One Tree Hill summit project

New tree planting proposal

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3.0 Site assessment

3.1 Selection criteria

The three key criteria considered important for success of a replacement tree are species, source, and size (at time of planting).

3.1.1 Species

The following four species are known, reputed or recorded to have some association with the One Tree Hill (Maungakiekie) summit.

Totara (Podocarpus totara)
Pine (Pinus radiata)
Puriri (Vitex lucens)
Pohutukawa (Metrosideros excelsa)

The characteristics and attributes of each species have been analysed. The two species that strongly meet the cultural and physiological requirements of the site are totara and pohutukawa. These species are proposed as possible replacements for the existing pine tree.

Totara has a significant historic cultural connection with the site. The species has a mature form that is likely to be similar to the previous pine tree, the species is reasonably adaptable and hardy and is expected to have a long life span.

Pohutukawa also has a strong cultural connection with the site and the Auckland Region. The species is likely to develop a multi-leadered and spreading growth habit. However, pohutukawa is very adaptable and hardy, naturally occurring on exposed sites similar to the summit of One Tree Hill (Maungakiekie) and having a long life span.

Puriri are reputed to have been planted by Sir John Logan Campbell in an attempt to replace the original totara during the 1870's. (The previous pine tree was planted as a group to shelter the puriri). Puriri is not expected to adapt well to the environmental conditions at the summit of One Tree Hill (Maungakiekie) and so is not recommended.

Monterey Pine is an extremely adaptable and tolerant species and has survived on the summit of One Tree Hill for 125 years. It has been a proven performer in the exposed summit environment and can develop a strong character under those conditions. Pine is, however, expected to have less longevity than other species proposed. Culturally the use of this species as a replacement has not been favoured by public submissions received following notification of the Management Plan, and via letters and telephone calls received by Auckland City staff requesting that the replacement tree be a native species.

3.1.2 Source

Generally, a seedling that has grown in the same conditions in which it will be transplanted has the greatest chance of thriving. Iwi have also expressed a strong preference for trees sourced from the immediate or local area.

This includes trees deemed to be from original local vegetation found growing in One Tree Hill Domain, Cornwall Park, and in surrounding streets. Suitable parent pohutukawa and totara exist in the local area and seed and cuttings have been taken from them during the autumn of 2000.

Trees propagated from a mixture of cuttings and seed may be the best way of ensuring an acceptable level of genetic diversity, resulting in the ability to select a tree with the most appropriate inherent growth characteristics. To date there has been a good result from seed and cutting material taken from the parent pohutukawa, and the young seedlings removed from the trunk crevices of the pine tree are currently being cared for in a nursery. However, there was no successful seed propagation from the totara and the totara cuttings have only recently started to root.

3.1.3 Size

The minimum recommended size of a new tree for the site is Pb 40 grade or equivalent size planting bag.

A tree of this grade is expected to be approximately 1.0 metre high for pohutukawa and 1.3 metres high for totara. A timeframe of three to four years may be necessary, from the time seed is sown and cuttings are prepared, to an appropriate grade tree being ready to plant.

The maximum size recommended is a semi-mature tree approximately 5.5 to 7.0 metres in height (refer Section 2.3.5 Site Assessment - Engineering Considerations). With respect to tree size and form, a barely suitable large grade totara but no suitable pohutukawa have been identified within the local area. (It should be noted that the genetic origin of a semi-mature tree found within the One Tree Hill Domain and Cornwall Park area may be difficult to determine).