Hollow trees

In many ways, felling wedges are the humble heroes in advanced felling situations, providing remarkable lifting force for greater control and precision. As you know from your basic training, wedges are inserted before the felling cut is complete, and are knocked in with an axe or an impact breaking bar. They help the tree fall in the direction of the notch cut by lifting the tree in that direction. Wedges also prevent the tree from pinching the saw, or leaning back on the saw, while making a back cut. In addition, wedges can be used to release a pinched saw.

Impact tools, such as an axe, sledge hammer and impact bar, are used to drive felling wedges to lift a tree. To be prepared for advanced felling situations, your equipment should include a complete assortment of well-maintained impact tools ready to be used for various situations.

A winch is used primarily where extremely safe felling is demanded. Examples include felling a tree near buildings, overhead power lines and roads, as well as other confined spaces. A winch is also used to great advantage if the tree is difficult to assess in terms of lean, branch overhang, damage/decay, etc.

A pulling or rigging rope is usually essential when using a hoist/winch in forestry applications. The rope is used to extend the winching path long enough to bring the operator out of the risk area, or in combination with a block/pulley to redirect the winching path.

A block or pulley is a convenient way to redirect the winching path to get the operator out of the risk area. It is attached to an anchor point using a sling and a carabiner or a shackle, preferably made of steel.

A sling or lifting strap is usually needed to attach the winch and/or the block or pulley to an anchor point, such as a tree, stanchion, vehicle or something similar that can withstand the force from the winch and/or the block or pulley.

A pole saw is essential when working in a storm felled or damaged forest, since it increases the distance between the operator and the tree. Distance is particularly important when working with trees or branches under tension or in situations where the escape route is difficult.

The throw line is used to position the rigging (or climbing) rope at an ideal point in the tree to prepare for winching or hoisting. The throw weight helps prevent the throw line from getting tangled.

The throw saw is ideal in advanced situations where it is not possible to use a chainsaw or a pole saw. Examples include when it is not possible to roll the tree down from a power line or when it is difficult to make lump or step-down cuts.

Planning starts with a clear understanding of the work to be done. What are the expectations and challenges? How can you ensure that the task can be completed in the safest possible way?

This is your reality check. Without a thorough worksite and tree inspection, it is impossible to know the risks. So, open your eyes and activate your senses. What do you see, hear, feel and smell? It’s all about increasing your awareness and understanding.

Based on an understanding of the work that needs to be done and the results from the worksite inspection and Visual Tree Assessment, it is time to do a worksite risk assessment.

Safety is built on knowledge. Once you have inspected the worksite and the tree, and assessed the risks, it’s time to develop the work plan. But remember that identifying and mitigating risks is a continuous effort at every stage in your planning. For example, be aware that the work methods you decide on as part of your work plan, also have risks that you need to deal with. The same is true for the tools you need to complete the task. Know the risks!

The decided work method is based on the task at hand and the tools you have. However, remember the risks determine the tools you will need. What forces are needed?

Be sure to communicate the worksite risk assessment and the work plan to all members of your team. Everybody should understand the risks and the plan for executing the task. It is also now time to prepare yourself, your team and the worksite – taking preventive actions based on the risk assessment. Put on your PPE, block off the worksite, clear your escape routes, position your vehicle so that it is ready for immediate departure in case of urgency, and get out the first aid kit before you start working. Once all team members have signalled a “thumbs up”, the time has come to execute the task.

Now that you have carefully performed and followed each step in the work plan, you and your team are ready to execute the plan. This is where all the time and effort spent with the worksite inspection, the VTA, the worksite risk assessment and deciding on a proper work method really pays off. Making it more likely that you can complete the task safely. But remember: a good plan is not written in stone. More likely than not, you will have to adjust it as you carry out your work.

When planning the felling of a complex tree, you need to consider the tree’s height, diameter, lean, the wind direction and speed and of course the distance to surrounding trees, buildings, overhead power lines, roads and other obstacles. Selecting the right felling direction, felling tools and felling method are crucial for a successful outcome.

When felling a larger tree, or tree leaning against the direction of felling, think carefully about the type of felling tools you will need to make the tree fall safely and as planned. The felling tools you need are determined by two critical factors: the lift height in the felling cut and the tree’s felling force.

The lifting height is the distance that the felling tool must push apart the felling cut before the tree falls on its own accord. The diagram shows the required lifting height for different tree diameters, including the saw cut. The values apply to Nordic tree species and trunk forms and should be considered as a guide, not as exact figures. Using the diagram you can, for example, see if you need several wedges in height to bring down the tree.

A winch is used primarily in situations that demand extremely safe felling, such as adjacent buildings, overhead power lines, roads and confined spaces. A winch is also used to great advantage if the tree is difficult to assess in terms of lean, branch overhang, damage/decay, etc.

To ensure felling accuracy, make sure that the line of sight of the saw is adjusted to suit the length of the tree you plan to fell.

If the tree leans in the direction of felling, it is very likely that the tree will start to fall before the felling cut is complete. You then run the risk of the wood splitting violently causing half the tree trunk to jump out backwards – resulting in a serious accident. This also destroys much of the timber. You can avoid this by using the following method.

For severely forward leaning or already split wood, use the V-cut, deep V-cut or an opening on the pressure side to reduce the risk of splitting and allow the tree to fall slowly initially.

A tree that leans across the direction of felling wants to fall to the side of your line of sight. You should compensate for the side lean by aiming by the same distance in the opposite direction as the tree is leaning. For example: if the tree leans 1 m to the right, aim at least 1 m to the left. Insert the felling wedge at an oblique angle from the side of the lean allowing the felling force to shore up the tree.

Splits in the trunks are primarily caused by the internal natural tension in the wood on hard or very hard wood, such as beech. During felling or cutting much of the tension is released. Wood that splits during felling can be a major safety hazard. Split wood can also result in timber losses and, consequently, financial losses. Here are two methods you can use to avoid splitting.

Rot mainly attacks older and damaged trees. The disease weakens the wood fibres making felling hazardous. Fell the tree in the natural direction of felling or secure the tree with a winch.

Dry trees caused by infestation or forest fire, for example, should only be felled when there are many of them. A few dead trees are valuable to ecological diversity and should be left untouched.

Fire-damaged trees might be burned on the inside and may only be standing on the root protrusions.

Working in a storm-felled forest is one of the most dangerous missions. Taking care of uprooted trees, broken trees, leaning trees, trunks under tension, and trunks that are jammed in multiple layers is extremely hazardous work and should only be performed by professionals with excellent knowledge and long work experience.

Start by taking down the leaning tree. The tree’s roots are probably under strain and its position is unstable. For this reason, you must never walk in the tree’s felling area.

Bringing down broken trees with hanging tops is hazardous. If the tree is broken high up, you should handle it as a hang-up. Never walk under the suspended section.

When cutting uprooted fallen trees, there is a risk of falling forwards. Windfalls with large, uprooted trees must never be cut at the butt end first since these trees could kick over in your direction.

A storm cut is a special technique for cutting the roots of storm-felled trees. This method reduces the risk of jamming the guide bar or sawing into the ground.

Storm-felled trees are often exposed to high tension in the trunk because of the lean of the tree or because the tree is jammed with a bent trunk.