樟子松和落叶松径向生长对气候变化的响应

在全球变暖的背景下,升温可能会影响树木的生长,导致森林生态系统的平衡受到干扰。本研究利用树轮年代学方法中的生长-气候响应函数、滑动相关分析,探讨大兴安岭漠河地区樟子松和落叶松径向生长的限制因子,以及二者径向生长对快速升温的响应。结果表明: 樟子松和落叶松的径向生长受温度和降水的共同作用,樟子松对气候变化的响应比落叶松更为敏感,对气候因子的敏感性比落叶松更稳定。樟子松径向生长与当年生长季月均温及月均最低温呈显著正相关,而落叶松与冬季月均温及月均最高温呈显著正相关。冬季降水促进樟子松生长,前一年生长季后期降水抑制落叶松的径向生长。1990年快速升温后,降水对樟子松的限制作用由升温前的负相关转变为升温后的显著正相关,高温对樟子松的抑制作用大于促进作用;高温对落叶松的抑制作用增强,降水对落叶松的限制作用也在升温后增强,生长速率显著下降,二者生长速率与温度和降水的相关性变化存在明显差异。本研究可为大兴安岭森林生态系统管理与保护提供科学依据。     

Tree species growth response to climate warming varies by forest canopy position in boreal and temperate forests

Reports of forest sensitivity to climate change are based largely on the study of overstory trees, which contribute significantly to forest growth and wood supply. However, juveniles in the understory are also critical to predict future forest dynamics and demographics, but their sensitivity to climate remains less known. In this study, we applied boosted regression tree analysis to compare the sensitivity of understory and overstory trees for the 10 most common tree species in eastern North America using growth information from an unprecedented network of nearly 1.5 million tree records from 20,174 widely distributed, permanent sample plots across Canada and the United States. Fitted models were then used to project the near-term (2041–2070) growth for each canopy and tree species. We observed an overall positive effect of warming on tree growth for both canopies and most species, leading to an average of 7.8%–12.2% projected growth gains with climate change under RCP 4.5 and 8.5. The magnitude of these gains peaked in colder, northern areas for both canopies, while growth declines are projected for overstory trees in warmer, southern regions. Relative to overstory trees, understory tree growth was less positively affected by warming in northern regions, while displaying more positive responses in southern areas, likely driven by the buffering effect of the canopy from warming and climate extremes. Observed differences in climatic sensitivity between canopy positions underscore the importance of accounting for differential growth responses to climate between forest strata in future studies to improve ecological forecasts. Furthermore, latitudinal variation in the differential sensitivity of forest strata to climate reported here may help refine our comprehension of species range shift and changes in suitable habitat under climate change.     

Mixed-conifer understory response to climate change, nitrogen, and fire

California's Sierra Nevada mountains are predicted to experience greater variation in annual precipitation according to climate change models, while nitrogen deposition from pollution continues to increase. These changes may significantly affect understory communities and fuels in forests where managers are attempting to restore historic conditions after a century of altered fire regimes. The objective of this research was to experimentally test the effects of increasing and decreasing snowpack depth, increasing nitrogen, and applying prescribed fire to mixed-conifer forest understories at two sites in the central and southern Sierra Nevada. Understory response to treatments significantly differed between sites with herb biomass increasing in shrub-dominated communities when snowpack was reduced. Fire was a more important factor in post-treatment species richness and cover than either snowpack addition or reduction. Nitrogen additions unexpectedly increased herbaceous species richness. These varied findings indicate that modeling future climatic influences on biodiversity may be more difficult than additive prediction based on increasing the ecosystem's two limiting growth resources. Increasing snowpack and nitrogen resulted in increased shrub biomass production at both sites and increased herb production at the southern site. This additional understory biomass has the potential to increase fuel connectivity in patchy Sierran mixed-conifer forests, increasing fire severity and size.     

