My Latest Column on Heirloom Plants

Grandmother’s Garden. A cozy cottage nestled in Nature’s embrace. Bright flowers lean against the foundations, tree canopies envelop the roof; vines reach for freedom, yet order prevails. Sweet pea. Painted Lady. Canterbury Bells. Four-o’clocks. Jacob’s Ladder. Lamb’s Ear. Where else but an old-fashioned heirloom garden would you find flowers named as vividly as the blooms themselves?

O Tannenbaum or Why Am I Buying a Christmas Tree?

Winter came hard to central Indiana during my fourth grade year. Sometimes that happens. Like the state itself the winter isn’t flashy, it’s solid. I always wanted autumn to fade gracefully into a winter wonderland. Instead it would come with cold November rain, wind and rain that would lash the dead leaves and lay bare a thicket of dark gray trunks and branches.

Even harder than the winter that year was my fourth grade teacher. It was a new school for me and things weren’t going well. I was widely criticized for a diorama I made and brought to class that included a lake with real water. There were unforeseen technical problems.

And then there was my desire to join the FBI, which led me to experiment with fingerprinting. I had a theory this could be accomplished by taking apart a ballpoint pen. I proved my point but there was collateral damage to a brand new beautifully illustrated library book about the plains Indians.

Just like the winter my punishment was harsh. No mercy, I was headed to the big house. I waited on Paddlers Row for 45 agonizing minutes before the Principal commuted my sentence to a few stern words and an admonition to behave myself. I eagerly accepted his terms.

Even with the dim self-awareness a ten year old, I knew I’d never make it to Memorial Day. I’d be staring down a paddling machine before the year was out. I needed to suck up to the teachers and some how claw my way up the rigid fourth grade social structure. Salvation came in the form of a Christmas tree.

The teacher broke the sad news to us on a gray November afternoon. This year the North Madison School couldn’t afford Christmas trees for all the rooms. No tree. No canceling math class to decorate the tree. No dazzling brightly lit tree to stare at blankly while the Mr. Khepart droned on about fractions and the worst common denominator.

There would be no tree unless “. . . one of your parents grows Christmas trees?” No one raised a hand. I saw my opening and took it. “We live next to a big woods” I said. “That’s where we get our tree and I’ll cut one for the class too.”

I sensed old Lead Bottom was skeptical but I was dead serious. I was going from zero to hero come Monday morning. On a cold Saturday afternoon I set off alone in search of the perfect Christmas tree.

Trees that are forever green hold a special place in the human heart. While the fields lie fallow and the land lies frozen, evergreens remind us spring will come again. The Egyptians, Romans, Druids, and Vikings festooned their temples and dwellings with the boughs of evergreens.

They filled their homes with evergreens plants to mark the winter solstice, the year’s shortest day. It represented the triumph of life over death. Plus, a few well-placed branches could keep away witches, ghosts, evil spirits, and illness.

The story of the Christmas tree begins with the deliberate cutting of a venerated oak tree in 723 A.D. No doubt Saint Boniface has gone to the local planning council and obtained a permit to remove the sacred tree of Thor. Legend says he replaced it with an evergreen fir tree a Tannenbaum, a symbol of both the Holy Trinity and eternal life. I expect the real story is that the planning council required him to plant a new tree as a condition of approval for his permit.

Must have been a big oak tree because Saint Boniface is said to have built an entire chapel with the wood. Planting of the little tannenbaum marked the beginning of the Christianization of tribes in northern Germany. For the next 718 years not much happened. Coincidentally, not much happened with Christmas trees. About 1441 the Brotherhood of Blackheads erected a tree in their brotherhood house. From Estonia the tradition has taken off to become what it is today.

It started long ago with an evergreen bough over the door. Next came a whole tree. Wasn’t long before people started hanging fruits and nuts on it. Some say candles were inspired by the twinkling stars Martin Luther saw as he walked through the forest on a cold winter night. Last year I got a little John Deere Tractor ornament for my tree. Somehow all these things are connected.

