Leaf Longevity in a Timberline Tree Species Juniperus saltuaria in the Sergymla Mountains,Southeastern Tibet  

藏东南色季拉山林线物种方枝柏的叶寿命

作　　者：ZHANG Lin YANG Liu GUO Ying SHEN Wei CUI Guangshuai 张林;杨柳;郭莹;沈维;崔光帅(中国科学院青藏高原研究所,青藏高原地球系统与资源环境国家重点实验室,北京100101;中国科学院墨脱地球景观与地球系统综合观测研究中心,北京100101;中国科学院大学,北京100049)

机构地区：[1]State Key Laboratory of Tibetan Plateau Earth System,Resources and Environment,Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China [2]Muoto Observation and Research Center for Earth Landscape and Earth System,Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China [3]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Journal of Resources and Ecology》2022年第1期34-40,共7页资源与生态学报（英文版）

基　　金：The Key Scientific and Technological Research Projects in Tibet Autonomous Region (XZ202101ZY0005G);The Second Tibetan Plateau Scientific Expedition and Research (STEP) Program (2019QZKK0301-1)。

摘　　要：Leaf longevity is an important adaptive strategy that allows plants to maximize photosynthetic carbon gain.Due to the difficulty of identifying overwintering bud scars and distinguishing the age sequence of twigs,leaf longevity is rarely studied in Cupressaceae species,which further limits our understanding of the leaf economic spectrum (LES) for these populations.Here,we investigated the leaf longevity,as well as mass-based leaf nitrogen concentration (N;),of Juniperus saltuaria at different canopy heights for both subalpine and alpine timberline forests in the Sergymla Mountains,southeastern Tibet.We found that the mean leaf longevity was 4.2±1.2 years,and overall it did not differ significantly between different elevations.Along the vertical profiles of juniper canopies,the leaf longevity did not reflect a linear trend.With increasing leaf longevity,N;showed declining trends.We further analyzed the relationship between leaf longevity and the corresponding length of green twigs,and found that the length of green twigs could only explain 1%-3%of the variation in leaf longevity,indicating that the length of green twigs is a poor predictor for the variation in leaf longevity.In summary,for the J.saltuaria species in timberline or nearby subalpine forests,the effects of elevation and canopy depths on leaf longevity are minor,and the leaf trait analysis is in accordance with the prediction of LES.作为叶经济学谱系中的一个关键指标,叶寿命是植物为了获得最大化光合碳收获的重要适应策略。由于很难鉴别越冬芽鳞痕以及区别不同叶龄叶片,鲜有研究关注柏科物种的叶寿命,使得我们对该类群的叶经济学谱系研究缺乏了解。基于此,我们对西藏东南部色季拉山不同海拔、不同冠层高度的方枝柏叶寿命和单位重量的叶氮含量(N;)开展了调查分析。结果表明,方枝柏平均叶寿命约为4.2±1.2年,总体上不同海拔间叶寿命差异不明显。随树冠高度的垂直变化,叶寿命总体上并未表现出明显的线性变化趋势。随叶寿命的增加,N;呈现降低趋势。进一步分析了叶寿命与对应绿色小枝长度的关系,发现二者关系不显著或解释度极低,表明小枝长度不能很好地预测叶寿命的变化。总的来说,在高山林线以及邻近的亚高山地区,海拔和冠高的变化对方枝柏叶寿命的影响较小,而叶寿命与叶氮含量的关系符合叶的经济学法则。

关 键 词：canopy height ELEVATION leaf nitrogen concentration length of green twigs CUPRESSACEAE 

分 类 号：S791.44[农业科学—林木遗传育种]