Contrasting distribution and seasonal dynamics of carbohydrate reserves in stem wood of adult ring-porous sessile oak and diffuse-porous beech trees
Contrasting distribution and seasonal dynamics of carbohydrate reserves in stem wood of adult ring-porous sessile oak and diffuse-porous beech trees
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DOI：
10.1093/treephys/22.17.1201
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发表时间：
2002-12-01
期刊：
影响因子：
4
通讯作者：
Bréda, N
中科院分区：
文献类型：
--
作者：
Barbaroux, C;Bréda, N
我们测试的假设，阔叶林树种与对比木材解剖和液压系统（环孔与扩散孔）也不同的干木材中的碳水化合物储量的分布和季节动态。采用酶法测定了成年栎（Quercus petraea（Matt.）Liebl.）和山毛榉（Fagus sylvatica L.）树木在一年的周期中。碳水化合物的径向分布进行了调查，根据年轮年龄。在所有日期，橡树的TNC浓度比山毛榉树高两倍（41对23毫克克（DM）（-1）），与淀粉占高TNC浓度在橡树。栎属树木TNC浓度的季节动态（20-64 mg TNC g（DM）（-1））显著（P < 0.05）高于山毛榉属树木（17-34 mg TNC g（DM）（-1））。基于年轮年龄的TNC的径向分布不同物种之间：TNC仅限于边材环在橡木，而在山毛榉，它分布在整个木材从最外面的边材环的髓。虽然高TNC浓度在最外层的戒指占了大部分的观察到的季节性模式，所有10个最年轻的木质部环分析参与了TNC在山毛榉树的季节性动态。橡树边材最内层年轮的TNC浓度较低。茎生长和碳储量的积累在季节的前半部分同时发生，当时没有土壤水分赤字。当土壤含水量耗尽，茎生长停止在这两个物种，而TNC积累的影响可以忽略不计，并持续到落叶。对比动态和分布的碳水化合物储备在橡树和山毛榉参考之间的差异，在物候，早春生长和水力特性的环孔树和扩散孔树进行了讨论。
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.