How to kill an oak tree #973: Killing me slowly with backfill

God, this is disheartening.  Stopped for gas in Paso Robles, CA on Friday afternoon (Paso Robles = Oak Tree Pass in English - the most recent and perhaps most ill-fitting language of the area) and I saw this:

(Click to enlarge)

This tree is dying. It is a massive California white oak/valley oak (Q. lobata) with a crown spread of about 80 feet or so.

And therein lies the problem.  A crown spread of 80 feet equals a root system spread of more than 80 feet.  But when the gas station was built the grade was raised around the tree, save for a 10 foot diameter dish right around the trunk that was left at the original grade.

The grade wasn't raised by much - 6 inches in most places, maybe 12 to 18 inches farther away from the tree.  But that's enough, especially if (as I suspect) construction equipment compacted the soil in the drip line root zone.  Roots that were inches below the surface poised to swallow precious moisture from the rare Paso Robles cloudbursts and which had plenty of pores of air space in which to breath, are now several times farther from the hard packed surface, with no air space to breath and no water to drink.

The sad parts are:

1. Someone actually made an effort to help the tree by leaving a dish at original grade.  They just didn't know (I prefer that to thinking they knew and just didn't care) that the most valuable roots are way out below the drip line or beyond.  They didn't know that even a minor change in grade, especially when combined with soil compaction, can suffocate the fine feeder roots that are the lifeblood of any tree, no matter how huge.  The knowledge gap on construction sites is still, after all these years, immense.

2. The tree is dying so slowly - this gas station was built several years ago - that by the time it dies no one will connect its death to the damage that was done during construction.  Instead its death will be blamed on old age (Ha! This tree would live another 150 years left to its own devices) or on the insect and/or disease pests that aren't the primary cause of death but are only the secondary and opportunistic beneficiaries of the tree's stress and struggles.

The third and saddest part?

 (Click to enlarge)

3.  There's another tree right next door behind a car dealership that is dying in exactly the same slow way.

Sigh.

Obey the drip line people.  And if you're not going to - or can't - obey the drip line, then do the tree the honor of harvesting it and putting it to use, rather than leaving it to die a slow, drawn-out death that will leave its wood rotten and its spirit ruined.

It's the drip line, people!

A few weeks ago a wrote about how heartened I was to see more and more construction projects with protective fences set up around the drip line of oak trees in order to protect the root zones from soil compaction and grade changes.

Well, the last few construction sites I have seen... not so much.

(Click to enlarge)

Above: Mid-state Fairgrounds, Paso Robles, CA.  Below: Hwy 46 east of Paso Robles.  In both cases California white oak (Quercus lobata) - also called valley oak.

Granted there are mitigating circumstances and the construction crews might be doing the best they can under limiting circumstances.  The tree above is located in a roughly paved parking area and the fence marks the perimeter of the area of bare soil around the tree.  Despite the tough growing conditions this is obviously one heck of a healthy tree.  To some degree the pavement is probably serving the same function as mulch film - holding moisture in the soil.  Rip up the pavement and I guarantee you find a ton of feeder roots immediately beneath it.  So my fear is they are going to do just that:  Rip up the pavement and the feeder roots beneath, the compact the soil in the process of re-paving the area.  I hope I'm wrong.

No matter what, why wouldn't they have put the construction fence at the drip line or beyond?  Answer: Because the Mid-state Fair is in August when it's hot as Hades in Paso Robles and everyone wants to park in the shade.

In the lower photo the tree is on the shoulder of a soon-to-be-widened highway, and a fence, private property and a vineyard lane on the other side.  This photo is taken looking east.  No way you can fence out to the drip line to the north (road) or south (fence/vineyard lane).  And you don't really have to, since the road shoulder and the vineyard lane have probably limited root growth in those directions for years.

But you could, in order to compensate, extend the fenced area east and west to the drip line - or even far beyond the drip line.  There's no law (although sadly there's probably a CalTrans spec) that says tree protection fencing needs to be erected in a circle.  Most of the root growth of this great tree has been going out from the tree to the east and west.  Why not protect those roots from construction damage?

I keep a mental catalog of at-risk construction site oaks and follow them for years to see how they fare post construction.  I'll keep watching these in the years ahead.

Oak Abuse: Progress - all the way to the drip line

I have told versions and parts of this story dozens of times on this blog, but I can't convey the importance of the photographs below without telling it again.

