Delalandre Léo, Violle Cyrille, Fort Florian, Tschambser Julie, Saugier Lila, Fourtier Galadriel, Garnier Eric
CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France.
CEFE, Univ Montpellier, L'Institut Agro, CNRS, EPHE, IRD, Montpellier, France.
Ann Bot. 2025 Jul 24. doi: 10.1093/aob/mcaf171.
Intraspecific trait variations in response to nutrient availability are expected to depend on 1) the category of traits considered, and 2) species ecology, with species requiring high nutrient levels expected to be more plastic. However, there are few comparisons of trait responses including multiple species, and considering simultaneously i) above-ground traits approximating ecological strategies, ii) root traits involved in nutrient acquisition, and iii) traits integrating the whole-plant.
We studied 17 annual species coming from two contrasted environments in the same rangeland of southern France. Plants were grown in a common garden, under two fertilization treatments.
.We evidenced no effect of origin on trait values, suggesting little or no differentiation according to the environment of origin. Among the 14 traits measured, whole-plant traits, and in particular plant nitrogen content, plant dry mass, and root mass fraction, showed strong plastic responses to fertilization, whereas the response was weak or even absent for above and belowground organ-level traits related to ecological strategies, suggesting that they play a secondary role in plant responses to nutrient availability. Finally, species ecological preferences (i.e., their nutrient requirements), predicted the plasticity in plant nitrogen content per mass, whereas species position along the acquisition-conservation trade-off (approximated by leaf traits), predicted plasticity in plant dry mass. This cautions towards the systematic use of leaf traits as a proxy of species ecology and functioning.
Our results challenge the assumption that leaf traits universally reflect plant responses to nutrient availability. They advocate for a better characterization of traits directly involved in nutrient acquisition, and underscore the importance of considering how trait-trait and trait-environment relationships may depend on the group of species considered. These findings offer avenue for more accurate predictions of plant responses to nutrient gradients in natural and managed ecosystems.
预计植物种内性状对养分有效性的响应变化取决于1）所考虑的性状类别，以及2）物种生态学，预计需要高养分水平的物种具有更高的可塑性。然而，很少有对包括多个物种的性状响应进行比较的研究，同时考虑到：i）近似生态策略的地上性状，ii）参与养分获取的根系性状，以及iii）整合整个植株的性状。
我们研究了来自法国南部同一牧场两个不同环境的17种一年生植物。将这些植物种植在一个共同的花园中，设置两种施肥处理。
我们发现植物的起源对性状值没有影响，这表明根据起源环境几乎没有分化或没有分化。在所测量的14个性状中，整个植株的性状，特别是植物氮含量、植物干质量和根质量分数，对施肥表现出强烈的可塑性响应，而与生态策略相关的地上和地下器官水平的性状的响应较弱甚至没有响应，这表明它们在植物对养分有效性的响应中起次要作用。最后，物种的生态偏好（即它们的养分需求）预测了单位质量植物氮含量的可塑性，而沿着获取 - 保存权衡的物种位置（由叶片性状近似）预测了植物干质量的可塑性。这提醒我们要谨慎地将叶片性状作为物种生态学和功能的替代指标进行系统使用。
我们的结果挑战了叶片性状普遍反映植物对养分有效性响应的假设。它们主张更好地描述直接参与养分获取的性状，并强调考虑性状 - 性状和性状 - 环境关系如何可能取决于所考虑的物种组的重要性。这些发现为更准确地预测自然和管理生态系统中植物对养分梯度的响应提供了途径。
