Saturday, 18 June 2016

Clean, green, hmmm.

We went for a walk up the south branch of the Kowai river a couple of weeks ago.  For those who don't know this small river, it rises on the flanks of Maukatere-Mount Grey, splits into two branches and carves a route to the sea just north of Leithfield Beach village. It often dries up in the summer, sometimes going dry several kilometres inland.  Even when it is flowing, by the time it gets close to the sea it's so shallow and warm and turgid, much of its stoney bed is coated in various forms of algae. 

A couple of years ago there was a massive flood in the Kowai.  Very heavy rain in the foothills after a very wet autumn combined with the extensive clear felling of the exotic pine forest on the lower slopes of Maukatere.  The north branch of the Kowai rejoins the larger south branch a few hundred metres above the SH1 bridge at Leithfeld. By that point the flood was like a lahar -a torrent of massive boulders, trees, shingle and mud that once it subsided, had raised the river bed by a metre. 

Up above what we call the top ford on Marshman's Road, the damage from that flood is still raw and impressive. At one point the waters would have reached almost 4 metres above the current bed.  Huge deposits of yellow and blue clay litter the river bed and everywhere there's an ugly tangle of downed willows.  The fallen leaves of the willows that line the banks clog the stream, which was still very low despite recent rain.  Because the area in the headwaters is a mass of gorse, the flood brought down masses of seed and the river bed is sprouting a forest of the vile stuff.

What struck us as we wandered along was there was no bird song. We get used to the background chatter of birds on our own property but the Kowai was almost completely silent. 

As we walked along I could not help but feel anger and grief at what this sad little river once would have been.  

Maukatere was once covered in east coast beech forest.  The Kowai river would have risen amongst this forest with its complex understory of small trees, shrubs, flaxes, ferns, mosses and lichens and wound through bush on its way to its estuary where it formed lagoons and wetlands rich in fish and bird life. Its waters, filtered through the bush, would have been pristine. 

Now we have a largely denuded estuary, choked with gravel and exotic tree debris. The river bed along almost its entire length is choked with gravel and mud and festooned with the scars of gravel extraction and the tracks of various off road vehicles which use it as a playground.  It is full of pine and willow debris from the flood and gorse and broom and a host of other exotic weeds.  Its banks are lined with wildling pine, willow and poplar hybrids with blackberry, old man's beard, ivy and convolvulus choking the life out of any native that tries to reestablish itself or which people have planted in attempts to restore a little of what once was there.

It's pretty ugly. 

And when you emerge on the edge of the commercial pine forest that was sold to Ngai Tahu as part of the Treaty of Waiting settlement (*) and has recently been clear felled, it goes beyond ugly. It looks like a war zone - which, in a manner of speaking, it is.  The flanks of the bare mountain are scarred by the run off from those heavy rains 2 years ago. Deep gashes that were once bush lined gullies, will continue to pour clay and shingle and boulders down into the Kowai in heavy rain.   

Pinus radiata is not a pretty tree en masse and it pours its toxins into the soils beneath it to deter competitors. Not much likes to grow under densely planted pine trees and when you plant vast forests of them you create an environment that is hostile to most plants and animals.  Gorse will cope though - give it a bit of light and it will colonise and - as it seeds several times a year in NZ and its seed is almost indestructible - it spreads with astonishing speed and vigour. If you've ever burned gorse you'll know that it's also highly flammable. 

Someone once said to me when they were looking at my heap of composting horse and sheep poo that, given I grow native plants, I wouldn't need to use it because natives don't need such rich compost.  That struck me at the time as not just wrong factually but also a metaphor for a lot of what is wrong with NZ. 

That person never stopped to consider that the NZ bush is largely evergreen and foliage tends to be quite fibrous and slow to rot down; that it evolved in symbiosis with an vast array and number of birds, and that the deep litter on the forest floor would have been heavily fertilised by bird droppings which are full of readily accessible nitrogen - among other nutrients.  I wonder how much the vitality of our remaining bush is affected by the loss of its bird life.  

I look at Maukatere with its numerous scars and the tiny remnants of its once glorious beech forest and bush and think what a wonder it would be to regenerate it, to turn this symbol of all that is wrong about NZ into a beacon of hope for a greener and more sustainable, planet-friendly future. 

Over to you Ngai Tahu.  

*Ngai Tahu bought the Ashley Forest then a Crown asset, freehold at market value in 1989 as part of the deed of settlement, and granted Carter Holt Harvey long-term forestry rights which were assigned to Matariki in 2005.  Ngai Tahu owns the land and Rayonier manages the Ashley Forest for Matariki Forests which is part owned by Rayonier.  The Department of Conservation manages the top of the mountain, the tiny remnant of native bush at Lake Janet and the tracks which lead up to the lake and the summit. 

1 comment:

  1. Nice post, I've done some work on river restoration projects in the North island, even just doing a relatively small stretch of river say 1km is a massive undertaking with at least one person working away on the project most days of the year. Cutting down willow trees, dragging them away, cutting gorse and blackberry. Blackberry always resprouting back. In some places after removing the broom it has reseeded in the same place and has taken over again. In that instance it's easier to just cut it away from where your native plants are with the knowledge that eventually the native forest will get above it and shade it out. The broom acts as a bit of extra shelter for the young natives.

    It's interesting that with treaty claims Māori now have some of their land back, but it's been given back in terrible condition. I assume Māori face the costs of land repair as well which isn't exactly a fair deal.

    A lot of weeds have got away on us in NZ. I don't think we'll properly be able to restore land to what it used to be because those weeds will always be there. But we can try and it is the right thing to do, to cool down/shade water systems and provide habitat for insects/birds/fish, and create something similar to what was.