藏东南色季拉山林线物种方枝柏的叶寿命     

张林  杨柳  郭莹  沈维  崔光帅 《资源与生态学报(英文版)》2022,13(1):34-40

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。  相似文献   

Differences in seasonality and temperature dependency of stand transpiration and canopy conductance between Japanese cypress (Hinoki) and Japanese cedar (Sugi) in a plantation          下载免费PDF全文

Takami Saito  Tomo'omi Kumagai  Makiko Tateishi  Nakako Kobayashi  Kyoichi Otsuki  Thomas W. Giambelluca 《水文研究》2017,31(10):1952-1965

In this paper, we present an investigation of interspecies differences in transpiration of the 2 most common plantation forest tree species in Japan, both in the family Cupressaceae with different northern limits of native distribution, Japanese cypress (Hinoki; Chamaecyparis obtusa Sieb. et Zucc.) and Japanese cedar (Sugi; Cryptomeria japonica D. Don). The stem sap flow rate was measured in 2 nearby stands of similar leaf area index in a 42‐year‐old plantation. Single‐tree and stand‐scale transpiration rates (E_tre and E_sta, respectively) were observed during an ideal autumn environment. At the stand scale, mean sap flux density of Hinoki was greater than that of Sugi, whereas total sapwood area per ground area was smaller in Hinoki than Sugi. Because the 2 variables had counterbalancing effects on transpiration, E_sta of Hinoki was similar to (94% of) that of Sugi. This offset was also found between the mean E_tre of the 2 species. E_sta was similar between the stands from May to October, whereas E_sta of Sugi was notably greater than that of Hinoki from February to April. During these 3 months, the difference in cumulative E_sta was 21.7 mm, which accounted for 79% of the difference in annual E_sta between Hinoki and Sugi (192 and 219 mm/year, respectively). We found that canopy conductance (G_c) and its sensitivity to the mean vapour pressure deficit during daylight hours in Sugi were particularly high in early spring, whereas those in Hinoki shifted gradually throughout the growing season. This difference was related to the optimal temperature of G_c in Sugi, which was approximately 10 °C lower than that in Hinoki. Our results suggest that plantations of water‐conserving species such as Hinoki produce timber slowly but yield water resources generously. Moreover, for plantations of trees sensitive to high temperature, such as Sugi, managers should be concerned about possible future decline caused by anticipated global warming.  相似文献   

The most ancient member of the Sequoioideae – the new genus Krassilovidendron Sokolova,Gordenko et Zavialova (Cupressaceae s.l.) from the Albian–Cenomanian of Western Siberia (Russia)     

《Cretaceous Research》2017

The new genus Krassilovidendron Sokolova, Gordenko et Zavialova with the type species Krassilovidendron fecundum Sokolova, Gordenko et Zavialova is described on the basis of numerous compressions of polymorphic shoots in organic connection with seed and pollen cones from the Albian–Cenomanian of the Kubaevo locality (Russian Federation, Kemerovo region, Western Siberia). The new taxon is characterized by an assemblage of features that distinguishes it from all known extant and fossil conifer genera: shoots with helically arranged leaves varying from amphistomatic small scale-like leaves to strictly epistomatic linear-lanceolate leaves; terminal, ellipsoidal to obovate seed cones, bearing 14–26 helically arranged peltate bract-scale complexes (bract and ovuliferous scale are completely fused) with a cylindrical vascular bundle, bifurcating into abaxial and adaxial dichotomizing bundles; up to 22 inverted seeds of various shapes with a protruding micropyle and inconspicuous lateral wings, which are arranged in two to five arcuate rows; solitary terminal pollen cones with helically arranged microsporophylls, each bearing four abaxial microsporangia; and small pollen grains with a relatively short papilla, numerous orbicules on the surface, and a three-layered ectexine with a tectum of strongly fused granules, an infratectum of smaller and more loosely arranged granules, and a thin footlayer. The new taxon possesses a combination of characters indicating it belongs to the subfamily Sequoioideae. Krassilovidendron shares the greatest number of features with Sequoia Endlicher and Sequoiadendron Buchholz, and fewer characters with Metasequoia Miki ex Hu et W.C. Cheng.  相似文献