In the second part of our series we discuss two more misconceptions, first “Tree roots grow down” and secondly “Lopping and Topping are legitimate tree techniques.”

1. Tree Roots Grow Down

Wrong. For many years, it was believed that tree roots grew down into the earth to provide stability, in the same way that a fence-post is driven deep into the ground to hold up the fence. However, this is not how roots provide stability.

For a more accurate picture, imagine a tent in windy weather. The guy-lines provide tension in a horizontal direction, which keeps the tent standing far more effectively that the pegs which anchor the tent body into the ground. This is how roots work, pulling the soil tightly towards the stem. The majority of a tree’s root system will be found in the top 2 feet (0.5 meters) of soil, and the root network will extend far beyond the tree’s dripline.

Now that you are armed with this knowledge, imagine what happens to a roadside tree when a utility contractor excavates a pavement to put in new pipes. What if they then dig up the road to lay a new foundation? The “guy-lines” on two sides of the tree have been severed. This is exactly what had occurred prior to the great storm of 1987. The result: thousands and thousands of trees across London fell – onto roads, houses, and pedestrians! Time to change how we look at roots!

2.“Lopping” and “Topping” are legitimate tree techniques

Every day I see vans out on the road which proudly advertise “Lopping” and “Topping” services. In the 1800s, that is how tree work was done. Cities were being built and industry was booming. Trees were just an inconvenience and tree surgeons were pitiless in their approaches.

In the modern era we know better. “Topping” a tree, as the name suggests, means removing the top of the tree. This removes the apical bud (the terminal bus on the leading shoot which is responsible for extension growth), which causes chaos in the tree’s system. The growth hormones are redirected leading to bizarre growth patterns, and the large wound created will almost certainly lead to fungal colonisation which may compromise the structural integrity of the remaining limbs. The only time “topping” is ever a legitimately employed is in the creation of hedges, in pollarding, or (rarely) for safety reasons.

Similarly, “lopping” is the act of removing large limbs and is usually synonymous with “unnecessarily pollarding”. While there are many management plans which justly call for a reduction in crown size, this will usually be by small amounts, and will be done in according with the Hamburg Tree Pruning System. Sensitive reductions limit the size of the wounds, and encourage the natural growth patterns and overall health of the tree. Pollarding is a specific management technique with specific applications. Indiscriminately “lopping” a tree is never the answer and should remain in the past, where it belongs.

Part 3 will be published early next month. If you have any enquiries, please contact us at james@arbuk.co.uk or via the contact form on our site http://www.arbuk.co.uk/contact.html