Is planting trees always and everywhere a Good Thing? MCFly’s biodiveristy reporter Dave Bishop takes a critical look.
Recently, several people contacted me to let me know that there is soon to be a tree planting event near to where I live. I think that they were a bit surprised when I told them that I wasn’t interested and, in fact, am generally opposed to tree planting. I think they were surprised by my reaction; after all, if you’re a ‘Green’ person isn’t planting a tree one of the noblest things you can do? Well no, actually, it isn’t! All too often it’s a facile, unintelligent action which can cause more harm than good.
Let me explain:
Around four decades ago the local authorities ‘reclaimed’ the area now known as the Chorlton Ees and Ivy Green Local Nature Reserve by planting trees all over it. In doing so they completely ignored
the essential character of the area which still contained some large patches of unimproved grassland with a rich flora; it’s no accident that local people still call the area ‘The Meadows’. As the trees grew
taller they shaded out the flora and gradually dried out the ground. Because the trees had been rather thickly planted, and no-one had thought to thin them out, they grew tall and spindly. Recently they’ve begun to blow over in winter gales – which is not surprising as they’ve also got weak roots (if you dig up a growing tree and re-plant it you inevitably damage its roots).
In our culture, trees seem to be seriously misunderstood organisms and I think that, taken together, these misunderstandings represent one of symptoms of the culture’s estrangement from the natural
First, a tree plantation is not equivalent to an ancient wood. That’s because an ancient wood is not just a collection of trees but an ecosystem containing many different organisms besides trees (you
can actually cut down all the trees and still have an ancient wood) and you can’t plant one! Second, trees ‘plant themselves’ – and have been doing so for millions of years! In fact many of our best wildlife sites are currently being invaded by self-seeded trees –this process is known as ‘natural succession’. It’s worth remembering that you don’t have to plant native trees – just fence off an area and let natural succession do the job for you. Will a plantation or secondary woodland, resulting from natural succession, ever become as rich and biodiverse as an ancient wood? The short answer is, I don’t know – ask me in four to five hundred years!
Finally, (centuries) old trees are very important organisms for biodiversity. Their trunks, live and dead branches, leaves, bark and rot holes form habitats for a whole host of organisms including mosses and lichens, beetles, birds and bats; an old tree is an entire ecosystem in its own right. But old trees are seen as messy and untidy and ‘diseased’ and get chopped down; there are very few left in the Manchester region.
If you truly want to understand trees I recommend that you read Oliver Rackham’s book, ‘Woodlands’ (Collins, 2006). I suspect that you’ll find that most of the things that you thought you knew about trees in the British landscape are wrong!
Among lots of things that ‘everyone knows’ about trees is that they soak up carbon dioxide, thus countering climate change. Rackham, though, tells us that Britain is too small and if we completely covered it with trees we would have little effect on the atmosphere’s CO2 burden (but we’d do a lot of ecological damage in the process).
Recently Miles King, Conservation Director of the Grassland Trust (www.grasslands-trust.org.uk), commented on the Woodland Trust’s ridiculous plan to plant 6 million trees, in 2012, to mark the Queen’s Silver Jubilee. He wrote:
“The Woodland Trust press release extolled the virtues of trees as carbon stores. The planting scheme will be making Britain greener in more ways than one – as well as the beauty of the trees themselves, they will reduce the impact of pollution; the carbon lock-up potential from six million trees is roughly equivalent to the annual carbon dioxide output of a million cars.
This statistic didn’t look quite right to me so I did some calculations – and yes, what it actually means is that over the lifetime of the trees – a couple of hundred years – and assuming a lot of caveats, they will soak up the CO2 produced by a million cars in one year.”
He went on to write:
“What’s really interesting is that converting intensively managed grasslands to wildlife-rich grasslands creates the same amount of carbon storage as planting trees. And you can carry on grazing them, unlike plantations.”
It’s worth pointing out that species-rich, unimproved grasslands are much more endangered habitats than tree plantations.
Finally, developers and their apologists tend to rely on tree planting as a sort of universal panacea for the biodiversity lost as a result of their activities. Transport for Greater Manchester, for example, seems to think that the enormous damage that they have done to South Manchester’s biodiversity can be compensated for by planting a few trees.
Bishop’s First Law: ‘An organisation’s concern for, or knowledge of, the natural environment is inversely proportional to its propensity to plant trees.’
Dave Bishop, February, 2012
Dave is heavily involved with Friends of Chorlton Meadows, but the above piece was written in a personal capacity.