A New Way to Plant Urban Trees

At the 2010 GreenBuild, Peter MacDonagh, the Kestrel Design Group, James Urban, FASLA, Urban Trees + Soils, and Peter Schaudt, FASLA, Hoerr Schaudt Landscape Architects, argued that without new tree planting techniques that use healthy loam soils, major “one million” urban tree planting campaigns will fail, wasting lots of money in the process. MacDonagh said “urban forestry is broken. We need to remake with a different approach.”

Finding out What Works for Urban Trees

Urban trees are now understood to be a central part of green infrastructure systems and provide a range of benefits. They reduce the urban heat island effect, manage stormwater, and provide shade that lengthens the life of materials. In the summer, shadier streets also means lower neighborhood temperatures, which can reduce air pollution that increase asthma rates. “All of these benefits are great, but they won’t happen if we keep planting like we have. It will be a mirage,” argued MacDonagh.

MacDonagh said larger, older trees are far more valuable than youger ones, so work needs to be done to preserve these and use new techniques to enable younger trees to stay in place longer. Citing data, he argued that a 30-inch diameter breast height (DBH) tree provides 70 times the ecological benefits of a 3-inch DBH tree. For example, a large tree intercepts 79 percent of rain hitting the ground, providing the “best green infrastructure you can find.”

The key to preserving larger older trees and keeping younger ones in place up to 50 years or more is to use large amounts of loam or bioretention soils that are 65 percent sand, 20 percent compost and 15 clay silt. These soils are not only the best growing mix for trees, but also filter out heavy metals, phosphorous, and nitrogen most efficiently. Nitrogen runoff can cause algae blooms and kill other life if it’s allowed to get to the watershed in large amounts.

The rule needs to be two cubic feet of loam for one square feet of tree canopy. So, for a tree that provides a 700 square foot canopy a designer needs to use 1,400 cubic feet of high-quality soil. These soils can be combined with “silva cells” that prevent soil compaction to enable the growth of tall, healthy trees. To prove this, MacDonagh showed the work of Bartlett Tree Lab’s Urban Plaza study, which demonstrated that loam soil grew trees had 300 times more leaves and were 1.7 times taller than those grown in compacted soils. “This is important because the average street tree only lasts 13 years.”

To sum up, MacDonough said “codify minimum loam soil volumes, diversify tree species to prevent devastating blights, set minimum canopy targets, and plant small trees properly.” Otherwise, “those million tree campaigns will be exercises in futility.” 

Overcoming Obstacles in the Built Environment and Dealing with Increased CO2 Emissions  

James Urban, FASLA, said structural soils, which combine broken up rock and soil, have issues so urban tree planters came up with a new idea: suspended pavements. In a new project, Queens Quay, along the Toronto waterfront, these suspended pavements use 48-inch deep silva cells, which kind of look like rubber packing crates, and 1,680 cubic feet of loam per tree. Within the combined loam and silva cells are irrigation systems that move water to the trees. Given the Toronto government was concerned that this system wouldn’t work, Urban says they first tested in a small strip and demonstrated that the approach works.  

Here Urban complained about one major obstacle: low tree quality. He argued the “American nursery business isn’t doing its job” and one firm tried to deliver trees with “girdling roots, a fatal flaw that would have killed the tree in five years.” He added that the current nursery “stock of trees is horrible.” If we are going to do million tree campaigns, he asked, “How can we check each one?”

In another project, The Bosque on the new Lincoln Center roof in New York City, Urban worked with Diller, Scofidio + Renfro on planting 30 trees on a roof deck. “There were lots of obstacles — everything is going on in the built urban environment.” Urban navigated the shallow roof, elaborate lighting systems, and thin paving on top of the deck. He ended up adding in “geogrids” and gravel that helped ensure the new platform could provide a safe growing environment for trees and also bear the weight of a light pick-up truck or ambulance.

Urban added that in addition to the CO2 emissions created from hauling in those soils, there were also tons of emissions released from the trailers and cranes that were used to install the huge trees. “Are urban trees really sustainable? Our carbon footprint was so large that these trees will never be able to sequester the amount we just put into the atmosphere.” He argued landscape architects must stop pretending urban trees sequester carbon when they are actually net-producers of carbon if you factor in transportation and installation. Also, landscape architects may be specifying other unsustainable materials (see earlier post).

Still, many progressive city governments including New York City see massive tree planting campaigns as a core part of their climate adaptation plans (see earlier post). Perhaps the questions are: Is there a way to mitigate uban trees’ installation and transportation-related emissions in the short-term with a greener installation technique? If not, does improved long-term resiliency to climate change somehow make up for increased short-term CO2 emissions?

Urban Trees Are Key to Successful Public Spaces

Peter Schaudt outlined his firm’s well-regarded Uptown Normal traffic circle (see earlier post) in Normal, Illinois, which was funded by federal, state, and local governments, “so you can imagine the number of meetings.” Schaudt decided to create a “people space in the center of a roundabout,” which some government officials didn’t think would be safe.