I got into this whole wacky oak caper back in the 80s.  I grew up in the northwest suburbs of Minneapolis and watched new housing development after new housing development roll over the oak woodlands where I used to hike, run, fish and (if we're being honest) blow things up and generally goof around.  In high school I worked at a local nursery and garden center loading up cars with the crushed landscape rock, plastic weed fabric and edging, seedless green ash trees and Crimson King Norway maples that replaced the oaks that were lost (oaks, of course, were far too "slow growing" and "messy" to plant back into the landscape).

I entered the Urban Forestry program at the University of Minnesota to learn how homes could be built in wooded areas with a minimum of damage.  I quickly learned that greater minds than mine (and I have yet to find another forester's mind that isn't) had already figured this out.  So I decided to be the guy who would bridge the gap between foresters and the rest of the world - developers, builders, homeowners - and bring that information to a wider audience.  My one and only attempt to make myself useful.

I started a non-profit organization called Lasting Woodlands, and put out a kind-of-sorta-when-I-had-the-time-and-money-bi-montly newsletter, put on seminars, spoke to builders and realtors groups and generally made a pompous nuisance of myself.  We're talking a lot of very late nights at Kinko's.

Lasting Woodlands was mostly famous for putting the non- in non-profit, and died a slow death in the 1990s as my other career - that of tree tube peddlar - demanded more and more of my time. Equally unprofitably.

But my interest in and passion for protecting construction zone oak trees has never abated, and I have continued to try to use every forum possible to spread the word - including some TV spots back in Minnesota a couple years ago (here's a link to the post with with that video - sorry for the glare off my forehead).

When speaking to builders I always found that the sarcastic approach worked best.  Actually, I don't know if the sarcastic approach worked best but since it's my default approach to everything it's what I went with.  I also knew that most times I was talking to builders or realtors it was a captive audience of folks getting continuing education credit toward their license renewals, so I could be pretty well assured they wouldn't get up and walk out on me.  I would tell builders, "Look, anyone can kill an oak tree the obvious ways - cut it down, bash into it with a bulldozer, snap off its branches in the middle of oak wilt season so that the tree dies by the 4th of July.  Those things don't take any skill at all.  But it takes a real expert to kill an oak tree so that it dies slowly over the course of several years, so that by the time it dies no one realizes the damage was done years before when the house was built."  The arboreal version of the perfect crime.

Then I would tell the assembled builders exactly how to kill an oak tree slowly.

First, you need to realize that the roots of an oak tree extend out away from the as far as - and usually much farther than - the longest branches.  The imaginary line from the longest branch tips to the ground is known as the drip line.  The circle created by tracing the drip line around the the entire tree is the root zone.

Second, you need to know that the vast majority of roots - especially the feeder roots that absorb moisture and nutrients - are in the top few inches of soil.

Third, you need to know that soil consists largely of air, and roots need that air to survive.

Fourth, you need to know how to kill those roots.  There are 4 time-honored methods of doing this:

1) Lower the grade of the ground in the root zone (thus scraping away and removing feeder roots)

2) Compact the soil in the root zone by driving construction vehicles underneath the branches - here's a tip: vehicles with tires are much more effective at compacting the soil as compared to vehicles with tracks

3) Raise the grade of the ground in the root zone (thus suffocating feeder roots under tons of fill)

4) Severe the roots to install utilities, sprinkler systems, etc.

The two great things about damaging the roots are a) it really takes very little damage to send the tree into a downward health spiral, and b) that downward spiral can occur over the course of several years.  By the time the tree dies no one will attribute its demise to construction activities that happened a decade ago, and instead will blame its death on whatever insects or diseases secondarily attacked a stressed tree already in decline.  Like I said, it's the perfect crime.

The only downside to this perfect crime is that - on the off chance anyone is actually concerned about saving the trees - it is equally easy to prevent.  Just put up a fence around the drip line - better yet a bit beyond the drip line - and don't allow any changes of grade or construction traffic in that area. 

No, you won't get the thrill of knowing you committed a tree murder that will never be solved, but you will get the less exciting but nonetheless palpable satisfaction of having done the right thing.

In the last two plus decades I have seen a dramatic increase in the use of protective fencing on construction sites.  Sadly it generally is set up to protect only the trunks - and not the root zones - of mature trees, a further twist on the perfect crime that is as sinister as it is brilliant:  The trunk protection fence makes it look like you care about saving the tree, while giving free access to do the root zone damage that won't show up for years.  Brilliant!

