When 1,000 trees aren't equal to 1,000 trees: the Sewer District's fuzzy math

In 2019, Cuyahoga County issued an update to a 2013 Urban Tree Canopy Assessment. The update found that, "despite concerted efforts in many local communities to increase tree canopy," over the years 2011-2017 the county's tree canopy had suffered further decline from 37.0% to 34.7% of total land area.

A supplement to the update, prepared by a forester with the Ohio Department of Natural Resources, included this interesting statement: "A healthy 50-year-old sugar maple will sequester 120 times the annual amount of carbon of a 10-year-old tree. Tree crowns start to have an impact on cooling as they begin to fill out, between 15 and 20 years of age. Therefore, planting trees will not change canopy cover benefits for two to three decades. Consequently, a tree planted in 2020 will have little or no impact on the canopy until 2040 or 2050."

Remember that as you read the rest of this post.

The revelation that the Northeast Ohio Regional Sewer District (NEORSD) "restoration" plan for Horseshoe Lake Park would remove over 1,000 trees, most of them healthy native trees, and that this information was kept hidden from the public until the plan was finalized, has sparked enormous community outrage. On April 6, concerned community members packed a Cleveland Heights city council meeting to speak out in support of saving the Shaker Lakes, and many of them specifically cited the trees as important.

The standard response from both the Sewer District and city elected officials to complaints about the trees has been that the plan will also plant 1,106 new trees. (Note: I actually feel sympathy for the newly elected officials who weren't responsible for approving the plan and now feel an obligation to defend this bad plan and the indefensible process through which it came about.) A recent project implementation FAQ, in the section about new plantings, states, "Trees: 1,106 (1", 2" & 4" caliper)."

It's very obvious that a sapling is a paltry replacement for a mature tree. We all know that. But it's actually even worse. The tree replacement is even more laughably inadequate than these numbers would lead you to believe.

The complete plan calls for removing 1,070 trees that were tagged in NEORSD's tree survey. It groups those trees by their breast height diameter (diameter of the trunk measured 4.5 feet off the ground, a term that is basically synonymous with caliper when describing tree size). This information tells us that the tree survey only covered trees that were at least 3" in diameter.

I took this picture in the woods near the dam:

There are a lot of trees in this picture. Very few of them have tags, because most are too small to have been tagged. Only those that do have tags would be included in the count of 1,070 trees to be cut down. But this picture was taken in a section of woods that's going to be completely razed: 

"What's the big deal?" you might ask. "Those extra trees are so small."

Okay, apply that logic to the trees that are being planted.

The rebuttal to complaints about removing over 1,000 trees, in which it's stated that 1,106 trees will be planted, is clearly meant to say, "Look, we're planting more trees than we're cutting down!" But this simply isn't true.

In order to say that the number of trees being cut down is smaller than 1,106, we have to use a definition of "tree" that's restricted to trees of at least 3" in diameter.

What happens if we apply the same definition to the trees being planted? If the definition of "tree" is "tree that's at least 3" in diameter," how many such trees are being planted?

Want to try guessing?

Well, the answer is...

Wait for it...

46.

Yes, of the "1", 2" & 4" caliper" trees being planted, the plans call for just 46 to be 4" caliper. We can see this in the page about plantings from the 100% design document (the quantity numbers for trees of size 4" sum to 46): 

(As I understand it, trees that say "6-8' HT" under "size" are the 1" diameter trees. Apparently the smaller trees are listed by height. I checked some listings for some of these tree species to confirm 1" caliper typically corresponds to 6-8' height.)

To verify that I'm interpreting this document correctly, we can also look at planting maps from NEORSD's presentation to the city planning commissions. On the "cities-funded plantings" slide, there are exactly 46 large green circles representing 4" trees:
 

 

On the "District-funding plantings" slide, there are zero such trees:

 

 

If someone tells you they're going to plant over a thousand trees in a park, and the trees will include one inch, two inch, and four inch diameter trees, you probably wouldn't guess that just 4% of those trees would be four inches in diameter and the other 96% would be the even smaller trees.

 

This is similar to how if someone tells you they're going to restore nature in a park, you probably wouldn't guess that they're going to cut down over a thousand trees in said park. But here we are.

 

You can't have it both ways. Either trees smaller than 3" in diameter count, or they don't. I'm not asking for those awful metal tags to be added to all the smaller trees that are going to be cut down, but we should at least get an estimate of the actual number of trees to be cut down, which is at least several hundred larger than the tree removal number we've been given. Otherwise, just tell the truth about the numbers you have, and say, "we plan to cut down over 1,000 trees that are at least 3" in diameter, and we plan to plant 46 trees that are at least 3" in diameter."

 

A four inch diameter tree is still a small tree. One or two inch diameters? Those are tiny. 

Over half of the 1,070 trees that are marked for removal are at least ten inches in diameter. Over half of the trees to be planted are just one inch in diameter.

 

A tree that is ten inches in diameter has a trunk with 100 times the cross sectional area of a trunk with a one inch diameter:

 

The average cross sectional area of trees to be planted is about 2 square inches. The average cross sectional area of the tagged trees they're supposed to be replacing is about 280 square inches, about 140 times larger. (That's just looking at the difference in cross sectional area; the difference would become larger still when you account for the removed trees being much taller and having more branches.)

 

That is, the trees that are being planted to supposedly replace the 1,000+ trees being cut down are less than 1% of the size, and it will take many decades before they'd have a chance of catching up, if that ever happens at all. (Remember: A healthy 50-year-old sugar maple will sequester 120 times the annual amount of carbon of a 10-year-old tree. A tree planted in 2020 will have little or no impact on the canopy until 2040 or 2050.)

 

 

And to be clear, I'm not saying that if a much larger number of trees were being planted, it would make things significantly better. I'm pointing out the sheer impossibility of making up for this large-scale removal of mature trees with new tree plantings.

It's hard to express just how insulting it is that, in response to complaints about cutting down over 1,000 trees (something that was covered up until after public engagement was over and the plans were completed), we're just fed this line about planting 1,106 trees with no acknowledgement of how utterly inadequate the new trees would be as a replacement for the trees being removed. And no attempt to explain how the supposed benefits of the project could outweigh the costs of losing all those trees. Instead, the loss of hundreds of mature native trees is just handwaved away.

Look, I'm all for planting a bunch of native trees and other native vegetation. That sounds great. What if we did that, and didn't cut down hundreds of mature native trees?

Joseph Charnas, one of the members of the public who spoke at the April 6 council meeting and whose words really stood out to me, said this (click to see his remarks in the meeting video on YouTube):

"I volunteer with the Heights Tree People. I do not speak on their behalf by any means, but I try to volunteer with them a few times a year. They're a wonderful group if anyone is looking for something to volunteer with. Since they've been in working order they've planted 1,200 trees across the Heights. And that is all for naught when all of these trees are cut down and replaced with saplings that no one in this room will ever see grow to maturity. So, I speak just for the trees, I guess. Thank you." 

The fact that an unaccountable public utility would go forward with a mass tree removal plan for a public park despite widespread public outrage, and would in one fell swoop effectively wipe out all the future benefits of all those trees that all those hard-working volunteers have planted, is outrageous.

It also breaks my heart.