There is a trend in tree work to default to the most conservative answer when it comes to risk. We decide whether a tree should live or die based on the assumption that any defect makes the tree unsound and that makes it likely to cause major damage to life and property. This attitude may be motivated by the desire to stay out of court, by the desire to win more lucrative removal contracts or by genuine concern for public safety. But extend this attitude to its logical conclusion and we're left with a short, bleak urban canopy.

Let me back up...

This April, I got an email through my website seeking a second opinion. A neighborhood tree company had been knocking on doors and had insisted that a large, mature tree in Lakewood needed to be removed. The solicitor misidentified the Hackberry (Celtis occidentalis) as a Silver Maple (Acer saccharinum), but he did spot the massive section of decay in the lower trunk and marked it as a point of concern.

When I arrived on the property, two things were immediately clear. First, the tree was indeed at risk of partial failure. Second, the tree was a focal point of the property. It was the client's pride and had been a major reason for the purchase of the home! Despite the split in the stem from an old lighting strike slowly creaking in the spring wind, I knew I needed to find a way to keep the Hackberry around for a few more years if I could. I spent more than an hour pacing beneath that ponderous canopy, sucking air through my teeth and trying to picture the physics at work. Here was an overextended canopy over the home. There was an 8" wound more than 10 years old where someone had removed a central leader. Here was a branch base beginning to buckle with the forces being exerted on its calloused, partially-decayed stem attachment.

But I also saw very encouraging signs. While the cavity and splitting were considerable, there was ample sound wood and callous holding things together. The tree had begun leafing out right on time for a Hackberry and was producing vigorous shoots throughout its crown, indicating that the tree's overall health was good.

The principal problem was the split where one of the major leaders attached to the main stem.  The leader in danger of failing extended over the driveway and partially overhung the neighbor's yard.  By  looking at the angles in question, I felt it would be possible to shorten the branch so that, in the event of failure, any damage to the neighbor's property would be minimized.  At the same time, careful shortening of the limb would lessen the leverage acting on the weak section of trunk, lessening the likelihood of failure.  Of course, the client would still be wise not to park underneath the leader - this much would have to me made clear.  As we were entering the windy fall season, when the risk of a late snow was very real, I felt the tree needed an IMMEDIATE lightening of leverage.  We scheduled a three hour emergency pruning session and inspection, which revealed further interesting defects, but solidified my resolve that the tree could be retained.  Once aloft, I could tell that the tree still had sufficient strength to cope with wind and snow for a while.

This is the nature of the work.  Educated arborists endeavor to treat patients in the best way they can.  We make care decisions based on experience with other trees, on knowledge garnered at conferences, in publications and in conversations with colleagues.  But it is also the nature of the work to navigate with a fair amount of uncertainty.  Trees cannot communicate their symptoms or needs clearly.  In the litigious environment we inhabit, it makes sense that arborists might default to the "safest" answer and remove anything remotely threatening, but what values are we sacrificing by doing so?  If this tree had been over a busy street or in the middle of a public park, the exposure would have made the decision much clearer.  With near constant human presence underneath the tree, it's unreasonable to keep such a tree standing without building some kind of barrier to protect public safety.  In this case, while the tree does threaten a structure, it's the owner's perogative to accept their level of risk once they have been fully informed by an expert in the field.

So it came to a difficult conversation with the homeowner; here was a tree I felt confident could provide considerable benefit into the future. How far into the future, however, was certainly a question.

These are the jobs that make life as an Arborist worthwhile. 

I spent a few days pondering the tree, losing sleep and picturing all the angles of the Hackberry's canopy. I finally sent the client two bids; one for removal and one for a relatively heavy-handed structural pruning intended to keep the tree from failing until it had actively begun to decline.  Along with the bids, I wrote an extensive email detailing all the scenarios, the risks and the costs associated with keeping the tree: I recommended a yearly inspection regimen and some upgrades to overall care, and highlighted the fact that there was little money being saved, since the tree's eventual removal was likely to cost just as much as it would if it was done now.  In addition to the "hospice care" costs, I discussed the less tangible benefits of preservation:  It was still a contributing member of the mature canopy in the neighborhood, was still quite strong and vigorous (by no means on its last legs), and it was shading the house, which would keep things much more comfortable in the approaching heat of summer.  Few of these benefits have price-tags attached, but from a quality of life perspective, they are priceless.

Removal had its own benefits associated.  Peace-of-mind and considerable cost savings over time were the largest.  For my company, a removal would be a large, fast cash infusion at more than double the price of pruning, and I would never have to worry that my counsel had led a client to keep a potential hazard in their front yard.  In many ways, removing the tree would have been the "easy way out." Less stress for everyone.  

Everyone except the tree.

Thankfully, they elected to keep it around.

Even in the worst-case "staged removal" scenario, where we remove larger pieces as time progresses, the less tangible benefits of maintaining the Hackberry on hospice care were enough to outweigh the costs.


