Less is more: vegetation changes coincide with white-tailed deer suppression over thirty years

Abstract

Although ecological impacts of overabundant white-tailed deer (Odocoileus virginianus) are well documented in eastern North America, few studies have evaluated the long-term effects of adaptive deer population suppression after a period of overabundance. We examined vegetation community changes over a period of 30 years (1992–2021) on the Long Point Peninsula, Ontario, Canada following a >85% reduction of a previously overabundant white-tailed deer population. We documented a significant increase in species diversity and shifts in the species composition of understory plants and woody vegetation. We then evaluated several hypotheses to explain these patterns. Our results provide support for the all-you-can-browse hypothesis, in which the abundance of woody stems above the browse layer did not increase within the first 3 years of sampling but, consistent within an expected period of recruitment, increased by >1,500% from 1995–2021. We also found support for both the lawn maintenance hypothesis, with a significant decline in the proportional abundance of non-preferred species relative to preferred species, and for the seed bank hypothesis, with native species accounting for nearly 80% of new species observed over the sampling period. We conclude that the effective, long-term management and continued suppression of an previously overabundant white-tailed deer population can lead to increased vegetation community heterogeneity and diversity, which is likely one of the most important steps for the regeneration of woody stems and native vegetation communities.