Herbivore population regulation and resource heterogeneity in a stochastic environment.

dc.contributor.authorHempson, G.P.
dc.contributor.authorIllius, A.W.
dc.contributor.authorHendricks, H.H.
dc.contributor.authorBond, W.J.
dc.contributor.authorVetter, S.
dc.date.accessioned2016-05-24T14:27:40Z
dc.date.available2016-05-24T14:27:40Z
dc.date.issued2015-08
dc.description.abstractLarge-mammal herbivore populations are subject to the interaction of internal density-dependent processes and external environmental stochasticity. We disentangle these processes by linking consumer population dynamics, in a highly stochastic environment, to the availability of their key forage resource via effects on body condition and subsequent fecundity and mortality rates. Body condition and demographic rate data were obtained by monitoring 500 tagged female goats in the Richtersveld National Park, South Africa, over a three-year period. Identifying the key resource and pathway to density dependence for a population allows environmental stochasticity to be partitioned into that which has strong feedbacks to population stability, and that which does not. Our data reveal a densitydependent seasonal decline in goat body condition in response to concomitant densitydependent depletion of the dry-season forage resource. The loss in body condition reduced density-dependent pregnancy rates, litter sizes, and pre-weaning survival. Survival was lowest following the most severe dry season and for juveniles. Adult survival in the late-dry season depended on body condition in the mid-dry season. Population growth was determined by the length of the dry season and the population size in the previous year. The RNP goat population is thereby dynamically coupled primarily to its dry-season forage resource. Extreme environmental variability thus does not decouple consumer resource dynamics, in contrast to the views of nonequilibrium protagonists.en_ZA
dc.identifier.citationHempson, G.P. et al. 2015. Herbivore population regulation and resource heterogeneity in a stochastic environment. Ecology 96(8), pp. 2170-2180en_ZA
dc.identifier.issn0012-9658
dc.identifier.urihttp://hdl.handle.net/10539/20397
dc.language.isoenen_ZA
dc.publisherEcological Society of Americaen_ZA
dc.subjectAfrican semi-arid grazing systemen_ZA
dc.subjectCapital-income breederen_ZA
dc.subjectConsumer resource dynamicsen_ZA
dc.subjectDensity dependenceen_ZA
dc.subjectDry seasonen_ZA
dc.subjectEnvironmental stochasticityen_ZA
dc.subjectEquilibriumen_ZA
dc.subjectKey resourceen_ZA
dc.subjectLife history strategyen_ZA
dc.subjectNonequilibriumen_ZA
dc.subjectRangeland debateen_ZA
dc.subjectWet seasonen_ZA
dc.subjectbody conditionen_ZA
dc.subjectdata seten_ZA
dc.subjectgoaten_ZA
dc.subjectgrazing pressureen_ZA
dc.subjectherbivoryen_ZA
dc.subjectheterogeneityen_ZA
dc.subjectlife history traiten_ZA
dc.subjectplant-herbivore interactionen_ZA
dc.subjectpopulation dynamicsen_ZA
dc.subjectpopulation sizeen_ZA
dc.subjectpopulation structureen_ZA
dc.subjectrangelanden_ZA
dc.subjectstochasticityen_ZA
dc.subjectsurvivalen_ZA
dc.subjectweaningen_ZA
dc.titleHerbivore population regulation and resource heterogeneity in a stochastic environment.en_ZA
dc.typeArticleen_ZA
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