What's in my garden...

Thanks for that Steve, interesting stuff.

I knew that resident plant populations varied over time according to the prevailing climatic conditions, I didn't realise though that Scots Pine was the only tree which managed to hang on through the ice age.

I suppose it depends on how you define 'native' really. I've always thought of native as being something which arrived here naturally, as opposed to being introduced by humans.

By that definition, the likes of oak, silver birch and ash could qualify as native.
Whereas sycamore, elm and horse chestnut, to name just three examples, were all introduced by humans.

 

There is the spindle tree which is apparently was a native of scotland and made it through the ice age as well.. obviously with a warming of the climate after the ice age this tough tree colonized further south.. I believe it's only found in parts of the southeast now?

Yes if you define native as having got here on their own, then yes these trees are native, but their origins lie away from this land.

Of course back before the ice age, Europe was one big landmass and whatever appeared in western Europe generally appeared in what we now call Britain, which at it's western point would have been fairly mild, similar climate to now in western England.. so plants like Ulex gallii (which are still around today) would have flourished, along with Calluna vulgaris, which was, I think around in Scandinavia too. However with a climate cooling after the ice age, more cool tolerant deciduous plants would have followed the ice sheets demise into western Europe, and found there way into Britain before the land was cut off. This means either the glaciers took a long time to recede, or the Ice age wasn't constantly evident (ie the glaciers forthcame and died back multiple times), allowing these hardy trees to colonise and move further west bit by bit.

But then you have to ask the question, if we continued warming in the future (pure conjecture), how long before these trees native boundaries are pushed back east?.. I'm pretty sure they're on the edge of their tolerance now, as it stands. Though looking at how voracious Sycamore seedlings are.. not any time soon