Stem-growth response of Pinus sylvestris and Picea abies to nitrogen fertilization as related to needle nitrogen concentration

 Responses of stem-volume growth to N application were evaluated in relation to foliar N concentrations. Data from N-fertilization experiments in 28 Pinus sylvestris stands and 21 Picea abies stands were used. Relative stem-growth responses were negatively related to concentrations of N in current-year needles of unfertilized trees. There appeared to be a threshold value of 15–16 mg (g DM)^–1 N in current-year needles, above which N-application is unlikely to stimulate growth. However, relations were non-significant between N concentrations in current-year needles and the absolute stem-growth response [dm³ ha^–1 (5 years)^–1]. The indicated threshold values are discussed in relation to other variables reflecting the N richness of the environment.--> Received: 20 December 1996 / Accepted: 30 September 1997     

Connections between climatic variables and the growth and needle dynamics of Scots pine (Pinus sylvestris L.) in Estonia and Lapland

The relationships between climatic variables and Scots pine (Pinus sylvestris L.) growth and needle dynamics were studied in three stands in Estonia and in four stands located near the northern timberline in Lapland. The trees sampled in Estonia had low correlations with the analysed climatic variables (air temperature, precipitation and indices of atmospheric circulation). Moreover, the weak cross-correlation of the time-series of the Estonian sample trees indicated that Scots pine is affected mainly by local factors in that region. In Lapland, however, height increment and needle production correlated strongly among trees within a stand (mean r=0.45 and 0.46, respectively) and between stands (r=0.32 and 0.37). Radial increment also showed a high inter-correlation among the trees within a stand in Lapland (r=0.45). Both height increment and needle production were strongly influenced by the temperature regime of the previous summer in Lapland (mean r=0.64 and 0.64, respectively). Radial increment was correlated with the mean July temperature of the current year (mean r=0.29). The correlations between the indices of atmospheric circulation and tree attributes were weak, while the strongest correlation was between the Ponta Delgada NAO index (PD–NAO) and height increment and needle production in Lapland. Height increment, needle production and radial increment have increased since the 1990s in the trees growing in Lapland. This may indicate a positive effect of climate warming on tree growth in Lapland. In Estonia, where climatic conditions do not limit tree growth, the climate warming seems not to directly influence the growth and needle dynamics of Scots pine.     

马尾松的生长与气候关系的年轮分析

马尾松的生长与气候关系的年轮分析兰涛,夏冰,贺善安（江苏省－中国科学院植物研究所,南京２１００１４）ＴｒｅｅｒｉｎｇａｎａｌｙｓｉｓｏｎｒｅｌａｔｉｏｎｏｆＰｉｎｕｓｍａｓｓｏｎｉａｎａｇｒｏｗｔｈｔｏｃｌｉｍａｔｅｆａｃｔｏｒｓ．￥ＬａｎＴａｏ;Ｘ...     

河北塞罕坝樟子松径向生长动态变化及其与气象因子的关系

树木是森林生态系统的基本组成, 其生长受气象因子的影响, 基于此, 该研究通过监测樟子松(Pinus sylvestris var. mongolica)的径向生长, 研究樟子松生长日动态规律、季节动态规律及其与气象因子的关系, 探讨河北塞罕坝地区樟子松森林生态系统对气候变化的响应机制。此外, 以往研究树木生长大多数基于树轮年代学, 缺少短期树木径向生长动态的研究。该研究利用径向生长记录仪监测河北塞罕坝机械林场内樟子松连续3年(2016-2018)的树干径向动态变化。结果表明: 由于树干的水分吸收与蒸腾作用, 樟子松树干径向昼夜变化呈现季节性规律, 可划分为4个阶段: 春季萌动期、夏季生长期、秋冬交替期和冬季休眠期。塞罕坝樟子松树干径向生长开始于每年4月初; 4月初至5月中旬为水分恢复阶段; 5月中旬至7月中旬为快速生长阶段; 7月中旬至10月中旬为缓慢生长阶段; 10月中、下旬生长趋于停止, 并有树干径向收缩现象。以一天为时间尺度, 在快速生长阶段(5月初至7月中旬)樟子松径向生长主要受空气温度的影响; 缓慢生长阶段(7月中旬至10月下旬)降水量、空气温度均影响樟子松径向生长。以15天为时间尺度, 温度对樟子松径向生长的影响显著。结果显示樟子松的生长动态规律及其影响因子, 为未来樟子松生理研究提供参考时间节点, 同时在极端低温与干旱的情况下, 为半干旱地区樟子松的生长状态提供参考依据。     

