Functional diversity in a tritrophic system: Effects on biomass production, variability, and resilience of ecosystem functions

Abstract

Diverse communities can adjust their trait composition to altered environmental conditions, which may strongly influence their dynamics. Previous studies of trait-based models mainly considered only one or two trophic levels, whereas most natural system are at least tritrophic. Therefore, we investigated how the addition of trait variation to each trophic level influences population and community dynamics in a tritrophic model. Examining the phase relationships between species of adjacent trophic levels informs about the degree of top-down or bottom-up control in non-steady-state situations. Phase relationships within a trophic level highlight compensatory dynamical patterns between functionally different species, which are responsible for dampening the community temporal variability. Furthermore, even without trait variation, our tritrophic model always exhibits regions with two alternative states with either weak or strong nutrient exploitation, and correspondingly low or high biomass production at the top level. However, adding trait variation increased the basin of attraction of the high-production state, and decreased the likelihood of a critical transition from the high-to the low-production state with no apparent early warning signals. Hence, our study shows that trait variation enhances resource use efficiency, production, variability, and resilience of entire food webs.

Storm impacts on phytoplankton community dynamics in lakes

“…Algae and cyanobacteria, the foundation of aquatic food webs, are highly diverse in their taxonomy and functional traits. Storm‐induced changes to lake abiotic conditions and physical displacement of phytoplankton throughout the water column could drive the outcome of phytoplankton species competition and thus shape community composition (Huisman et al, 2004; Reynolds, Huszar, Kruk, Naselli‐Flores, & Melo, 2002; Smith, 1983) and food web dynamics (Ceulemans, Gaedke, Klauschies, & Guill, 2019; Ellner, Geber, & Hairston, 2011; Tirok & Gaedke, 2010). Traits such as size and morphology, life history, physiological responses, and adaptive capacity (Padisák, 2004; Reynolds, 2006) mediate phytoplankton survival, competition, growth, and reproduction (Litchman, de Tezanos Pinto, Klausmeier, Thomas, & Yoshiyama, 2010).…”

Top predators govern multitrophic diversity effects in tritrophic food webs

“…Although it has often been highlighted how important the effects of the third trophic level on ecosystem functions are (Bruno and O'Connor 2005, Duffy et al 2007, Abdala‐Roberts et al 2019, Daam et al 2019, Ehrlich and Gaedke 2020), relatively few studies have attempted to take these effects into account explicitly. Ceulemans et al (2019) showed that functional diversity increases the biomass production, temporal stability, and biomass transfer efficiency to higher trophic levels of a tritrophic food web, when diversity is increased simultaneously at all three trophic levels. This model analyzed one particular food‐web structure in detail, which raises the question of whether the observed trends are to be expected in general, or whether they are context dependent as well.…”

“…To capture the potentially high variation in biomass dynamics sufficiently, we randomly selected a total of 128,000 parameter combinations from ecologically plausible intervals for the eight different food webs, as well as tested 200 initial conditions per parameter combination. These parameter values were drawn from intervals geometrically centered around values that are particularly relevant for planktonic systems (Ceulemans et al 2019), but are sufficiently wide to capture the behavior of many different types of food webs (see Table 1). This procedure allows us to obtain results of high generality, as they apply to the average behavior of tritrophic systems, independent of its parametrization.…”

History of co‐occurrence shapes predation effects on functional diversity and structure at low latitudes

“…Furthermore, prior research examining the effect of consumer pressure on functional trait responses has largely been done in terrestrial plant assemblages (de Bello et al., 2006; Carmona et al., 2012; Díaz et al., 2007; Laliberté & Tylianakis, 2012), and trait responses to consumers in other systems remain largely unexplored (Ceulemans et al., 2019). In plant communities, consumer pressure is hypothesized to increase functional diversity by reducing competitive dominance and promoting trait dissimilarity (Grime, 2006; Laliberté et al., 2013; Sasaki et al., 2009), but additional factors such as habitat type, productivity and environmental gradients coupled with intense grazing can influence functional diversity (de Bello et al., 2006; Carmona et al., 2012; Laliberté et al., 2013; Laliberté & Tylianakis, 2012).…”