Long isolated, with remnants of the supercontinent Gondwana in it’s rocky foundations, New Zealand has developed a unique assemblage of native flora and fauna. Giant evergreen conifers and vast swathes of ancient beech trees, both stemming from ancestral roots in the Mesozoic. Flightless birds and endemic reptiles that have evolved over millions of years without the threat from mammalian predation. This is a land of unique appeal to the naturalist, ecologist or conservationist.
But far from being a Lost World landscape-museum locked in time, the 800 year human occupation has come down hard in terms of impact. The contemporary challenges in human-landscape interactions in New Zealand are equally as fascinating as the individual histories and pathways behind them.
Twenty-five percent of New Zealand is currently covered by native forest (Manaaki Whenua/Landcare Research, n.d.(1)). Whilst that not alarmingly low by comparison to some European countries (Hemery, 2017), it is nowhere near the 80% cover before the arrival of humans (Dawson, 2007). The great ‘New Zealand bush’ as it is often referred to consists of two main types of native forest type; mixed conifer-broadleaf, largely typifying the stands of the North Island, and beech forest, dominating the south island (Orwin, 2007(1)).
The Podocarp family, largely southern hemisphere dominant and consisting of over 17 genera, represent the most numerous conifer trees of New Zealand. These include a variety of species including the Rimu, Kahikatea and Totara (Encyclopaedia Britannica, n.d.). Once common among the sub-tropical forests of northern North Island, but now restricted to a few precious stands in Northland and the Coromandel Peninsula is the ancient and giant conifer Kauri. Prized by both Maori and European settlers for it’s strait grained wood, Kauri was ideal for fabricating their waka (canoes) and sailing ships respectively. Kauri trees often stand proud of the surrounding canopy of ‘smaller’ trees, growing to well over 30 metres with an incredibly straight trunk with diameter of anywhere between 2 and 7 metres (Orwin, 2007(2)). Whilst the threat from logging may have subsided, the survival of this iconic tree is seriously threatened by disease; Kauri dieback. The offending microscopic pathogen, (Phytophthora agathidicida) was only identified as recently as 2009. It spreads through damp soil, ‘swimming’ using it’s tail-like flagella. Upon making contact with Kauri root it will reproduce and colonise, and in doing so infect the trees root, leading to the mortality of the whole tree through blocking nutrient transport. Unfortunately, the pathogen is incredibly prolific and can be spread from one area of forest to another, by just a pinhead worth of soil (Keep Kauri Standing, 2016).
Heading onto South Island, we enter the domain of the New Zealand stands of great Southern Beech forest. Stretching as an almost continuous band from Nelson Lakes through Westland and on into Fiordland, the Nothofagus or false beech as it was called by a Dutch Botanist in 1850 is also present in part today and extensively in the fossil records of SE Australia, New Caledonia, Eastern Polynesia and Antarctica and South America from the late-Cretaceous onwards. The leaves of the Southern Beech, whilst similar in appearance to those of the European Beech are generally much smaller with just 5 lateral veins. The four species of Southern Beech found in New Zealand each have their own ecological niche and thus the great swathes of forest are often all-dominated by that one species. The Silver Beech for instance, tolerant of cold, wet conditions, thrives and dominates in Fiordland. The forests are relatively light and open, with an understory consisting of young beech trees, few epiphytes or climbers take hold (Orwin, 2007(3)).
The canopy of New Zealand’s forest should sway to an overture of songbirds, from the Bellbird to the Tui whilst the flightless Kiwi, Takahe and Kakapo scuttle around the understory. Unfortunately, the 21st century reality is of relative silence. If something scuttles away under your feet whilst tramping through the bush, it’s more likely to be a furry Australasian or Eurasian import of the mammalian class than one of these iconic birds.
