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What is the real status of Seattle's "urban forest?" Do we have fewer trees than we used to, or are the figures quoted by the city of Seattle bogus – a case of comparing arboreal apples and oranges?
Blogger David Sucher questions some numbers I quoted in my recent story about the sad state of the city's tree canopy. On his City Comforts blog, which focuses on urban design, he said some of the numbers were "dubious" and warned that "we should beware governments (and gullible echo-chamber journalists) offering 'facts.'"
The basis of his criticism is that he finds the contention that Seattle's tree canopy has diminished dramatically in the past 35 years hard to believe:
For anyone who has lived in Seattle for the past 40 years and has been watching the physical environment, it's not credible that "Thirty-five years ago, tree canopy covered 40 percent of the city. Today, that's down to 18 percent."
I agree that the number is shocking, but those are the numbers cited by the city in its 2007 urban forest plan [4.2 MB PDF].
Sucher speculates the deforestation numbers are exaggerated because they come from a 1998 American Forests study that covered the greater Seattle metro area and that deforestation outside Seattle has skewed the numbers. He suggests that the numbers for Seattle proper – within the city limits – would not be as bad.
I've been in touch with the city's senior urban forester, Mark Mead, and asked him for clarification on the numbers. Here's what he's told me so far.
First, the city stands by its estimate of the current canopy in the city which is 18 percent – less than half of what is currently recommended for cities like ours. That number refers specifically to Seattle proper, not suburbs and outlying areas. The estimate is not only based on the 1998 study of the Seattle metro area study and a more detailed study in 2000 using LIDAR – which is a high-tech way of measuring topography using light (lasers) instead of radio waves (like radar). He calls the method "highly accurate." That forms the basis for making estimates and canopy models. Those are augmented by other tree data. For more on the city's tree-counting and canopy calculating methodology below, see the footnote below.
The next question is, what was the canopy like in 1972? Unfortunately the city can't retroactively apply its more detailed current methods, so the earlier data is derived from a 1970s satellite survey of the region.
When I pressed Mead, here's what he said:
Today, we know that about 18% of the city is covered by tree canopy. In comparison, past research found that the greater Seattle area had about 40% just 35 years ago. While the improved accuracy and scale of data between these two estimates makes direct comparisons fuzzy, it is fair to say that the number of trees in Seattle has diminished rapidly. Without more accurate information from the past it is a fair estimate to say we have lost over a million trees worth of canopy in the last 30 years.
So the bottom line is that Mead is confident of the current canopy estimate, which measures Seattle proper, and that he believes tree-loss has been substantial since the 1970s.
But Sucher is correct that the 40 percent to 18 percent canopy comparison is, in effect, an apples to oranges comparison. The methodology has changed with time.
So is the trend in the ballpark or is it outrageously overstated? If you accept the city's current, and supposedly more accurate, estimate that there are about 1.4 million trees in Seattle proper and that we've lost – perhaps conservatively – 1 million in the city since the '70s, that amounts to a 40 percent loss of trees. That is less than the over 50 percent cited for the metro area, but still a huge decline.
Sucher's blog post, titled, "Fewer trees in Seattle now? Or more?" seems to wonder if the urban tree population has actually increased in the last 35 years. Mead says no, we've been losing trees rapidly.
Of course, there is almost always a financial incentive to exaggerate a problem. and city-watchers are often cynical with good reason. The city would like more resources to manage the "urban forest," including tools to undertake a more detailed survey of the city's trees. The importance of this is accelerating due to global warming and the need to clean up Puget Sound. A story in The Seattle Times last week reported the results of a study indicating that stormwater runoff is the number one cause of pollution in the Sound. That's a problem that gets much worse when you cut down urban trees. Call it death by a thousand cuts – or a million droplets.
And Seattle city government, developers, and private citizens all share responsibility. Remember the controversy over tearing down the Maple Leaf neighborhood's old hospital? The real concern was less for the building than the grounds, the so-called Waldo Forest and its beautiful old trees. The building was deemed not to be a landmark. The wrecking ball and the chainsaw were then legally let loose: The historic building wasn't up to snuff, therefore the trees were expendable. Seattle's venerable trees don't get the protections or consideration we sometimes accord buildings even though their environmental contribution is far greater.
