Format: ORAL

Rosemary Newton1, Calum Sweeney1,2, Rachel Day1, Kaitalin White1, Wayne Dawson3,4, Bradley Myer5, Kelvin Floyd5, Marcella Corcoran1, Carey Kelting1, Sally Poncet5, Ken Passfield5, Felix Forest1, Colin Clubbe1, Juan Viruel1*

1 Royal Botanic Gardens, Kew. TW9 3AE, Richmond, UK 2 National Parks and Wildlife Services, Kenmare Road, Killarney, Kerry, V93N673, Ireland 3 Department of Biosciences, Durham University, Durham, DH1 3LE UK 4 Department of Evolution, Ecology and Behaviour, University of Liverpool, Liverpool, L69 7AB, UK 5 Indigena Biosecurity International, Nelson, New Zealand * Author for correspondence: j.viruel@kew.org

Climate change and invasive species are major causes of biodiversity loss. Invasive species are highly competitive in ecosystems due to their ability to germinate and grow in a wide range of conditions, their capacity to produce high reproductive outputs and their effective dispersal strategies. Climate change has already severely impacted several ecosystems across the planet, such as sub-Antarctic regions with temperatures rising there fastest in recent decades. The effects of climate change can exacerbate the impacts of invasive species by enhancing features that favour invasiveness, such as tolerance to a broad range of environments. Islands are particularly vulnerable to the effects of climate change due to reduced habitable space, small populations, and low functional redundancy. The remote sub-Antarctic island of South Georgia is 160 km in length with a vegetated area of approximately 30,000 ha predominantly confined to near coastal regions due to snow and ice being prominently present inland. South Georgia has a history of use as a land base for extraction of natural biotic resources from the surrounding coasts and ocean. Due to human occupation, non-native flora and fauna were inadvertently and/or intentionally introduced. Today, the introduced flora with 41 species outnumbers the native flora with 24 species. To mitigate this problem, the South Georgia Non-Native Plant Management Strategy was implemented during 2016-2020 to reduce the population size of non-native species on the island. We evaluate the efficacy of this eradication programme by quantifying the incidence of invasive species seeds in the soil seed bank. We designed a molecular barcoding approach to enable accurate identification of seedlings by evaluating the resolution of traditional barcoding markers (i.e., rbcL and matK) and optimising a high-throughput sequencing molecular barcoding method. We applied this method to identify seedlings that emerged from soil samples collected at key areas on the island.