That pine trees are self-colonising on our un-farmed landscapes is no great surprise.
Landscapes constantly evolve as we change land tenure and land use, and a consequence of removing grazing animals from tussock grassland is that woody plants will take a foothold and conifer spread is entirely expected and foreseeable.
Peter Willsman (ODT 28.12.11) asserts "Otago's pristine landscapes face a major invasion of wilding conifers" that is scary and needs to be attacked like an enemy. Another correspondent (ODT 3.01.12) describes wilding pines as "the greatest environmental threat the South Island faces", and yet another (ODT 11.1.12) calls wilding pines a cancer. But is this really the case?
The Central Otago and Canterbury high country tussock landscapes are cultural landscapes. They are neither "natural" nor pristine, but are the result of 150 years of farming practices: sheep grazing and burning. While these are not totally benevolent land-use practices, they have served to produce the wide open iconic tussock pasture landscape. With Crown control of these land-use practices and the constant footsteps of the steward farmer on these lands, the tussock landscape was managed and maintained.
One of the most certain effects of tenure change in the high country is that the landscape will change. Tenure review, the process of transferring some of this land to a freehold estate and returning the rest to full Crown control, has been implemented during the past 15 years.
The land reverting to the Crown conservation estate, and with those pastoral farming management practices removed, will inevitably be open to the colonisation by woody plants the most successful of which is the wild conifer.
With other land being converted to freehold ownership, the management restraints have been removed and new land uses are changing the landscape.
Much of this land is being actively converted to irrigated green monocultural grass and dairy farms, and other land is succumbing to the insidious invasion of vineyards and the domesticated gardens of lifestyle blocks. Are those changes any more desirable than the succession of woody plants towards a forested landscape?
In New Zealand there has been considerable effort and investment in forestry, and conifers make up the vast majority of our timber plantations.
Furthermore, conifers are hardy and quick-growing in New Zealand, having adapted to this environment even better than in their native lands. From plantations they provide timber products; from high grade construction timber to posts, firewood and biomass for energy (as described by another correspondent ODT 11/1/12).
From shelter belts and small woodlots they provide many environmental goods; shelter, shade, soil stability, timber. It seems somewhat ironic that when this successful plant self-colonises on nearby lands it becomes public enemy No 1.
As long as we have conifer plantations and shelterbelts we will have an endless seed source to spread on to nearby lands.
The efforts to clear wilding pines are two-fold: one, to cut down existing trees and two, to remove ongoing seed supply.
Even if the first effort succeeds, the second will not without the elimination of all conifer trees and their seeds. I suggest that we must look at the conifers on these lands as a resource, not as a problem weed. Conventional weed-response thinking will not succeed. As with all land-use decisions, we must work with nature, not against it.
I am not a great lover of conifer trees, but it cannot be denied, they are successful colonising plants.
They may be high consumers of ground and surface water, but they may also shelter and shade the land and soil from the harsh high-country climate and allow a foothold for other colonising plants.
Perhaps in several hundred years a mixed woody forest cover will develop with increasing biodiversity. It is unlikely that a native bush cover will as readily re-colonise the land.
The wilding pine problem is merely a symptom of a changing relationship with the land and landscape. Land tenure is becoming corporate, land management is becoming industrialised, land relationships are becoming commoditised. All these trends work against a land ethic and against sustainability, but those are the choices that have been made.
If we want to retain the Otago high country as tussock country, we must return to and support the caring farmer on his and her land with their sheep. There is no better land management tool than the regular footsteps of a farmer over the land.
