Pressing down, holding up

Based on an observation by my brother-in-law...

The oak: a woodland multistor(e)y

Such strength of trunk,
Lower limbs heavy as humvees
Or, as an English oak, Rolls-Royces
Held out at arm’s length –
Above then, a rank of standard family choices –
Estates or MPVs,
Then on up the bark-and-metal strata
To find Minis and Smart cars
Packed tight,
Their lightness amplified
By leaf-green paint-jobs –
Spraygun foliage
Aphid-waxed and tree-cut;
Out to the sparrow-bearing mopeds,
Bikes like ripe fruit
And old spare parts on twigs –
Fractal chrome.