Mature trees are conflicting creatures in the urban canopy.  They overhang structures, lift sidewalks and send roots into sewer pipes.  They require expensive maintenance pruning to keep in good health, sometimes need costly plant-health-care treatments to battle fungal and insect invaders, and even a trained arborist is hard-pressed to give any sort of guarantee on their longevity.  But imagine for a moment a perfectly "safe" canopy - one where all risk has been mitigated away.  It looks a lot like a canopy of short-statured trees growing away from people and homes.  I don't think it takes a person who works intimately with trees to see how distasteful that scene would be.

Preventing a risk-less, sun-blasted city, then, becomes a matter of advocating for the sometimes-dangerous, always interesting older tree.  As an arborist, it's that advocacy that makes me tick.  I love to see the good ones taken care of and the not-so-good taken out of the way so that the canopy can grow fuller and stronger.  It means being crystal-clear with clients on risks, benefits and future prospects, but I think it leads to a better-managed urban forest, more-pleasant neighborhoods and much happier trees!

It's difficult to know what to write about on a day like today.  Last night, a winter storm rolled into town, calling up memories of a flooded Boulder County last year.  This morning, the steady drizzle turned to sleety snow, and now we're faced with worries of an entirely different nature.

Here in Colorado, most of the domestic trees we've planted are exotics from more temperate climes.  They leaf out enthusiastically as the weather warms up for spring time, filling the air with pollen and the sheen of fresh chlorophyll.  We eagerly await the opening of Lilacs, the exhuberant pink and white of Apples in flower.  But there can be a downside to all these early-rising plants; storm damage.

Careful rigging made this removal of a Hybrid Cottonwood in Arvada, Colorado smooth and safe.  The tree was leaning directly over the house and had major limbs within 8 feet of the roof-line.  Opposite the house is a small Elm - this tree's replacement - which also couldn't be damaged during the removal.  Scroll through the slideshow and see how skilled use of heavy lines, large pulleys, technical felling and lowering devices got this potentially dangerous tree on the ground with NO DAMAGE to property or adjacent plant material, save a few divots in the grass from the large stems coming down at the end.  When a crane is cost-prohibitive or the tree is too far away from the front, rigging can provide the solution to conundrums like this Cottonwood.

Just another day working in trees, spiking up a moderately sized Cottonwood, right?

At several points during the day of this removal, I caught myself saying. "Yup, looks close enough."  I've reached a junction in my career where I've done lots of technical pruning and rigging over small drop zones or with valuable items underneath.  A few times when I've said "close enough," my plan hasn't been.  It only takes one limb carelessly dropped or one piece of wood caught by hand to break a plate glass window, crack a flagstone patio or to inflict a nagging injury on my own body.  The stakes are fairly high in arboriculture, and one "close enough" moment will effectively result in a wash on the day's work.  It can cost twice the price of a job to fly by the seat of your pants!

I'd like to think it's a kind of wisdom that led me, in the case of the Cottonwood above, to question myself every time I said aloud "seems ok" in the canopy.  For me (and for the homeowner) it was definitely worth taking even an extra half hour to set rigging to avoid breaking things on the property or people in the work zone.

There's a reason we carry liability insurance - miscalculations do happen - but an Arborist never wants to have to use that safety net.

This was an interesting one. I've been blessed to have some very cool technical removal experience in my past, but this one really took the title for most complex removal I've ever attempted. I have to thank everyone who trained me for helping me arrive in a place where I could even conceive of how to get this one done safely.  I also have to thank my awesome crewman, Tim, for his cool head and open eyes.

Hmm. Presents a bit of a conundrum, doesn't it?

There's not much of a drop-zone here.  The roof extends on all sides of the tree a minimum of 15 feet, and the tree is in the exact peak of the roof.  Lengthwise, the shortest distance from the stem is 20 feet.

I would have loved to have used a crane, but the cabin in question is on a hillside and the only remotely flat ground nearby is a septic tank and leech field. Hmm.

Bucket truck? The stem was a good 70 feet tall from the base, and the pieces of wood near the bottom weighed close to 300 lbs for a 24" section. Assuming you could get a truck close enough to work from, that's not exactly the kind of weight bucket truck manufacturers like to see lowered from their man lifts.

The solution (you all knew this was coming) was rigging. Creative, careful, adaptable rigging!

Phase one was a mobile zip line from the trunk of the tree to the ground below.  Tension was managed using a friction based lowering device by Buckingham called a port-a-wrap.  The line was held taut as the pieces fell onto slings attached to auto-locking carabiners.  As the piece rode closer to ground and clear of the roof, the line tension was released, allowing for a smooth, controlled landing.

We successfully dropped all the Ponderosa's limbs as well as a large amount of the stem onto the zip line without coming close to hitting the roof directly below.  All of our material landed about 30' away from the building, in fact, which I counted as a major win.