Unlike Saint Boniface, I didn’t have a permit or even permission when I set out in search of my salvation. The woods weren’t technically our property. It wasn’t legally our property either but I knew Mrs. Owen was old. She was probably pushing sixty and the odds of her being out there with a shotgun were low. If I could avoid the bull and any other grown ups I should be OK.

We lived in rural farm country where the glacier-flattened cornfields of northern Indiana meet the limestone hills of southern Indiana. Behind our house the land dropped off quickly into a low wet forest. Far away, on the other side of the woods where the land flattened into fields and pastures I knew I would find the perfect Christmas tree.

Once down the hill I crossed the creek with a run and a leap and took the short cut to Paradise Pier. Beside the sandbar I took Fallen Log Bridge across big creek. That’s where the easy travel stopped. I was leaving my territory and out of my comfort zone. I got a later start than I should have. Was it getting dark? Glancing at the sky I couldn’t tell how much light I had left. I pressed on; without that tree I had no future.

I emerged from the woods on the edge of an old pasture. Gray sky, light wind, only dead grass and trees as far as I could see in all directions. No sign of a gun toting Mrs. Owens wearing sensible shoes.

Coming over a rise I saw the cattails first and then the dark green shapes of Christmas trees! Beautiful, perfect Christmas trees. Not wanting to exaggerate my exploits I recently checked this area using Goggle Earth. I can report that Goggle Earth is wrong. I know it was more than 200 yards even though at that time my legs were shorter and my imagination bigger.

The crushed boughs of Eastern Red Cedar will fill any home with the smell of Christmas. It stays dark green for weeks and doesn’t dry out and drop litter. It also doesn’t have needles. It is a type of juniper. When I proudly brought my Christmas saving tree into the classroom the kids laughed at it. “That’s a bush! That’s not a Christmas tree!” The children explained with refreshing candor.

That was a strong dose of reality for a ten-year-old boy. If I’d had an Internet search engine at the time I could have pointed out that the Eastern Red Cedar is the 6th most popular Christmas tree in America. Plus it was free. Plus it beat the heck out of math class!

For Americans, the Christmas tree in the home is a tradition that goes back to about the start of the twentieth century. For most of my fourth grade classmates it was a tradition three generations old yet some very rigid opinions had been formed. Some liked firs, others liked pine trees. None us knew what a blue spruce was.

Home Christmas trees might be new but the human connection to evergreens goes back eons. In the darkest coldest days of winter they inspire hope. The world isn’t dead, it’s resting. Spring will come; life goes on.

Like most ten year olds I quickly rebounded from my humiliation. After the janitor unceremoniously tossed out my perfect Christmas tree, somebody donated a short fat pine. I went through tree counseling and over the years came to accept pine trees and fir trees and blue spruce as legitimate Christmas trees. I even embraced the silver tinsel artificial trees with the rotating light disk.

Maybe old sourpuss felt sorry for me because I made it through the year with little more than a few harsh words. Maybe any kind of Christmas tree can make you a better person. Having one in the house sure made me a better kid.

Heirloom Gardening – Unedited

What’s an heirloom? Something handed down. A watch maybe? A diamond ring? Your grandmother’s old clock, which somebody else broke, and you got blamed for? The thing that defines all heirlooms also distinguishes each one: its story. The story might be simple like who gave what to whom but it’s usually a lot more interesting because heirlooms are a gift of value and an act of love. What’s an heirloom? Something you don’t mess around with especially if somebody else already broke it.

What’s an heirloom plant? Now that’s asking a really hard question. Like other relics, heirloom plants are handed down. They have a story, a legacy. Unlike other heirlooms you don’t always get these from family members and they aren’t always gifts. You can buy these old fashioned plants at your local garden center. You can find their stories in books and on websites. Nurseries do a brisk business selling the latest old plants.

Seed and plant sellers use the term heirloom to describe old-fashioned plants grown before 1950. These plants continue to give season after season because you can harvest the seed and replant them. You can’t harvest the seed from modern hybrids they’re sterile but a forgotten patch of heirloom nasturtiums will suddenly reappear in spring. Those creamy orange and red blossoms are a gift from last season, an heirlooms’ heirloom.

