In a mixed,Fagus sylvaticaL.-Acer pseudoplatanusL., young plantation, trees of both species absorbed water from superficial soil layers despite the presence of roots and water in deeper layers. Admixture proportion and tree density were weak predictors of water acquisition depth, as well as fine root vertical distribution, although it might be due to distinct periods of root and isotope investigations. Promoting mixed forests and reducing stand densities have been proposed as effective ways to maintain the productivity of temperate planted forest stands in a changing climate. The objective of this study was to analyse how stand density and the degree of admixture of European beech and sycamore maple interactively influenced the water acquisition profile of individual trees. We used a stable isotope (deuterium) approach to determine the profiles of soil water acquisition of both species in a 16-year-old plantation where trees had been planted along crossed gradients of tree density and species proportion. The profiles were then compared with the vertical distribution of fine root of these species in the plantation. All the target trees mostly absorbed soil water from the first few centimetres of soil despite homogenous vertical water availability and the fact that a great part of the fine root biomass was located below 10 cm. Admixture proportion and tree density had negligible effects on soil water acquisition depth. No vertical differentiation of soil water acquisition between the two species was observed, suggesting that mixing these species does not promote reduction of belowground competition for resource acquisition. The vertical distribution of fine root may be a weak predictor of water acquisition depth.

中文翻译：

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外加剂比例和树木密度对欧洲山毛榉 (Fagus sylvatica L.) 和美国梧桐 (Acer pseudoplatanus L.) 的取水深度没有影响

在混合的 Fagus sylvaticaL.-Acer pseudoplatanusL. 幼苗种植园中，尽管根系和深层土壤中存在水，但两个物种的树木都从表层土壤中吸收水分。外加剂比例和树木密度是吸水深度以及细根垂直分布的弱预测因子，尽管这可能是由于根和同位素研究的不同时期。促进混交林和降低林分密度已被提议作为在气候变化中保持温带人工林生产力的有效方法。本研究的目的是分析林分密度以及欧洲山毛榉和梧桐枫的混合程度如何交互影响单个树木的水获取剖面。我们使用稳定同位素（氘）方法来确定这两个物种在一个 16 年历史的人工林中土壤水分获取的概况，该人工林沿着树木密度和物种比例的交叉梯度种植树木。然后将这些剖面与人工林中这些物种的细根的垂直分布进行比较。尽管垂直可用水均匀且大部分细根生物量位于 10 厘米以下，但所有目标树木主要从最初几厘米的土壤中吸收土壤水分。外加剂比例和树木密度对土壤吸水深度的影响可以忽略不计。没有观察到两个物种之间土壤水分获取的垂直差异，表明混合这些物种不会促进减少对资源获取的地下竞争。细根的垂直分布可能是吸水深度的弱预测因子。