主播大秀

It’s late May and I’m standing on the Great Orme – the enormous slab of limestone rock jutting out into the Irish Sea from the north Wales coast. 主播大秀 to over 360 species of flowering plants, this Important Plant Area is globally significant and one of the top 5 botanical sites in Britain.

But, bathed warm sunshine, we’ve not had any rain here for weeks. Indeed, across the UK we’ve had less than half the average rainfall for April. The grass under my feet looks thin and parched, leaves are curling up on the hoary rockroses and bloody crane’s-bills, and the once proud flower spikes of early purple orchid are actually drooping at their tips, the flowers withered and shrivelled.

At one time, we thought climate change would simply lead to warmer temperatures, with the prospect of nice mild winters and lovely hot summers. But our atmosphere is far more complex than that. We’re becoming familiar with idea that our weather is likely to be more unpredictable in the future, with forecasts of more storms, more extreme rainfall and more heatwaves.

But over the past decade, a more subtle change in our climate has become apparent that could have big impacts on our wild plants and flowers.

We’ve suffered a few of these spring droughts recently and they affect plants and wildlife in a variety of ways. The paucity of rain in April and May affects different plants in different ways:

• Winter annuals. Flowers like scarlet pimpernel, spotted medick, lesser trefoil and common cornsalad form a group of plants known as winter annuals. They germinate in autumn, grow through the winter and flower in spring before the heat and drought of summer. If the spring is very dry though, these plants can quickly wither and die before they have a chance to finish flowering and set their seed.

• Spring annuals. Many other annual flowers – such as small toadflax, corn marigold, common fumitory, eyebrights and yellow rattle – germinate in early spring, flowering in summer and setting seed in autumn. If the soil becomes too dry soon after germination, the small seedlings can easily become droughted and die, or produce far fewer flowers on stunted plants.

• Delayed or aborted flowering. Plants that come into flower in early spring, especially shrubs such as blackthorn, woodland flowers like bluebells and violets, and grassland flowers like spring cinquefoil and cowslips need sufficient moisture in spring to bloom well. In severe drought conditions, the production of flowers can be aborted entirely for that year, or delayed – put on hold until the rain arrives. Sometimes it helps prolong the display a bit, but it can affect pollinator relationships if the emergence of pollinating insects doesn’t then coincide with flowering.

• Flowering of orchids. Recent monitoring of some orchid populations has shown that a dry spring one year can affect the number of flowers produced in spring the following year. As orchids come into growth in spring, tiny root buds that go on to produce the underground tubers (swollen roots) for next year are also initiated. In dry springs, these root buds seem to suffer and the resulting tubers don’t get large enough to flower the next year.

Back on the Great Orme we’ve had some rain, but only passing showers that haven’t really replenished soil moisture. On the shallowest soils over the limestone, even the rockrose and crane’s-bill flowers are withering. Under conditions of stress like this, many plants divert their resources to conserve precious roots, shoots and buds so they can re-grow when conditions improve; transient things like flowers are the first to be aborted, followed by soft, sappy leaves to help reduce water loss. Many of the early purple orchids won’t set seed this year. Neither will the winter annuals, which flowered but haven’t produced seed. Even the Great Orme berry is in trouble, its flowers dry and brown with no sign of fruit being set. With just six wild bushes of this native Cotoneaster known to exist in the world, that’s a real worry.

The long-term consequences of drier springs are not known. Most of our vegetation is actually pretty robust and resilient, well adapted over thousands of years to the vagaries of our climate. Annual plants, for example, usually produce very long-lived seeds that - tucked up in safely the soil seed bank - allow them to germinate following bad conditions like these. And perennial plants have tough roots, tubers, rhizomes and shoots that allow them to recover from periods of drought.

But if dry springs become normal in the future – with repeated droughts in decades to come during what should be the prime growing season and affecting the production of flowers and seeds - we’re likely to see changes in our flora. And that could have consequences for all our wildlife.