But more recently I have been seeing protective fencing on construction sites that is actually, well, protective. 
There are two sights that fill my forester's heart to bursting:  Seeing a newly planted oak tree reach its (astounding) growth potential, and seeing a properly installed drip line fence.

So, without further adieu (because this post has already included way more adieu that anyone could be expected to read), I applaud the California Department of Transportation - Caltrans - for exemplary use of the drip line fence during a renovation of Hwy 101 near the Santa Margarita exit.

Even younger oaks are worthy of drip line protection

(since young oaks are generally where old oaks come from)

 

Even better: Fence the drip line of a stand of trees;

you might end up accidentally saving some non-oaks

in the process, but that can't be helped.

 

That last caption was a bit of sarcasm just to see if you're still with me.

If you are ever out and about and see either construction damage in progress, or in the wildly unlikely event that you actually see well-deployed construction fencing, please let me know and send pictures!

Recession Good For Oaks

(Click to enlarge - sorry about the lighting)

Next time you are bemoaning the precipitate drop in the value of your property relative to what you owe on it, keep in mind that the current economic downturn has had one silver lining:  Reduced construction activity means less construction damage to oaks.

Some of you might remember I posted photos of this beautiful bur oak a couple of years ago, along with dire predictions of its imminent demise (when it comes to the fate of oaks on construction sites sites I'm not a glass-half-empty kind of guy; I'm a glass-is-totally-empty-and-it-was-filled-with-the-wrong-beverage kind of guy).

I later learned that the elderly couple who sold this parcel to developers did so based on the developers' assurance (ahem) that they would take special care to protect this treasured tree.  The developers immediately demonstrated their concern for the tree by laying out and starting to build roads through the root zone in two directions.

I said at the time that once those roads were completed the clock would start ticking on a slow death, a death that would take long enough that developers and property owners would never think to attribute it to construction activity.

That hasn't happened... because the roads haven't happened.  What has happened instead is that two fast food joints just up the road have (tragically) shuttered their doors and new construction on this parcel of land stopped completely.

So this oak is spared for now.  I'd like to think that the developers are using this respite to bone up on preventing construction damage to heritage oaks.  I'd also like to think that white and pink unicorns will prance though my backyard tonight...

... which raises the questions (in my very twisted mind) - do unicorns browse oak seedlings?  and if so, will tree tubes protect them?



Construction Damage Clip

I grew up (to the extent that I grew up at all) in the western Minneapolis suburbs in the 1970's and early 1980's. I watched suburban development replace the (mostly) oak woodlands I played and hiked in as a kid. I worked summers at a garden center in Plymouth and loaded cars and trucks with the plant materials (Crimson King Norway Maples, potentillas, spireas), landscape fabric, crushed rock and plastic edging that were used to replace the native woodlands that were lost.

I entered forestry school intending to be the guy who figured out how to build in wooded areas with minimal damage to existing trees, and how to re-plant what couldn't be saved with native plants. Once in forestry school I quickly realized that I didn't have to figure these things out. A lot of folks much, much smarter than me had already figured these things out. Donald Willeke. Dr. David French. Steve Kunde. Many, many others. I decided instead that I was going to be the guy to bridge the gap between all of those brilliant people and the general public. I was going to be the communicator.

I got off to a good start. In 1988 with Don Willeke's help I started a non-profit organization called Lasting Woodlands. I published a newsletter on construction damage and celebrating our native woodland plants (being a forester I'm sure I focused too heavily on trees and not enough on shrubs, ephemerals, and other important components of a healthy woodland system!).

I gave my first seminar on preventing construction damage to trees 22 years ago. I wish I could say that I fulfilled my initial promise as the communicator of this information. I didn't. But I will.

Hopefully this is at least a small start. Again with deepest thanks to Ron Schara of Minnesota Bound and his top-notch production staff, here is the short clip I did on construction damage prevention that aired in May. If it made just one homeowner or builder stop and give some thought to protecting a 36" diameter oak on their property then it was worth it. (Actually, it was worth it no matter what because I enjoyed working with Adam and Steve from MN Bound. What I mean is if it saved one tree it was worthwhile.)

... proving once again that there is nothing as painful in the world as having to watch and listen to yourself on video!

