In our wood we have a rare species, a species that is endemic to our corner of Britain – it is found nowhere else in the world. It is so rare that there may be only 2000 individuals in existance, and they are all found in a small area, 30 miles in radius, of which our wood is part. What is this amazing species I hear you ask? Well – it’s a tree, a species of whitebeam. No, don’t go – it’s a fascinating story, really.
It starts with the common whitebeam (Sorbus aria), which actually isn’t all that common. It’s a broadleaf, deciduous tree with a smooth grey bark (see above). Its leaves are thick, oval in shape and have irregular teeth around the edges. The tree is distinctive because the underside of the leaves are covered in thick white hair, hence its Anglo-Saxon name whitebeam (beam means tree). In the spring, the common whitebeam is quite early to leaf and in May it bears white flowers which are insect pollinated. In the autumn, the fertilised flowers produce red berries (called chess apples in the north-west); these berries are food for wildlife and can be made into jellies. The timber of the whitebeam is a hard white wood with a fine grain, so is ideal for wood turning and fine joinery; the wood was used to make machinery cogs before iron became commonplace. Whitebeams are found in calcareous woodland and prefer not to be shaded; they will be outcompeted in woodland that is not managed. Nothing too unusual about this tree you think, until you look at its reproductive biology – the common whitebeam is able to cross-breed with other sorbus species (including rowan and wild service tree, both of which are in our wood). And where a cross occurs the offspring becomes ‘apomictic’, meaning that it can produce offspring without sexual reproduction; its seed grows into a clone of the parent. Now to me, that’s just weird – who would have thought crossing two species would result in that? And why? But now we have a tree that can go it alone. It can just keep churning out perfect copies of itself with no need for another tree to pollinate it. That’s pretty cool.
So now we have the perfect conditions for new species to arise. Any small genetic variation becomes locked into the population because it passes directly to the offspring. Over time a distinct population grows up, and so it has been with our whitebeam. This is how we have ended up with a very rare species here in our wood. It’s wonderful to stand next to these trees knowing how special they are. But there is also a feeling of responsibility. Our whitebeam is threatened because of habitat loss, part of which is due to the lapse in the practice of coppicing in the local woodlands.
It’s sad to think we could lose a species, but what would we be losing? How can we tell we have these trees in our wood? How do these marvellous trees stand out? Well, if I’m honest, it’s pretty hard to tell them apart from the common whitebeam. It is mostly to do with the leaves which are more diamond shaped than the rounded leaves of the common whitebeam; they are pointed at the base, are widest in the middle of their length, and pointed towards the tip. Also, there are fewer veins spreading from the main vein when compared to the common whitebeam. It is true that we could lose our special whitebeams, but being hard pushed to tell the difference between them and the common whitebeam, I find myself asking, does it matter? Really – do I care?
I did have to think about it. But, yes, I do care. And at this time when the world is losing biodiversity at an alarming rate, don’t even think it’s my call to make. I have a woodland in which there are representatives of a species that has fewer individuals on this planet than there are tigers. That makes these trees pretty special to me, though admittedly they aren’t crowd pullers or attention grabbers. So this year we will be managing the woodland round our special whitebeams to give them the best chance they can have of being here for the next generation to enjoy. With the hurdle of climate change on the horizon, anything I can do to help maintain biodiversity in our wood is worth it – and every little helps.