东北镜泊湖硅藻对近现代气候变化和人类干扰的响应过程

全球气候变暖和人类活动加剧已经导致中国大量湖泊生态系统功能退化,而目前对东北地区湖泊生态系统变化的认识主要源于短期的监测。以东北镜泊湖为例,通过沉积记录和现代监测资料,分析一个多世纪以来以硅藻群落为代表的湖泊生态系统对气候波动和区域人类活动的响应过程。研究结果表明,在人类干扰显著加强之前,风力扰动是镜泊湖硅藻群落变化的一个重要因子,表现为Aulacoseira属种取代小型浮游种(Cyclostephanos、Stephanodiscus和Discostella)成为优势种。20世纪70年代以来,Asterionella formosa、Nitzschia palea和Fragilaria crotonensis的相继增加则反映了流域农业活动加剧、农业化肥大量施用以及污水排放导致的湖泊营养水平升高。温度的持续上升已经引起东北地区一些湖泊硅藻群落结构发生显著变化,但镜泊湖的硅藻记录却未显示这一气候变化的信号。考虑湖泊-流域形态和人类活动的不同,研究认为近几十年气候变化对镜泊湖硅藻群落结构的影响被强烈的人类干扰所掩盖而未显现出来。     

Morphological variation in salamanders and their potential response to climate change

Despite the recognition that some species might quickly adapt to new conditions under climate change, demonstrating and predicting such a fundamental response is challenging. Morphological variations in response to climate may be caused by evolutionary changes or phenotypic plasticity, or both, but teasing apart these processes is difficult. Here, we built on the number of thoracic vertebrae (NTV) in ectothermic vertebrates, a known genetically based feature, to establish a link with body size and evaluate how climate change might affect the future morphological response of this group of species. First, we show that in old‐world salamanders, NTV variation is strongly related to changes in body size. Secondly, using 22 salamander species as a case study, we found support for relationships between the spatial variation in selected bioclimatic variables and NTV for most of species. For 44% of species, precipitation and aridity were the predominant drivers of geographical variation of the NTV. Temperature features were dominant for 31% of species, while for 19% temperature and precipitation played a comparable role. This two‐step analysis demonstrates that ectothermic vertebrates may evolve in response to climate change by modifying the number of thoracic vertebrae. These findings allow to develop scenarios for potential morphological evolution under future climate change and to identify areas and species in which the most marked evolutionary responses are expected. Resistance to climate change estimated from species distribution models was positively related to present‐day species morphological response, suggesting that the ability of morphological evolution may play a role for species’ persistence under climate change. The possibility that present‐day capacity for local adaptation might help the resistance response to climate change can be integrated into analyses of the impact of global changes and should also be considered when planning management actions favouring species persistence.     

Tree-ring growth of Pinus nigra Arn. subsp. pallasiana under different climate conditions throughout western Anatolia

Pinus nigra Arn. subsp. pallasiana (black pine) is one of the most widely grown tree in Turkey. It is the third most widely distributed tree species after Quercus L. and Pinus brutia Ten. Black pine grows in 20% of all forested areas in Turkey. In this dendroecological study, we identified the most important climate factors affecting radial growth of black pine in western Anatolia and classified its responses to climate. Twenty-eight site chronologies developed by different researchers were used in the analysis. Response functions were calculated for each chronology to identify the effect of climate on radial growth. Hierarchical cluster analysis was used to sort response functions and to classify the chronologies into groups based on climate responses. The individual responses of these chronologies to temperature and precipitation were classified in four main groups. Climatic and phytogeographic differences were the major factors influencing the formation of clusters. The results suggest that the major limiting factor is drought caused by low precipitation, especially in May, in almost all sites. The drought effect is much stronger in the transition region to the steppe, Central Anatolia and Mediterranean Regions than the Black Sea Region. Black pine trees respond positively to higher temperature at the beginning of growing season in almost all areas except in transition region to the steppe.     

火干扰因素对藏南地区高山松径向生长及气候响应特征的影响

森林火灾在二十一世纪内的发生频率逐步升高。大量研究发现森林火灾与树木生长之间存在有紧密的相关性。因此探究森林火灾对于树木生长的影响,分析火灾的不同强度对于树木径向生长是否有着显著的差异,将对于评估森林保护指标有着重要的实际意义。实验基于树木年轮学的研究方法,探究西藏林芝市本日山及九五六两场森林火灾对高山松径向生长的影响,分析在火灾前后高山松径向生长与气温及降水之间的响应关系。基于林芝市比日山及九五六两个火烧区域,建立了受轻度火影响和受中度火影响的高山松样地。利用树木年代学的方法,对年轮宽度指数与1961-2020年气温及降水分别进行相关分析,同时结合火灾的发生时间,将时间序列划分为:1961-2006年火灾前和2007-2021年火灾后。结果显示, 轻度火影响的高山松径向生长对气温和降水敏感,特别是在3-8月最高气温上呈现出显著性的增加。中度火影响的高山松径向生长则显著降低。火灾干扰明显抑制了高山松的径向生长,特别是火因子在平均气温和最高气温的干扰上对其径向生长具有明显抑制作用。受到轻度火影响的高山松径向生长在短期内有较为明显的增加趋势,但长期并不显著;而中度火影响的树木径向生长则在短期内不明显下降,但长期显著。受到轻度火影响的高山松中,其径向生长与最低气温之间呈显著的负相关,且使得高山松对外界环境的响应更为敏感,而中度火影响的高山松则并未表现出这种显著的响应状态。因此对于在高海拔地区而言,森林火灾对于树木径向生长有着显著的干扰的同时也提升树木与外界环境的响应程度。     

