Update on Sustainable Management of Geothermal Vegetation in the Waikato Region, New Zealand

Geothermal vegetation - influenced by surface expressions of heat from the Earth’s interior - is naturally rare in New Zealand, and internationally. The varied nature of geothermal manifestations, due to varying combinations of temperature, chemistry, hydrology, and localised protection from frosts, results in rare and unusual habitats for plants. These naturally uncommon ecosystems are classed as threatened and critically endangered, and include habitats for species occurring outside ‘normal’ latitudinal and altitudinal ranges. The varied nature of geothermal vegetation, one of the most threatened ecosystems in New Zealand, has important implications for management, including retention of existing areas and the maintenance and enhancement of ecological values. Most geothermal vegetation in New Zealand occurs in the Central North Island in the Taupo Volcanic Zone, with c.74% of the total extent of New Zealand’s geothermal vegetation located within the Waikato Region, and the remaining 26% located within the Bay of Plenty Region. Inventories of geothermal vegetation and identifications of management priorities have been undertaken regularly in the Waikato Region since 2000. The latest inventory, undertaken in 2014, covered over 863 ha of geothermal habitat at c.64 sites within 15 geothermal systems. Energy production (thermal and hydro-electricity, heating, and industrial uses), land use changes such as mining, farming, forestry, urban development, tourism, and fire has resulted in the loss of significant geothermal areas in the past, and such activities continue to threaten geothermal vegetation. Invasion of pest plants, particularly introduced conifers and other woody plant species, continues to be a major threat at many sites. Threat mechanisms operating at each site, vulnerability to those threats, actions required to address them, and the benefits and priorities of ecological management have been identified. Pest plant control programmes are being implemented at many sites, however pest plant control remains a High priority at c.16 sites. Pest animal management is a High priority at one site, whilst exclusion of domestic stock is an Immediate priority at one site and a High priority at four sites. For sites where management requirements have been ranked as being Immediate or High priorities, action should be instigated as soon as practicable. In most cases, holistic management of sites is recommended. Active restoration management is being undertaken by the Department of Conservation, tangata whenua, regional and local government, private landowners, and forestry companies. There are considerable opportunities for further restoration initiatives, at other sites and where work has already been undertaken. New threats have also been recognised, showing the importance of regular monitoring and inventory assessments. Continued monitoring and appropriate planning is a key requirement to improve management of this nationally rare ecosystem. Monitoring, protection, and restoration, where possible, are essential requirements to halt the decline of these fragile and unique ecosystems.