叶大小与小枝大小关系反映了植物对木质部同其所支持的光合作用面积的配置比例关系,不同生境中其生长关系的变异体现植物对异质环境的适应方式。在祁连山北坡高寒草地,利用ArcGIS建立研究区域的数字高程模型(DEM),并提取样地坡向数据,...叶大小与小枝大小关系反映了植物对木质部同其所支持的光合作用面积的配置比例关系,不同生境中其生长关系的变异体现植物对异质环境的适应方式。在祁连山北坡高寒草地,利用ArcGIS建立研究区域的数字高程模型(DEM),并提取样地坡向数据,采用标准化主轴估计(standardized major axis estimation,SMA)方法,研究了不同坡向狼毒(Stellera chamaejasme)种群叶与枝的生长。结果表明:随着坡向由南坡向东坡、西坡和北坡转变,狼毒叶面积、叶片数和枝长度均呈逐渐增加趋势;狼毒叶片数、叶面积与枝长度均呈异速生长关系,枝长度增加的速度大于叶片数和叶面积增加的速度;随着坡向由北坡向东坡、西坡和南坡转变,狼毒叶片数与枝长度的异速斜率逐渐增大,叶面积与枝长度的异速斜率逐渐减小。生境对狼毒枝条与叶片的生长具有显著影响,北坡具有更适宜狼毒生长的生境条件,南坡土壤水分匮乏等不利影响使狼毒枝条与叶片变小,并且单位长度枝条支持更多的叶片。展开更多
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...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.展开更多
文摘叶大小与小枝大小关系反映了植物对木质部同其所支持的光合作用面积的配置比例关系,不同生境中其生长关系的变异体现植物对异质环境的适应方式。在祁连山北坡高寒草地,利用ArcGIS建立研究区域的数字高程模型(DEM),并提取样地坡向数据,采用标准化主轴估计(standardized major axis estimation,SMA)方法,研究了不同坡向狼毒(Stellera chamaejasme)种群叶与枝的生长。结果表明:随着坡向由南坡向东坡、西坡和北坡转变,狼毒叶面积、叶片数和枝长度均呈逐渐增加趋势;狼毒叶片数、叶面积与枝长度均呈异速生长关系,枝长度增加的速度大于叶片数和叶面积增加的速度;随着坡向由北坡向东坡、西坡和南坡转变,狼毒叶片数与枝长度的异速斜率逐渐增大,叶面积与枝长度的异速斜率逐渐减小。生境对狼毒枝条与叶片的生长具有显著影响,北坡具有更适宜狼毒生长的生境条件,南坡土壤水分匮乏等不利影响使狼毒枝条与叶片变小,并且单位长度枝条支持更多的叶片。
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)。
文摘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.
