Sometimes trees have to be felled. This can be for a variety of reasons,
Sometimes trees have to be felled. Either due to disease, land development, encroachment on surrounding property or to allow replanting of different trees or plants. Tree felling can broadly be split into two main categories:
Straight-felling is always the preferred option where space allows. It is quicker, more cost effective in labour and from a risk assessment point of view it reduces work at height.
The tree is simply felled by a man standing on the ground and felling aids are used to encourage the tree to fall in the correct direction.
When straight felling a tree we have a few major considerations:
Is there room for the tree to fall in one piece without striking targets?
Are there any phone lines or power lines running through or around the tree?
Is the tree weighted in the wrong direction?
Is the trunk of the tree in a healthy enough condition that the tree can be safely controlled with a felling cut?
Are there any dangerous branches in the tree that are a risk to the saw operator?
Felling aids range from simple wedges, that are hammered in at the back of the tree to encourage it to fall a certain way, to mechanical winches anchored on to other items in the desired felling direction (usually other trees).
Dismantling of trees is the alternative to straight felling. A climber will work his way up the tree and remove each branch individually. In some cases the climber only needs to remove enough of the crown to allow the rest of the tree to be felled. In other cases the entire tree is dismantled all the way to ground level.
When dismantling trees the climber and ground crew will work in tandem to avoid any targets below. Domestic tree surgeons in cities probably spend 90% of their life dismantling trees as domestic gardens seldom have the space available to drop trees whole. Rigging techniques can be used to direct and lower the falling branches in a certain way to prevent damage to buildings or gardens.