Incorporating the effects of generalist seed predators into plant community theory

Abstract

Summary1. Post-dispersal seed predators contribute substantially to seed loss across many ecosystems. Most research has focused on understanding sources of variation in seed loss, without appreciating the implications of seed predation for plant coexistence, community assembly and broader community theory. Meanwhile, research aimed at understanding coexistence and community assembly processes in plant communities has focused on axes of dispersal and resource competition and the traits influencing these processes, without accounting for the role of generalist seed predators. 2. We review the unique features of post-dispersal seed predation and assess the implications of seed loss on three critical components of plant community organization -coexistence, community structure and plant invasions -pointing to both important gaps in theory and empirical knowledge. We highlight how understanding fundamental controls on plant recruitment is central to determining how seed predation affects plant recruitment and coexistence. We discuss how accounting for seed predator foraging strategies may shift trait-based inferences of community assembly. 3. Synthesis. We argue that seed predation by generalist consumers, which is pervasive in temperate communities, should be better incorporated into plant community theory. Experiments that specifically incorporate the presence and attributes of the seed predator community and that follow seed fate would fill important knowledge gaps. Particularly needed are studies focused on strengthening the connections between seed removal and plant establishment and linking selective and density-dependent foraging strategies to plant traits. Advancing our understanding of the processes regulating plant coexistence and community assembly requires that future research not only acknowledge but also incorporate generalist consumers' effects on plant communities.

Productivity and related soil properties mediate the population‐level consequences of rodent seed predation on Blanketflower, Gaillardia aristata

“…The above limitations notwithstanding, this work adds to a growing body of literature emphasizing the strong impacts rodent seed predators can have on plant populations (reviewed by Larios et al, ). More importantly, this study suggests that the magnitude of these effects are predictable across environmental gradients based on an understanding of how biotic and abiotic conditions affect recruitment and other demographic rates.…”

“…Plants commonly lose seeds to various consumers (Crawley, 2001;Hulme, 1996;Larios, Pearson, & Maron, 2017;Louda, 1989), yet the factors that determine whether seed loss leads to diminished recruitment and reduced plant abundance are not always well understood (Maron & Crone, 2006;Maron, Baer, & Angert, 2014;Von Euler, Ågren, & Ehrlén, 2014). In general terms, how strongly seed number links to recruitment is governed by the extent to which a plant population is seed and/or safe site limited (Harper, 1977).…”

Seed density affects post‐dispersal seed predation: evidence from a seed removal experiment of 62 species

“…Post-dispersal seed predation is one of the most important determining factors for plant demography, biodiversity maintenance and evolutionary processes (Janzen 1971;Hulme 1998;Larios et al 2017;Hegstad & Maron 2019). During the fruiting season, dispersed seeds often form different spatial patterns that depend on their dispersal syndromes, which leads to a large spatial variation in seed density that may influence the intensity of post-dispersal seed predation and has attracted a lot of attention in recent decades (Stapanian & Smith 1984;Lott et al 1995;Hulme & Hunt 1999;Romo et al 2004;Jansen et al 2014;Cornils et al 2017).…”

Seedling recruitment correlates with seed input across seed sizes: implications for coexistence

“…Theory predicts that more fecund, smallseeded species are likely to occupy most microsites, and thus recruitment of these species is often thought to be microsite limited rather than limited by the absolute number of seeds produced (Harper 1977, Turnbull et al 2000, Levine and Rees 2002. For example, in systems where mice are the major postdispersal seed predator, sizedependent seed predation can result in large-seeded species being more vulnerable to seed predation than small-seeded species (Brown and Heske 1990, Reader 1993, Larios et al 2017, Maron et al 2018. In annual grasslands smallseeded species may also compete with themselves for germination sites, but in perennial grasslands, most microsite preemption comes from long-lived dominant bunchgrasses.…”