envirohistory NZ

New Zealand’s tallest forest tree, the kahikatea (Dacrycarpus dacrydioides), once dominated the forests that covered much of New Zealand’s swampy lowland areas. Far from a solitary tree, the kahikatea groups closely with other kahikatea, intertwining its buttressed roots with its neighbours for support in the unstable swampy ground. (It is perhaps for this reason that the kahikatea has evolved with such a tall, straight trunk with no lower branches, to enable it to “huddle” with others for stability). In autumn, throughout the lowlands of New Zealand, numerous forest birds chattered noisily in its canopy, feeding on its abundant red berries. These berries, called koroī, were also a valued food source for Māori, who skillfully climbed up the smooth branchless trunks to harvest them.

Captain Cook and his companions had great hopes for this 60 metre high giant when they first encountered it along the banks of the Waihou River, and named it “white pine”, reflecting their confidence in its suitability as timber.

But, in addition to their blissful disregard for its pivotal ecological role in the swamp forests of lowland New Zealand (irrelevant in any case if one’s plan for colonisation involves the wholesale destruction of the ecosystem itself), they were also unaware of the fact that the kahikatea is an ancient survivor from the Jurassic period, evidenced by geologists’ discoveries of its pollen and leaves in Jurassic rocks, some 160 -180 million years old. This was a time when neither birds nor flowering plants had evolved; rather than kereru/wood-pigeon, kaka and tui, the kahikatea’s prolific fruits were probably feasted on by pterosaurs (or flying dinosaurs, commonly known as pterodactyls).

However, as Geoff Park writes in Nga Uruora, it was not long before it was discovered that while undoubtedly tall and straight, the softness of the kahikatea’s wood made it unsuitable for naval or building applications. Though this may have otherwise saved the kahikatea forests from wholesale destruction, their unfortunate location – on lowland, fertile soils – made their demise almost inevitable in the rush to colonise New Zealand and convert its swampy forested “wastelands” into “productive” farmland.

In 1913, a Royal Commission was asked to determine how areas of New Zealand still remaining under forest should be dealt with. Their conclusion was unequivocal, and was the death knell for the kahikatea:

As is well known the soil of white-pine swamps, when drained and the trees removed, forms one of the richest of agricultural land, which when grassed, is extremely useful for dairy farms… their value in this regard is a strong plea in favour of the removal of the trees forthwith.

Another development was to accelerate its destruction, however. In 1882, refrigerated shipping was developed, and there was a sudden demand for millions of boxes for the butter and cheese being produced by the country’s newly created dairy farms. Kahikatea’s soft, pale, odourless wood was perfect for these boxes, at it did not taint the products in the long journey to Britain. All around the country, there was a renewed frenzy to fell and mill these primordial giants, including along the Waihou River. There, the Bagnall brothers’ riverbank mill at Turua milled kahikatea, where it was loaded on to barques to be shipped to Australia to be made into boxes. The kahikatea forests were thus set on a one-way trajectory of destruction; in the 8 years between 1909 and 1917 alone, the remains of kahikatea were reduced by 63 per cent.

The descendants of the Bagnall brothers were to come to regret their part in the destruction of these immense and ancient trees. As Geoff Park relates, in 1937, one of the Bagnall children wrote a piece in The New Zealand Herald called “Where the Village slew the Forest”, about a “grand and noble forest” and “the beginning of the end for the feathered world that inhabited its depths”. And in 1984, in her book about Turua, Shirley Bagnell wrote of her deep sorrow the death of “trees that had taken such ages to grow”.

On his travels to research his book in 1987, Geoff Park was disappointed to discover that the only trace left of the “grand and noble forest” that grew along the Waihou is a a small dry remnant left as a “memento” of this age by the Bagnalls, where under the trees “the ferns and mosses have long yielded to nightshade, ink weed, dock and thistles.” and where “trees, grass and sheep govern”. Today, there are few places that kahikatea can be seen in anything like the splendour of their original natural environment – the primary place being South Westland. Other small remnants can be found in places such as Deans Bush in Christchurch and Nga Manu, Waikanae, on the Kapiti Coast.

Photo top left: Towering kahikatea in Deans Bush. The oldest kahikatea within Deans Bush are estimated to be 550 years old. (Photo: Stephen Tweedy. Click here for larger photo. Not to be reproduced without copyright owner’s permission). Above right: Kahikatea seeds. Above left: Two men grading box loads of butter, in a factory in Auckland, circa 1939. Photograph taken by H Drake. Permission of the Alexander Turnbull Library must be obtained before any re-use of this image, ID MNZ-1485-1/4.

See also: The conquest of the noble forest of Waihou; The place of an echo: Putaringamotu (Deans Bush); A Kapiti environmental history – Nga Manu Nature Reserve.

Sources/further reading: Nga Uruora – Ecology and History in a New Zealand Landscape (1995), by Geoff Park. See Resources page for more details; Te Ara Encyclopedia of New Zealand articles on kahikatea and conifers.