Hugelkultur in damp NI

These nice folks at Lackan Cottage in Co Down are making Hugelkultur beds:

They're using birch cuttings by the looks of it; I haven't a big lot of experience in this area, but do you guys think these beds have enough wood in them? Northern Ireland is pretty damp, so the water retention is perhaps less of an issue - my guess is these will decompose pretty rapidly into straightforward raised beds - maybe just a couple of years - but they'll certainly be productive. We get a LOT of growth here with our lovely temperate (if damp) climate.

Incidentally, they're also crowdfunding an eco classroom - this is a great project, and Northern Ireland needs such things in a big way. Please consider going over and showing them some Permies crowdfunding love!
[I have no formal connection with Lackan Cottage - just keen to see permaculture kick off in my region, and they seem keen & sensible]
Cheers,
-Shane

Hi Shane
it looks great so far and I would not worry about too much water
its only going to hold so much[like a sponge]and pass the rest on
we get on an average of 300''+of snow every winter and 1-6'' of rain a week and our first hugelbed is doing great
its only about 20' long and has fruit trees at each end
my wife and I are starting number 2 this week

Mike