Название: Life of a Chalkstream
Автор: Simon Cooper
Издательство: HarperCollins
Жанр: Природа и животные
isbn: 9780007547876
isbn:
There is never what I would call a really good time to embark on a restoration; every month, every time of year has its merits, but inevitably there is disruption to the natural order of things – removing the bad and encouraging the good. The bad comes in all shapes and sizes: people, fish, animals, mammals and even plants. Yes, there are even bad plants on the chalkstreams, the most invidious of which has its origins on the foothills of the Himalayas.
My problem with Himalayan balsam is that I rather like it. The tall plants stand high above the surrounding vegetation in vast swathes and the light red-pink funnel flowers are a sea of colour that gently waves in the late summer breeze. The smell from the flowers envelops the riverbank. It is a dry, sweet smell – lightly medicinal and cathartic at the same time. It is completely alien to anything else that grows in the meadows. It looks different, smells different and has the most amazing way of distributing seeds when the flowers have died and the tall plants are denuded of leaves, just leaving brown seed pods. Brush past the balsam and the seed pods burst with an audible ‘pop’, shooting their kernels yards around. It happens with quite some force; you will feel the sting if they bounce off your face or hands. Young children love to grasp the plant at the base, shaking it with all their might while the rat-a-tat of seeds sails harmlessly above them.
Imported as an exotic species from Nepal in the early 1800s, Himalayan balsam is now established in Britain, but has had particular success on rivers where the seeds, which can survive two years, are distributed by the water. As a single plant it is no great problem, but that is not in the nature of Himalayan balsam. It is an invader that grows faster than any native plants, shading out and eventually killing all others. Walk the banks in October where the balsam has taken hold, and the area looks like a wasteland. Everything beneath the balsam is dead. In truth it looks like the ground has been sprayed with a toxic weedkiller, and come winter, that soil is bare and ripe to be washed into the river.
Fortunately for me and river keepers everywhere, Himalayan balsam is an enemy that can be defeated. For now, in October, there is not much I can do, but come early summer when the balsam pops its heads above the surrounding growth we will walk through the meadows pulling out the plants by hand. Mercifully they are shallow-rooted, so they come out easily or snap off at the base like soggy celery. However, not all my enemies are so easily defeated.
Mink have thrived in the abandoned Gavelwood. Wily creatures, the thick undergrowth and clogged streams are heaven-sent for this predatory invader. Predatory they certainly are. Fish, water voles, field mice, duck chicks, frogs, baby moorhens, even rabbits – if it moves mink will eat it. The mink I see at Gavelwood are American mink – Neovison vison – which first arrived about a century ago as escapees from the fur farms that were established between the world wars. Despite their fearsome reputation they are really quite cute; I always think they look like a bigger, elongated version of their favourite prey, the water vole. Mink have the most beautiful dark brown fur, almost black in some light. Strangely, though all the mink you spot today are this colour, they all originated from the light-coloured mink imported by the fur trade. Clearly, however, being white in green meadows was a poor lifestyle choice. After a century of wild living it is a moot point as to whether mink can still be regarded as an invader. Non-native definitely; indigenous never; but successful settlers yes. They took hold at precisely the same time that the otters declined. It was no fault of the mink that the otter almost became extinct in Britain, but nature abhors a vacuum.
On that filthy late October day the success of our survey and the work Steve had done with the digger was there to see. The silt and mud were gone, smeared over the grassland around the hatches. The wet surface of the slabs on the base of the river glinted back at me. Some of them were truly huge; a full 10 feet square and nearly a foot thick. One could only wonder at how they were ever put into position all those centuries ago. The digger stood by ready to drag out the reeds within the hour.
I wasn’t exactly sure where Steve, Dan and the irregulars were working that morning, but the whine of the chainsaw through the rain from somewhere far downstream gave me a rough idea, so I followed the noise. For all our hard work over the past month North Stream really looked in quite a sorry state. I am tempted to say worse than when we had started, but it is always this way, a sort of darkness before the dawn.
The ground along the bank was churned up; deep ruts showed where the tractor had strained and dug deep to pull out the worst of the trees. Every so often I would come across a round circle of ash where the lads had lit fires to burn up the detritus. There was a pile of tree stumps, too big to burn and unwieldy to cut up, so they would be taken away to be dumped and end their lives in a rotting heap. This would be a paradise for woodpeckers seeking easy food and a palatial home for woodlice. From time to time I came across some long, straight tree limbs which had been carefully trimmed and set aside. This was our kind of recycling; logs and branches that would be useful for building weirs, flow deflectors and groynes in the river when we reached the next stage of the restoration.
The entire bank was pockmarked by tree stumps, cut level with the ground: the cream white of the ash; dark red of the alder and burnt orange of the hawthorn. The hazels looked like bundles of cigarette filters pushed into the ground. The fact is we only pulled out the stumps we had to; by far the most were left in the ground. There is no point in ripping them out, as the root structure will live for years and bind the bank together. Some of the stumps will sprout again, indeed species like the alder thrive as a result of the extreme pruning. And as North Stream evolves over the coming years, we’ll let some grow back into mature trees for cover, shade or simply extra interest.
If I thought the banks looked bad, the stream itself looked worse. The water reflected the sky; it was dark and gloomy. Barely flowing, the surface was covered in twigs, chainsaw shavings, dead leaves and chopped vegetation. On the far bank the bushes and trees had shed all their leaves, the spindly branches dripping from the rain. The only comfort I took was in the windbreak they provided from the north wind whipping the rain across the meadows. A north wind is the enemy of all fly-fishers – the cold kills off hatch and stops the fish feeding, which gives rise to that old saw, ‘When the wind is from the north only the foolish angler sets forth.’ However, today was not the day to worry about the north wind, which is an almost daily occurrence in winter, sweeping as it does down the river valley. Days like this are always the fun parts of a restoration, when months of planning and weeks of work come to fruition. Today all we needed to do was dig out the plug of reeds, lift the boards in the Portland hatches and let the river flow in. And that is what we did.
Steve used the digger to scoop out the reeds and we laid them to one side. The flag irises, with their yellow flowers that bloom in May and June, were too beautiful to discard, so we’d replant the rhizome roots down North Stream to kick-start the regrowth in the spring in the parts of the stream left bare by their removal. The reeds gone, the water started to build up against the honey-yellow oak boards. These boards are never completely watertight; water weeps through the gaps between them. So as the flow backed up and the pressure increased, water squirted through the holes as if from a hosepipe. We were ready to open up. Standing on the bridge boards over the hatches we worked in pairs to lift the top boards out. The lower four quickly followed and within moments the fast flow from the Evitt rushed into North Stream. Like excited schoolboys we followed the bulge of water as it forced its way downstream. From time to time it came across an obstruction. Then the water would begin to back up, but when the force grew too strong the obstruction would give way and the flow continued. On it went down North Stream, carrying the mud and debris in its path. Under Bailey Bridge and the final straight to the main river. Standing by the deflector we watched the confluence of the two currents, the first time anyone had seen this for maybe forty or fifty years. True it wasn’t the prettiest of sights, with the dirty water of North Stream adding a nasty stain to the clarity of the Evitt, but the knowledge that our plan had worked was enough for now. Given a few weeks North Stream would flush itself clean, and then the fish would return.