Schaudt thinks the new space, which features a set of urban trees, outer lawn, bog water infiltration system, and circular stream filled with cleansed water, represents the “park of the future.” Instead of seeming dangerous, the circle interior offers a safe space in large part due to the trees, which separate the cars from the social space. Trees in the traffic circle and nearby streets were also supported by silva cells, loam and drip irrigation, using Urban’s approach but on a smaller scale.

The circle’s trees were set-up to live a long time – Schaudt says he plans for the “4th dimension — time,” and likes to show clients what the site will look like in 25 years.

Lastly, MacDonagh added that well-planted trees are not only more cost-efficient, they also provide more ecosystem benefits. To demonstrate cost-efficiency, he pointed to research conduced by Minneapolis’ government, which found that they could either spend $3.5 million on new stormwater conveyance pipes to deal with runoff or spend $1.5 million on silva cell systems. On ecosystem service benefits, another study showed that 13-year old trees planted in standard structured soils had a net cost of $3,000, while a 50-year old tree planted in bioretention soils and silva cells offered $9,000 in benefits over its total lifecycle.

26 thoughts on “A New Way to Plant Urban Trees

  1. faslanyc 11/19/2010 / 11:18 am

    thank you for this.

    When MacDonagh says that big trees intercept 79% of rain “providing the best green infrastructure you can find” it becomes clearer why people don’t totally buy into the idea. I presume this is for an area within the perimeter of the crown? And how does intercepting the rain (for a split second, before it runs onto the ground) provide great infrastructure? Extremely confusing.

    Anyways, I wonder why these guys don’t discuss myccorhizal inoculation as a possible effective strategy for nutrient poor and compacted soils? My initial thought is that it’s because they’re just interested in pushing their product/idea, but perhaps it is a bad idea? Who knows?

    • Mike 02/03/2011 / 11:19 am

      Interesting article and even more interesting comments.
      Regarding quality of trees: While many nurseries aren’t quite known for their products their are many more that are. Higher quality trees go to places where people are willing to pay for them. They often don’t end up in very public places (state, federal…) or projects with highly competitive bidding systems.
      Often marginal trees develop problems after planting no matter where or how they were tended to in the nursery. Girdling roots as Mr. Urban brought up is such a case. This is often the result of the transplanting procedures and in many cases can be corrected. Silva cells or CU structural soils they have very little relevance to their development. Design and planting is half of the equation, follow-up care is the other half.
      Overall I am very happy to hear people recognize and discuss the importance of soils.
      Does James Urban have a website?

  2. Todd Degner 11/19/2010 / 7:49 pm

    FASLANYC – If I may, each of these men, whom I know personally, are motivated by a love for their fellow man and making the world better. Among many other things, that means taking care of trees. PP&J are also some of the most thoughtful guys in the biz.

    Miccorhizal and fungal associations already exist in the urban soil environment. However they are limited in diversity and quantity. This situatiuon cannot be overcome until we begin fracutring and decompacting soil. As LA’s we are responsible for promoting and designing an envirioment where the soil can perform at the highest level possible. Otherwise, we only maintain our 10 tree lifespan in the urban context.

    Regarding Peter M’s comment, it must be said that there are several points at which trees ‘intercept’ rainfall. His point seemed to be that all of the cumulative interception points (there are arguably 10-12 of them) will lead to this number. Additionally, in an urban context, what are the alternatives to canopy cover? Answer: Pavement, rooftops, other herbaceous vegatation, existing open bodies of water, or compacted turf. Each of these perform very poorly compared with a single established tree- even one growing in a tree coffin.

    Anyhow, I enjoyed seeing each of these men again at USGBC. Great show this year! Jim and I were discussing the many great opportunies to not only create more soil volume, but to create a more effective soil mix that would better mimic the forest floor.

    FYI – Bryant Scharenbroch at Morton is nearly finished with his field research which examines the most beneficial amendments/treatments for newly planted urban trees and so far he has indicated that mulch, compost, and teas/hummates are leading the pack against all other soil mixes, fertilizers, or approaches. Now that we know how to more effectively create soil volume and still achieve the other hevily engineered objectives that a streetscape requires (Thanks to guys like PP&J), we can hopefully begin to tackle, with equal vigor, the efficacy of our soil perscriptions. If we can just double the lifespan of urban trees over the next 20 years, what an amazing impact. GO TREE GUYS!!!

    -Todd A. Degner

  3. Steve Mercer 11/21/2010 / 9:28 pm

    You have touched on one issue that has often been overlooked. This is the quality of trees being produced by nurseries. We have made a commitment to produce a superior product than what the nursery industry is accustomed to producing. This can only be achieved by starting at propagation and continuing with newer pruning practices that cause trees to develop a more fibrous root system than what ball and burlap trees can deliver. (See picture on page seven of the Rootmaker catalog -lower right hand corner – http://www.rootmaker.com/catalog/07DecRMCatE.pdf ) Our production practices start with Air pruning Propagation trays, and from there the trees are moved to Grow-bags that fit inside the holes of concrete blocks. From there we move them to the field and plant them in ground grow bags. The trees self prune (roots) themselves automatically right up until time to ship them. By the way the American standard for Grow Bags is different from B&B. For example the American Nursery Standard for a 4″ B&B shade tree is a 44″ Root Ball. The very same tree in a Grow bag is 28″. The Tree planted in the grow-bag will have 95% or more of its roots and those roots will be more in volume and more fibrous than the same tree grown as a B&B tree. This equates to higher survivability, in the case of street trees longer longevity, less cost for shipping and less cost for labor during installation. Because it is a production practice that is not what mainstream nurseries are using.