Such depredations continue, despite the city's own alarm. In response to my story, Duff Badgley wrote to tell me about a major mixed-use development along the Ship Canal that has applied for permits. It would cut down 70 mature trees, he says, and replace them with, among other things, 1,200 parking spaces.
And Tina Cohen, a certified arborist in Seattle, had this to say:
The main problem with tree preservation is Seattle DPD [Department of Planning and Development] allows too large a footprint on rebuilds, and there's no requirement for green space. The current conditions don't allow for retaining existing trees when lots are short platted or monster houses replace modest homes. Last year Richard Conlin proposed an ordinance limiting the size of single family homes, but it hasn't moved forward.
Until the building code changes, I am pessimistic about trees in our town.
Sucher might be right to question whether the city is trying to hype the tree holocaust – perhaps there's a tendency to overstate it due to a feeling of urgency or guilt. But unless you're prepared to call city forester Mead a liar, he and the city's staff have concluded that the problem is big, both citywide and regionwide. My sense is that Seattle is trying to walk its environmental talk. It knows to be credible it has to take action to fix a problem that it has enabled, if not created, by decades of forest-unfriendly policies. Turning that around won't happen unless the city stops undermining its green intentions.
It is fair to wonder which city will win out in the end: the tree-loving city or the boomtown that can't build enough fast enough. Now that the city has quantified the problem, maybe it's time to start measuring the results so the future data will be indisputable.
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Comments:
Posted Thu, Dec 6, 8:02 a.m. Inappropriate
If my neighborhood is any indication.......: If my neighborhood is any indication of tree canopy loss then indeed we are losing trees at a rapid rate in our city. In the last two years five butt ugly townhouses and mini-McMansions have been built in previously open spaces within four blocks of my home with the loss of dozens of trees. Few have been replaced that I can see. Rather ground cover or fast-growing shrubs have taken their place. From the look of the city as a drive or ride the bus around town, this is happening all over. I could not estimate the percentage of tree canopy lost over the last 35 years, but surely it is a rapid decrease given the vast amount of construction in that time and the destruction of trees on previously unbuilt property, as well as old growth trees on existing home sites removed to make way for new domiciles, or to improve ones views. And this view doesn't take into account the loss of trees through old age, storm damage, disease, pollution, etc, without them being replaced. It doesn't take an arborist, or a web columnist to figure out that we are losing trees, native and imported, faster than we are replacing them. The question is, what are we prepared to do about it?
Posted Thu, Dec 6, 9:01 a.m. Inappropriate
A bit of a nonsequiter: It was pointed out to me several years ago my an arborist friend that the city of Seattle, per capita, has fewer trees than any city west of the Mississippi. Sacramento, apparently, has the most (with Pittsburgh claiming the top spot in the country). I've been able to verify the claim about Sacramento but not Seattle. If true, it's pretty alarming that we're losing trees instead of gaining them.
Posted Thu, Dec 6, 1:15 p.m. Inappropriate
Some more memory: Good job, Knute. Part of my comment from my own blog at
http://tinyurl.com/26tnpw
When I think back over 40 years about how Seattle has changed -- and not changed -- on a neighborhood-by-neighborhood basis I just cannot figure out where these trees were that have supposedly disappeared.
You old folks: just think about it. Go down through your mental list of the parks and areas of town with which you have been familiar and see if you remember that those places had more trees then than they do now:
Are there fewer trees at Greenlake and Lower Woodland? At Seward Park? At Carkeek? At Discovery Park and Magnusons Park? (Which two parks didn't even exist in 1972 but were in process of being transformed from Fort Lawton and Sand Point Naval Air Station respectively.) Did any of those parks have more trees 35 years ago? What about the Arboretum? More then? Not in my memory. I can't see any possible answer but that our parks probably have more or at least the same number of trees now as they did then.
Then consider street right-of-way which to begin with Seattle is somewhere around 50% of the land area of the city. (I am fuzzy on the number; it might be40% or it might be 60% but it is a huge number.) Street right-of-way includes sidewalks and planting strips. That is a huge area. So ask some questions about right-ow-way. First are there a whole lot of new streets which have been developed on existing but never opened right-of-way in the past 35 years? I'd say no. Has there been a great deal (or any) cutting of street trees? I certainly can't think so. Sure every once in a while we lose a street tree to a vehicle accident or to a disease. But those trees are replaced almost immediately. Moreover the City has had street tree planting programs -- either publicly-funded or as part of construction permit requirements -- for that entire period. So I find it hard to believe that we have lost many trees from public right-of-way.