Heirlooms are the plants that grew in your grandmother’s garden. They are the same plants that grew in the bungalow garden. These are the plants that graced the cozy cottage nestled in natures embrace. Relaxed plants like sweet smelling verbena spilling onto a pathway or wisteria hanging from an arbor. They had gigantic watermelons too. Remember those? Took two men to move them. We didn’t mind picking out those brown seeds cause you could shoot them at your sisters by squeezing them between your thumb and finger.

Parents used the cutting of the melon as extortion to make kids behave at a picnic, as in “Get outta’ that creek or you won’t get any watermelon!” Today’s parents sometimes have to threaten legal action to get kids to eat those seedless melons from the grocery. If you can remember back to when the promise of eating watermelon was enough to get a kid out of a creek then you can probably remember when heirloom plants were simply called plants.

1950 is the arbitrary cut off date for heirloom plants but the change happened gradually. Humans have bred plants for thousands of years. By 1850 physicians, scientists and Augustinian monks were systematically studying the natural world and publishing their ideas in tracts and pamphlets. There was an eager market for knowledge, after all plants were both food and medicine.

After a hundred years of Industrial Revolution, the Victorian English found themselves with something new, leisure time. Time was a luxury not to be wasted. Pamphlets in hand they threw themselves into gardening with a passion. In America, gardening was one of the few acceptable hobbies in Puritan and Quaker communities. But whether the breeders were amateurs or educated professionals they didn’t understand genetics. Mendel hadn’t finished tending his peas. As a result, heirloom plants are a bit more finicky.

By 1910 scientist were breaking the genetic code. At the time all those A&T universities actually did agriculture research. Seed companies used the research and expanded. In 1930 the Congress made it legal for companies to patent their new plants. Gradually patents made backyard breeders obsolete. 1950 is the cut off date for heirlooms because about that time plants changed rapidly and dramatically.

By 1960, when my family moved to our new home near Mooresville, Indiana we grew the new modern hybrid vegetables. Jetson vegetables. In the 1960’s we’d buy anything that was “new and improved”. With flowers it was a different story. They were mostly holdovers. They were heirlooms after all.

I don’t remember my Mother ever buying a plant but our yard was full them. Plant lovers love to share plants. She got her plant sharing tradition from her southern roots. We had Mrs. Kenworthy’s white peonies, Mr. Mountain’s bright red ones and Aunt Bertha’s brown and yellow iris. Mother’s garden is filled with heirloom plants, heirlooms in every sense of the word. Now I understand why she got so mad when I used to mow them down. “Those were flowers? I didn’t do it. I think Kevin cut those.”

One reason my Mom’s heirloom plants grew so well is that like them we had a limited range. There’s a limit to how far you can drive a ’57 Ford Fairlane with five adults and nine children and still make off with half your hosts backyard. Ever lose your seat to a clump of brown and yellow iris? They have laws against that now.

Why should heirloom plants have a limited range? They don’t all have a limited range but many do. That’s because the plants (mostly the vegetables) were bred by people in far-flung places and thrived in that specific location. They were bred for size and taste but often lacked the vigor to grow when the growing got tough.

Since starting this article I’ve asked about a dozen colleagues about heirloom plants. Their faces light up. Yes they’ve heard of them, they planted some last year! And how did they do? A little crestfallen here, well, not so well. They died. Or they produced a strange growth. Across the board they are eager to try again.

These are all experienced gardeners but they live in California. Many popular heirlooms were bred on the east coast. Out here we have different soils, less rain, lower humidity, even different pests and diseases. We also have spectacular heirloom gardens but with plants well adapted to the California lifestyle.

The popular heirloom tomato ‘Radiator Charlie’s Mortgage Lifter ’ was bred for a valley in West Virginia but sold everywhere. This season’s big seller is the Black Krim from the Crimea. Even experienced gardeners have to recalibrate their thinking. Heirlooms aren’t like Big Macs, the same from coast to coast.

