dusk, the green Pai~ and age are gnarled forms, in bare rn~-.... ' clutching at the earth, knotting on the cliff face, in tortured branches, dark against the washed sky." 2 r POHUTUKAWA ECOLOGY, ESTABLISHMENT, GROWTH, AND MANAGEMENT David Bergin, Ensis Gordon Hosking, Project Crimson New Zealand Indigenous Tree Bulletin Series No. 4 Published by Ensis in association with the Project Crimson Trust New Zealand Forest Research Institute Limited Private Bag 3020, Rotorua New Zealand 2006 "Th~redis dusR; the green gnarlid forms, in bare rdc,.._ clutching at the earth, krlotting on the cliff face, in tortured brancl;les, dark against the washed sky." 2 TABLE OF CONTENTS Introduction 4 Part 7 - Seed collection and propagation 49 Part 1 - Description 6 Collection of seed 49 Seedlings 6 Storage of seed 49 Plant development 6 Raising of seedlings 50 Mature trees 7 Raising plants from cuttings 51 Branching 9 Part 8 - Planting 53 Bark 10 Planting sites 53 Roots 10 Planting trials 55 Leaves 13 Plant size 57 Flowering 15 Stable tree form 57 Pollination 16 Driftwood 58 Seed formation 17 Shelter 58 Part 2 - Distribution 18 \X'eed control 59 1atural range 18 Part 9- Tree growth, wood quality and use 61 Planted trees 19 Growth rates 62 Part 3 - Relationship with other species 21 Wood quality 64 Distinguishing between species 22 Current uses 65 H }'brklisation 23 Part 10 - Management of existing trees 69 Genetic variability 25 Animal damage 70 Part 4- History and early utilisation 26 Control of weeds 72 Significance of flowers to ;\{aori 26 Development threats to pohutukawa 72 .\laoridom and long-lived trees 27 Challenges in tree management 74 Maori medicinal uses 27 Tree stability 74 Other Maori uses 27 Safery issues 76 Boat building 27 Management of individual trees 77 Other early settler uses 28 Mangement of large trees ilCar buildings 81 Part 5 - Ecology and habitat 29 Management of pohutt1kawa on cliffs 81 Ecological Characteristics 30 Good practice guidelines 86 Habitat 31 Part 11 -Regional case studies 87 A di,·erse coastal forest 38 • orthland Region 87 Successional trends 38 Auckland Region 89 Associated animals 39 Waikato Region 91 Part 6-T hreats and injurious agencies 40 Bay of Plenty Region 93 Possums 40 Part 12 - Quick reference guidelines for planting 95 Goats and domestic stock 42 and managing pohutukawa Insects and disease 42 Conclusion 100 Tmerna! decay fungi 44 References 100 Cormorants (shags) 44 Glossary of plants and animals 102 Rabbits 44 Acknowledgements 104 Exposure 44 1-Jnman impact 45 Plant pests 47 Volcanicity 47 Coastal erosion 48 3 Pohutukawa (Metrosidetos e.,"<ce/sa Sol. ex Gaertn.) is one of Fires and land clearing for settlement and pastoral farming the best-known and best-loved native trees in I ew along the coast contributed to the elimination of an Zealand. Endemic to this country, it is a distinctive multi­ estimated 90% of the original pohutukawa forest (Forest stemmed tree up to 25m high, and is found mainly along Research Institute 1989). The decline continues, largely the coastal fringe, often on rocky cliffs, throughout the due to browsing damage caused by the introduced brush tail northern half of the North Island. Pohutukawa once possum. formed an almost continuous belt of forest around New Zealand's northern coasts. Its spectacular and profuse Over the last decade widespread concern about continued crimson flowers are formed during the summer in the losses has led to increased emphasis on the planting and period coinciding with Christmas holidays. The first management of pohutukawa, and greater interest in the European settlers used it to decorate their homes at protection of existing trees and stands. Much of the work Christmas time, the dark green leaves and red flowers has been inspired by the Project Crimson Trust, set up forming a substitute for holly. It has since been accorded in 1990 to provide a focus for conservation of existing iconic status and is now regarded as New Zealand's pohutuka\\ra and restoration of the species as Christmas tree. a characteristic of the northern coast. Project Crimson has promoted and Maori people regard pohutukawa as a sacred tree, one of assisted large-scale community-based the rakau rangatira (chiefly trees) that feature protninently pohutukawa planting and in their history and legends. Many existing pohutukawa protection programmes. trees are tapu (sacred), some marking the burial sites of ancestors. A tree at Te Reinga, the northern tip of Cape Reinga, has great significance in Maori m}rthology. T he spirits of the dead are said to descend through its branches and entwined roots as they begin their journey back to the homeland of Hawaiiki. Pohutukawa had many uses for early Maori and E uropean settlers. Leaves and bark were gathered for a variety of medicinal purposes, and the potential of its strong dutable timber was soon realised. ln the early days of colonisation, shiploads of pohutukawa timber were exported, and the magnificent coastal stands were severely depleted. The Project Crimson Trust recently commissioned the of pohutukawa and related species, its clistribution, writing and