The dynamics of vegetation grazed by a food‐limited population of Soay sheep on St Kilda

A long-term study on St Kilda reveals that the Soay sheep population's dynamics are closely tied to vegetation productivity, with grazing impacts varying significantly across different plant communities. The research shows that while highly palatable species like Festuca rubra and Ranunculus acris declined in Holcus / Agrostis grasslands due to intense grazing, overall plant species richness increased as grazing-tolerant species thrived under defoliation. Notably, the population's growth slowed and stabilized between 2011 and 2020, correlating with increased plant production in Holcus / Agrostis grassland. The study emphasizes the resilience of this plant-herbivore interaction, with no significant rise in unpalatable species, suggesting that measuring primary productivity and herbivore offtake offers deeper insights into population dynamics than biomass changes alone.

Crawley, M. J., Pakeman, R. J., Albon, S. D., Pilkington, J. G., Stevenson, I. R., Morrissey, M. B., Jones, O. R., Allan, E., Bento, A. I., Hipperson, H., Asefa, G., & Pemberton, J. M. (2021). The dynamics of vegetation grazed by a food‐limited population of Soay sheep on St Kilda. Journal of Ecology, 109(12), 3988–4006. Portico. https://doi.org/10.1111/1365-2745.13782