making road by tree -- will I kill it?

[Superduper]

Hi, wanted to get some input and advice from folks who have experience working around/near trees. Have redwood tree -- about 24" in diameter. Need to cut down the soil level near the tree on one side to put in a drive. Will be as close as 5' to tree. Will eventually excavate as much as 24" down. I estimate that when job is complete, there is the potential for taking out as much as 20% of tree roots. Question: Will this kill the tree or will the tree eventually recover? Will it be better if I take the soil down 6" per year until I get to where I want it? I know that when transplanting plants, pruning some roots will not hurt the plant too much and they eventually recover. If I do it before fall, I figure the tree will have all winter to recover. What do you guys think? Quoting actual experiences would be most appreciated.

 

[slowrev]

There is a fair possibility it will kill or at least damage the tree noticibly.
That is just my opinion. Based on losing an Oak in similar circumstances.
A professional arborist can better advise you.

 

[thcri]

Will this kill the tree or will the tree eventually recover? Will it be better if I take the soil down 6" per year until I get to where I want it?

Your going to hit some pretty good sized roots going down that far. Doing it a bit at a time is not going to make any difference. I would try and go out away from the tree as much as you can.

murph

 

[John_Mc]

Slowrev is right. There is a good chance of at least doing some damage to the tree. The further away you can stay from it and/or the shallower you dig, the less damage you should do.

How much damage is likely is highly dependant on the species of tree, the existing soil conditions, and whether the tree is already subject to one or more stressors (pests, drought, etc.)

I'm not familiar with redwood (not something you see here in Vermont), so I don't know much about their root systems. One thing to explore is whether root pruning ahead of time on the side where you intend to dig would help avoid some potential for damage or not. (Can you afford to wait through at least one growing season if it turns out root pruning would help?)

John Mc

 

[Bird]

Kind of like Slowrev, when we built my brother's house, we left two very large oak trees right in front of the house. One was only 4 or 5 feet from edge of the gravel drive into the garage. But we also put in a circle drive in front of the house, gravel at first, later added a layer of recycled asphalt. He drove his Chevrolet Topkick Matco Tool truck on that circle drive every day, so he got within 10' of each of those oaks. Both trees died. When he saw they appeared to be dying, he called a tree expert to come look at them to see if they could be saved and the guy told him it was the shock of having traffic running over the root system, even though we had not removed any dirt or directly disturbed the roots at all.

So, I don't know anything about redwoods, but from what you say you want to do, and from what I've seen happen to oaks, I'm inclined to think you're about to kill a tree.

 

[EddieWalker]

There are allot of redwoods with massive damage to them and they live through it without any problems. Just think of the one people can drive through. There are all sorts of roads right next to them from what I've seen and they look great.

I'm no sure if you can just cut away, or if there is a trick to it. My first guess would be to do it in the dead of winter when most trees are dormant. Do they go dorment in winter?

They are aggressive growers that practically take over like weeds. If you have no other choice, wait unitil the end of January and go for it.

Eddie

 

[Superduper]

Thanks for the input. The project does not have a particular time table and if there is a way to do it without disturbing the tree too much, I am inclined to follow that path. There is no way to make the path any further away. As far as comparing Oaks to redwoods, they have different types of root systems. Oaks have a large tap root, redwoods do not. Rather, their root systems are shallow and fibrous. I have read that redwood tree roots can extend as far as 200 feet from the tree. Redwoods are not deciduous but are evergreens so they do not hibernate as far as dormancy goes but they are not active growers during the winter. My experience, in fact, is that the window of time for them to send out new growth is pretty short.

Inviting an arborist might be in order. But before I go that path, I thought somebody here might have some personal experience. Thanks for all your input.

 

[woodlandfarms]

We've got some Sequoia's, redwoods, and regular firs... We had an arborist up to our place for the same reason.... There is a very, very good chance you will kill the tree. While you can drive through a redwood, the roots itself are not damaged...

This all said the process can be slow (a few years) to die. Also, stranger things have happened and going up our road that has been excavated quite some time ago directly agains some 35" pines the trees are just fine. Maybe the carving was done when they were young and could recover, I have never asked...

I would say move your road or accept the end of the tree...

