Two Jobs – Desert Natives and Introduced Trees

We’ve been pretty busy the last few days with some long hours, and projects waiting at home at the end of the work day. I would like to briefly share some interesting photos and information from the last few jobs. We spent 2 days creating a more “defensible space” around the perimeter of a house. The concept of defensible space is that there is an unburnable area around the house that can help save it if a wildfire sweeps through an area. When houses have trees and brush right up to them, there is little hope. I say a MORE defensible space because we didn’t remove any live trees, just pruned off deadwood and branches laying on the ground or very low to the ground. We also took out some small desert shrubs but not all. This will help in the event of a fire, but it is not a classic defensible space.

Most of the trees we worked on were Mesquites which have an interesting growth habit. The new growth comes off the top of the branches and their weight pushes the branches down over time, overshadowing them and eventually leading to their death! Almost all the Mesquites you will see out in the wild have lots of dead branches down underneath them. The dead branches act as stabilizers and help prop the tree up during storms, and when the live branches are full of beans. When we put Mesquite trees in a landscaped area, keep cutting off the deadwood and trim them up from the bottom they are sometimes unstable and blow over in storms. Branches also have a habit of breaking off from the weight of the beans. For this reason it is important to keep Mesquites thinned in a landscape setting. The area where we worked has not been kept trimmed. There were a large number of dead branches under the trees and lots of broken limbs hanging down to the ground. This had killed many of the Creosote branches under the trees as well. Here is a photo of the mess we started with:


And here is how the same area looked after we finished:

... and After.

It does look pretty bare – many of the Mesquite trees were in bad shape and little was left after the deadwood was taken out. We did completely remove several trees that had no life left in them.

We were working with a local landscaper (who shall remain unnamed) who came up with the work plan. He planned to tow our chipper around the back of the house (through the desert!) so we would have a shorter distance to drag branches. The chips would be spread to help keep the bank around the house from eroding. The hitch on the tractor and the hitch on the chipper are different. He thought he had a way to make them compatible, but this soon failed. He ended up using the chipper’s tow-chains to connect it to his tractor’s drawbar. Here is what it looked like:

An Interesting Hitch!

The tongue of the chipper was dragging on the ground part of the time and the jack-stand ended up stripping out but no lasting harm was done. You can see in this next picture we were wondering if the chipper would run over the tractor going down this hill!

Which will get to the bottom of the hill first? The tractor or the chipper?

We finally finished that job and took our tools over to another property where we were supposed to trim some Mulberry trees. I’ll show you some pictures of the process and try to explain some reasons why it is important to NEVER TOP A TREE! Topping used to be a common way to maintain trees. Topping is a practice where the entire top of the tree is cut off! It results in a very ugly tree! Studies have shown that when a branch is indiscriminately cut off, it starts rotting down its length. The tree can’t stop (or “compartmentalize”) the damage as it can when a cut is done properly. Removing the end of the branch removes the apical bud which is dominant and keeps all the other buds on the branch suppressed (a VERY simplified explanation…). This allows all the dormant buds along the branch to grow, resulting in a profusion of watersprouts. These watersprouts are not attached as strongly as a regular branch, and since they are anchored on a place that is decomposing, are prone to failure.

The following picture shows an improper cut. The end is dead and decomposing, the rest of the branch is covered with watersprouts.

Results of an improper cut!

On the following picture you can see the inside of a Mulberry branch that has been topped repeatedly. The outer light wood is young sapwood, the next layer of dark wood is solid heartwood. The inside part that is light is the rotten core. You can see where the end of the old branch was cut off and all the woundwood that is grown around it. The rotten center continued down the entire branch.

Inside a "knob".

When making a recommendation on care for a previously topped tree, there are several things to consider. First, here in Arizona, nobody want to lose their shade! So, our best recommendation – removal, is seldom taken unless there is a large liability in the event of failure. The other option is to periodically take off all the watersprouts from the tree to keep their weight from getting so much that the tree fails. This is what we spend a good bit if time doing in the winter months. The trees really look ugly when we finish, but they should hold on another year and provide some shade.

If a young branch is “topped” there is some hope that by restorative pruning the tree can be saved. In these cases we need to go in and remove most of the sprouts at the topping cut and hope the tree can heal over the damage. It is unsightly and takes years of effort to fix a problem caused by a few minutes of misguided cutting!

Here is Shannon taking off some small branches. The chipper is grinding up some limbs and shooting them into the dump trailer. We can usually take the chips somewhere for use as erosion control or mulch. If you would be interested in a load, please let me know!

Shannon cutting sprouts.

Shannon and the chipper in action!

We finished the 3 trees in the front yard but didn’t have time to finish the tree in back. That will be Monday’s job!