Learning about The Tangihua Forest

Introduction to Northland’s native Trees and plants at the Tangihua lodge

Learning about Northland native trees and plants in the Tangihua Forest is aimed at teaching students to see and recognize individual trees rather than just a forest.

• Their place in a regenerating forest.
• As a food source
• As a habitat.

The role trees and plants play in the Tangihua ecosystem Northland

Trees and plants are vital for any ecosystem. They provide a range of roles including producing food and shelter, regulating water runoff, regulating the climate and producing oxygen.

Food

Plants are able to obtain nourishment from carbon dioxide, minerals from the soil and water plus convert energy from the sunlight (photosynthesis) into food for the plant. This food includes carbohydrates, vitamins, oils, and other essential substances.

By eating the leaves, fruit, flowers, nectar or wood made by plants other living creatures are able to exist.

Shelter

Trees and plants provide a place for birds, and other creatures to live plus provide shelter from the wind, sun and rain.
Plants provide shelter not only with their branches but also by providing the plant litter on the forest floor. Leaves, branches and at times entire trees fall to the forest floor where they decompose. This produces an entire ecosystem plus recycles nutrients into the soil for future generations.

Building soil

Regulating water flows

A hectare of native subtropical forest requires a large amount of water in order to grow and exist. This water is locked up in the plant and evaporated via the leaves (evapotranspiration) back into the atmosphere. The plant litter absorbed and holds large amounts of water. The structure of forest trees and plants significantly slow down runoff.

Regulating the climate

By releasing water into the atmosphere, absorbing sunlight and providing shelter from wind, trees help regulate the temperature and moisture content of the surrounding air.

Oxygen

Trees and plants are the earth’s source of oxygen without which no animal would exist.

Shapes the ranges

Tree roots help prevent slips and erosion. Other plants trap soil e.g. swamps and as they break down build up the valleys.

The Tangihua Forest is unique.

Northland has a unique subtropical/temperate climate which has resulted in a type of forest found no where else in the world.

The Tangihua Forest is a conifer, broad leaf Kauri forest.

Conifer, broad leaf forests are the most complex of New Zealand forests, especially in sub tropical Northland. The relative high rain fall and free draining soils allow for a wide variety of plants.

1. From the forest floor to 1m specific plants, mainly ferns, grasses, mosses liverworts and herbaceous plants which can survive in low light
2. From 1.5m to 5m shrubs and young trees that are yet to reach the canopy layer.
3. From 10 to 15m sub canopy trees and tree ferns and maturing trees
4. From 20 to 25m the canopy trees, mainly broadleaf
5. 25m plus – emergent conifers

Some trees and plants grow through multiple layers of the forest.
An example is the Kauri tree which towers over other trees. Vines grow from the ground to the canopy and epiphytes can live anywhere on a tree.

Conifer

Conifers produce cones and have needle or scale-like leaves and are evergreen. Conifers appeared 360 million years ago and live up to 1200 years or more in the case of Kauri.
Examples found in the Tangihua area are kahikatea, kauri, kawaka, matai, miro, rimu, tānekaha and totara.

Broad leaf

A broad leafed tree is considered to have flat leaves and produces seeds inside of fruits.
In New Zealand they are usually over 15m in height and most live for 200 – 400 years.
Examples of broad leafed trees in the Tangihua Forest are black maire, broadleaf-papaumu, hinau, karaka, kohekohe, nikau, puka, pukatea, puriri, rata, rewarewa, taraire, tawheowheo, titoki, towai.

An old Rata tree covered in Rata vines on the nature trail.

These trees support a wide range of vines and epyphites.

Vines

Conifer, broad leaf forests have the widest variety of vines in New Zealand.

Vine definition: A climbing or trailing woody-stemmed plant which requires support such as a tree. Vines climb both up and down trees using tendrils. Some, such as rata, germinate in the tree and send their tendrils to the ground. Others germinate on the ground and creep along the ground until they find a tree to climb.

There are numerous types of vines incuding subcanopy climbers, canopy climbers, root climbers, twining stem climbers, tendril Climbers, hook Climbers.

Examples of vines in the Tangihua forest are rata, clematis, bush lawyer, supplejack, kieke.

Epiphytes

Epiphytes are plants that grows on another plant, especially one that is not parasitic. There are at least 108 epiphyptes in NZ. This includes ferns, shrubs, orchards and lilys.

Some plants germinate in the soils in the tree made by the epiphytes when their leaves break down. This includes the puka, northern rata, some orchids.

See Tangihua Forest description at the bottom of this page for various forest types and their locations and the top left index for individual plant species.

