Tuesday, 16 April 2013

Tree circles (Week 2, Tuesday)

Today was team working again, and we did tree rings on the Pagoda vista.

No, not the tree rings inside a tree trunk, which can be used to identify the age of a tree. I mean we weeded, edged and mulched the circular, grass-free areas around the pairs of trees that flank the heritage walk that is the vista, which - I am told - are "double-banked matched pairs", meaning they are pairs of the same tree, flanked on the outside by another pair of trees.

I was not feeling very well, haven't been since yesterday when I had to stay at home, so did not think of taking any pictures. However, a secret admirer took one of me working from a distance (no, I can't be seen, it was too far away, but that's the area).

Will have to go back and check on some of the trees we did, as they attracted my attention being Acer saccharum (sugar maple), and they must look pretty when they put out their leaves, although I suppose they really come into their own once it's autumn.

The technique to make round circles consists in tying your half moon to the tree trunk with a non-stretcheable piece of string, then working around the tree, so I had the opportunity to practise a lot with this new tool.

I was also told why we need to cut quite deep edges into the grass: I always finds that understanding why you are doing something helps to learn and remember. But it is surprising how few people are able to formalize their (especially practical) knowledge into communicable information, to explain how and why they are doing something. It's a rare skill, and as a former Knowledge Manager I have confronted - and had to bridge - this reality often in my career. I am lucky, however, to have found some people here that are excellent at sharing their knowledge.

So... because the grass roots expand sideways by rhizomes and stolons, they would start creeping into the rings and towards the trees. If, instead of soil, they find air, they stop, so you get a neat and tidy ring. Hence, you need to cut an edge that reaches down all the depth of the grass roots.

Incidentally, did you know that because of the root/shoot ratio principle, the length of the root is in proportion to that of the canopy? It is the principle at the basis of pasture management for soil fertility. When grass grows long, the roots grow long, then, when grass is mowed, a part of the roots die back, and remain into the soil as biomass; then it grows again and so on... if you want to know more about it you can Google "Joel Salatin", an American farmer who centres his farming on this principle.

... but back to our sward, we keep the grass quite short, and so are the roots, and that is how deep tree rings work by preventing the spread of grass towards the trees.

When mulching, you have then to take care to keep the mulch away from the edges (again to prevent grass spreading into it) as well as from the tree trunk (to avoid rotting).

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