b870725b-d0da-4dd4-9ca4-20bebb62c4d7 https://ipt.gbif.org.nz/resource?r=tristan_observations Tristan_Observations Kelvin Floyd Indigena Biosecurity International

Auckland NZ

kelvin.floyd@gmail.com http://www.indigena.co.nz Bradley Myer Indigena Biosecurity International

Nelson 7010 NZ

brad@indigena.co.nz http://www.indigena.co.nz Trevor Glass Government of Tristan da Cunha, Conservation Department

SH

pointOfContact 2026-03-23 eng Alien plant observations from Tristan da Cunha collected during surveys done in 2023 and 2025 by staff from Indigena Biosecurity International Occurrence Tristan da Cunha alien invasive plants GBIF Dataset Type Vocabulary: http://rs.gbif.org/vocabulary/gbif/dataset_type_2015-07-10.xml Observation GBIF Dataset Subtype Vocabulary: http://rs.gbif.org/vocabulary/gbif/dataset_subtype.xml Indigena Biosecurity International - www.indigena.co.nz To the extent possible under law, the publisher has waived all rights to these data and has dedicated them to the Public Domain (CC0 1.0). Users may copy, modify, distribute and use the work, including for commercial purposes, without restriction. Creative Commons Zero v1.0 Universal https://spdx.org/licenses/CC0-1.0.html CC0-1.0 http://www.indigena.co.nz https://ipt.gbif.org.nz/archive.do?r=tristan_observations Tristan da Cunha -12.33417 -12.281433 -37.06354 -37.095151 Alien vascular plants from Tristan da Cunha family Commelinaceae family Corynocarpaceae family Lamiaceae family Araliaceae family Pittosporaceae family Myrtaceae order Dipsacales order Geraniales order Cucurbitales order Asterales class Pinopsida family Cannaceae family Rosaceae kingdom Plantae order Arecales order Ericales family Amaryllidaceae order Solanales order Alismatales family Arecaceae class Magnoliopsida family Solanaceae family Caryophyllaceae family Pinaceae phylum Streptophyta family Iridaceae order Poales order Malpighiales family Araceae order Asparagales order Myrtales family Polygonaceae order Zingiberales family Onagraceae class Liliopsida family Poaceae family Geraniaceae family Rubiaceae family Brassicaceae family Juncaceae family Fabaceae family Crassulaceae order Lamiales family Urticaceae order Caryophyllales family Caprifoliaceae family Asphodelaceae family Moraceae family Hydrangeaceae order Rosales order Fabales order Saxifragales order Commelinales family Convolvulaceae family Primulaceae order Brassicales order Gentianales order Cornales order Pinales family Asteraceae family Salicaceae order Apiales Rapidly spreading invasive plant species threaten unique biodiversity values and community livelihoods in the Tristan archipelago. This project's goal was to eradicate all known New Zealand Flax plants on Inaccessible Island World Heritage Site, plus train and enable a Tristan-led eradication of all emergent Pōhutukawa trees and self-sown Monterey pine on Tristan itself. A comprehensive survey of all Tristan’s other invasive plants will provide Tristan Conservation with a prioritised long-term management & eradication strategy, safeguarding natural habitats and vital agricultural land. This project is managed by the Royal Society for the Protection of Birds This fieldwork followed the extensive 2007–2008 survey conducted by Gremmen and Halbertsma, who identified 137 alien vascular plant species and documented the threats they pose to the island’s unique endemic biodiversity and agricultural production. Two subsequent assessments were carried out under the Darwin Plus initiative (DPLUS191) through the Building Capacity for Invasive Plant Management across Tristan’s Northern Islands project, undertaken by Kelvin Floyd in 2023 and Bradley Myer in 2025. Given the limited time available, the aim of these two visits was not to conduct another extensive survey, but rather to reassess the extent of previously prioritised species and to identify any additional alien species of concern. A total of 170 species were identified. The checklist can be found here: https://doi.org/10.15468/3hpfkqThis dataset contains the observations from the 2023 and 2025 missions During their assessments, Kelvin and Bradley surveyed the distribution where possible of the species identified by Gremmen and Halbertsma, and recorded a combined total of 33 additional alien species. This brings the total number of introduced plant species recorded on Tristan da Cunha to 170. It includes agricultural species (beneficial and undesirable), garden plants and escapees, and horticultural species (beneficial and undesirable). This project is generously supported by the Royal Society for the Protection of Birds and Darwin Plus. DPLUS191 is a main sized project. https://darwinplus.org.uk/project/DPLUS191Many thanks to Trevor Glass, the conservation Team and the good people of Tristan da Cunha unknown Bradley Myer Indigena Biosecurity International