Minnesota Bound: Construction Damage To Trees

Here's the third of my recent appearances on Minnesota Bound, this time focusing on construction damage to trees. Just click on the May 9 episode - the piece is after the wonderful piece about a bass fishing tournament in memory of a young man whose life was way too short.

Nearly 25 years ago (good grief I'm getting old) I started a non-profit organization called Lasting Woodlands, Inc. with the twin goals of a) educating people about how to build in wooded areas with minimal damage to existing trees, and b) encouraging people to replace vegetation inevitably lost to construction with native plants.

The concept grew out of my own twin experiences, circa 1986: I grew up in the western suburbs of Minneapolis, and watched as suburban development swept through the (primarily) oak woodlands that I had hiked, played and fished in and around. I always tried not to be a NIMBY ("not in my backyard") type of person; after all the house I grew up in was built 20 years previously in fields that had been some other kid's "wilderness." I saw suburban expansion as inevitable (or at least beyond my ability to stop). I just believed that it could be done differently.

At the same time I was spending my summers working for a nursery & garden center, so I saw first hand what these new homeowners were replacing the native vegetation with - Crimson King Norway maples, lots and lots of seedless green ash (which is not exactly looking like a good idea right now). spireas, potentillas, and tons and tons of crushed rock over plastic landscape fabric (I know because I'm the guy who bagged up the crushed rock and loaded it in people's cars - an activity of dubious environmental value, but a GREAT summer job for a kid!).

I enrolled in the Urban Forestry program at the University of Minnesota. I met giants in the field: Dr. David French, Donald Willeke and others. I realized that forestry people KNEW how to protect trees from construction damage, but that there was an enormous information gulf between what foresters knew and what homeowners and builders knew. I set out to change that.

I wrote a newsletter, and a humbling, amazing number of forestry professionals (all of whom knew a whole lot more than me), homeowners and builders supported it. I gave seminars and talks wherever I could. I like to think it made at least a small difference.

Somewhere along the line a lot changed. I ran smack dab into the whole "need to make a living" thing, after avoiding it as long as possible (and longer than I should have). Job changes necessitated moves to parts of the country where I wasn't as well connected. The allure of staying up until 3am at Kinko's to get out another newsletter that I largely paid for out of pocket began to wear a bit thin.

The need for this information to become part of the public consciousness is still as great as it ever was. That's why filming these three spots for Minnesota Bound, and especially this one about construction damage, has been so much fun and so rewarding for me. It's a reminder of why I got into forestry in the first place. It's a chance to spread an important message. My own interests and concerns have expanded far beyond the issues of construction damage & oak wilt to encompass broader issues of land use and environmental & human health (in other words permanent tree crops and eating acorns!) but I know that peoples' relationships with the environment begins in their own yard. And that makes this information as important and timely today as it was 25 years ago.

Thank you, Ron Schara, Adam McFarlane and Steve Plummer. Ron for giving me time on his wonderful show, and Adam & Steve for their patience and editing wizardry (and let me tell you it took some wizardry to make these pieces coherent!).

How To Kill A Tree: Exhibit A

Last August 10 I posted about a magnificent bur oak here in Northfield MN that is now threatened by a commercial development. With tongue in cheek I suggested ways that the construction company could do a nice, clean job of killing the tree. Call me cynical, but I predicted a slow death for this gorgeous tree.

The construction crew is off to a good start... in killing the tree.

Step 1: Position a new street directly under the branches, well inside the drip line (even though you have about 1/2 mile of frontage to work with and could easily position the street elsewhere.

The street is a triple threat: To construct it the grade had to be lowered, scraping away critical feeder roots. Then the soil had be be thoroughly compacted, squeezing out the air spaces the roots need. Finally, it will serve to drain rain water away from the tree.

Step 2: Continually drive & park construction vehicles inside the drip line to compress the soil in a complete ring around the tree.

For bonus points, do this in spring when soil is damp to really squeeze the air pores out of the soil!

Step 3: Use the nice, shady area under the tree for storing heavy construction supplies (necessitating more vehicle traffic over the root zone).

Step 4: Get ready to construct a frontage road WAY inside the drip line - requiring more regrading & compaction, and leading to a further diversion of rain water.