publication of a book b)7 Philip Simpson historical use, ecology, and habitat. In addition it describes entitled PohlltlfkaJI!a & Rata: Ne111 Zealand>.r Iron-Hearted current threats to the species from a number of injurious Trees (Simpson 2005). This provides a detailed and agencies. Parts 7-10 cliscuss methods for the management scientifically comprehensive account of pohutukawa of pohutukawa including seed collection, propagation, including its origins, ecology, historical and cultural planting, promotion of growth and wood quality, and significance, and a description of the decline and current management of existing trees. A picture of tbe status conservation measures that are being undertaken. In and special features of pohutukawa in four northern addition, Smith (1999) has compiled a bibliography of regions administered by local regional councils is presented pohutukawa and rata inclucling annotated references to in Part 11. Finally, a set of guidelines is prm·ided for the many books on pohutukawa. people who are enthusiastic about continued planting and management of pohutukawa. This Bulletin provides a "ready-reference" summary of some aspects of Simpson's work, specifically a description Pohutuk:awa has many distinctive features that enable it to live and thrive in the seemingly inhospitable rocky sites and coastal cliffs of northern New Zealand. From seedling to mature tree, remarkable regeneration and survival strategies as well as specialised physical characteristics contribute to its tolerance of frequently extreme environmental conditions. Seedlings Pohutukawa seed germinates soon after it comes in contact with moisture. At first, energy is directed towards growth of the radicle or primary root, which has hairs that cling to moist surfaces such as rock or bark. The root is then able to penetrate cracks in the substrate. Very young seedlings have two leaves (cotyledons) which are only 1-2 mm long. Additional .roots form at the base of the developing stem and these too become attached to damp su.rfaces. One or two shoots are formed from buds associated with the earliest leaves. After the first season of growth, a small cluster of roots and shoots is formed. New!J gem1inated pohutukawa seedling. Plant development Often a number of shoots arise from a central base, and the young plant assumes a rounded, or slightly conical, form. Eventually, one or more of these shoots becomes dominant. If the plants are g.rowing closely together, single stems will be more common. Widely spaced trees commonly have multiple trunks spreading from their base. Planted pohutukawa 6 )'Cat-s old, part of a Prqject Crimson community planting, East Cape. Poht1tukmva established in the open typicaf!J Jonn a r·otmded crown of foliage. 6 Epicormic shoots A common characteristic of pohutukawa is the formation of epicormic shoots and coppice growth. The bright shiny green coppice shoots emerge from the base of a seedling, while epicormics arise from the stem and branches of older plants. Simpson (2005) suggests that epicormic shoot formation is related to the harshness of the open coastal environment. Dieback and breakage of the crown of pohutukawa caused by drought, frost, or animals may stimulate the development of buds buried in the bark, and the growth of epicormic shoots. Exposed stems and trunks, even of old trees, can develop epicormic shoots, particularly where significant pruning or thinning of crown foliage is carried out. Epicom1ic shoots ocmrring along afl exposed branch of a stressed large poh11111ka1va tree. Bright green coppice shoots from lower stetJJs of a stres.red container­ gronm seedling. Where pohutukawa seedlings have been planted on exposed open sites, crown dieback can sometimes occur and is often associated with coppicing from the base. M ature trees Pohutukawa usually grow to 20 m in height with trunks Pohutukawa form is highly variable. Typically trees are 2m in diameter (Allan 1961). Canopy spread is commonly multi-stemmed from the base and, with age, large trees around 20 m in diameter. The largest specimens, however, often become sprawling with long branches that arch can have a crown diameter of over 50 m and can be up over the ground. Where stems touch the ground, roots to 25 m tall, with trunk diameters exceeding 3 m (Gerald are formed. Some trees have single trunks of various Collett, Treecare Services, pers. comm.). heights. Trunks and limbs can be entwined by one or The distincli11e large crown of old pohutukawa, North Shore, Lorge mature pohutukawa hangs out over a beach 1vhere erosion jro111 A11cklond, with Rangitoto Island in the distance. high seas has undermined part of tbe bank. 7 The 'ParnellpohutukaJva" planted 100years ago in the Rose Gardens in centrai.AJtckland displqys a spectacular sprmllling babit as numerous trunks loop over the ground (inset) and take r-oot 1vhere th'!)' come in contact 1vith the soiL more roots or stems of various dimensions and sometimes The spreading gnarled form of mature pohutukawa may a mass of aerial adventitious roots develops from the develop in response to stimuli provided by strong winds stem or branches.