Herbivore population regulation and resource heterogeneity in a stochastic environment

A study of goat populations in the Richtersveld National Park, South Africa, reveals that population dynamics are tightly coupled to dry-season forage availability. Despite environmental stochasticity, density-dependent declines in body condition due to resource depletion directly influence pregnancy rates, litter sizes, and juvenile survival, with adult survival depending on mid-dry season body condition. Population growth is primarily determined by the length of the dry season and previous year's population size, contradicting theories that extreme variability decouples consumer-resource dynamics. The research combines long-term monitoring of 500 tagged females with demographic data to link forage resource heterogeneity to population stability.

Hempson, G. P., Illius, A. W., Hendricks, H. H., Bond, W. J., & Vetter, S. (2015). Herbivore population regulation and resource heterogeneity in a stochastic environment. Ecology, 96(8), 2170–2180. Portico. https://doi.org/10.1890/14-1501.1