究,总结了火山活动的辐射效应和气候效应对树木生长和陆地碳循环产生影响的机制.大型火山喷发形成的平流层气溶胶一方面引起散射辐射增加促进光合作用,另一方面,还引起总辐射减弱抑制光合作用,由于散射辐射的影响相比更强,总体上火山辐射效应有利于陆地碳汇的增加.火山的气候效应体现在全球尺度的降温和区域降水的改变.降温作用在低纬地区促进植被的光合作用,在高纬地区抑制光合作用,同时在全球尺度减弱生态系统的呼吸作用,总体上也有利于增加碳汇.对火山造成降水变化影响的评估目前还存在较大不确定性.在对这些机制总结的基础上,本文评述了当前的认识盲点和研究难点,以期为未来进一步推进火山喷发影响的研究、完善地球内外系统联动机制的认识提供参考.

关键词：火山爆发陆地生态系统火山冷却效应散射辐射碳循环

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