Heenan et al. (2024) on the basis of molecular data, used in isolation of other lines of evidence elected to treat all Aotearoa / New Zealand Kunzea as one widespread species K. ericoides. Their work did not consider the morphological and cytological disparity, nor the sympatry / syntopy between the species recognised by de Lange (2014), and the analyses used to derive their conclusions have been disputed by others as the authors did not pay attention to the cautions on the modelling and statistical analyses pointed out when using multi-coalescent theory (Sukumaran and Knowles 2017).

The species is accepted by the New Zealand Plant Conservation Network (www.nzpcn.org.nz) and New Zealand Indigenous Vascular Plant Threat Listing Panel.

As defined here, Kunzea ericoides is a arrow range endemic with often pendulous branches, glabrescent branchlets (branchlet hairs minute, divergent, sparse), bright-green linear-lanceolate leaves, and corymbiform inflorescences (de Lange 2014, 2023). The species is widely sympatric / syntopic with K. amathicola, K. robusta and K. serotina.

Kunzea ericoides is a large tree, endemic to Aotearoa / New Zealand where it occurs on Te Wai Pounamu / South Island (north of the Buller and Wairau Rivers). The population size is estimated to be more than 100,000 mature individuals. The existing main threats to the species are clearance for plantation forestry, felling for firewood, wild fires and invasive weeds. However, an extreme decline of the species is anticipated in the near future from the rust Austropuccinia psidii, to which there is no known cure. Based on a suspected decline of up to 30 % over three generations this the species is assessed as Near Threatened.

This species is endemic to Aotearoa / New Zealand where it occurs on Te Wai Pounamu / South Island (north of the Buller and Wairau Rivers). Distribution map is generalised.

No accurate counts of individuals have been made. However, the species is widespread and common over most of its range. Some contraction has happened within land cleared for farming, horticulture and for urban centres. Beyond this historic and minor ongoing loss (the species is still being cleared from private land, for firewood and for land development) Kunzea ericoides is secure, common, at times locally dominant within its range. While no population counts have been made there is likely to be >100,000 mature individuals. Beyond the threat of Austropuccinia psidii which has yet to be realised in this species, current decline rates are probably <5% over three generations.

This species is likely to live for over 50 years. There is no information available on when the species begins to reproduce. Consequently a generation length of 20–30 years is given to measure continuing decline. The population decline is measured over a moving window considering two generations in the past and one generation into the future as decline is continuing (1960–2050). If A. psidii affects K. ericoides in situ, it is thought that across this time the population is suspected to experience a decline of up to 30%.

Kunzea ericoides is found in a wide variety of habitats from early stage seral shrubland through to tall forest ranging from sea level to 1,600 m asl. In montane areas it is frequently found within north-facing canopy gaps developed within montane black beech (Nothofagus solandri) and mountain beech (N. cliffortioides) forests, often close to the upper tree limit for these species in the Richmond Range and parts of north-west Nelson. The species is also commonly encountered in coastal forest, though rarely on sand dunes, and it can be a conspicuous tree of lowland areas, especially along river flats and on outwash gravels within the Waimea Plain and on sections of the northern bank of the Buller River (de Lange 2014, 2023).

While no obvious substrate requirement is evident, it appears to avoid permanently waterlogged soils and peat and it is scarce from wetlands, though it may at times be common in the vegetation bordering these habitats. Free draining soils and recent alluvium is commonly colonised, as is open ground within lowland to upper montane forests. On the extensive karstfield of north-west Nelson K. ericoides is often prominent, especially in places where there has been a history of logging, mining, farming, or frequent fires. K. ericoides is also a common component of the ultramafic areas of D’Urville Island, Mt Dun, the Red Hills and upper Takaka.

K. ericoides is an important primary tree coloniser of formerly cleared ground in many parts of its range. In these situations, perhaps more than any other, the dense leaf litter produced by the often closely growing trees is ideal for a wide range of terrestrial orchids and fungi (de Lange 2014).

The key threats to the species are clearance for plantation forestry, felling for firewood, wild fires, invasive weeds and Austropuccinia psidii. This rust is now the most serious threat. It reached Aotearoa / New Zealand from Australia in 2017. The impact of this rust on Myrtaceae worldwide is serious, and it is known to kill inoculated Kunzea species in cultivation susceptibility trials, so it is regarded as a serious threat to members of the genus and indeed all of the indigenous Myrtaceae in Aotearoa / New Zealand (de Lange et al. 2018). It is solely for this reason that K. ericoides has such a high threat listing in Aotearoa / New Zealand. Currently there is no cure for this disease. At this stage wild occurring infected Kunzea have yet to be reported but it is inevitable that occurrences will happen. Once they are recorded the impact and long-term survival of K. ericoides and other allied species must be regarded as uncertain. In the case of K. ericoides the species is further also threatened by some loss of trees for firewood, and through land clearance for plantation forestry, farming, horticulture and for urban centres.

This species is felled for firewood.

The key threat to Kunzea ericoides will inevitably be Austropuccinia psidii. All other known threats can be effectively managed but the rust, so far, has not been. The impact on wild Kunzea is as yet unknown but it is believed that it will be severe, infections of inoculated cultivated plants result in the death of seedlings and saplings within less than a year from the first infection. As the rust continues to spread, and infections increase, there will be more spores spread, so the severity in infections of host plants is anticipated to increase. Currently there is no known cure for Austropuccinia, all that can be hoped for is that some lineages of host plants have or develop resistance. To date there has been no evidence for this.

As the rust is wind dispersed quarantine measures are also ineffective. The seed of Kunzea has short-term viability and viability is affected by desiccation and freezing, so conventional seed banking is of limited value. Current measures to secure the species should consider holding tissue-cultures. Consideration should be given to cultivating the species outside the global distribution of Austropuccinia, to see if at those sites the species can be secured in Botanic Gardens and other threatened plant collections.

Research into finding a cure for Austropuccinia is a global issue and many organisations are working in this area. Like all research however, those investigations are subject to funding issues and political whim. Austropuccinia is a global problem, a global response is needed – only time will tell if humanity understands the consequences of the loss of the Myrtaceae on world ecosystems and takes the right steps to find solutions to help manage this rust.

It is assessed as ‘Threatened / Nationally Vulnerable’ qualified ‘De’ [Designated], ‘DP’ [Data Poor] by de Lange et al. (2018).