Key message

Beech trees growing in biodiverse patches in Belgium have higher radial growth and are less physiologically sensitive to drought than those in monocultures. Forest diversification therefore alleviates the negative effects of drought on beech.

Abstract

Common beech, a widespread and economically important tree species in Europe, is known to be drought sensitive. For ensuring its survival under increasing future drought conditions, we need to advance our understanding on the relationships between drought and its growth performance. Diversifying forests has been proposed as a management strategy to mitigate the effects of drought, because a more complete use of the available water is expected. We made use of a tree species diversity gradient in Belgium to study if beech trees growing in diverse forest patches are more resistant and resilient to drought than beech trees in monocultures. Combining dendrochronological and stable carbon (δ¹³C) and oxygen isotope (δ¹⁸O) data allowed for studying the effect of tree species diversity on the response of beech growth to drought regarding stem radial growth and physiological performance. Up to 62% enhanced stem radial growth strongly increased growth stability, and higher resistance to drought was observed for beech trees in diverse forest patches. Beech performs best in three-species mixtures, particularly those with oak and maple. In drought years, beech growth is more reduced in monocultures than mixtures. During these drought years, δ¹³C values increased, and the increase was weaker in beech trees of diverse stands compared to monospecific stands, indicating enhanced stomatal conductance and growth continuation in mixtures. δ¹⁸O patterns did not indicate a clear effect of diversity or the response of beech trees to drought. Overall, our results indicate that until now, still the positive effects of diversity on beech growth outperform the negative effects induced by drought.

中文翻译：

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树种的多样性改善了山毛榉的生长并改变了其对干旱的生理反应

关键信息

与单一栽培的山毛榉树相比，比利时生物多样性丰富的山毛榉树径向生长更高，对干旱的生理敏感性更低。因此，森林的多样化减轻了干旱对山毛榉的负面影响。

抽象

常见的山毛榉是欧洲普遍存在且在经济上很重要的树种，已知对干旱敏感。为了确保其在日益增加的未来干旱条件下的生存，我们需要加深对干旱与其生长绩效之间关系的理解。已经提出了使森林多样化作为减轻干旱影响的管理策略，因为预计将更充分地利用可用水。我们利用比利时的树种多样性梯度研究了在单一森林中生长的山毛榉树是否比单一栽培的山毛榉树对干旱更具抵抗力和抵抗力。组合dendrochronological和稳定的碳（δ ¹³ C），氧同位素（δ ¹⁸O）数据可用于研究树木物种多样性对山毛榉生长对干旱响应的影响，涉及茎的径向生长和生理性能。高达62％的茎径向生长得到了增强，极大地提高了生长稳定性，并且在各种森林斑块中观察到山毛榉树具有更高的抗旱性。山毛榉在三种树种的混合物中表现最好，尤其是橡木和枫树。在干旱年代，单一栽培的山毛榉生长比混合栽培的减少更多。在这些干旱年，δ ^13个C值增加，并且增加在不同的机架的山毛榉树较弱相比单特异性站，指示在增强混合物气孔导度和生长延续。δ ¹⁸O型图没有表明多样性的明显影响或山毛榉树对干旱的反应。总体而言，我们的结果表明，到目前为止，多样性对山毛榉生长的积极影响仍然优于干旱引起的负面影响。