Ackama nubicola is a small tree endemic to Te Ika a Maui / North Island in Aotearoa / New Zealand, where it is only found in one location in the Waima Forest. The area where 98% of the population is found is smaller than 1 ha, and the total extent of occurrence is less than 100 km². There is a continued decline in the habitat quality and population size mainly due to possum and goat browsing. There are fewer than 1,000 individuals remaining. It is assessed as Critically Endangered.

This species is endemic to the Waima Forest, south of Hokianga Harbour and north of Waipoua Forest, Northland, Te Ika a Maui / North Island, Aotearoa / New Zealand. Distribution map is generalised.

The population is estimated to include c. 500–600 subadults and adults in one subpopulation covering an area of c.1 ha, and then with sporadic trees / and stands of 5–20 trees in six widely scattered sites elsewhere within the Waima Forest (de Lange et al. 2002, 2010; de Lange 2023). Thus far, it is known only from this forested area, which covers an unnamed mountain range on the southern side of the Hokianga Harbour.

It is confined to cloud forest above 500 m asl and regenerating partially cleared land and reverting farmland (de Lange et al. 2002, de Lange 2023). The largest cluster of individuals occupies regenerating farmland - and is probably artificially high as a consequence of past land clearance. Other sites are found at gulley and stream heads, on slip scars and on track sides. Ackama nubicola is naturally confined to sites prone to frequent disturbance in a region known for the highest rainfall in Northland. Seedlings often germinate on the trunks of Alsophila smithii and Sphaeropteris medullaris. Longevity of trees though unknown is probably less than 100 years based on the ages of the allied Ackama rosifolia. Common associates include Ackama rosifolia, Veronica flavida, Alsophila smithii, Sphaeropteris medullaris, Metrosideros robusta and Olearia rani var. rani.

It is threatened by possum (Trichosurus vulpecula) browsing. Possums, introduced to Aotearoa / New Zealand from 1837 onwards are a major threat to the indigenous flora of that country. Possums target young growth and especially immature inflorescences of Ackama nubicola. Flowering and fruiting has only been observed following extensive possum control. Feral goats (Capra hircus) are also a threat, though goat numbers in the Waima Forest are now much reduced. Successful recruitment has not been confirmed since this species' discovery in 2001, nearly all seedlings and saplings seen have been destroyed by browsing pressure from possums.

Ackama nubicola is fickle in cultivation, plants are prone to sudden collapse and will not tolerate drying out. Despite attempts to cultivate trees in 2002–2003 the species is still not known from cultivation.

As this species is difficult to maintain in cultivation it is not known to be commercially available (de Lange 2023).

The Waima Forest is subjected to periodic wild animal control, which may at times include aerial drops of Sodium fluoroacetate (1080) which is extremely effective at controlling possums to the levels needed to induce flowering and fruiting in Ackama nubicola. However, 1080 drops are controversial and not favoured by many people and some iwi (Maori people) who exercise mana whenua (traditional ownership of the lands) thus its long term use at Waima Forest is not certain. Other practical solutions to possum control in that forest are not considered viable. Without sustained possum control Ackama nubicola is unable to recruit, and over time heavily browsed specimens are killed. Until a more publicly acceptable possum control approach is developed, Ackama nubicola requires 1080 drops to manage possum levels roughly every 5 years to ensure flowering and fruiting. There are no other options to prevent the loss of this species.

New Zealand Threat Classification System assessed this species as ‘Threatened / Nationally Critical’ Qualified ‘CD’ [Conservation Dependent], ‘OL’ [One Location], ‘RF’ [Recruitment Failure] (de Lange et al. 2018, 2024).