Tree Structure and Tree Climbing Safety

Posted by Professional Tree Climber on 5/5/2017 to Tree Climbing Safety
Tree Structure and Tree Climbing Safety

Know What to Look For

Tree work is a very dangerous profession and keeping ourselves safe and alive is the main goal – along with efficiently doing our job. For this blog, we are going to go over some tree climbing safety that has to do with tree structure. As climbers, we are scaling large, woody perennials that stretch towards the sky with long fibrous branches coming from mighty trunks anchored into the ground via miles of roots. This entire structure can have defects that are hidden under the bark or be very obviously exposed. By knowing what to look for, we can make our work days much safer.


Tree Climbing Safety Begins On the Ground

Let’s start the tree climbing safety discussion with walking onto a job site. As we pull up to the job we usually know what tree we will be climbing. Take a good look at this tree from a distance. This will give you a good perspective of the lean of the tree, as well as the surrounding area. Are there power lines near the tree? Power lines are usually easier to see from farther away than up close. Does the tree have a noticeable lean one way or another? A leaning tree could have had the root plate lifted during the last big wind storm and now the roots that once held the tree firmly to the ground are broken under the soil. Look around the base of the tree for heaving soil or air space under the root plate. If you see either of these, be sure to devise a plan to conduct your rigging and climbing from a safe location – perhaps from another tree or with a high line. 


Trees that have a heaving root plate can easily topple in a slight wind or when new leaves are weighed down by water after a storm. Heavy rainfall can also cause the roots of the trees to give way in loose soil. Always inspect the ground as you are walking up to a tree that you will be climbing; this will give you a good idea of what stressors the tree has and what you need to do while tree climbing to mitigate any further stress on the tree. Be sure to look at the soil for cracks and holes as well. You would hate to walk right into a ground bee’s nest first thing in the morning! 



Is There Fungus Among Us?

While you have your head down, keep an eye out for mushrooms or fungus on the tree. The fruiting bodies of fungus thrive in decayed wood. Fungus can be a sure sign of interior decay in trees. A large concentration of fungus can also give you a good warning of what the structural integrity of that tree may be. While looking for mushrooms, you should also be looking for associated cavities that the mushrooms are growing near. Many trees have cavities but the extent of how deep they go is what we want to look for. Take a stick and poke it in the hole to get an idea of the size of the decayed spot. Keep in mind too that trees with multiple holes leading into a cavity are much weaker than trees with just one hole. 



If you do find a hole leading into a tree, DO NOT reach your hand into the hole! Wildlife tends to live in these cavities and you don’t need to get bitten by who knows what because you decided to reach your hand into somewhere it didn’t belong! Take a stick and feel around inside the hole and hopefully any wildlife will get the clue and promptly vacate.


While you are still looking at the ground around the tree, you should also be looking for dead branches that are laying on the ground and near the drip line of the tree. If there are dead branches on the ground, there is a pretty good chance that there are also dead branches in the tree. Make a mental note of where they are and be sure to share this information with your ground crew so nothing is shaken loose on them while you are ascending or working the tree. Also, look for large “widow makers” that are lodged in other limbs; these are large limbs that will surely end in catastrophe if they fall and hit someone. 



Look For Co-Dominate Stems

Trees with more than one leader are called co-dominates. A co-dominate tree, or a co-dominate stem, usually has two or more leads that are growing closely together. Some trees grow like this and are still structurally sound. The ones that you really need to look at are the ones with a tight “V” crotch. If you follow down a ways where the two limbs meet, you will see that there is bark between both of those sections of wood. This is called “included bark.” This separation between the two leads, as well as the included bark, make co-dominate stems that are more susceptible to breaking and splitting, as well as much weaker generally than trees with a straight trunk leading sky ward. This is why cables are often installed in co-dominate stems to help make this weak point of the tree structurally stronger.



While looking for co-dominate stems, it is also a good idea to look for associated cracks located near where the leads come together. Cracks can be generated from high winds or heavy snow loads. I can remember more than one time that I’ve ascended into a tree only to find that my perfect rigging point actually has a stress crack that I couldn’t see from the ground. Sometimes cracks can be located by lines down the trunk of the tree that are now sealed over; this looks like a bulging line running down the trunk. This is considered a seam that has been repaired, but it should still be taken into account while rigging and climbing.


Sections of the trunk that are missing bark are great indicators of a fungal infection or construction damage. Construction damage leads to the death of many trees, due to removal of absorbing roots and structural roots. This damage can take several years to kill the tree, but it can also lead to problems underground that are hard to detect. Look for scraped or removed bark on trees where construction has recently taken place. Make note of any missing bark and do a bit of investigative work to find out why it’s missing. Is it fungus that can lead to a cavity inside the tree? Is it a pest that has compromised the integrity of the tree? Is it construction that has excavated half of the root system that holds the tree firmly in the ground?


Now that you have the trunk and ground level of the tree under control we can look at the crown of the tree and other factors to look for while working the tree. Be sure to check back in on our blog for the following tree climbing safety blog post to keep you safe and secure while working in the trees. If you have other things that fellow climbers should look for on the ground, be sure to share them in the comments below!

We want to hear your feedback! Please leave us a comment: