A natural experiment on the effects of high deer densities on the native flora of coastal temperate rain forests

• DOI: 10.1016/j.biocon.2005.06.006
• Publication Date: 2005-07-18T13:49:46Z
• Authors: Stephen A. Stockton; Sylvain Allombert; Anthony J. Gaston; Jean-Louis Martin
• Keywords: 0106 biological sciences; 13. Climate action; 14. Life underwater; 15. Life on land; 01 natural sciences

Abstract The introduction of Sitka black-tailed deer ( Odocoileus hemionus sitkensis Merriam) to Haida Gwaii (Queen Charlotte Islands, BC, Canada) in the late 19th century, provided an opportunity to understand the long-term effects of deer populations on the vegetation of temperate rain forests in the absence of their natural predators wolves ( Canis lupus L.), and cougars ( Puma concolor L.). Using seven small islands with different browsing histories (no deer, deer for 50 years), we tested the long-term effects of high deer densities on plant cover and species richness in the understorey of forest interior and forest edge habitats. Overall vegetation cover exceeded 80% in the lower vegetation layers on islands without deer and was less than 10% on the islands with deer for more than 50 years. Although overall plant species richness was similar on islands with or without deer, plant species richness at the plot scale (314 m 2 ) was reduced by 20–50% on islands with deer for >50 years. The differences were most pronounced for the species-rich edge communities and among herb and shrub species. These results suggest that in the absence of predators, deer have the potential to greatly simplify the forest ecosystem.