Then consider neighborhoods. Did Capitol Hill or Madison Park or Magnolia have more trees then? Did Maple Leaf or Roosevelt or West Seattle? Or Wedgewood or Seward Park or Ballard? My memory tells me that with very few exceptions we probably have more trees in the neighborhoods because of those tree-planting programs I mention above and also because so many people in Seattle appreciate greenery and so we plant trees on our own property. When a new house is built or there is a major addition to an existing house, I would bet that new landscaping -- including trees -- is part of the development.
The one exception to my guess of "more trees now than then" might be the steep greenbelts surrounding Queen Anne and parts of Beacon Hill in which there has been some development over the past 35 years. But those are small areas of the city and the greenbelts are still largely intact. So development in the greenbelts could not be much more than a small part of the story.
Think about the downtown core from Lake Union to Jackson Street. Did it have forests in the 1970s? It had a few scattered trees here and there on the few vacant lots but it seems to me that street tree programs must surely have added more than were taken away by private development.
Also consider the substantial industrial areas of the Duwamish Valley and Interbay. They don't have many trees now and they didn't then. But I'd bet again that because of street trees plantings they actually have more trees now than in the 1970s.
Do I have the facts? No. (And it will take some real historical geography to get it. For example, the street trees on upper Roosevelt in the Maple Leaf neighborhood were planted as part of the Forward Thrust bond Issue of 1968. Were they already in place in 1972? Were they planted afterwards? It makes a difference to the analysis.)
Posted Thu, Dec 6, 1:27 p.m. Inappropriate
RE: Some more memory: I went to the City site to look at a larger version of the map in Knute's article. It is a PDF and can be magnified. I then compared Seward Park as it appears on the Google Satellite Map with the this map. They look like different places. By comparison to the Google Stellite image the City map of Seward Park looks like a desert. Strange!
Posted Thu, Dec 6, 2:56 p.m. Inappropriate
RE: If my neighborhood is any indication.......: I have a few BIG gripes with your post WileyGates.
1. What makes you think, as an owner of a single family home, that you can take the high road? Although the townhomes and mansions may have been responsible for tree loss in 2006/2007 upon construction. When they built your house in the (I assume) early to mid 1900's it was also directly responsible for tree loss, possibly even old growth. Just happened in a different era.
2. I happen to live in a townhome and couldn't be happier. The price was ~$100,000 less than houses built in the early 1900's in the same neighborhood. Plus everything is brand spanking new. The townhome uses much less energy than a turn of the century house as well. Requires no other investment when moving in. New buyers looking to purchase an early to mid 1900's home in Seattle proper in all likelihood could be easily walking into ~$75k worth of "maintenance" such as: new roof; rewiring; plumbing; a lot of them have uneven/slanted flooring that makes you feel like you are walking in a fun house; a "mildewy" interior odor; cracks in the foundation; asbestos based siding; single paned windows; an oil tank buried in the yard; Insurance rates are three times that of a townhome because of the houses age; more expensive taxes; Costs more to heat them. Then they'd have to deal with a quirky and often poor interior design. Plus, useless space in the basement because of potential flooding during a rainstorm!
3. What is so unique about the droves of single family home in Ballard, Fremont, Wallingford, Roosevelt, Phinney, Crown Hill, or any other middle class 1900-1940 era Seattle neighborhood? Most have a top story with a basement, hardwoods, and a similar exterior design.
If you want to really look at the real culprit of a vanishing Seattle tree canopy, look at all the houses that were built between 1900-1950. Before then, it was all old growth trees!
Don't get me wrong. I have nothing against a single family home and hope to live in one in a close-in neighborhood in the future. In city townhomes and condos (while a relatively new phenomenon) provide a fantastic entrance for younger individuals/couples and lower incomers to the highly coveted close in Seattle neighborhoods that they love.
