|Holding Back Succession - can nature ever be free from being managed, conserved or reserved?|
Here is a ragbag of circular arguments for you. The cornfields of England have lost many wildflowers: cornflower, corn marigold, corn buttercup, shepherd's needle and pheasant's eye. Thirteen species of 'arable weeds' are now categorised as nationally scarce, seventeen are threatened species and six are regarded as extinct in the wild (but may crop up somewhere). On the plus side, crop yields have soared producing grain surpluses and a new source of income in setaside (which also has no arable weeds).
The better modern-day control of arable weeds has lead to some interesting knock-ons. The decline in grey partridge is related to the eradication of knotgrass. How so? Knotgrass is the sole food of the larvae of a small leaf beetle. These larvae form a large part of the diet of grey partridge chicks, providing protein for growing tissues and bones. Take away the knotgrass and the food chain that supports grey partridge suffers.
Another way to control arable weeds is to turn cropland into permanent grassland. Few of these arable weeds can out-compete perennial grasses and the discontinuation of turning the soil over reduces the chance of annual seed germination from its huge bank in reserve. Plough up one of these pastures and the mayweeds reappear, as does the annual field pansy and maybe the bright red poppy, which is hard to eradicate on chalkland fields. Not so the cornfield flowers, their seeds a long-time lost, as are those of the wildflowers distinctive of yesteryear flax and hemp fields. You won't get them in the flax fields of today.
Chalkland and limestone meadows and pastures support an abundance of wildflowers, but they are the perennials like tormentil, creeping clover, salad burnett, thyme, selfheal, birds foot trefoil, eyebright and ladies mantle. Add to these the rock rose, milkwort and heartsease pansy in the throes of summer and you could think that there are compensations for losing the annual wildflowers of the arable fields. But you are easily pleased if you just accept that list of wildflowers for they are just the perennials that survive the lawn mowing tendencies of sheep. The grass cut close, these perennials survive by remaining squat and forestalling their munching and ferment. Take away the sheep and these perennials grow taller and in fuller character, their colourful flowers redolent of past time hay meadows. Growing taller, they are joined by more colourful splashes from red clover, dropwort, harebell, scabious, orchids and ladies bedstraw. These latter perennials can't accommodate the munching and will not be apparent if sheep are left on the pasture to graze. And they will probably disappear altogether if the sheep are taken away.
Why would the removal of sheep lead to the loss of wildflowers when the temporary absence of sheep provides such great gains? Nothing magical here - over the years, sheep grazing moderates the growth of the more vigorous grasses, allowing the low growing flowers to compete and retaining the ability for the taller wildflowers to periodically reappear when the sheep are taken off. However, leave them off for some years and the emergence of scrub charts the downfall of the meadow or pasture. Farmers appear to loath woody scrub, signaling as it does the might of nature in reclaiming its own. From scrub, it is a short distance to trees - that ultimate antithesis to grass. Grass does not grow in shade and you can't sustain multiple-stomached beasts without plenty of grass. And of course the wildflowers of the meadow also find it difficult to grow in shade and will be lost as well.
When agriculture first arrived here some 5000 years ago, it must have been quite heartening for neoliths to realise that chopping the trees down that covered most of Britain would create a mass of juicy grassland that livestock would thrive on. The livestock could be eaten, but they would also serve two other purposes: they prevented the regeneration of the woodland by munching off tree seedlings; and their physical capacity made them ideal to drag field hoes, turning the soil over and allowing it to be sown with the improved annual grasses brought from the golden crescent of the middle east - the cereals as we now know them today.
By now you may be spinning in the circles I've drawn. You may also have realised that the existence and longevity of many wildflowers is inextricably linked into agriculture. From the seashore to the mountaintops, plants only get to grow in nature if the agricultural practice of the area at any one time is constant. Agriculture has never been that stable: boom and bust, flooding and draining, subsidy and scheme, we let agriculture rule our land use. A heath is only a heath if we manage it; an arable field is never a natural phenomenon; and a meadow or pasture will only stay that way with animals. I'm still reaching for some empirical answer to all this, loving wildflowers more than I do agriculture. Will the astonishing meadow flowers that I saw this weekend in the Dales continue to exist if trees take it over? Will the sundews, marsh orchids and cranberries be there next year on my local moor now that the sheep have been returned after the cull? How can I get all the diversity that I want and still feel that nature is in control and not mankind?
Mark Fisher, 4 August 2002