There are two other important points about this photograph:

1. The billboard in the distance is for Cannon River Tree Care, a highly competent local tree care company. If CRTC had been contacted at the start of the project this tree would be safe with a Zero Access fence outside the drip line. Unfortunately, no one ever calls a qualified arborist before construction, because they simply don't know that the things they are doing will kill the tree. That's because it's a death in slow motion taking place over years. By the time the owners realize the tree is failing they don't make the connection between the tree's current poor health and root damage that was done during construction years before.

2. The building in the distance houses a small printing shop that I often use for projects. This spring I was discussing this tree with them (they love the view of this lone tree from their window). They expressed concern about the tree's future, but said that the family that had lived on the property and who sold it to the developers had stipulated that the tree must be preserved.

It's a sad but all too familiar story: A landowner who wants the tree to live. Builders who think that by simply not wrecking the above-ground portion of the tree it will survive, and who are completely unaware of the consequences of the below ground damage they are doing. Qualified tree care professionals who are not contacted before construction, but will be contacted years down the line when nothing can be done.

Am I being cynical? Perhaps. Is it possible for this tree to survive? Yes, but the odds are against it.

As (Soon To Be) Seen On TV

I just filmed three short spots to appear on Ron Schara's Minnesota Bound TV show. The tentative schedule is:
April 18 - Oak wilt prevention
May 2 - Protecting trees from construction site damage
May 9 - Planting new trees, with an empasis on planting (fast growing!) oaks

The show airs on Sundays at 11:35pm, and then again the following Saturday at noon.

Thanks a million to Steve Plummer and Adam McFarlane of Ron Schara Productions for taking a break from working with pros to put up with filming a rank amateur trip over his tongue. And thanks to Ron for airing the pieces. I hope they raise awareness of oak wilt, construction damage, and the need to plant more oaks.

The show can also be viewed online. I'll post links when the episodes are up.

How To Kill An Oak Tree: Construction Damage

Like I always say, I can't stand to see people who are obviously trying to kill an oak tree doing a half-hearted job.

This gorgeous bur oak is located just south of my town of Northfield, MN on the future site of a brand new KFC. (Memo to city planners: We need a new KFC like we need a hole in the head. What we need is some good PIZZA. But I digress...)

Click on the image to enlarge. A token effort has been made not to disturb the soil under the tree, but as you can see the heavy equipment has been driving and grading well inside the drip line, and cement culverts are busily compacting the soil.

Obviously somone thought about protecting this tree. How much better it would have been if they had put up a perimeter fence 10 feet outside the drip line. How much better it would have been if they had consulted a qualified arborist to draft a simple tree preservation plan.

Because we know how this story ends. The new KFC will be built, and the tree will look fine. For a while. Then next year or the year after it will start showing signs of stress or die back. Then, 3 to 5 years from now the tree will be dead and someone will spend hundreds - or thousands - of dollars removing it (certainly a helluva lot more than it would have cost to have an arborist draft a protection plan). An no one will make the connection between the damage that happened during construction - the soil compaction, the re-grading - with the tree's death a few year later.

How To Kill An Oak Tree

So often when I'm driving around I see people trying to kill oak trees (at least I'm assuming they are trying to kill them, since I can't think of any other rational reasons behind what they're doing to them), and not making a good, proper, clean job of it.

So, as a public service to those who are trying to kill oak trees but only doing a half-hearted job of it, here is a list of fool-proof ways to do away with the offending trees:

1. Prune an oak in April, May and June so as to make it susceptible to oak wilt. This isn't guaranteed to kill the tree - in many ways oak wilt is not a very efficient pathogen - but you get bonus points because if the tree does become infected it will likely infect neighboring oaks through interconnecting root systems.

2. Compact the soil in the root zone (which extends out past the longest branches) with heavy equipment (like your car). This reduces water infiltrations and squeezes the air spaces out of the soil, suffocating the roots.

3. Pile additional soil or fill over the root zone. Don't worry, it doesn't take much. In fact, it takes less fill than you think to prevent oak roots from getting the air and water they need.

4. Sever root systems (the closer to the tree - and therefore the higher the % of the root system lost - the better, but remember the root system extends out past the branches so you can trench pretty far from the tree and still do great harm).

And remember, kids: A combo platter of the above is even more effective. But be patient. You might have to wait months or even years to see the results of your handiwork. Oaks are tough old things. Don't worry, sooner or later your efforts will pay off with dead trees.

You're welcome.