Find a plant that will tolerate your gardens conditions and stay on top of it. One plant doesn’t fit all sites and you can’t plant and forget. Know your site. Find heirloom plants that interest you and will grow in your valley. Be willing to invest the time to tend and monitor the plants.

Heirloom plants and bulbs are a perfect fit for the bungalow garden. Used well they create a relaxed, informal look. They punctuate a landscape with splashes of color. The growth of new flowers marks the changing season. “The marigolds sure are looking good. Better clean up the grill for the 4th of July.” [Could use a Labor Day reference here]

What’s an heirloom plant? It’s an old fashioned plant with a story. It might be an annual that rewards your attention by returning year after year about the same time. It could be your great grandmothers vine ripe tomatoes or a melon so juicy you have to change your shirt after you eat it.

If you only remember one thing about heirloom plants remember this, know exactly where there are if you’re gonna mow the grass.

The End

Where Are All the Camperdown Elms?

What’s the best tree for your bungalow garden? Based on name alone, the Camperdown Elm has to be in the running for Most Romantic Tree. Feels good just saying it. The weeping branches conjure up visions of a child’s secret garden; safe in its embrace, peering through the leaves, a sanctuary from life’s harsh words and sharp edges.

But digging a little deeper, the story of the Camperdown elm takes a decidedly un- romantic turn. Around 1840, a gardener for the Earl of Camperdown was walking through the woods in Dundee, Scotland. There he came upon a gnarled sprig growing along the forest floor. In this age of Victorian curiosities the gardener spied an opportunity.

How do Professionals Select Trees?

Of the 1517 trees that grow in California how can you pick the best trees for your project? When I started specifying trees in southern California most landscape architects called The Western Garden Book the bible. Today we have something almost as good as divine guidance, we have a searchable data base.

A searchable data base is an interactive program that lets you sort trees based on criteria you select. There are several of these search engines which I will describe shortly. But first, of the dozens of tree characteristics you can chose from which do you start with? Which will help you whittle down that list to a manageable number of choices? I start with three criteria:

  • Will it grow in this climate?
  • How much water does it need?
  • How big will it get?

WILL IT GROW HERE?

How do you know a tree that will grow on your site? By climate zone. Most of the country does this using the USDA Plant Hardiness Zone Map. It predicts which plants will grow where based on minimum winter temperature. It works well in flatter continental areas but not out west. That system puts the Olympic rain forest in the same zone with parts of the Sonoran Desert.

Given our unique compartmentalized terrain, we needed a system that includes “a broad range of factors such as cold, heat, humidity, wind, proximity to the Ocean, snow and length of growing season.” (Sunset. p. 17) Sunset introduced the West’s climate zone maps in 1954.

Always know your climate zone. Experts look it up. At least they should but as the cold snap of 2007 illustrated that doesn’t always happen. After a decade of mild temperatures some plant specifiers were left red faced when insurance adjusters pointed out that dead trees were planted out of zone.

ABOVE: Sunset. “Sunset climate zones: Los Angeles region” 2015. August 12, 2015.

In southern California a few miles can make a huge difference. Here at world quarters out on the far edge of Ventura we have a blend of zones 23 and 24. Perfect weather. Ojai is just ten miles away but separated from us by four climate zones. When using a searchable database start with the trees that grow in your Sunset climate zone. That’s your first criteria.

Above: Ventura, CA – Zone 24 – Quercus agrifolia, below coast live oaks – May 2015

Above: Ojai, CA Zone 20 – Quercus agrifolia, coast live oaks – May 2015

HOW MUCH WATER DOES IT NEED?

In California knowing how much water your trees need is critical because that will limit the shrubs and groundcovers you can use. All the plants in a given irrigation zone (valve) need to share the same water needs because they share the same water. The University of California has built a searchable data base that is really simple to use. Just pick your city and quickly get a list of site appropriate trees, shrubs and groundcovers grouped by water needs. This is WUCOLS IV with the classifications you need to comply with state law.

