高山林线树木光合作用适应性研究进展

高山林线作为一类特殊的生态过渡带, 各类环境因子随海拔升高具有明显的梯度变化规律。林线过渡带物种组成与植被格局变化、林线上下界及树线推移等长期受到生态学与植物学研究的关注。不同生活型的林线植物, 尤其是木本植物对高海拔林线逆境光合响应方式与策略的差异, 直接导致林线植被组成与分布格局的变化, 最终影响林线上下界以及树线的形成。并且, 作为陆地生态系统对全球气候变化响应最为敏感的地区之一, 林线植物光合作用响应性变化特征已成为预测全球气候变化条件下林线植被未来动态变化的重要参数。文中主要从叶片形态与结构以及叶片光合生理代谢等方面, 综述山地木本植物适应林线逆境的相关研究进展, 以期有助于理解高寒地带林线生境植被分布格局形成以及物种组成变化的驱动因子, 为在全球气候变化条件下开展林线植物光合作用响应性研究提供参考作用。     

温度、降水与树木径向生长关系研究现状

树木的生长与立地环境密切相关并受气候变化的影响,树木年轮宽度是反映气候与环境变化的一个重要参数,主要是根据树木径向生长的特点获取数据,进而重建环境因子的变化史实。树木径向生长特点和环境因子之间的关系密切,论述了温度、降水对树木径向生长的影响,同时介绍了林线处树木径向生长与温度和降水的关系,提出了将林线形成的时间过程和林线的空间格局结合起来进行综合、系统地研究,以揭示气候变化与林线、树线之间的响应机制。     

全球高山林线研究现状与发展方向

当山体达到一定高度时出现的森林分布上限——高山林线，归根结底是一条低温界限。逾百年高山林线的观测与研究，旨在阐明高山林线成因以恢复气候高山林线。迄今出现的各种（可归为5类）高山林线成因假说，虽然每一种都可以解释一定地域的高山林线现象，但在全球尺度上，仍然缺乏一种可以普遍解释全球高山林线现象的假说和理论。另外，由于高山区域较少的人类干扰及短（海拔）距离内显著的环境因子梯度、结合高山林线特殊的结构、功能及对气候变化的高度敏感性，林线研究已经成为全球气候变化研究的热点区域之一。本文综述了全球高山林线知识现状，并对将来高山林线研究提出了一些建议。     

祁连山林线区域青海云杉种群对气候变化的响应

研究祁连山林线区域青海云杉种群结构、年轮生长及林线位置对气候变化的响应。结果表明:在区域气候变暖的背景下,青海云杉林线种群1～30龄的幼龄个体数量最多,占总数的80.9%;100年来林线种群密度大约增加了23倍,但林线位置并没有发生明显变化;年轮分析得出,气候变暖导致近30年来林线树木径生长明显增加,青海云杉树木年轮指数与当年夏季、秋季以及上一年夏季平均气温显著正相关,与上一年秋季及当年6月份的平均气温呈极显著正相关。     

不同种源树木径向生长对气候变化响应研究进展

树种群体的地理变异是林木选择育种的基础，研究不同种源径向生长的气候敏感性，对于种子调拨及优良种源的选择具有重要意义。本文综述了不同种源径向生长对气候变化的长期和短期响应，指出同一树种不同种源对气候变化具有不同的响应特征。利用不同种源径向生长对气候变化的响应，可指导未来气候下的种源选择。然而，国内有关同一树种不同种源对气候变化的响应研究仍十分缺乏，树木种源生长对气候变化的响应研究亟待进一步深入开展。采用树轮气候学方法探讨不同树木种源径向生长对气候变化的响应，可有效促进我国森林培育管理，指导选择生产力高、适应性强的种源用于更新造林。     

国外植物物候对气候变化响应的研究进展

植物物候易于观测, 对气候变化响应敏感。国外在物候观测、网络建设和物候对气候变化响应的研究方面取得了显著成果, 对于推动我国植物物候对气候变化响应方面的研究工作具有重要作用。综合论述了国外物候观测和网络建设、植物物候对气候变化响应的研究方法和主要研究成果, 并探讨了未来植物物候对气候变化响应研究的发展趋势。     