In terms of a lessening tree canopy, as human population continues to grow exponentially worldwide, it is just a fact that we are going to have to deal with. After traveling to other cities the size of Seattle or larger, I'd say we are WAY ahead of the game. Plus I (and one of my neighbors) planted trees in our backyard!
Posted Thu, Dec 6, 3:49 p.m. Inappropriate
Has this 'crisis' already been solved?: This isn't a new 'crisis' - certainly in the long run (last 150 years), tree cover has decreased. The lack of trees compared to suburban Cities is stark. But there have been programs for quite some time addressing this subject, and I suspect they have been effective.
Mr. Berger's methodological speculations are accurate, but perhaps not well composed - the big question may well be when the low point was. 1970 or shortly thereafter is probably about close enough, for the purposes of historical discussion - everything else is really just extra copy to fill a regular writer's 'quota'.
And there are efforts to address these problems at the City of Seattle that merit commendation. I was a participant in one - a Street tree focused program funded by utility revenues (small trees are better under power lines)and administerd by Seattle DOT. It was a volunteer training program that also asked for a certain number of volunteer hours - though not designed for pros it was attended by a few in related fields. The overall feel was a feel of responsible enlighted self interest.
Why is it we don't see more of that from government? Could it be that there are actually troublemakers running things?
So, Knute, (and Dave) - any ideas how we might 'measure' that?
Lastly - one problem in existing greenbelts is invasion of ivy which can kill big trees - this has probably gotten worse since 1970. Big trees are valuable - one big tree is worth more that a dozen small ones. I don't think you should deny a building permit to save a tree, but requiring the planting of a few trees to replace might not be a bad idea - maybe a 1-2 hundred dollar charge for each tree, passed on to a non-profit planting organization for purchase of citizen planted trees?
Keep the troublemakers out of the overhead and folks might actually like it!
-Douglas Tooley
My Blog
Lincoln, Tacoma
Posted Fri, Dec 7, 8:03 a.m. Inappropriate
Just keep cutting trees, Seattle: And then wake up in wonder and surprise when that creek/river/culvert runs through your house.
Developers always have their way. Why? $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
and guess whose pocket(s) are being lined. You keep voting them in, you should know their names.
Gosh, maybe those tree huggers have a point. We ARE cutting off the nose to spite the face - destroying the very thing that would save us - whining and asking for federal assistance when our own actions have taken away lives and property, not to mention destroying the environment on our way to, what, Annihilation?
Evergreen State my ass.
Posted Fri, Dec 7, 9:29 a.m. Inappropriate
Some of the loss is hidden. . .: I am currently involved in a project to re-green a section of the Burke-Gilman. We're pulling out invasive plants, and putting in native plants and saplings.
In working on the project, I got to talk to a forester with the Parks Dept., who pointed out that part of the problem is not visible, but a problem none the less: Many of the deciduous trees that make up the canopy in the parks and greenbelts are reaching the end of their expected life-span!
There are quite a few short-lived species out there, that can only realistically stay up for 30 to 50 years, and Seattle planted a lot of them 30-odd years ago. In the meantime, invasive species like Himalayan blackberry and English Ivy have been strangling saplings, choking out the natural replacement trees that should have been coming up.
So, even if one finds the current canopy "acceptable", we need to take action now to prevent a serious thinning over the next decade or so.
Posted Fri, Dec 19, 12:01 p.m. Inappropriate
I love trees and maybe Seattle needs them. However, I feel it is crazy if not approachging criminal, in a time of a deepening recessionm, to continue Seattles Urban forestry plan.
The first step in achieving a good tree canopy is maintaining the tress that exist. Drive down 8th street in West Seattle off Roxbury and see the trees that have been planted under power lines and see how they are in desperate need of trimming. In the next wind/ice storm, they will snap and it will cause us to loose power.
Planting tress that shed leaves along sidewalks on hills that children use to get to school is rediculous. Not only will it become extremely slippery, but will clog the storm drains.
Lets plant tress in areas that won't cause a greater expense.
For every one planted in my front yard along the street, I would rather have 2 or 3 in my back yard.
I realize that these tress were budgeted in 2007, but if government is not flexable enough to curtail or postpone plans when finances are short, then something is wrong. Use our money wisely and not create a need for a BailOut.
MERRY CHRISTMAS