If you have a project in Thousand Oaks go to the website and select your city under the South Coastal dropdown menu. That takes you to a page where you can generate a list of the 215 “Low” water use trees that will grow in T.O. You have answered both your first and second critical questions with one data base query.

Above: The University of California has built an excellent searchable data base

HOW BIG WILL IT GET?

When specifying a tree pretend you live in a small apartment and you are getting a puppy. No matter how cute it is you have to ask, “How big will this thing get?” Too big in the photos below. You can search for trees by size using SelecTree hosted by UC San Luis Obispo.

Above: screen grab from SelecTree foretells trouble ahead for these fig trees.

Above: screen grab explains why this sycamore looks like a knight in a Monty Python skit.

Once you know your site’s climate zone and your desired water use you can use SelecTree to find trees that are the right size. If you are honest the list will be shockingly short. It takes some experience and judgment but if you don’t do it those puppies are liable to get huge and you will be whacking away at it like it’s a medieval knight piñata at a Monty Python festival.

In out hypothetical project above we were looking for low water use trees for a project in Thousand Oaks. That’s Sunset climate zone 21. If I search SelecTree for trees that grow in zone 21 and are less than or equal to 35 feet high, it returns a list of 592 trees. If I add “Soil Moisture Dry” I get a list of 216 trees (recall WUCOLS IV listed 215).

That’s still a lot of trees but we’ve taken our list of 1517 trees and found 216 small to medium size trees that will grow on our project site with little water. When it comes to tree size you also need to think about the canopy shape and branching structure. If the space is tight you might want to do a massing study like the one shown below.

The most important lesson I have learned specifying trees in southern California is that experts look it up. The web has excellent free resources to help. You can begin to create a manageable list by answering these three critical questions:

  • Will it grow in this climate?
  • How much water does it need?
  • How big will it get?

In future posts I will discuss some techniques I use to further refine my choices and pick the perfect trees for each project. But next time I will be asking that burning question: How much are my trees worth? Like Madonna said, it’s a material world.

John Burke, Ventura, CA August 2015

Kathleen Brenzel, ed. The New Sunset Western Garden Book (New York: Time Home Entertainment, 2012).
Agricultural Research Service. “USDA Plant Hardiness Zone Map.” 2015. Aug 12, 2015.
University of California. WUCOLS. “Plant Search Database.” 2015. Aug 13, 2015
SelecTree. \“SelecTree: Search Trees by Characteristics.” 1995-2015. Aug 13, 2015.

How Much is that Shade Tree in the Window?

If you want to develop property in southern California you need to know the dollar value of your trees. This is true whether you are building senior housing in Oxnard or remodeling your garage in Thousand Oaks. Trees grow slow in the arid west making them precious and valuable. Your mature oak tree might be worth several thousand dollars and if you want to cut it down you will have to pay.

Above, in Hong Kong a developer spent $3 million dollars to save this Banyan Tree (Ficus retusa). Is it the most valuable tree in the world?

F. Scott Fitzgerald himself could not write an interesting blog post about tree appraisal. So let’s just cut to the chase shall we? If you are getting a tree appraisal report what do you need to know to review it? There are several points in the appraisal process where your arborist should exercise sound judgment and render an expert opinion based on evidence. Errors in judgement can cost you thousands of dollars.

If you have built anything in California recently you were probably asked to get a “tree report” and if your plans required removing any “protected trees” you had to have them appraised probably using the “Trunk Formula Method”. The trunk formula attempts to measure the value trees add to a piece of real estate.

For small lots with a few native coast live oaks the value of the trees can be tens of thousands of dollars. For larger commercial sites the value of the trees can easily run into the hundreds of thousands and much more if mature native oaks are involved. Whether it is a bigger garage or a housing development the value of the trees on the land is a big consideration in the overall development budget especially if they are protected by a local government.

Above: I recently appraised a large coast live oak like this one for $10,000

The trunk formula has been around since at least 1905 when a University of Massachusetts professor created it to place a value on “shade and ornamental trees”. It is one way of looking at tree value. The trunk formula method is considered a “cost approach” to value rather than an income approach like you would use for timber.

