Meta‐ecosystem processes alter ecosystem function and can promote herbivore‐mediated coexistence

Abstract

Herbivory and dispersal play roles in the coexistence of primary producers with shared resource limitation by imposing trade–offs either through apparent competition or dispersal limitation. These mechanisms of coexistence can further interact with meta‐ecosystem effects, which results in spatial heterogeneity through the movement of herbivores and nutrients. Here, we investigate how herbivores influence autotroph coexistence through a meta‐ecosystem effect, and how this effect couples mechanisms of coexistence to ecosystem structure and functioning. We articulate this framework through a parameterized one resource‐k producer–one herbivore meta‐ecosystem model. The results show that herbivore movement with nutrient recycling can generate spatial heterogeneity to allow coexistence where the well‐mixed system predicts competitive exclusion. Furthermore, the presence of movement alters local and regional ecosystem functioning even when coexistence would occur without movement. These results highlight how meta‐ecosystem theory can provide a mechanistic context for the observed complexity of biodiversity‐ecosystem function relationships.

Metacommunity framework and its core terms entanglement

“…Thus, a high population combined over all species on a patch, i.e., patch share of Nall, inevitably depresses resources compared to patches with fewer individuals. Although patch energy regenerates, a patch does not compensate here for energy consumption through recycling, for example, as considered by others (e.g., Marleau & Guichard 2019). Richness however may have a more complex relationship with such density or biomass gradients (Duffy 2002).…”

“…Multidimensionality occurs when several variables may jointly determine an ecological outcome or dynamic. It is pervasive in ecology under various guises (e.g., contingency; Lawton 1999) and has been recognized as severely challenging our ability to predict future states of communities and their ecosystem consequences (e.g., Arnoldi et al 2019, Marleau & Guichard 2019. The core problem is that where multiple variables jointly determine an outcome, a single ecological process (e.g., dispersal) can lead to clear differences in slightly different contexts.…”

A general meta-ecosystem model to predict ecosystem functions at landscape extents

“…Early meta-ecosystem theory used spatially implicit or two-patch ecosystem models to investigate how allochthonous flows impacted ecosystem stability and functioning (Loreau and Holt 2004, Gravel et al 2010, Marleau et al 2010, Gounand et al 2014. The theory expanded through models that include multi-patch systems (Marleau et al 2014, McCann et al 2021, ecological stoichiometry (Marleau et al 2015, Marleau andGuichard 2019), non-diffusive movement of organisms (Leroux and Loreau 2012, McLeod and Leroux 2021, Peller et al 2022 and has been used to explain phenomena varying from nutrient colimitation (Marleau et al 2015) to trophic functional structures (Jacquet et al 2022). However, there is no current theoretical model investigating the spatial flow of both abiotic (i.e., resources, nutrients) and biotic (i.e., organisms) compartments across different ecosystem types (e.g., terrestrial-aquatic), in multipatch systems (Massol et al 2017, Gounand et al 2018a).…”

Traits affecting nutrient recycling by mobile consumers can explain coexistence and spatially heterogeneous trophic regulation across a meta‐ecosystem

“…Meta‐ecosystem theory has built on these findings to show how nutrient flows can interact with spatial flows of higher trophic levels to impact coexistence and yield interdependencies in regulation across coupled ecosystems (e.g. Gravel et al, 2010; Marleau & Guichard, 2019). However, meta‐ecosystem theory has largely overlooked the role of mobile organisms in mediating flows of recycled nutrients between ecosystems (Gounand et al, 2018).…”

“…Recycling has a net top-down effect when consumer production increases relative to producer production, which decreases producer stocks (minus sign) coupled ecosystems (e.g. Gravel et al, 2010;Marleau & Guichard, 2019). However, meta-ecosystem theory has largely overlooked the role of mobile organisms in mediating flows of recycled nutrients between ecosystems (Gounand et al, 2018).…”