Hunting-induced defaunation drives increased seed predation and decreased seedling establishment of commercially important tree species in an Afrotropical forest

Rosin, Cooper; Poulsen, John R.

doi:10.1016/j.foreco.2016.10.016

Cited by 36 publications

(41 citation statements)

References 51 publications

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“…, McMeans et al. , Rosin and Poulsen ). Anticipating how food‐webs respond to a changing climate and habitat requires theory that connects data on the space‐time delivery of this foundational resource with the capacities of consumers to abide variation.…”

Section: Introductionmentioning

confidence: 96%

“…Masting trees and shrubs supply a pulsed resource that constitutes the base of forest food chains, both supports and destabilizes consumer populations, and mediates the structure of communities in ways that are poorly understood (Jones et al 1998, McShea 2000, Ostfeld and Keesing 2000, Clotfelter et al 2007, McMeans et al 2016, Rosin and Poulsen 2016. Anticipating how foodwebs respond to a changing climate and habitat requires theory that connects data on the space-time delivery of this foundational resource with the capacities of consumers to abide variation.…”

Section: Introductionmentioning

confidence: 99%

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Foodwebs based on unreliable foundations: spatiotemporal masting merged with consumer movement, storage, and diet

Clark

Núñez

Tomasek

2019

Ecological Monographs

114

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Mast‐fruiting trees represent a pulsed resource that both supports and destabilizes consumer populations. Whereas a reliable resource is abundant on average and with limited variation in time and space, masting is volatile and localized, and that variability ramifies throughout food‐webs. Theory is developed to evaluate how the space–time structure of masting interacts with consumers who exploit alternative hosts, forage widely in space, and store reserves in time. We derive the space–time–species covariance in resource supply and combine it with the space–time–diet breadth of consumers, or ambit. Direct connection to data is made possible with Mast Inference and Forecasting (MASTIF), a state‐space autoregressive model that fits seed‐trap and canopy observations and predicts resource availability within the canopy and on the forest floor with full uncertainty. A resource score can be assigned to each consumer–habitat combination that integrates the benefits of a high mean supply weighed against the variance cost. As the consumer ambit increases, the volatility of an unreliable resource shifts from a variance cost to a mean benefit. Consumers foraging in the canopy (arboreal arthropods and rodents, song birds) experience space‐time covariance between host trees. Consumers on the forest floor (seed and damping‐off fungi, arthropods, rodents, ground‐nesting birds, mammals) experience instead a redistribution of that covariance by dispersal. For consumers lacking mobility, demographic storage in the form of episodic birth cohorts following mast years is important for population persistence. Consumers additionally compensate volatility with diet breadth. Depending on the dominant masting strategies of host tree species in the diet, habitats differentially limit consumers depending on the misalignment between consumer ambit and spatiotemporal covariance of hosts. The impact of adding or subtracting a diet item can be gauged with the standard error (SE) rule or the benefit of an added diet item balanced against the variance cost, both of which depend on the existing diet, the abundance of the new host, and the consumer's foraging ambit. Results rank habitats by their capacities to support wildlife and other consumers from a resource perspective. Results are connected directly to data, with full uncertainty, by MASTIF.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Foodwebs based on unreliable foundations: spatiotemporal masting merged with consumer movement, storage, and diet

Clark

Núñez

Tomasek

2019

Ecological Monographs

114

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“…, Galetti et al. , Rosin and Poulsen ). Our assessment of these interacting factors suggests two distinct patterns to seedling establishment that are dependent on logging history.…”

Section: Discussionmentioning

confidence: 94%

Defaunation and habitat disturbance interact synergistically to alter seedling recruitment