The Trunk Formula Method has been revised over the years. It was adopted by the National Arborist Association in 1957 and since then it has become the industry standard appearing in the Guide for Plant Appraisal which is in its 9th edition.

Most local governments want an appraisal done by an arborist certified by the International Society of Arboriculture (ISA) and some ordinances specify that the Trunk Formula Method be used as opposed to the other cost approaches described in the guide such as Replacement Cost, Cost of Repair, and Cost of Cure.

These types of appraisals are usually based on cancel checks or signed contracts. They are the appraisal methods that the Internal Revenue Service wants to see if you are claiming a loss on your taxes. The IRS doesn’t care about the birds and bees just the dollars and cents.

Unlike these more objective methods of appraisal, the trunk formula attempts to measure all variables that are believed to make up the totality of a given tree’s value.

The trunk formula is a combination of objective and subjective variables. The size of the tree is the starting point, specifically the cross section of the trunk measured at 4.5 feet above ground. When you actually measure a tree at 4.5 feet you will see that even size is not as cut and dried as it sounds. Other variable are more subjective. For example the formula allows the appraiser to consider things like air purification, noise attenuation, aesthetic contribution and wildlife attraction.

If you are receiving or reviewing a tree report it is helpful to realize that the variables can be sorted into three categories:

  • Variables the arborist measures in the field
  • Variables the arborist looks up in an official publication
  • Variables scored by the arborist based on evidence in the report

Example: coast live oak (Quercus agrifolia) with a 24” DBH

To show how these three categories work let’s take an example of a tree with a two foot diameter trunk. This is often abbreviated DBH for diameter at breast height. This is because most arborist are like me, lazy. We don’t like to bend over if we don’t have to so we measure trees at breast height or 4.5 feet above ground. Been going on a long time.

Above: I use a flexible tape to measure the circumference of this coast live oak 4.5 feet above grade (DBH).

In our simple example the tree has a two foot diameter trunk. That means it has an area of 452 square inches. If it was a relatively fast growing tree like an oak or alder then I could look up its cost per square foot which is $62. I look up that cost in the regional supplement for Southern California. That gives us a starting point, called a Basic Tree Cost of $28,000. If this had been a slower growing tree like a camphor it would be worth $84 per square inches giving it a Basic Tree Cost of $38,000.

The appraiser adjusts that initial Basic Tree Cost by multiplying it by the Species Rating which is a percentage looked up in the regional supplement. A committee of regional experts sorted the various species into five groups. Oak trees are in the 1st group and have a Species Rating of 90% so I begin by multiplying the Basic Tree Cost by 90% reducing the tree’s value to $25,200.

If we had chosen an alder tree for our example it would not be so valuable because the regional committee of experts place alders in group 3 with a species rating of 50%. After adjustments for the species a two foot diameter alder would be worth $14,000.

So far the appraisal has been based on objective variables that are fairly easy to measure or look up in a table. The next adjustment is based on the “Condition” rating of the tree. It is called condition because it is a measure of both health and structural integrity. The arborist scores this variable on a 25 point scale.

Most trees in landscapes are NOT in excellent condition. Trees are meant for the forest where their branches grow all the way to the ground or they are surrounded by their friends and no one steps on their tender absorbing roots.

When scoring Condition, arborist award up to 5 points each for roots, trunk, branches, twigs and foliage. Of the thousands of trees I have appraised most score in the 60 percent range. That adjustment would reduce the value of our example oak tree to $8,400.

These Condition scores should be included in your report perhaps as an appendix.

The last variable affecting the value of our tree is based on the arborist assigning a score to three components that make up the “Location”. Location is the average of the “Site”, “Contribution” and “Placement” percentage ratings.

Unless you have a very large property the site rating should be the same for all the trees being appraised. After all the trees are on the same site. There are criteria given for rating sites but much is left to the discretion of the appraiser.

Photo: I rated this site in the bottom third.