Tree limit dynamics of Betula pubescens ssp. tortuosa in relation to climate variability: evidence from central Sweden

Abstract. The tree limit of Betula pubescens ssp. tortuosa (mountain birch) in the southern Swedish Scandes was monitored during 1972–1992. The study included various aspects of growth, vigour and reproduction of Betula. The main focus was on the character and mechanics of the tree limit/climate equilibrium system. The tree limit, which changed in response to a temperature rise early this century, remained constant in position and tree physiognomy did not change, although the past 50 yr or so have been colder. Indeed, growth and reproductive effort and capacity decreased in this period. Obviously, most resources in Betula were used to resist stress in the mature phase, resulting in delayed recession of trees. Unless drastic warming occurs, stem dieback is predicted for the near future. Even a minorclimatic disturbance would have an effect, because resources are gradually being depleted. Radial growth correlated most closely with the mean temperature in July. Particularly at the present-day tree limit, the variance in annual growth could be largely explained by climatic factors. The hypothesis is that long-term tree limit dynamics during the late Holocene is merely a matter of fluctuations in vegetative vigour and stature of old individuals. At the population level, response to climatic variability appears to be greatly delayed.     

Radial growth response of Pinus sylvestris L. and Fagus sylvatica L. to technological solutions applied in rope climbing parks

Vitality is a genetic preservation factor that keeps a tree in the right condition. Changes in tree vitality are a measure of the impact exerted on trees by environmental factors, such as injuries to trunks and branches, and are among the basic parameters of the state of their preservation. The dynamics of changes in the width of annual increments of trees is one of several parameters characterizing the level of their vitality. The aim of the study is to determine changes in radial increment and linking them to the level of the vitality of Scots pines (Pinus sylvestris L.) and European beeches (Fagus sylvatica L.), on which the standard (old system) and specially designed (new system) systems of fastening of wooden platforms were installed as part of adventure park infrastructure. In the old system, the platforms were installed on square wooden beams placed in milled tree trunks, while in the new system on semi-circular metal brackets matching the curvature of the trunks. The present research is aimed to determine the dynamics of incremental trends in trees with different platform systems in relation to the reference group, and to determine the impact of the tested support systems on trees with different levels of vitality. Most of the studied trees were in the optimum stage of increment. The initial tree vitality level recorded at the beginning of the experiment was clearly better for the beech stands. In the case of Scots pine, the average vitality was close to stable. Pines that were initially in better condition responded much worse to the installation of old system platforms compared to those with the specially new platform system. A similar trend was also visible in the case of beeches, but the differences were not that clear and the annual increments of the trees with platforms installed were slightly higher compared to the reference trees. The trees that were initially in worse condition, both pines and beeches on which the old system of platforms had been installed, responded by increasing the width of annual increments during the measurement period. The described response of trees most probably does not result from the lower harmfulness of the old support system, but from the defensive responses of trees subjected to stronger stress.     

祁连山东部青杄年内径向生长动态对气候的响应

树木径向生长对气候因子的响应是树轮气候学的基础。在我国西北地区,虽然已有大量的树轮-气候响应研究,但是响应分析多基于数理统计结果,缺乏对树木生长过程的理解。基于此,于2013年到2015年在祁连山东部吐鲁沟国家森林公园内通过Dendrometer连续监测了树轮气候重建中常用树种青杄的径向生长,通过平均值法提取2013到2015年生长季内不同时间尺度(1天、7天、10天)的平均径向生长量及对应时间段的平均气候状况。不同时间尺度径向生长量和气候因子的相关分析结果表明,时间尺度的延长削弱了树干水分昼夜变化的干扰,但水分仍然是青杄径向生长的限制因子。为了进一步分析青杄径向生长与气候关系随时间的变化情况,以31天为窗口将日径向生长量与气候要素每隔一天进行滑动相关,结果显示:5、7月青杄的径向生长与降水的关系稳定,都呈显著正相关,但是6月降水的年际变率较大,导致树木可利用水分的变幅也较大,因而树木径向生长与6月水分的响应关系不稳定,存在较大的年际差异,而这可能是一些树轮-气候响应研究中轮宽与6月降水关系不显著的原因。     

