well in east sussex at least. i was pruning some sycamore trees on saturday (not the best time of year but work is quiet) and sap was actually dripping from the wounds!
this is good news if you want to tap trees for their sap but i suspect that it may be worth waiting until the buds start opening as the flow is likely to be greater. of coarse different species will come out of dormancy at different times.
just a word about tapping trees for sap. please please dont drill deeper than necessary!!! there is no need and it is highly damaging to the tree.
a bit of theory-
the sugary sap comes from the phloem which is a thin layer just beneath the bark. this is made of vessels that connect the roots to the leaves. as the tree photosynthesizes it stores energy from the sun in the form of sugar. this sugar is the trees food as well as building material. any left over sugar is transported to the roots for storage. in autumn the trees leaves fall off and photosynthesis stops (in the case of deciduous trees. evergreens do not have a dormant stage but the rate of photosynthesis does slow). in spring the tree comes out of dormancy and the sugars stored in the roots travel up the phloem to the dormant buds. these buds are produced before autumn. the sap gives the buds energy to open and produce new leaves to resume photosynthesis.
the time the tree comes out of dormancy is controlled by temperature. when i was working on saturday i pruned a row of three sycamores and noticed that the one tree that was in the shade of the house for most of the day had the leest amount of sap flow.
as the phloem is so thin and close to the bark there is no reason to drill past this layer.
beneath the phloem is the cambium which is where new phloem and xylem vessels are produced. xylem is basically wood. it is split up in two layers, the sapwood and the heartwood. the sapwood transports water and minerals from the roots. the heartwood is inactive and only purpose is to support the tree.
when you drill into the tree it will expose the tree to fungal spores. these spores are constantly present in the air so WILL enter the wound. the deeper you drill the more of a head start you give the fungi.
forget what ray mears says about plugging the tree will prevent infection. a wooden plug is not fungi proof as will actually become a source of food and place for the fungi to develop. trees have ways to resist fungal attack but as the plug does not (this resistance to fungal attack is called compartmentalization if your a real tree geek
).
different species of tree have greater resistance to fungi than others but birch's defences are fairly poor and the wood rots very quickly.
if you drill deep into the tree the fungi will decay the tree from the inside out and the trunk will essentially become a tube. imagine bending a straw or cardboard tube, it will suddenly fold and collapse. the same thing happens to hollow trees.
going by this it is wise to not tap any trees near buildings, roads etc. because hollow trees are a hazard.
don't tap your tree in your garden!
i hope i havent bored you too much and thanks for your patience reading this
pete
this is good news if you want to tap trees for their sap but i suspect that it may be worth waiting until the buds start opening as the flow is likely to be greater. of coarse different species will come out of dormancy at different times.
just a word about tapping trees for sap. please please dont drill deeper than necessary!!! there is no need and it is highly damaging to the tree.
a bit of theory-
the sugary sap comes from the phloem which is a thin layer just beneath the bark. this is made of vessels that connect the roots to the leaves. as the tree photosynthesizes it stores energy from the sun in the form of sugar. this sugar is the trees food as well as building material. any left over sugar is transported to the roots for storage. in autumn the trees leaves fall off and photosynthesis stops (in the case of deciduous trees. evergreens do not have a dormant stage but the rate of photosynthesis does slow). in spring the tree comes out of dormancy and the sugars stored in the roots travel up the phloem to the dormant buds. these buds are produced before autumn. the sap gives the buds energy to open and produce new leaves to resume photosynthesis.
the time the tree comes out of dormancy is controlled by temperature. when i was working on saturday i pruned a row of three sycamores and noticed that the one tree that was in the shade of the house for most of the day had the leest amount of sap flow.
as the phloem is so thin and close to the bark there is no reason to drill past this layer.
beneath the phloem is the cambium which is where new phloem and xylem vessels are produced. xylem is basically wood. it is split up in two layers, the sapwood and the heartwood. the sapwood transports water and minerals from the roots. the heartwood is inactive and only purpose is to support the tree.
when you drill into the tree it will expose the tree to fungal spores. these spores are constantly present in the air so WILL enter the wound. the deeper you drill the more of a head start you give the fungi.
forget what ray mears says about plugging the tree will prevent infection. a wooden plug is not fungi proof as will actually become a source of food and place for the fungi to develop. trees have ways to resist fungal attack but as the plug does not (this resistance to fungal attack is called compartmentalization if your a real tree geek
). different species of tree have greater resistance to fungi than others but birch's defences are fairly poor and the wood rots very quickly.
if you drill deep into the tree the fungi will decay the tree from the inside out and the trunk will essentially become a tube. imagine bending a straw or cardboard tube, it will suddenly fold and collapse. the same thing happens to hollow trees.
going by this it is wise to not tap any trees near buildings, roads etc. because hollow trees are a hazard.
don't tap your tree in your garden!
i hope i havent bored you too much and thanks for your patience reading this
pete