So what went wrong, both in terms of the land surface forest cover and the feathered inhabitants that are such a vital part of New Zealand’s identity? At this point, the great Southern Beech re-enters the story, in a strange and complex way. A reproductive characteristic of the beech is the cyclical yet random nature of exceptional flowering and seeding years, known as masting. During mast years, high quantity of colourful flowers develop and consequently later in the season the forest floor is awash with beech seeds. This in turn leads to a boom in marsupial and mam-alien predators in the New Zealand bush who chew their way, both through young saplings and predate on birds and their eggs, in particular those of the ground dwellers.
This great ecological challenge is of course, just one of the impacts that our own species has inflicted during it’s short tenure of New Zealand. Research by Landcare Research has used evidence from radiocarbon dating of Pacific rat bones and rat-gnawed native seeds to place human arrival at 1280 AD. This is the most robust arrival date identified for Polynesian settlers in New Zealand, backed up by evidence from archeological sites and ecological changes in flora and fauna (Landcare Research Manaaki Whenua, n.d.(2)). The Pakeha/European settlers of the 1800’s brought with them larger nomadic and domesticated herbivores such as deer, cows and sheep that brought further complexity to the relationships between landscape, flora and fauna.
And it is complexity that defines contemporary conservation debates in New Zealand.
In response to the bush and bird munching predators (or pests), the Department of Conservation (DOC) has long promoted it’s Battle for our Birds programme. This is largely based around the aerial drop of biodegradable 1080 pesticide (Sodium Fluoroacetate) as well as ground-based trapping. Concerted efforts over the years have led to the eradication of pests from 100 offshore islands and significant knock-back of the populations of rats, possums and stoats on the mainland (DOC, n.d.(1)).
The Battle for our Birds campaign has obtained further traction with the July 2016 NZ government commitment to an ambitious ‘Predator Free 2050’ target. The company ‘Predator Free 2050 Ltd’ has been tasked, in collaboration with DOC, landowners and conservation groups to undertake research and landscape scale predator control solutions to achieve this target (Predator Free NZ, n.d.).
At a political level, the implications of the NZ Biosecurity Act of 1993 created some of the most rigorous biosecurity practices anywhere. A response to the vulnerability of the New Zealand landscape, flora and fauna to alien and invasive species, the implications are evident on the landing card completed by all arriving international visitors before they clear customs. The emergent principle of ‘Check, Clean, Dry’ has become best practice to counter a range of invasive pests (MPI, 2017). The water-borne diatom Didymo (Didymosphenia geminato), a Northern hemisphere import (ISSG, n.d.), that has infected many pristine water courses with its massive blooms and the microscopic pathogen leading to Kauri dieback have one thing in common, they can be spread by single drops of water, fragments of damp soil or plant material, all at the single cell level. Thus ‘Check, Clean, Dry’ is of paramount importance and cleaning stations have been setup at recreational sites, such as boat slipways and trailheads (DOC, n.d.(2)).
The grand restorative conservation plan outlined by Predator Free 2050 is not universally celebrated however and there are various critiques, particularly around the widespread use of the 1080 pesticide (poison). Indeed, a political party, named ‘Ban 1080’ promotes the preservation of native birds through more humane and targeted approaches rather than the lag-time and suffering caused by oral-intake pesticide. They also cite the impact on non-target animals such as farm animals and pets as rationale for a more precautionary approach (Ban 1080, 2014). These concerns as well as those around the deliverability of the ‘Predator Free 2050’ target itself have led to calls for a more Integrated Landscape Management approach to creating connected ecological networks and habitat corridors rather than the more polarised procedures of predator eradication schemes (Linklater, 2017).
More than anywhere, issues caused by human-induced imbalance of ecological processes resonate strongly in political debate but also in everyday discourse in New Zealand. The ‘100% Pure’ brand and Silver Fern icon illustrate a strong connection between New Zealanders and the land on which their society is built. These challenges, driven by the dynamic earth-ecosystem processes of Aotearoa, require agile responses but also critical and ongoing debate of the efficacy or ethics of any responses. Nothing is a foregone conclusion.
Aotearoa; Journeys into the Long White Cloud continues with Part 4; Utopia Islands? Reflections on the Long White Cloud
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