Why does removing a complete ring of bark around a tree trunk ('girdling') eventually kill it?
The phloem lies in the bark.
The phloem lies in the bark. Girdling strips away a full ring of phloem, cutting the only path that carries sugars made in the leaves down to the roots. The roots, starved of food, slowly die, and without roots the whole tree dies — even though the xylem underneath can still send water up for a while. It shows how vital the phloem is for feeding the roots.
Key point
Girdling removes the phloem ring, so sugars can't reach the roots and they starve.
Common mistake
thinking the tree survives because water still rises through the xylem.
Memory tip
no phloem → roots get no food → tree dies from below.
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