Friday, 19 June 2015

The great tree tube challenge

Across both Corehead and Carrifran we have been busy with our annual bracken bashing (see previous posts in June and July 2014 for why). At both sites we have LOTS of bracken. It's impossible to beat it back everywhere so this year we have a number of target areas that we are focussing on. We've also been trying to get in early and bruise/cut it when it's young to have a better overall effect.

But in tackling this issue, it's thrown up the debate once again about tree tubes. Love them or hate them they are a very common part of modern day planting, used by a number of organisations. There are all sorts on the market from solid tubes to mesh guards and all varying in height.

At both Corehead and Carrifran we have areas where trees have been planted in tubes. These were decisions taken a number of years ago. However now we generally take the following approach;

If it's in bracken, keep it in a 60cm tube. The tube helps to encourage faster growth up to the light. It also helps to protect the tree if dead bracken falls on top of it and means we can find the trees much easier to beat around.
The tree is easy to pick out with the tube on

When working in large areas and steep terrain it is really useful for volunteers to be able to easily identify the trees

When just planted in vole guards it is easy for little trees like this hawthorn to be missed
 
Or in a worst case scenario those not planted in the protection of tree guards can get smothered by the dead bracken

All other new trees being planted have just vole guards for protection. This gives some level of protection but also enables the tree to take on a much more natural form. Trees like to throw out branches low down as well as high up and in vole guards are much less restricted. These low branches keeps them more protected from deer rubbing on the main stems which can remove large strips of bark. And we've been noticing that once trees get to a certain size, the tubes can actually cause damage.

Note the little area of damaged bark pressed tightly against the tube
This tree looked fine
but on closer inspection suffered from bark rubbing as well
Trees grown in guards take on an artificial 'lollipop' shape. This can make them top heavy and lead to them blowing over
And we've found that some species, such as these juniper, really shouldn't be in tree guards at all!
This little hawthorn is growing without any protection and has been able to develop branching low down as well as higher up
And even with the protection of a vole guard, this hazel has been able to take on a very natural shape

Montane species such as juniper and downy willow are planted without protection. We have found that these higher up species which really do like to spread out low down do not fare well in any kind of guard. This is an area we are still exploring and working on but suggestions including planting in higher densities and in clumps are being considered.

By....
a. taking this approach
b. replacing dead trees (and where possible increasing the number of trees planted, something we do a lot of at Carrifran)
c. maintaining our fences to protect planted areas from nearby sheep and goat populations
d. keeping on top of our deer population and
e. removing tubes when the tree is established
we think this is currently the best way forward. Less tree tubes mean less of a visual impact, less cost and less of a plastic footprint that we need to get rid of. It's not that we don't think they have a place, it's just that we don't think that place is on every tree.

Lynn
Site Officer

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