树轮生态学研究进展

树轮生态学是现代树轮年代学的重要分支, 在全球气候变化引起的资源、环境等压力日益增大的今天, 越来越显示出树轮生态学研究的理论和现实意义。文中简要概述了树轮分析在森林干扰、群落动态、森林结构、林分更新方式以及高山林线研究方面的进展。树轮生态学将对我国树木个体生长情况和群落动态的研究, 虫灾、火灾、风灾和森林动态的关系以及森林管理相关的研究发挥重要作用。     

藏东南急尖长苞冷杉生长状况研究

运用标准木解析法对藏东南不同海拔高度急尖长苞冷杉的树高、直径生长进行研究的结果表明：冷杉在生长期对气候变化的反映十分敏感，在100年以内，适生区树高平均每年生长0．328m，是林线处的5．6倍，直径平均每年生长0．48cm，是林线处的3．4倍。极端气候条件是决定冷杉种群在林线附近生存、生长和扩展的限制因子。     

非结构性碳水化合物对气候变化响应研究进展

为探索森林生态系统非结构性碳水化合物变化对气候变化的响应,该文综述了当今非结构性碳水化合物的研究概况,并结合CO_2浓度升高、干旱胁迫以及氮沉降3种主要的全球气候变化阐述非结构性碳水化合物的响应特征。今后研究应从整个生态系统的角度出发,为探讨植物群落的碳利用策略以及对环境变化的响应和适应机制提供理论依据。     

气候因素对木材细胞结构的影响

综述针叶材年轮内管胞个数、尺寸、壁厚和树脂道个数及阔叶材年轮内导管个数和尺寸等木材细胞结构对温度和降雨的响应。影响木材细胞结构的因素除气候外,还有非气候因素,在研究木材细胞结构对气候变化响应时,应尽可能地考虑到后者的影响。本文也综述一些非气候因素,如地形、土壤、海拔、大气污染、病虫害、种植密度、施肥和灌溉等对木材细胞结构的影响,以期充分认识影响木材细胞结构的因素,为木材细胞结构对气候变化响应的研究和林业应对气候变化提供参考。     

Larix olgensis growth-climate response between lower and upper elevation limits:an intensive study along the eastern slope of the Changbai Mountains,northeastern China

Larix olgensis is a dominant tree species in the forest ecosystems of the Changbai Mountains of northeast China.To assess the growth response of this species to global climate change,we developed three tree-ring width and biomass chronologies across a range of elevations in the subalpine forests on the eastern slope of the Changbai Mountains.We used dendroclimatic analyses to study key factors limiting radial growth in L.olgensis and its variation with elevation.The statistical characteristics of chronologies suggested that elevation is a determinant of tree growth patterns in the study area.Response function analysis of chronologies with climate factors indicated that climate–growth relationships changed with increasing elevation:tree growth at high elevation was strongly limited by June temperatures of the previous year,and as elevation decreases,the importance of temperature decreased;tree radial growth at mid-elevation was mainly controlled by precipitation towards the end of the growing season of the current year.Biomass chronologies reflected a stronger climatic signal than tree-ring width chronologies.Spatial correlation with gridded climate data revealed that our chronologies contained a strong regional temperature signal for northeast China.Trees growing below timberline appeared to be more sensitive to climate,thus optimal sites for examining growth trends as a function of climate variation are considered to be just below timberline.Our study objective was to provide information for more accurate prediction of the growth response of L.olgensis to future climate change on the eastern slope of the Changbai Mountains,and to provide information for future climate reconstructions using this tree species in humid and semi humid regions.     

Vulnerability of Pinus cembra L. in the Alps and the Carpathian mountains under present and future climates

Proactive management should be applied within a forest conservation context to prevent extinction or degradation of those forest ecosystems that we suspect will be affected by global warming in the next century. The aim of this study is to estimate the vulnerability under climate change of a localized and endemic tree species Pinus cembra that occurs in the alpine timberline. We used the Random Forest ensemble classifier and available bioclimatic and ecological data to model present and future suitable areas for P. cembra and estimate its current and future vulnerability. Future projections for years 2020, 2050 and 2080 were simulated using two IPCC Special Report on Emission Scenarios run under four global climate models.     

Effects of atmospheric and climate change at the timberline of the Central European Alps

? This review considers potential effects of atmospheric change and climate warming within the timberline ecotone of the Central European Alps. After focusing on the impacts of ozone (O₃) and rising atmospheric CO₂ concentration, effects of climate warming on the carbon and water balance of timberline trees and forests will be outlined towards conclusions about changes in tree growth and treeline dynamics.

