Liminal spaces are often engrossing, and in nature they are doubly so. In a few paces I had stepped from mature woodland into scrubby moorland, swapping a bubbling cascade of chaffinch song for the honeyed sadness of the willow warbler, my first this year, secreted as if by magic from the thick mass of birch saplings that have sprung up along the fringes of the wood.
Down the slope in front of me, I heard a mistle thrush, and south over Totley Moss, the looping song of a curlew drifting back to earth. But it was the willow warblers that filled the air.
Not only was this scrub a physical threshold, time itself seemed to be pausing for breath on this chilly spring morning. A marshy pond wore a chopped fringe of ice; the track’s dark earth was frosted white.
Fifty yards away, two red deer hinds watched me from below a stunted Scots pine, motionless but for the twitch of their nostrils flaring at my scent. I circled my hand loosely around the twigs of a low birch and felt them scrape across my palm as I drew my hand up the tree’s stem. The buds were still quite tight, certainly in comparison to a horse chestnut I’d just passed that was spilling out despite itself.
A birch can bounce back from frost damage, but there’s always the biological cost of repair. So the shift from dormancy to life is a balancing act for this scrappy pioneer. Birch thrives at northern latitudes and some level of winter chilling suits it.
The threat of climate change and the birch’s commercial importance has resulted in a careful study of its winter temperature needs; luckily, it’s more tolerant of warmer winters than was feared. It also does particularly well with higher levels of carbon dioxide.
Throw in its proven role in watershed management, and you wonder why every moor hereabouts doesn’t have a vibrant growth of birch on it. Alas, the routine burning of moorland for grouse shooting stymies that. But the patient birch is waiting for us.
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