In my reports I usually devote a short passage to describing the site. Experience creates a certain level of comfort with shorting sites into thirds meaning is this site one of the best third, the worst third or somewhere in the middle?

Photo: I rated this site in the top third.

For our example let’s assume our site is in the middle third and give it a percentage of 60%. That gets averaged with the “Contribution” and “Placement” scores for each individual tree. These scores should be shown in the report because they are key components of the trunk formula. If you have fifty trees on a Site they should not all have the same contribution and placement scores. If they do you should ask your appraiser why.

For our example oak tree let’s say I rate its contribution 80% and its placement 85%. Those ratings combined with the 60% site rating give us a Location rating of 75%. Adjusting the oaks value for Location reduces its appraised value to $6,300.

Above: this pepper tree makes a nice contribution but the placement is not so good.

A new 10th edition of the Guide for Plant Appraisal is being reviewed right now. I will discuss the changes in a future blog post.

John Burke, Ventura, CA September 2015

The most expensive tree in the world? GardenDrum May 27, 2013, Copyright 2014 GardenDrum AU. 8/28/2015. http://gardendrum.com/2013/05/27/the-most-expensive-tree-in-the-world/

Council of Tree and Landscape Appraisers, Guide for Plant Appraisal, 9th edition (2000). International Society of Arboriculture, Champaign, IL. 2000.

Species Classification and Group Assignment, A Regional Supplement. Western Chapter of the International Society of Arboriculture. 2004.

Saving Trees During Development

Which Trees to Save? Industry Standards and Best Management Practices can help you make smart choices.

Is it Possible?

Above: code said 36” path of travel, the city (T.O.) said save the tree.

Recently a client was directed by a design review committee to “save as many trees as possible.” He came to me to ask what was possible. Fortunately there are industry standards to guide us.

The written standards and best management practices are voluntary. These are consensus standards representing scores of organizations like the USDA Forest Service, Davey Tree, ISA, ASLA and many others.

The standards and BMP’s help arborists and landscape architects decide when to hold ‘em and when to fold ‘em. Any tree can be saved given a big enough budget ($3 million for a Hong Kong Fig tree). The question isn’t what’s possible but what is feasible? What makes sense?

One of my favorite tools when deciding which trees to preserve is a 100 point evaluation guide in Fite’s BMPs. (p8) This guide helps me rate trees in eight categories that predict long-term survival or rapid decline.

General Conservation Suitability Worksheet

  • Distance from Trunk to Root Cut/Fill
  • Health
  • Defects
  • Construction Tolerance by Species
  • Age (Relative to typical lifespan)
  • Distance from Trunk to Construction
  • Soil Quality/Tolerance
  • Species Desirability

This worksheet can save time by focusing your attention on the trees that are close calls. Using an electronic spreadsheet, you can quickly sort out which trees are sure to go and which are likely survivors.

General Conservation Suitability Worksheet + Plus Appraisal

Above: the potential for long-term survival compared in a spreadsheet.

By the time the arborist or landscape architect gets involved the engineer has probably already made the decisions that will determine the fate of most trees on the site. Trees growing in the footprint of proposed buildings and streets can’t be preserved in place and unless they are extremely valuable specimens, it seldom makes sense to move them.

A tree appraisal can help when deciding the feasibility of moving a tree or altering the site plan. An appraisal method like the Trunk Formula values a tree by taking into consideration all of the contributions a tree makes to a given site. If a tree is worth $200 that’s an easy decision. If a tree is worth $50,000 it deserves more scrutiny.

If the engineer or architect knew the value of the trees up front, it could help them design the site. I use AutoCAD to analyze the high value, close call trees like the cedar in the screen grab below.

Using Cad to examine is it possible?

Above: CAD analysis needs an accurate survey.

Conservation Suitability Spreadsheets and CAD analysis are excellent guides to help owners, planners and designers decide what is feasible when it comes to tree preservation. But sometimes even experts can’t tell what will happen until you open the ground and see the roots.

It was feasible

Above: five years later the sycamore is still shading the playground.

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