How much do you love the native woodlands of Britain? Nurseries like ours sell more native trees than anything else, so you'd probably think that I'd be one of their biggest fans. And I am. For now.
We get asked about native plants for woodland & gardens a lot. I'm impressed by many people with the desire have to use native trees. Some of the conservation projects that we work for will only accept trees that were grown here in the UK, from UK seeds, ideally from the same region as their project.
Why would I have foreboding about conserving our trees?
I'm no climate change expert and I don't know what will happen to the British climate over the coming decades. One thing is certain, however: if the climate does indeed become significantly drier and warmer, with little to no frost in winter and more droughts in summer, several common native trees will be unable to survive without human assistance & some would disappear altogether.
What exactly is a native tree?
Some countries & islands have had their trees more or less in place for millions of years, many of which are "endemic" - unique to that region. This is not the case in Britain.
Britain only has one tree sub-group that is endemic: Types of Whitebeam called "apomictic". Put simply, apomictic means that they gave up on sex and now make near clones of themselves (which I don't think is very British, even for a tree).
- The last ice age ended about 12,000 years ago.
- The English Channel grew rapidly in size 8,500ish years ago, from a big river to something like its present width.
- Trees that managed to colonise Britain during the 3,500 or so years after the end of the ice age are called "true natives".
- Trees that where brought by human colonists arriving after birth of the English Channel 8,500ish years ago are called "naturalised".
European trees that were well suited to the cold where able to "chase" the ice-sheets as they retreated from Ice Age Britain, capturing newly exposed, moist soil before the competition. This is why we have so many trees that love boggy, wet ground. We also have trees that need a winter freeze for making fruit or for their seeds to sprout in spring.
In evolution terms, our trees are recent colonists, essentially still the same as their European relatives. They dashed in to grab a cold soggy land, before being cut off from the mainland and trapped here. They have not had a reason to change their cold & damp loving ways.
This means two things to me:
- If all the British native trees where wiped out tomorrow, Europe would only lose a single small group of prudish Whitebeam trees.
- Britain's tree population is cut off from the mainland. Trees that are better at surviving in hot conditions can spread from Spain up to France, but they can't then hop on a boat to Dover by themselves (stuck to the bottom of your shoe would work, though).