Southern Ocean Islands Invaded: Conserving Biodiversity in the World’s Last Wilderness

Abstract

The Southern Ocean islands are some of the most isolated landmasses in the world. Few of the islands support permanent human settlements or land based industries and as such they remain as some of the most uninvaded landscapes globally. Over 250 non-native plants are currently established across the region. Most are grasses and small herbs, and as such have similar growth forms to the native vegetation. Many of the invasive plants present today arrived several hundred years ago with whaling and sealing gangs, others have been introduced more recently with cargo and building programmes associated with research stations. The Southern Ocean Islands provide a unique opportunity to study and manage invasive plants as the islands have low propagule pressure and very few confounding factors that drive invasion processes elsewhere, such as herbivores, agriculture and land clearance. Invasive plants vary in abundance and distribution on islands and residence time has been shown to significantly influence their area of occupancy. The high protection status of the islands has led to numerous management actions and restoration programmes, some involving invasive plant eradication attempts. Rigorous biosecurity measures are essential to stem future introductions and ensure the island ecosystems remain intact.