Phase 2 was much more complicated.  This tree was the largest in the immediate vicinity.  Everything nearby was much smaller, much shorter and much less stocky.  Nevertheless, we needed a place to put our lowering point to get the large pieces of the stem off of the tree.  In a normal situation, it would be easy enough to catch most of the wood on the stem itself by fixing the block below the cut.  In this case I wanted to be as certain as possible that the 300-pound or more pieces of green Ponderosa Pine would fall clear of the roof-line.  I didn't trust that once I got within 15' of the roof I would be able to stop the wood from smacking it.  One good tap had the very real potential to add up to repair costs that would have far exceeded my fee for performing the work.

This was one case where "close enough" was definitely not going to cut it.

So we got crafty.  I used two of the smaller adjacent trees as anchor points for a tyrolean traverse of sorts.  We set a high-line and tied an alpine butterfly knot to anchor our lowering block effectively in mid-air.  It took lots of patience, moving the block often to find the best location and adding as much tension as possible to the system -the whole time trying not to risk breaking the tops out of the anchor trees.

The floating block worked exactly as we intended it to.  We were able to get the trunk to within 8 feet of the roof line, and then used it (with applied mechanical advantage on the lowering line) to get the remaining portion of the stem felled without punching a hole in the roof.  The two day operation was an incredible success, and we proved that you don't need heavy machinery or a helicopter to deal with complicated situations like a tree growing through a roof.  What you DO need are rope and rigging skills, a very calm and efficient team, clarity and a heaping portion of patience.

This job was a real test for everyone involved, but the feeling of accomplishment at the close of day 2 was pretty incredible.  We'd gone from a 70 foot Pine in a horrible location to a stump right at the roof line.  Most importantly, there had been zero damage to the property, and both Tim and I were able to go home safely at the end of the project with nary a scratch.  These kinds of jobs can be stressful, and they involve a lot of planning and thought well in advance, but when they go well it's all worth it.  I was so happy at the end of the day to be able to tell my client the tree had come down and the house was still intact!

BIG thanks to Devin Chamberlain for the photos from Day 1, and even bigger thanks to Tim Davis for being a great rope runner and a standup guy!

Tree care is dangerous work. Arborists climb aloft, drop branches and wood and use sharp implements in close proximity to their own limbs and tensioned safety ropes. All of our systems are reliant on tie in points which resist engineering (there has never been a tree that came with a working load limit), and the safety systems we use are only as good as the person operating them. Throw in a dose of fatigue and you can see how accidents might occasionally happen.

As professionals, we do everything we can to avoid mishaps. If we're paying attention and using our best practices, arboriculture is safe and everyone goes home tired but happy. To this day I've never had to pluck myself or another climber from a compromised position (I'm knocking on wood as we speak).

But part of being safe is being prepared for the eventuality that something bad MIGHT happen. To that end, Arbor Roots's Caleb Jones and I hauled a 250lb bean bag mannequin 30 feet into a Siberian Elm several times this Saturday to practice Aerial Rescue scenarios. First he got stuck mid-canopy, unable to lower himself (our mannequin didn't have thumbs, it turns out), but his climbing system was still functional. I called an (imaginary) ambulance, strapped on my harness and headed up the tree to help out the hapless fellow. Maintaining verbal contact even with an unresponsive subject is important, so I walked him through my actions as I used my positioning lanyard to get control of his upper body and attach him to me. In that scenario, rescue was as easy as operating the subject's climbing system to lower him as I descended.  The lanyard kept me and the subject from swinging away from one another, and as we reached the ground I was able to gently lay him in a position the imaginary EMTs could work on him in.

From there, things got more complicated. He got stuck on ascent THREE TIMES (bean bag persons also don't have much in the way of stamina for foot lock climbing, evidently) and Caleb and I had to improvise pick-off systems with what we had on hand. In a pick off scenario, the stranded climber must be lifted because he's stuck on a bound ascent system or because his lines have been compromised by cutting, tangling or breakage. Our 250lb friend had to be hoisted 8" or more in midair so he could be attached to my climbing system and released from his jammed klemheist. Since I weigh 145lbs soaking wet in boots and a jacket, I needed some mechanical advantage. Thankfully, all I needed was my handled ascender and a few carabiners to construct an effective 2:1 haul system. Thank goodness for physics!

Around sunset our heavy, floppy friend was safely on terra firma and Caleb and I had refreshed some valuable skills we hope we never have to use. Aerial Rescue is like the safety belt in your car. The vast majority of trips are blissfully uneventful, but the one time something goes wrong it comes in handy. It was a Saturday well spent, even hauling a 250 pounder repeatedly 30 vertical feet, for the peace of mind in knowing that IF the unthinkable occurs, I have the necessary aptitudes to get someone quickly and safely to the ground where they can receive the care they need.