MWRPP Report 20.11: Deer impacts on three-year-old revegetation following fence removal.

Impacts caused by deer to vegetation within riparian zones of south-eastern Australia are increasing. While fenced exclosures provide good protection against deer impacts, the timeframes for which fencing is required and the likely scale of impacts caused by herbivores after fence removal from established revegetation are less clear.This study assessed plants in ten 15 × 15 m exclosure plots of planted and direct seeded revegetation at 2 years, and again at 3.5 years—six months after fences were removed from half of the plots. Revegetation was assessed for herbivore impacts (browsing, stem breakage, rubbing), plant heights and stem density. The negative effects of fence removal on the revegetation were stark. Herbivore impacts on plants where fences had been removed were almost ubiquitous, with trees rubbed and shrubs suffering stem breakage and biomass loss. There was early evidence to suggest plant growth and stem density were being adversely affected.Removal of fences from revegetation after 3 years in riparian zones with high deer densities will likely mean vegetation will be highly negatively impacted in the short-term. The long-term effects of rubbing, stem breakage and biomass removal are not yet fully understood. It is recommended that the fenced plots remain fenced and that both fenced and unfenced plots be resurveyed in one- and two-years’ time to assess the longer-term effects of the impacts. In areas of high deer density, deer impact mitigation measures will most likely be necessary if and when fences are removed if revegetation is to persist.