高山林线生态交错区木本植物幼苗分布特征、更新机制及其对气候变化的响应

木本植物幼苗是高山林线生态交错区的重要组成部分,其更新对气候变化背景下树线的移动至关重要.本研究通过对近几十年来全球范围内林线生态交错区的木本植物幼苗分布特征、更新机制及其对气候变化响应的研究总结得出:林线生态交错区木本植物幼苗的空间分布类型主要为渐变型和聚集型,且不同分布类型对树线动态的指示意义各异.在全球尺度上,其分布的海拔高限通常与生长季长度、均温和物种特性等有关,而在区域尺度上则多受降水影响.在幼苗更新初期,种源在很大程度上决定了种子的萌发及分布位置,之后微环境的促进作用为幼苗的定植提供庇护,提高其存活率,而在更新后期多种生物和非生物因素及其相互作用则非常关键.气候变暖促使林线生态交错区气温升高、降水充沛,有利于幼苗生长,使其向高海拔区域扩张而成为树线上移的先兆,但部分物种受遗传特性或适应策略影响,仅表现为密度增加,使树线保持相对稳定.未来应借助树轮、14C等精确定年技术,通过长期的野外定位观测和室内模拟,加强多时空尺度下林线幼苗的空间分布特征和更新机制研究,分析不同类型林线内木本植物幼苗的适应策略,预测气候变化背景下的树线动态,为山地生态系统恢复及保护提供科学依据.     

Ecological and methodological drivers of non-stationarity in tree growth response to climate

Radial tree growth is sensitive to environmental conditions, making observed growth increments an important indicator of climate change effects on forest growth. However, unprecedented climate variability could lead to non-stationarity, that is, a decoupling of tree growth responses from climate over time, potentially inducing biases in climate reconstructions and forest growth projections. Little is known about whether and to what extent environmental conditions, species, and model type and resolution affect the occurrence and magnitude of non-stationarity. To systematically assess potential drivers of non-stationarity, we compiled tree-ring width chronologies of two conifer species, Picea abies and Pinus sylvestris, distributed across cold, dry, and mixed climates. We analyzed 147 sites across the Europe including the distribution margins of these species as well as moderate sites. We calibrated four numerical models (linear vs. non-linear, daily vs. monthly resolution) to simulate growth chronologies based on temperature and soil moisture data. Climate–growth models were tested in independent verification periods to quantify their non-stationarity, which was assessed based on bootstrapped transfer function stability tests. The degree of non-stationarity varied between species, site climatic conditions, and models. Chronologies of P. sylvestris showed stronger non-stationarity compared with Picea abies stands with a high degree of stationarity. Sites with mixed climatic signals were most affected by non-stationarity compared with sites sampled at cold and dry species distribution margins. Moreover, linear models with daily resolution exhibited greater non-stationarity compared with monthly-resolved non-linear models. We conclude that non-stationarity in climate–growth responses is a multifactorial phenomenon driven by the interaction of site climatic conditions, tree species, and methodological features of the modeling approach. Given the existence of multiple drivers and the frequent occurrence of non-stationarity, we recommend that temporal non-stationarity rather than stationarity should be considered as the baseline model of climate–growth response for temperate forests.     

Cryptic hybrids between Pinus uncinata and P. sylvestris

We tested the performance of molecular markers and biometric traits in the identification of hybrids between closely related mountain pine (Pinus uncinata) and Scots pine (Pinus sylvestris). A plastid DNA marker and a set of morphological and anatomical needle traits were applied in analyses of individuals from several sympatric stands of the species and a single‐species' population from southern Europe, used as a reference. A polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) marker from the plastid trnL–trnF region and morphological and anatomical traits clearly discriminated between the pure species. Significant differences were found between P. uncinata and P. sylvestris, mostly in the shape of epidermal cells and the number of stomata. Four putative hybrids with P. sylvestris morphology, but with P. uncinata plastid DNA haplotypes, were found in a population from Sierra de Gúdar near Valdelinares, the southernmost locality of the latter species in eastern Spain. Discrimination analyses between and within populations placed these individuals on the edge of an agglomeration of P. sylvestris individuals. The results suggest that hybridization between the species is rare, but can result in cryptic hybrids morphologically similar to the maternal species. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163 , 473–485.