Carl

 

[Superduper]

Well, I did some research and found a website (University of California - California Tree Failure report program) which documents 4292 reported cases of tree failures in California. Of the tree failures, the most commonly reported species are: Quercus (21.0%), Pinus (18.0%), Eucalyptus (13.0%) and Cupressus (10.5%). I believe Quercus is the Oak Tree so clearly, the Oak is very sensitive to many factors. I have read that Oaks are one species of tree that does not like it's root system disturbed after they have matured.

The website entertains questions related to tree failures. The following question was posted:

QUESTION: 95 foot sequoia sempervirens with a DBH of 42" and 40 foot crown spread and average health. Excavation for a new home (basement) 8 feet deep within 4 foot of the tree trunk base for 40 feet (20 feet on either side) on the South side of the tree. Roots up to 8 inches were severed. Soils are clay type. Two story home now sits 10 feet away on the South side of the tree. A target (home) exists 40 feet to the North. My question, any history of whole tree failure due to this type of constuction impacts? My experience is Redwoods are on of the more stable species.

ANSWER: There are 4292 reports in the database. 85 of those are Sequoia sempervirens failures. Of those, 25 are root failures (18 with some decay noted). 20 failed in moderate to high winds. No root pruning was noted in any of the root failures, but two were in altered stands where some root disruption may have occurred.

So far, it is encouraging that there were not more reports of Redwood tree failures and no failures reported due to root pruning. My project is nowhere near the scope of the one indicated above. As a matter of fact, the drastic level of construction and excavation so close to that tree is scary and it remains to be seen what impact it will have as the question was posted merely 2 weeks ago. Will continue to do more research.....

 

[hunterridgefarm]

I agree with bringing in a Arborist. They can inspect the tree and show you how to make clean cuts on the roots that you dig up. You do not want to just "shread" the roots when excavating for the road. Once you have established the roadbed you need to make a clean cut on the roots that were exposed and damaged. This helps in preventing disease and insects infesting the root system. The Arborist also has chemicals they can inject in the ground around the tree to help prevent shock and aid in its recovery.

 

[MadDogDriver]

Agree with consulting an Arborist as well. They're the experts in this matter. As a rule of thumb, I've always been told to not dig within the canopy of a tree (kind of difficult to do in many cases though), so gonig with the Arborist can help tremendously.

 

[bx23barry]

Have ya thought about not digging but bringing in fill and making a small hill/mound in the road over the roots?

 

[Superduper]

Have ya thought about not digging but bringing in fill and making a small hill/mound in the road over the roots?

Nah, not an option. The reason for digging is because that area is already 3 feet higher than the garage floor and water infiltrates into the garage wall (block wall) which is why I want to bring the level of the soil back in line with the foundation. The road is to allow access (occassional) for vehicles to go back behind the garage area and the tree is about 14' from the garage wall. I figure I would need at least 7 or 8' for the road. The road does not need to be paved but I may put down paver bricks to allow moisture to continue penetrating the area. The plan was then to build a stacking type concrete retaining block wall. Don't know if it's feasable or not yet. Not sure what I'll do yet, still investigating my options.

 

[John_Mc]

Have ya thought about not digging but bringing in fill and making a small hill/mound in the road over the roots?

Piling a significant amount of dirt over the roots will probably kill them anyway. You basically "smother" the roots and the micro-organisms upon which the tree depends for the uptake of nutrients.

In addition, driving over the area causes soil compaction and tends to shear the tiny hair-like roots which do the bulk of the nutrient uptake. An occasional run across it might not cause significant damage, but if this was his main driveway, it could well be a problem. One thing that will help minimize this is avoiding driving over it in wet conditions.

John Mc

 

[toolaholic]

I live in Marin Ca. , am a gen contr.. Had an arborist out yesterday about an 18" redwood vs. retaining wall. wall was planned to be within 3' of tree. too close,will change. Some advice from Her buy,50' of soaker hose and soak 24 hrs.at drip line of tree once a month or so .sap was running on another one on property, bettles killed it! Reason NO WATER . We will be cutting some roots within its canopy!
Best fix, loads of water! little feeder root ends supple the tree water. When you cut the big roots the tree may come over in high wind! My customer HAS to make decision today!!good luck , tough call!!

 

[BTDT]

I would say it may or may not kill it. There are trees all along county roads around here with all kinds of traffic. They tend to kill a lot of speeding teens in curves. One thing you might check, or watch for, is reflected light from roof. I put a tin roof on a house we used to live in, and the additional sunlight seemed to scorch the leaves during the summer. It didn't kill tree, but sometimes it looked pretty sick.