Spatial Variability in Plant Predation Determines the Strength of                     Stochastic Community Assembly

Germain, Rachel M.; Johnson, Laura T.; Schneider, Stefan; Cottenie, Karl; Gillis, Elizabeth A.; MacDougall, Andrew S.

doi:10.1086/670928

Cited by 55 publications

(105 citation statements)

References 54 publications

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“…; MacDougall & Wilson ; MacDougall, Duwyn & Jones ; Germain et al . ; Drystek & MacDougall ). These events can unfold in a range of ways depending on the palatability preferences of consumers and whether predation is frequency‐dependent, but have been difficult to test due to uncertainties regarding consumer diets.…”

Section: Introductionmentioning

confidence: 99%

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Selective plant foraging and the top‐down suppression of native diversity in a restored prairie

Schneider

Steeves

Newmaster

et al. 2017

Journal of Applied Ecology

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Summary Clarifying what species are being consumed at what times can improve our understanding of how anthropogenic change affects food web dynamics, with implications for community assembly including restoration. This includes human‐based changes to plant communities via species introductions, which can interact with consumer feeding preferences to indirectly alter assembly outcomes including reduced restoration success if planted species are preferentially targeted. We used DNA barcoding of plant material in rodent scat, combined with field‐based feeding trials, rodent trapping, and rodent exclosures to test for dietary preferences and assembly impacts of native rodents on a restored and regionally rare tallgrass prairie of central North America. We examined whether native rodents preferred non‐targeted and mostly non‐native oldfield plants that are more locally abundant, thus protecting the rarer native planted species from consumption, or if rodents preferred native plants regardless of abundance. Our results supported the latter outcome. Barcoding revealed that native rodents consumed mostly non‐planted oldfield species for 10 months of the year (92% of the diet). The exceptions were August–September, when planted prairie species accounted for 87% of plants consumed and coincided with their peak seed production. Cafeteria trials suggested diet seasonality to be explained by food limitation – native prairie seeds were consumed year‐round when made available. Non‐targeted oldfield species thus appeared to be of sufficient quality to support rodent populations (peaking at 23 individuals ha−1 in summer), but without rescuing rarer prairie species from targeted granivory and resulting in reduced prairie diversity outside of experimental exclosures. Synthesis and applications. Our work illustrates how anthropogenic‐based changes to producer communities may affect feeding pathways in grassland food webs, potentially facilitating establishment by non‐target species via indirect consumer effects that can be difficult to detect. These findings suggest that rodents may reduce the restoration success of tallgrass prairie in our region, with some planted species likely to suffer future recruitment difficulties due to granivory. Managers may need to consider multiple trophic levels with restoration, not just the commonly planted producer communities but also the consumers and predators associated with them.

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Section: Introductionmentioning

confidence: 99%

“…The site was cultivated for decades before a species‐rich mixture of tallgrass species was planted in 2010 (Germain et al . ; Drystek & MacDougall ). The area surrounding the restored field is dominated by mostly non‐native ‘oldfield’ plants ubiquitous to central North America (Cramer & Hobbs ).…”

Section: Introductionmentioning

confidence: 99%

Selective plant foraging and the top‐down suppression of native diversity in a restored prairie

Schneider

Steeves

Newmaster

et al. 2017

Journal of Applied Ecology

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“…Actual patterns of colonization, local extinction, and local shifts in abundance surely represent a complex interplay between stochastic and deterministic forces acting at various scales (Germain et al 2013). Actual patterns of colonization, local extinction, and local shifts in abundance surely represent a complex interplay between stochastic and deterministic forces acting at various scales (Germain et al 2013).…”

Section: Discussionmentioning

confidence: 99%

Do metacommunity mass effects predict changes in species incidence and abundance?

2017

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Metacommunity matrices contain data on species incidence or abundance across sites, compactly portraying community composition and how it varies over sites. We constructed models based on an initial metacommunity matrix of either species incidence or abundance to test whether such data suffice to predict subsequent changes in incidence or abundance at each site. The models reflect both species and site mass effects in using products of the row and column totals to predict the incidence or abundance of each species expected at each site. We tested these models against empirical data on vascular plant incidence and abundance collected from two sets of forested sites in both the 1950s and 2000s. Predictions from these models parallel observed changes in species incidence and abundance in these distinctly different metacommunities and differ greatly from null model predictions. The abundance model shows greater power than the incidence model reflecting its higher information content. Predictions were more accurate for the more diverse forests of southern Wisconsin that are changing quickly in response to succession and fragmentation. Simulations show that these results are robust but sensitive to sampling intensity. Because these models require no data on site conditions or species' characteristics, they provide a useful baseline to assess more complex models based on species' functional traits, local site conditions, or landscape context. They may also prove useful to conservation biologists seeking to predict local population declines and extinction risks.

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“…Such changes in the relative composition of the seed pool may interfere with stochastic assembly processes from the local species pool (Tofts and Silvertown 2002; Germain et al. 2013). …”

Section: Discussionmentioning

confidence: 99%

Plant density can increase invertebrate postdispersal seed predation in an experimental grassland community

Dudenhöffer

Pufal

Roscher

et al. 2016

Ecology and Evolution

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Janzen–Connell effects are negative effects on the survival of a plant's progeny at high conspecific densities or close to its conspecifics. Although the role of Janzen–Connell effects on the maintenance of plant diversity was frequently studied, only few studies targeted Janzen–Connell effects via postdispersal seed predation in temperate grassland systems. We examined effects of conspecific density (abundance of conspecific adult plants) on postdispersal seed predation by invertebrates of three grassland species (Centaurea jacea, Geranium pratense, and Knautia arvensis) in experimental plant communities. Additionally, we examined the impact of plant species richness and different seed predator communities on total and relative seed predation (= seed predation of one plant species relative to others). We offered seeds in an exclusion experiment, where treatments allowed access for (1) arthropods and slugs, (2) arthropods only, (3) small arthropods only, and (4) slugs only. Treatments were placed in plots covering a gradient of abundance of conspecific adults at different levels of plant species richness (1, 2, 3, 4, 8 species). Two of the plant species (C. jacea and K. arvensis) experienced higher rates of seed predation and relative predation with increasing abundance of conspecific adults. For C. jacea, this effect was mitigated with increasing plant species richness. Differences in seed predator communities shifted seed predation between the plant species and changed the magnitude of seed predation of one plant species relative to the others. We exemplify density‐dependent increase in seed predation via invertebrates in grassland communities shaping both the total magnitude of species‐specific seed predation and seed predation of one species relative to others. Further differences in seed predator groups shift the magnitude of seed predation between different plant species. This highlights the importance of invertebrate seed predation to structure grasslands via density‐dependent effects and differing preferences of consumer groups.

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Spatial Variability in Plant Predation Determines the Strength of Stochastic Community Assembly

Cited by 55 publications

References 54 publications

Selective plant foraging and the top‐down suppression of native diversity in a restored prairie

Selective plant foraging and the top‐down suppression of native diversity in a restored prairie

Do metacommunity mass effects predict changes in species incidence and abundance?

Plant density can increase invertebrate postdispersal seed predation in an experimental grassland community

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