? Presently, ambient ground-level O₃ concentrations do not exert crucial stress on adult conifers at the timberline of the Central European Alps. In response to elevated atmospheric CO₂ Larix decidua showed growth increase, whereas no such response was found in Pinus uncinata. Overall climate warming appears as the factor responsible for the observed growth stimulation of timberline trees.

? Increased seedling re-establishment in the Central European Alps however, resulted from invasion into potential habitats rather than upward migration due to climate change, although seedlings will only reach tree size upon successful coupling with the atmosphere and thus loosing the beneficial microclimate of low stature vegetation.

? In conclusion, future climate extremes are more likely than the gradual temperature increase to control treeline dynamics in the Central European Alps.

     

气候变化背景下干旱生态系统土地退化防治

气候变化是当今全球陆地生态系统所面临的最大胁迫因素。探讨气候变化背景下干旱生态系统土地退化防治, 增强减缓和适应气候变化的能力, 逐步恢复土地生态系统原先所具有的综合生产潜力, 是亟待解决的重要课题。文中分析了气候变化对干旱生态系统土地退化的影响, 从综合生态系统管理的视角, 探讨了保护与恢复森林、草地、农田生态系统以增强应对气候变化的能力以及改善民生的途径, 以期为全球气候变化背景下土地退化防治和干旱生态系统可持续管理提供新的思路。     

Influence of climate on radial growth of Pinus cembra within the alpine timberline ecotone

Radial growth variability and response to interannual climate variation of Cembran pine (Pinus cembra L.) were studied in the timberline ecotone on Mt. Patscherkofel (2246 m a.s.l.). The study area, which is in the inner alpine dry region of the Central Austrian Alps, is characterized by a continental climate with minimum precipitation in winter (about 150 mm during December-February) and frequent occurrence of warm dry winds (F?hn) in early spring. The hypothesis that spatial and temporal variability of radial growth is caused by site-related differences in sensitivity to winter stress (i.e., desiccation) was examined by applying dendroclimatological techniques. Ordination methods applied to tree ring time series revealed that spatial variability in radial growth is influenced by the local site factors elevation and slope aspect. Growth-climate relationships were explored using Pearson product-moment correlation coefficients and multiple regression analysis. Radial growth at the timberline was positively correlated with temperature in July and was also strongly correlated with mild temperatures in the previous autumn and high precipitation in winter (January-March). At the tree line, temperatures in the previous autumn and precipitation in late winter (March) also controlled radial growth, whereas July temperature was not significantly correlated with ring width. Because previous autumn temperature and winter precipitation were the main growth-determining factors at the timberline and the tree line, and both of these climate variables are known to influence susceptibility of trees to winter stress, the results support the working hypothesis. Analysis of climatic conditions in extreme growth years confirmed the high sensitivity of tree ring growth to precipitation in late winter (March) at the tree line plots. Furthermore, extent of growth reduction and release varied spatially and temporarily, with south- and west-facing stands showing a higher sensitivity to climate variation in the most recent decade (1990s) than the north-facing stand. This aspect-related change in sensitivity to climate may be associated with effects of climate warming on cambial activity.     

全球气候变化及森林生态系统的适应性管理

人类活动所引起的温室效应及由此造成的全球气候变化对全球生态环境的影响正越来越引起人们的关注。森林作为全球陆地生态系统的一个重要组分, 对全球气候变化的响应较为敏感。文中系统总结了全球气候变化对物种和森林类型分布、森林生态系统结构和物种组成、森林生产力、森林土壤碳氮循环和森林灾害等几个方面的影响, 以及森林生态系统管理面临的挑战, 在此基础上提出了适应未来气候变化的森林生态系统管理策略。     

不同森林经营措施对木材产量和碳储量的影响

在应对全球气候变化中, 林业具有特殊地位和重要功能, 以社会、经济和环境可持续发展为目标的森林可持续经营是全球趋势。文中阐述了森林在减缓和适应气候变化中的独特作用; 重点分析了不同营林措施对木材产量和碳储量的影响, 并结合可持续林业的发展趋势评价了不同经营模式框架下木材产量与碳储量之间的平衡; 针对全球气候变化对森林生态系统带来的挑战, 探讨了今后森林经营措施的研究重点和难点, 旨在为制定合理的经营方案提供理论依据。