Barbaroux C, Bréda N
UMR Ecologie et Ecophysiologie Forestières Equipe Phytoécologie, INRA, F-54280 Champenoux, France.
Tree Physiol. 2002 Dec;22(17):1201-10. doi: 10.1093/treephys/22.17.1201.
We tested the hypothesis that broad-leaved forest species with contrasting wood anatomy and hydraulic system (ring-porous versus diffuse-porous) also differ in distribution and seasonal dynamics of carbohydrate reserves in stem wood. Total nonstructural carbohydrate (TNC) reserves (starch and sugars) were measured enzymatically in the 10 youngest stem xylem rings of adult oak (Quercus petraea (Matt.) Liebl.) and beech (Fagus sylvatica L.) trees during an annual cycle. Radial distribution of carbohydrates was investigated according to ring age. On all dates, oak trees had twofold higher TNC concentration than beech trees (41 versus 23 mg g(DM)(-1)), with starch accounting for the high TNC concentration in oak. Seasonal dynamics of TNC concentration were significantly (P < 0.05) more pronounced in oak (20-64 mg TNC g(DM)(-1)) than in beech (17-34 mg TNC g(DM)(-1)). A marked decrease in TNC concentration was observed in oak trees during bud burst and early wood growth, whereas seasonal fluctuations in TNC concentrations in beech trees were small. The radial distribution of TNC based on ring age differed between species: TNC was restricted to the sapwood rings in oak, whereas in beech, it was distributed throughout the wood from the outermost sapwood ring to the pith. Although the high TNC concentrations in the outermost rings accounted for most of the observed seasonal pattern, all of the 10 youngest xylem rings analyzed participated in the seasonal dynamics of TNC in beech trees. The innermost sapwood rings of oak trees had low TNC concentrations. Stem growth and accumulation of carbon reserves occurred concomitantly during the first part of the season, when there was no soil water deficit. When soil water content was depleted, stem growth ceased in both species, whereas TNC accumulation was negligibly affected and continued until leaf fall. The contrasting dynamics and distribution of carbohydrate reserves in oak and beech are discussed with reference to differences in phenology, early spring growth and hydraulic properties between ring-porous trees and diffuse-porous trees.
具有不同木材解剖结构和水力系统（环孔材与散孔材）的阔叶林物种在茎干木材中碳水化合物储备的分布和季节动态方面也存在差异。在成年橡树（栓皮栎（Matt.）Liebl.）和山毛榉（欧洲水青冈L.）树木的一个年度周期内，对其10个最年轻的茎干木质部年轮中的总非结构性碳水化合物（TNC）储备（淀粉和糖类）进行了酶法测定。根据年轮年龄研究了碳水化合物的径向分布。在所有日期，橡树的TNC浓度是山毛榉树的两倍（41对23毫克克（干物质）⁻¹），淀粉是橡树中TNC高浓度的原因。橡树中TNC浓度的季节动态（20 - 64毫克TNC克（干物质）⁻¹）比山毛榉树（17 - 34毫克TNC克（干物质）⁻¹）明显更显著（P < 0.05）。在橡树中，芽萌发和早期木材生长期间观察到TNC浓度显著下降，而山毛榉树中TNC浓度的季节波动较小。基于年轮年龄的TNC径向分布在不同物种间存在差异：橡树中的TNC局限于边材年轮，而在山毛榉中，它从最外层边材年轮到髓心分布于整个木材中。尽管最外层年轮中的高TNC浓度占观察到的季节模式的大部分，但分析的所有10个最年轻的木质部年轮都参与了山毛榉树中TNC的季节动态。橡树最内层边材年轮的TNC浓度较低。在季节的第一部分，当没有土壤水分亏缺时，茎干生长和碳储备积累同时发生。当土壤含水量耗尽时，两个物种的茎干生长都停止，而TNC积累受到的影响可忽略不计，并持续到落叶。结合环孔材树木和散孔材树木在物候、早春生长和水力特性方面的差异，讨论了橡树和山毛榉中碳水化合物储备的对比动态和分布。
