Tree ferns are indicators of a consistently pretty wet climate. In New Zealand-Aotearoa, if you look closely (and not too closely if you’re driving) as you go over Haast Pass from the Lake Wanaka side to the West Coast, tree ferns go from zero, to abundant. The massive increase in rainfall to the west of the pass has surely got a lot to do with this.
But here and there, are some oddities. A few months back I was being shown around some rough country in the Horse Range, between Moeraki and Palmerston. In general, the broader area is probably too dry for tree ferns. But in detail, in little spots where the microclimate suits – the moist, shady areas below south-facing cliffs, there were dense groves of tree ferns.
Perhaps these microclimates explain the presence of tree fern spores in some pre-human deposits in dry Central Otago (McGlone et al., 1995; Clark et al., 1996; McGlone and Moar, 1998) and even in moa coprolites (Wood and Wilmshurst, 2012). The spores are unlikely to have blown in from wetter areas far away.
Tree ferns are also fairly physically resilient. They live for centuries, and at least in areas where the climate is very favourable, like the West Coast, it’s common to see tree ferns surviving after the original forest has been logged, and the area turned to pasture. In fact, tree ferns will thrive after logging. Their huge fronds likely make it tough for conifer seedlings to re-establish.
But what are we to make of Deans Bush-Pūtaringamotu, Christchurch? Here we have a patch of kahikatea-matai-totara dominated forest, preserved, amazingly, in the middle of botanical-nowhere. It’s had a rough time, but thanks to the efforts of many people, it’s now regenerating well (Molloy, 1995, The Envirohistory New Zealand Blog). I make the effort to wander through it whenever I can, but only recently did it dawn on me – hang on, where are the tree ferns?
On first-thoughts, this might be climatic. Deans Bush-Pūtaringamotu is an example of a forest in one of New Zealand’s drier locations. This is where kahikatea (Dacrycarpus), matai (Prumnopitys), and totara (Podocarpus) tend to dominate, though the bush also has some rimu (Dacrydium), which are more typical of our wet forests. But no tree ferns. Odd.
It was with this question on my radar that I became aware of ‘Pteridomania’ (Whittingham, 2012) – the Victorian obsession with ferns. As the book’s blurb on Amazon puts it:
Books and articles encouraged thousands to set out on fern forays. Their overwhelming desire to ‘capture’ a rare specimen led them to wade through streams, scale rock faces, descend gorges and lean over fast-flowing rivers. Accidents were common, sometimes fatal, and over-collecting and even fern stealing were rife.
Molly Duggins (2016) explored this phenomenon as it applied more specifically to New Zealand. She wrote that ferns:
were embraced as cross-cultural landmarks entangled in notions of locality, identity, and industry, with the … silver tree fern, taking on emblematic proportions as a national symbol in New Zealand.
The country was promoted as:
a unique indigenous landscape and as a modern and accessible tourist attraction … the ‘Pacific’s wonderland’ in natural history and travel literature.
The carefully cultivated marketing image eventually led to the ‘The South Pacific Fern Album’ (ca. 1889), a lavish production, which included pressed specimens of actual ferns. As Duggins puts it:
these albums were also engaged in constructing a romantic colonial nationalism through enacting the fernery’s collapse of the indigenous New Zealand landscape into an intimate and interactive form of modern spectacle.
New Zealand became the:
‘Land of the Ferns’ through increasingly spectacular displays geared to a global audience.
The apogee was a fernery built in Christchurch for the 1906 – 1907 New Zealand International Exhibition of Arts and Industries which received nearly two million visitors.
In this display, hundreds of native ferns, mosses, and lycopods were featured around a central pool crossed by a bridge constructed from tree fern trunks.
I only understand now, that I grew up with this image of New Zealand somehow being uniquely endowed with masses of ferns – I was genuinely surprised when I learned that the British Isles had ferns at all (they don’t have tree ferns).
So at the same time as the broader New Zealand countryside was being deforested, the tiny remnants of forest that remained near Christchurch had a particular kind of Hell unleashed on them.
In Challenger’s (1974) review of historical changes across the Canterbury landscape, an article is quoted by John Joyce from the 1919 Christchurch Star. I’ll re-quote most of it here:
Another thing of the past is the beautiful tree fern, which was ever to be seen growing in the nooks and shady corners of the cottagers’ gardens. Now this fern is scarcely ever to be seen. Very many people used to take a trip to Dry Bush or Kennedy’s Bush [both in the Port Hills, south of Christchurch] in those days and bring loads of ferns home with them, so that it was a usual sight to see young people coming back after their long walk on Sundays with as many ferns as they were capable of carrying. I often took a jaunt there myself and brought many a heavy load home with me. This went on for many years until the bush got completely denuded of its beautiful ferns – more especially after Joubert and Twopeny held their exhibition in the park along the Lincoln Road” in 1882 (as Challenger, 1974 pointed out).
Joyce went on:
Everyone who could afford to do so built a fernery after that exhibition, so that by the time the ferneries were built the tree ferns had disappeared from their native habitats close at hand, until Oxford bush and the West Coast had to supply the demand.
That’s pretty intense.
New Zealand fern expert John Lovis (1995) specifically noted the absence of tree ferns in the bush thirty years ago. However, he noted that according to early records, from around 1850-1870, they did exist then. But by the time the appropriately-named Flora Murray listed the ferns of the bush in 1924, tree ferns were not among them.
So could it be that the present absence of tree ferns from Deans Bush-Pūtaringamotu is because they were selectively blitzed a century and a half ago? It certainly seems so. In other words, they are not naturally absent because of climate, but locally extinct because of humans.
It seems that what we have in Christchurch might be an early example of a kind of Instagram-Fever. Focus massive attention on some place, or thing, and then love it to death.
Thought-provoking.
References
Challenger, S. 1974. Changes in the Canterbury Landscape. Garden History, 3, 57-56.
Clark, G.R., Petchey, P., McGlone, M.S., and Bristow, P. 1996. Faunal and floral remains from Earnscleugh Cave, Central Otago, New Zealand. Journal of the Royal Society of New Zealand, 26: 363-380.
Duggins, M. 2016. The world’s fernery’: New Zealand, fern albums, and nineteenth-century fern fever. In K. Pickles and C. Coleborne (Eds.), New Zealand’s Empire. pp. 102-123. Manchester University Press.
Lovis, J. 1995. Native ferns. pp. 181-192, In Molloy, B. (Ed.) Riccarton Bush: Putaringamotu. Christchurch: The Caxton Press.
McGlone, M.S., Mark, A.F., and Bell, D. 1995. Late Pleistocene and Holocene vegetation history, Central Otago, South Island, New Zealand. Journal of the Royal Society of New Zealand, 25(1), 1-22.
McGlone, M.S., and Moar, N.T. 1998. Dryland Holocene vegetation history, Central Otago and the Mackenzie Basin, South Island, New Zealand. New Zealand Journal of Botany, 36: 91-111.
Molloy, B. (Ed.) 1995. Riccarton Bush: Putaringamotu. Christchurch: The Caxton Press.
Murray, F.B. 1924. Botany of Riccarton Bush. In C. Chilton (Ed.), Riccarton Bush (pp. 14-34). Christchurch: The Canterbury Publishing Co.
Whittingham, S. 2012. Fern Fever: The Story of Pteridomania. Frances Lincoln.
Wood, J.R., and Wilmshurst, J.M. 2012. Pollen analysis of coprolites reveals dietary details of heavy-footed moa (Pachyornis elephantopus) and coastal moa (Euryapteryx curtus) from Central Otago. New Zealand Journal of Ecology, 37, 151-155.
