|Reference : Community assembly along a soil depth gradient: contrasting patterns of plant trait c...|
|Scientific journals : Article|
|Life sciences : Agriculture & agronomy|
Life sciences : Environmental sciences & ecology
Life sciences : Phytobiology (plant sciences, forestry, mycology...)
|Community assembly along a soil depth gradient: contrasting patterns of plant trait convergence and divergence in a Mediterranean rangeland|
|Bernard-Verdier, Maud |
|Navas, Marie-Laure |
|Vellend, Mark |
|Violle, Cyrille |
|Fayolle, Adeline [Université de Liège - ULg > Forêts, Nature et Paysage > Gestion des ressources forestières et des milieux naturels >]|
|Garnier, Eric |
|Journal of Ecology|
|Yes (verified by ORBi)|
|[en] Determinants of plant community diversity and structure ; Environmental filtering ; Functional community structure ; Functional convergence ; Functional divergence ; Null model ; Plant traits ; Soil resource gradient ; Trait-environment relationships|
|[en] 1. Understanding how environmental factors drive plant community assembly remains a major challenge in community ecology. The strength of different assembly processes along environmental gradients, such as environmental ﬁltering and functional niche differentiation, can be quantiﬁed by analysing trait distributions in communities. While environmental ﬁltering affects species occurrence among communities, functional divergence or convergence is strongly related to species abundances within communities, which few studies have taken into account. We examine the trait-mediated effect of these two processes along a stress-resource gradient.
2. We measured species abundances and the distributions of eight traits related to vegetative and regenerative phases in plant communities along a gradient of soil depth and resource availability in Mediterranean rangelands. We quantiﬁed environmental ﬁltering, deﬁned as a local restriction of trait range, and trait divergence, based on abundance-weighted trait variance, using a two-step approach with speciﬁcally designed null models.
3. Communities presented a clear functional response to the soil gradient, as evidenced by strong trends in community-weighted trait means. We detected environmental ﬁltering of different traits at both ends of the gradient, suggesting that, contrary to widespread expectations, trait ﬁltering may not necessarily be the result of abiotic ﬁltering under harsh conditions but could likely also result from biotic interactions in productive habitats.
4. We found marked shifts in trait abundance distributions within communities along the gradient. Vegetative traits (e.g. leaf dry matter content) diverged on shallow soils, reﬂecting the coexistence of distinct water- and nutrient-use strategies in these constrained habitats and converged with increasing soil resource availability. By contrast, regenerative traits (e.g. seed mass) tended to diverge towards deeper soils, while plant reproductive heights diverged all along the gradient.
5. Synthesis: Our study highlights how the combination of abundance data with traits capturing different functional niches is critical to the detection of complex functional responses of plant communities to environmental gradients. We demonstrate that patterns of trait divergence and ﬁltering are strongly contingent on both trait and environment such that there can be no expectation of a simple trend of increasing or decreasing functional divergence along a gradient of resource availability.
|ANR programme O2LA (09-STRA-09) ; DIVHERBE project (ACI ECCO, ECOGER programme)|
|Researchers ; Professionals ; Students|
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