"Chris Hogg" wrote in message
...
In the last couple of years I've seen two conifers (at least one a
Leylandii) that had been tied to stakes with polythene rope when they
were comparatively small, and the rope never slackened, so that it cut
deep into the trunk as the tree grew.

But much to my surprise, on both occasions the trunk below the
strangle was considerably thinner than that above, roughly half as
thick I would say. Intuitively, I would have expected it to be the
other way around, as I would have thought the strangle would inhibit
the upward flow of sap, nutrients etc. to the trunk and branches
above.

What's the explanation?


--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net
____________-
This is totally as expected. The tie is stopping 'food' manufactured in
the leaves reaching below the constriction via the phloem [bark] whereas
water and minerals from the roots travels unhindered upwards, via the xylem
[wood] Hence the roots and parts below the tie are being starved and would
eventually die, killing the whole plant as they would lose the ability to
'send' water etc.upwards. However the cambium [forms phloem and xylem] has
the ability to grow sufficiently to bridge the gap and permit survival; if
the gap is not too great
..Best Wishes Brian.