Geothermal vegetation in the Ng? Tamariki geothermal system: Ecology and management

Abstract

The Ng? Tamariki Geothermal System (NTGS) is located c.20 kilometres north of Taup? and has around six hectares of geothermal vegetation and habitat. The system contains many relatively small and active geothermal manifestations that are widely dispersed in and alongside Orakonui Stream, Waikato River, and Mangamingi Stream. The diversity of geothermal habitats includes steamy habitats (alongside springs and streams), sinter deposits, wetlands, and thermally heated ground providing habitat for key geothermal plant species. The NTGS is classified as a ‘Development Geothermal System’ by Waikato Regional Council. Rotokawa Joint Venture operate a geothermal power station in the NTGS. An 82MW geothermal power plant was commissioned in 2013, with consent granted for an extension in 2024. Regular monitoring of geothermal surface features and geothermal vegetation has been undertaken since 2012. Recently, a restoration management plan with a focus on key geothermal habitats at the Orakonui site has been prepared in collaboration with mana whenua (Ngati Tahu-Ngati Whaoa) and key stakeholders. The plan provides advice to manage key threats to vegetation and species in geothermal habitat here, particularly management of pest plants. This paper provides a summary of known site history, ecological values, monitoring results, an overview of restoration options, and recommendations for future management.