They were once the masters of the dank, damp places, undisputed lords of the river. They were magic and to be feared. If you were so brave as to cut one down the stump bled. The timber did not rot. The foliage was dark, the bark black, so black that, even in winter when the leaves had gone, the ground under the alders was always gloomy and oppressive.
The alders were here, of course, thousands of years before we were. Their pollen has been preserved in samples taken from peat bogs; their seed has been found among the earliest remnants of ancient man. At that time the whole of England was one vast forest. The dry ground was the scene of a strange, imperceptibly slow and protracted yet ferocious war of attrition waged between several species of trees. The prize was the possession of the landscape: the winner, in the first age, was the small-leafed lime. Then came men with their animals. Lime leaves were gathered as fodder. The lime’s defences were weakened and in came oak. Oak forest dominated England until the arrival of metal and the growth in the human population signalled its end.
But below all this, in the marshy places, where the soil was too wet to interest the farmers, the alders were yet safe. They survived here using the same weapon that had held off the limes and oaks: a special sort of root system that produces its own free nitrogen and enables the roots to withstand prolonged or even permanent immersion. The roots, together with the unique mixture of sedges and rushes which accompanies alder woodland, gradually consolidate the marsh, raising the level and sending the water elsewhere. Once the best ground higher up had been put to the axe, we began to drain the water-meadows, and to maintain this drainage the alders had to go.
Extensive alder woodland, or alder carr, as it is called, is now virtually unknown in England. The few alders that are left to us are thinly scattered along the margins of lakes and rivers, and only survive there by default. They are given gracious permission to remain, to represent their ancestors in the valleys where once they held sway. There is something sad about them now, as though they cannot forget past glories. The aluminium sign, “PRIVATE FISHING, NO DAY TICKETS, BY ORDER”, the two iron nails unfeelingly driven into the heartwood and allowed to rust, are just another humiliation, too minor even to notice or resent.
Even the river itself has been destroyed, an impossible act in the imagination of the ancestors. It is now a canal. The otters have gone, the trout, the variety of dragonflies. From the old times only the siskins really remain, ever faithful: small, acrobatic finches, streaked green, yellow, and black. With goldfinches and sometimes redpolls and blue tits they make flocks which move through the alder tops, prising the seed from the small, woody, cone-like lanterns of the old female catkins. The seed is rust-coloured and rich in oil, very nourishing for the finches on a dark November afternoon such as this. The siskins are especially busy, preparing for a long and chilly night spent immobile, losing heat, roosting high up in the alder branches. Their cry is a thinner, more metallic, version of the greenfinch’s wheeze, quite unmistakable, even when you and your bicycle are jolting and crunching along the towpath. You stop and look up, hoping for a glimpse of them at work. Alder seed is coming down in sparse showers. The seeds will float away if they hit the canal. Small as they are, much of their surface is given over to two minute waterwings. It must be hard work to eat enough to make a meal, but the siskins do it. In this, like the alders themselves, the siskins are too narrow and specialized. That is why they are relatively uncommon these days, much less plentiful than the goldfinches. The siskins’ diet is virtually restricted to the seeds of alder, birch, and of a few other trees; the goldfinches can take many other sorts of food besides: thistle and burdock seed especially, insects too. And, even among the alders, the goldfinches are more enterprising and opportunistic. At this very spot last winter a party of goldfinches was on the ice, picking up the alder seed where it had fallen. In this way the goldfinches saved themselves their usual exertions, and the food needed no special finding. It was there, spread out as though on a table.
The siskins are moving on. Dusk is approaching and you have only dynamo lights, not the safest way to illuminate rough ground, so perhaps you had better do the same.