Nelson 7010 NZ

brad@indigena.co.nz http://www.indigena.co.nz Data was recorded in the field then synced to the cloud and then aggregated with the other datasets. Botanical documentation on Tristan da Cunha began in 1793, when Aubert du Petit-Thouars collected three plant species. By 1910, 44 alien plant species had been recorded. A major botanical survey was undertaken during the 1937–38 Norwegian Scientific Expedition by Christophersen and Mejland. Further extensive collections were made by Stableford in the 1950s, followed by Wace and Dickson. Knowledge of the flora was later consolidated by Groves (1981). A comprehensive study by Gremmen and Halbertsma in 2009 mapped 137 introduced plant species across the island. Currently, invasive plant management is being conducted under the Darwin Plus initiative (DPLUS191) through the Building Capacity for Invasive Plant Management across Tristan’s Northern Islands project. As part of this initiative, representatives from Indigena Biosecurity International visited the island in 2023 and 2025, documenting weed species and geolocating their distribution. An extensive survey was conducted by Gremmen and Halbertsma, in 2007 - 2008. They spent 4 months on the island and identified 137 alien vascular plant species and documented the threats they pose to the island’s unique endemic biodiversity and agricultural production. Kelvin Floyd and Bradley Myer visited the island in 2023 and 2025 respectively. Their focus was re assessing the highest priority species based on the ecological impact of the alien invasive species. Alien species are primarily focused around the settlement of Edinburgh of the Seven Seas. In 2023 and 2025 data was selected from dropdown lists, which included the species list from Gremmen and Halbertsma, in 2007 - 2008. There were fields for including adventive species. Plantnet was used to verify unknown species. Bethan Lang programmer Tristan da Cunha is the most remote inhabited island in the world. The community has a long history here, and the Settlement Plain has been transformed from a natural landscape into a productive area. The island’s steep and mountainous geography has limited broader landscape development. Tristan da Cunha hence supports significant populations of globally threatened birds and plants. Tristan da Cunha's unique biodiversity is of global importance due to its high levels of endemism. The island group’s flora includes roughly 50 native flowering plants and 35 native ferns, with nearly half of these vascular plants being endemic. The territory is also globally significant for its avifauna, supporting 86 native bird species, including 11 endemic species such as the Tristan Thrush. The ecosystem types are vertically zoned by elevation, ranging from coastal areas – where the original tussock grassland communities have largely been lost due to grazing – to Phylica arborea woodland and fernbush, to high-altitude mire and feldmark vegetation. A total of 170 non-native plant species have been recorded on Tristan da Cunha. While a small number of additional introduced species occur on the other islands in the archipelago, the primary source of plant introductions is Cape Town, South Africa, from which the majority of shipping originates. Weeds pose a serious threat to biodiversity by disrupting ecosystem processes and outcompeting native species. Once established, many invasive plants produce large quantities of long-lived seeds, making eradication challenging. Successful weed management depends on accuracy, persistence, and timing. A clear management strategy ensures stakeholders understand their roles, are adequately resourced, and can act effectively, thereby safeguarding both ecological integrity and prior conservation investments. Proactive management remains the most effective and cost-efficient approach for protecting biodiversity and achieving long-term conservation outcomes. This project is generously supported by Darwin Plus. DPLUS191 is a main sized project. https://darwinplus.org.uk/project/DPLUS191 Darwin Plus (main) DPLUS191 https://darwinplus.org.uk/project/DPLUS191 The Tristan archipelago is one of the remotest in the world, home to 95+ unique species which have evolved in isolation. With the transport of people and goods across the globe, many plant species have been introduced into novel areas, with devastating and far-reaching consequences for the native biodiversity. Introduced species recorded on Tristan da Cunha were identified during November and December 2025 across the Settlement, the Pigbite, the 1961 lava flow, and the Potato Patches. Figure 2 illustrates the spatial distribution of survey and control efforts across the island. Due to time constraints and the limited accessibility of certain areas, it was not possible to locate and identify all species previously recorded by Gremmen and Halbertsma (2009) and Floyd (2023). In some cases, species recorded during earlier surveys may also have declined, been successfully removed, or persist at very low abundance, and were therefore not detected during the present assessment. 2026-03-23T04:10:47.637+00:00 dataset Floyd K, Myer B (2026). Tristan da Cunha: Alien Plant Observations 2023 and 2025. Version 1.6. Kaitiaki o te Ngahere. Occurrence dataset. https://ipt.gbif.org.nz/resource?r=tristan_observations&v=1.6 b870725b-d0da-4dd4-9ca4-20bebb62c4d7/v1.6.xml