Weekly walk, November 25th

Pond from the north

This week’s walk was a bit cold and damp, and proper boots were needed on the paths where, near the pond, they were rather squelchy.  With less vegetation, making evergreens stand out, and soft ground, it struck me as worth taking the rabbit spade to dig out any cherry laurels, and having done so, I think I’ve eliminated at least one more for good.  I also checked on a couple of spots where I’d dug some out earlier this year, and no sign of them coming back yet.  On the other hand, I realise there’s one the size of a small tree not far from the entrance, which will take a more determined effort.

We had a frost earlier this week, and I was curious to know if there’d be any obvious sign of it, as there was in my garden with some tender plants, such as nasturtiums, immediately struck down.  But no, implying that pretty well everything growing here naturally will have some mechanism for resisting the damage expanding ice crystals do to cell walls.  Not for here, but it’s fascinating to think what they might be.

I also found myself thinking more about the relation between fungi and trees.  Apart from the fungi I could see, which include one I now think I can identify as a stereum without recourse to the experts of ispotnature.org, there was another flush of what look like edible mushrooms – but I’m not risking it!  There was another, just a series of orange dots up a dry twig, which I remember noticing as a child,  also growing on dry twigs.  I wonder why I didn’t want to be able to give a name to it then, as I did for plants, trees and animals; I suspect it was because no adults then showed any sign of interest in fungi.

It also stuck me that we have at least one fungus whose fruiting body I’ve not yet seen, Ophiostoma novo-ulmi, which is responsible for the Dutch Elm disease, which, as elsewhere, knocks back all the elms in the reserve by the time they reach 3 – 4 metres in height.  The elms live on, as a sort of understorey brushwood, but never reach the towering heights I remember as a child.

And before long we may have another fungus, Hymenoscyphus fraxineus, which is responsible for Ash die back, and forecast to kill 90% of ash trees in this country.  Not far from the reserve, there are enormous ash trees, leaning over the railway, so I can see that causing some problems in due course for Network Rail.

I wonder how the fungi which cause these diseases are related to those which live off rotting wood, and I wonder what anti-fungal chemicals trees produce to ward off their attacks.

There are so many fascinating question in the life sciences!

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