Shifts and linkages of functional diversity between above‐ and below‐ground compartments along a flooding gradient

Abstract

Summary 1.Trait-based approaches have the potential to reveal general and predictive relationships between organisms and ecosystem functioning. However, the mechanisms underlying the functional structure of communities are still unclear. Within terrestrial ecosystems, several studies have shown that many ecological processes are controlled by the interacting above-and belowground compartments. However, few studies have used traits to reveal the functional relationships between plants and soil fauna. Mostly, research combining plants and soil fauna solely used the traits of one assemblage in predictive studies. 2. Above-ground (plants) and below-ground (Collembola) compartments were sampled over a flooding gradient in northern France along the Seine River. First, we measured the effect of flooding on functional and taxonomic assembly within both communities. We then considered the linkages between plant and Collembolan species richness, community traits and assessed whether traits of both compartments converged at high flooding intensity (abiotic filtering) and diverged when this constraint is released (biotic filtering). 3. Species richness of both taxa followed the same bell-shaped pattern along the gradient, while a similar significant pattern of functional richness was only observed for plants. Further analyses revealed a progressive shift from trait convergence to divergence for plants, but not for Collembola, as constraints intensity decreased. Instead, our results highlighted that Collembola traits were mainly linked to the variations in plant traits. This leads, within Collembola assemblages, to convergence of a subset of perception and habitat-related traits for which the relationship with plant traits was assessed. 4. Synthesis. Using a trait-based approach, our study highlighted that functional relationships occur between above-and below-ground compartments. We underlined that functional composition of plant communities plays a key role in structuring Collembola assemblages in addition to the role of abiotic variables. Our study clearly shows that functional diversity provides a new approach to link the above-and below-ground compartments and might, therefore, be further considered when studying ecological processes at the interface between both compartments.

Geographical variation in the trait‐based assembly patterns of multitrophic invertebrate communities

“…Foundation species can have profound effects on the species that rely on them, even though these interactions are non‐trophic in nature (Ellison, 2019; Kéfi et al, 2012). Such interactions between animal traits and plant traits have largely been overlooked in tests of trait‐assembly patterns (but see Abgrall et al, 2017; Pakeman & Stockan, 2014). Future studies could incorporate intraspecific trait variation of both the bromeliads and the invertebrates in such analyses of animal–plant interactions.…”

“…Finally, animal communities may not only experience environmental gradients directly, but also indirectly via the traits of the plants that animals consume or use as foundational habitat (Abgrall et al, 2017;Ohgushi et al, 2007;Pakeman & Stockan, 2014).…”

“…Although pairwise trophic interactions can be predicted from traits (Brousseau et al, 2018), scaling these pairwise patterns to community‐level trait‐assembly patterns still remains elusive (Wong et al, 2019). Finally, animal communities may not only experience environmental gradients directly, but also indirectly via the traits of the plants that animals consume or use as foundational habitat (Abgrall et al, 2017; Ohgushi et al, 2007; Pakeman & Stockan, 2014).…”

Understanding environmental change through the lens of trait-based, functional, and phylogenetic biodiversity in freshwater ecosystems

“…As hydrological conditions fundamentally govern the establishment, growth, reproduction, dispersal and extinction of many, if not most, freshwater organisms (Poff et al 1997), changes in physical habitat have profound effects on biodiversity patterns in freshwaters. Species with poor dispersal abilities and/or intolerant traits against rapid short-term habitat changes are in a jeopardy to be removed from a given freshwater ecosystem suffering from water level fluctuations, and temporally dynamic flood and drought events (Silver et al 2012;Abgrall et al 2017). In addition, long-lasting changes in physical habitats due to dam construction or channel modification and destruction of the riparian zone force species to evolve new traits as adaptations to new environmental conditions unless they go to extinct or disperse to new habitats (Bhat and Maguirran 2006;Espanol et al 2015).…”

“…In a second work on bacteria, ecologists investigated if an increase in water temperature would influence heterotrophic metabolic activities of biofilms grown under light or dark conditions (Romani et al 2014). In a third example, linking primary producers to consumers, functional composition of plant communities had a central role in structuring Collembola assemblages along a flood gradient (Abgrall et al 2017). Lack of species traits related to pure ecosystem functions may also be related to a rather slow emergence of species trait databases including information on freshwater assemblages especially for less-studied organism groups (see also Fig.…”