Granados

Brodie

Bernard

et al. 2017

Ecological Applications

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Vertebrate granivores destroy plant seeds, but whether animal-induced seed mortality alters plant recruitment varies with habitat context, seed traits, and among granivore species. An incomplete understanding of seed predation makes it difficult to predict how widespread extirpations of vertebrate granivores in tropical forests might affect tree communities, especially in the face of habitat disturbance. Many tropical forests are simultaneously affected by animal loss as well as habitat disturbance, but the consequences of each for forest regeneration are often studied separately or additively, and usually on a single plant demographic stage. The combined impacts of these threats could affect plant recruitment in ways that are not apparent when studied in isolation. We used wire cages to exclude large (elephants), medium, (sambar deer, bearded pigs, muntjac deer), and small (porcupines, chevrotains) ground-dwelling mammalian granivores and herbivores in logged and unlogged forests in Malaysian Borneo. We assessed the interaction between habitat disturbance (selective logging) and experimental defaunation on seed survival, germination, and seedling establishment in five dominant dipterocarp tree species spanning a 21-fold gradient in seed size. Granivore-induced seed mortality was consistently higher in logged forest. Germination of unpredated seeds was reduced in logged forest and in the absence of small to large-bodied mammals. Experimental defaunation increased germination and reduced seed removal but had little effect on seed survival. Seedling recruitment however, was more likely where logging and animal loss occurred together. The interacting effects of logging and hunting could therefore, actually increase seedling establishment, suggesting that the loss of mammals in disturbed forest could have important consequences for forest regeneration and composition.

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“…We extracted the values from several studies (Carvajal and Adler, 2008;Brewer and Rejmanek, 2009;Klinger and Rejmanek, 2009;Aliyu et al 2014;Cao et al, 2016;Rosin and Poulsen, 2016). We multiplied our observed values (seed removal) by the mean value (48%) from these studies.…”

Section: Discussionmentioning

confidence: 99%

Do consumer‐mediated negative effects on plant establishment outweigh the positive effects of a nurse plant?

Fujita

Yamashina

2018

Ecology and Evolution

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Many studies demonstrated the importance of facilitative effect by nurse plant on seedling establishment. Few studies evaluated the negative effects of consumers on plant establishment under nurse plants by dealing with them during multiple demographic processes. We investigated the balance between the facilitative effect and negative effects of consumers during multiple demographic processes in Malawi in southeastern Africa. We chose Ficus natalensis as a nurse plant and compared it with three other microsites in tropical woodlands: Brachystegia floribunda (a dominant woodland species), Uapaca kirkiana (a woodland species), and a treeless site. We quantified the seed rain, postdispersal seed predation, germination, and seedling survival of Syzygium guineense ssp. afromontanum (a common forest species). Within each microsite, we quantified the overall probability of recruitment. We also measured seedling abundance of S. guineense ssp. afromontanum. We found that Ficus natalensis exerted both positive and negative impacts on the establishment of S. guineense ssp. afromontanum. Ficus natalensis facilitated seed deposition, seed germination, and seedling survival. On the other hand, seed removal at postdispersal stage was highest under F. natalensis. Interestingly, B. floribunda also had positive effects on germination and seedling survival, but not on seed deposition. When we excluded the seed arrival stage from our estimation of the recruitment probability, the highest value was found under B. floribunda, not under F. natalensis. When we included the seed arrival stage, however, the order of recruitment probability between F. natalensis and B. floribunda was reversed. The probability was one order of magnitude higher under F. natalensis than under B. floribunda. Our estimation of the probability which included the seed arrival stage was consistent with natural patterns of S. guineense ssp. afromontanum establishment. Despite the presence of opposite effects, the net effects of F. natalensis on S. guineense ssp. afromontanum recruitment in tropical woodlands can be positive.

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Hunting-induced defaunation drives increased seed predation and decreased seedling establishment of commercially important tree species in an Afrotropical forest

Cited by 36 publications

References 51 publications

Foodwebs based on unreliable foundations: spatiotemporal masting merged with consumer movement, storage, and diet

Foodwebs based on unreliable foundations: spatiotemporal masting merged with consumer movement, storage, and diet

Defaunation and habitat disturbance interact synergistically to alter seedling recruitment

Do consumer‐mediated negative effects on plant establishment outweigh the positive effects of a nurse plant?

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