Interspecific variability of δ13C among trees in rainforests of French Guiana:: functional groups and canopy integration
Interspecific variability of δ13C among trees in rainforests of French Guiana:: functional groups and canopy integration
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DOI：
10.1007/pl00008871
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发表时间：
2000-08-01
期刊：
影响因子：
2.7
通讯作者：
Guehl, JM
中科院分区：
文献类型：
--
作者：
Bonal, D;Sabatier, D;Guehl, JM
研究了法属圭亚那3个低地雨林林分的树冠树种的日照叶片碳同位素组成(Delta(13)C)的种间变异性，该指标是叶片内在水分利用效率(WUE，CO2同化率/叶片水蒸气导度)的指标，它们的区系组成和土壤排水特性不同，但气候条件相似。我们用步枪从总共406棵树上采集了树叶，代表了102个物种。三个林分共有18种。平均物种增量(13)C在每个林分内变化在千分之6.0的范围内，与WUE变化大约三倍的范围相对应。出现在至少两个林分中的物种表现出非常稳定的Delta(13)C值，表明物种Delta(13)C具有密切的遗传控制。物种Delta(13)C值在以下方面存在显著差异：(1)叶片物候模式(落叶和常绿叶物种的平均Delta(13)C分别为-29.7‰和-31.0‰)，以及(2)不同类型的耐荫性，这些特征反映了生长动态对对比光照条件的可塑性。嗜日性物种表现出更多的负增量(13)C值(平均增量(13)C=-30.5‰；)(即较低的WUE)，而偏嗜性物种则为-29.3‰。然而，耐性物种(-31.4‰)比嗜日性物种表现出更多的负增量(13)C值。我们无法对这一结果提供直接的生态生理学解释。物种Delta(13)C与中午叶水势(psi(WM))之间的负相关关系表明，低Delta(13)C与高的全树叶比导水率有关。根据物种增量(13)的断面积加权积分计算的冠层碳同位素识别率(Delta(A))在三个林分中相似(平均Delta(A)=23.1 ppm/1000)，尽管林分物种组成和土壤排水类型不同，反映了三种不同耐荫类型在林分之间的相似比例。
The interspecific variability of sunlit leaf carbon isotope composition (delta(13)C), an indicator of leaf intrinsic water-use efficiency (WUE, CO2 assimilation rate/leaf conductance for water vapour), was investigated in canopy trees of three lowland rainforest stands in French Guiana, differing in floristic composition and in soil drainage characteristics, but subjected to similar climatic conditions. We sampled leaves with a rifle from 406 trees in total, representing 102 species. Eighteen species were common to the three stands. Mean species delta(13)C varied over a 6.0 parts per thousand range within each stand, cornsponding to WUE varying over about a threefold range. Species occurring in at least two stands displayed remarkably stable delta(13)C values, suggesting a close genetic control of species, delta(13)C. Marked differences in species delta(13)C values were found with respect to: (1) the leaf phenology pattern (average delta(13)C=-29.7 parts per thousand and -31.0 parts per thousand in deciduous-leaved and evergreen-leaved species, respectively), and (2) different types of shade tolerance defined by features reflecting the plasticity of growth dynamics with respect to contrasting light conditions. Heliophilic species exhibited more negative delta(13)C values (average delta(13)C=-30.5 parts per thousand;) (i.e. lower WUE) than hemitolerant species (-29.3 parts per thousand). However, tolerant species (-31.4 parts per thousand) displayed even more negative delta(13)C values than heliophilic ones. We could not provide a straightforward ecophysiological interpretation of this result. The negative relationship found between species delta(13)C and midday leaf water potential (psi(WM)) suggests that low delta(13)C is associated with high whole tree leaf specific hydraulic conductance. Canopy carbon isotope discrimination (Delta(A)) calculated from the basal area-weighed integral of the species delta(13)C values was similar in the three stands (average Delta(A)=23.1 parts per thousand), despite differences in stand species composition and soil drainage type, reflecting the similar proportions of the three different shade-tolerance types among stands.