The Tangihua Forest trees are ancient

35 million years ago many of our trees looked as they do now. In comparison this is what mankind looked like only 1.8 million years ago!

Kahikatea, a podocarp, can be traced back 110 million years. Identical pollen has been found dating back 37 – 54 million years ago.
Pollen from Rimu, another podocarp has been found in deposits laid down at the same time. The tree is identical to trees seen today.
The ancestors of these trees existed on the Gondwana landmass and became separated when Gondwana broke up. They have existed in New Zealand from the time New Zealand broke off from Gondwana and drifted into the Pacific.
They have survived intact and are unlike any other trees in the world.

The newer species of native trees such as cabbage trees probably arrived 15 million years ago. They have had time to change and adapt and are unique to NZ.

Tangihua Forest description

For the Tangihua forest Geographic and Geology visit The Tangihua ranges

Information taken from Natural Areas of Tangihua Ecological District, PNAP report:

The Tangihua Forest provides habitat for three threatened plant species and 22 regionally significant plant species.

Representative ecological units:

• Puriri–kowhai–totara forest on steep faces
• Towai–mamaku forest on moderate hillslopes
• Taraire–nikau–puriri forest on steep upper hillslopes
• Towai–tanekaha forest on steep upper hillslopes
• Tawa forest on steep faces

Other forest types include:

• Taraire–puriri forest on steep faces and gullies
• Kahikatea forest on moderate to steep hillslopes
• Towai forest on steep hillslopes
• Totara–puriri forest on steep lower hillslopes
• Kanuka/manuka–totara forest on ridges
• Kauri ricker forest on steep faces
• Rimu–tanekaha forest on ridges
• Manuka shrubland on hillslopes
• Taraire forest on steep hillslopes
• Towai–taraire forest on hillslopes
• Taraire–totara–towai forest in gullies
• Totara–taraire forest on hillslopes
• Taraire–kahikatea forest in gullies
• Kahikatea–taraire–totara forest in gullies

Tangihua forest ecosystems by location:

A – Northern border (Tangihua and Waihoa streams)

Puriri–kowhai–totara forest with frequent nikau and karaka. Occasional kohekohe, miro, taraire, ti kouka, tawa. Steep gullies: abundant taraire, common puriri, frequent tawa and totara.

B – South of area A

Taraire–puriri on steep face, with tawa, rewarewa, and occasional karaka, nikau, mamaku, ti kouka, kohekohe, puka.

C – South-west site

Towai–mamaku forest on moderate slopes with occasional kowhai, emergent totara, rewarewa.

D – Western site

Kahikatea–towai forest on steep slopes with occasional emergent rimu, kauri, rewarewa, totara. Occasional nikau.

E – Site near Omana Road

Towai dominant, with frequent taraire, rewarewa. Occasional kahikatea, mamaku.

F – Far west of site E

Taraire–puriri dominant, with rewarewa, tawa, kohekohe, puka, kanuka.

G – Tangihua Stream catchment

Totara–puriri forest dominant, with karaka, ti kouka, pukatea, nikau, mamaku, rewarewa, taraire, towai.

H – Eastern ridge

Kanuka/manuka–totara forest dominant, with puriri, ti kouka, kowhai, tanekaha.

I – Southeastern site

Tawa forest dominant, with puriri, taraire, rewarewa, mamaku, nikau, puka, ti kouka.

J – Northwest of I

Dense kauri ricker stand on steep face. Mature kauri scattered.

K – Central ridge of eastern arm

Taraire forest dominant, with puriri, karaka, kahikatea, totara, nikau, kohekohe, mamaku.

L – Northern boundary of eastern arm

Towai–taraire–totara–puriri–rimu–karaka forest remnant.

M – West of L

Totara–taraire dominant, with puriri, towai, lancewood, kahikatea, karaka, rimu, kohekohe.

N – East of M

Taraire–kahikatea dominant, with puriri, karaka, totara, rewarewa, kohekohe.

O – Further east

Kahikatea–taraire–totara forest dominant, with puriri and karaka. Mangeao common at higher altitude.

Species of botanical interest

Significant flora

Brachyglottis kirkii (Declining) (Cameron 1992),
kawaka (Naturally Uncommon),
Myosotis spathulata var. spathulata (Naturally Uncommon) (AK 7514),
Plectranthus parviflorus (Coloniser).

Regionally significant plants

meaning
Assessed by the Department of Conservation (Northland Conservancy) to be either rare or threatened within the Northland Region.

All non ‑ referenced species were recorded in Willetts (1985).