    Buyers and installers of the trees grown in grow-bags tend to view the trees as sub standard (they are comparing them to the B&B Standard). This is a common mistake and as a result because of this perception, buyers shy away from trees grown by this method. The very same thing happened back when all trees were planted bare root and the B&B method of trees first was introduced. Today the majority of producers using the grow-bag technology (technology is about 20 years old) are native tree growers. This is because the Native trees have such poor root systems that the ONLY way nurseries have been able to grow them successfully has been with in-ground Grow Bags. The grow-bag growing system has suffered from a lack automated machinery to plant the grow-bags in the field. B&B nursery growers who do look at the practice shy away from it as a result. I have designed and new planter and I am currently in the testing phase now. If successful, there is hope for better grown trees in the future that cost less to ship AND install, and will out perform their B&B brethren.

  4. Matt Moore 11/24/2010 / 1:25 pm

    I think anyone reading this article already understands that conventional tree pits in sidewalks are a thing of the past. I am glad to see Mr. urban acknowledge the negative carbon impact of some of these installations, but that is just one piece of the puzzle.

    I wonder what the carbon impact is of manufacturing and transporting plastic cells around the country? As a producer of Cornell University’s patented CU-Structural Soil, our material is rarely shipped over 100 miles.

    Why does Mr. Urban compare a 13-year cost of a structural soil planting to a 50-year benefit of a suspended pavement planting? We have CU-Soil installations going back almost twelve years in my area with no indication of impending doom, nor any reason to believe the trees will not continue to thrive for decades to come. And these are large, vigorous trees in a sidewalk environment.

    There is also no mention of utility access issues. Sooner or later, the city’s public works department or a contractor will have to excavate through the site for repair or installation of underground utilities. Structural soil can be excavated and replaced, but what happens to suspended pavement systems? Mr. Urban’s response to this issue during the panel discussion at September’s convention was that as much as he would like to see them properly excavated and replaced with new cells, the reality is that the crew is most likely to push the excavated material back into the hole, compact it & pour new concrete, “and the public works managers I talk to are okay with that”.

    There is no disputing that trees planted in uncompacted, loam/sandy loam soils are going to fare much better than those in a compacted tree pit in the typical streetscape environment. There is also no disputing that properly manufactured and installed CU-Structural Soil provides an excellent rooting environment with ample air & water movement, nutrient exchange & beneficial biological activity to promote a vigorous life for street trees.

    Also, while suspended pavement systems that are filled with the proper soil media can have the added benefit of stormwater filtration, CU-Structural Soil will not only aid in filtration, but due to it’s extremely porous nature, also can act as a stormwater reservoir, slowing the flow of water into the storm drainage system.

    I don’t mean to say that any one answer is the end-all, be-all panacea for street trees. In many cases, a combination approach may be appropriate and in some cases, trees should probably be replaced with a more appropriate alternative. No doubt tree selection and nursery practices are important issues as well, but the crux of this article was clearly to promote one specific aspect of and approach to street tree planting, to the exclusion of other alternatives. I would hope that future articles will explore all of the available options, for whatever topic is being presented, or that producers/promoters of alternative approaches be offered equal time and space to present their side of the issue.

  5. Elson Miller 11/24/2010 / 2:47 pm

    All interesting stuff. Yes, we all agree that healthy trees in an urban environment are good for the soul, good for heat regulation and to a certain extent, good for water transpiration instead of run off. We all agree that trees will grow much better in a perfect root environment.
    But on the other hand, trees and the urban environment are by description, a compromise between utility and nature.

    If you are to protect the tree roots with a massive underground plastic cage, with its own significant carbon footprint, then it is probably best not to try to do any real carbon calculations, but admit you are sparing no expense to keep what amounts to a costly work of public art on display.

    If that is the agreed goal, then price and inconvenience against aesthetic acclaim should be the relevant equation. By all means spend an extra $10,000 to plant the tree.

    My question is, what happens if despite this added cost, the tree dies from one of the many, many afflictions or abuses to which the urban tree is subject. Are you not left with plastic boxes more or less built into a massive dead root system. How do you go about replanting a new tree without replacing the whole system at a similar or greater cost and with the same extensive sidewalk disruption?

    Another question that occurs to me is the potential danger of the duel use of a rooting area as a stormwater retention tank. If the tank is surrounded by less pervious compacted soil, being the reason it is there in the first place, is there not a danger in a prolonged wet period that the tree may literally drown in the tank?

    There is no doubting the elegance of the concept, but the value engineer might have a problem with it.

    • Matt Moore 11/30/2010 / 12:35 pm

      The issue of “drowning” is highly unlikely as most, if not all installations of CU-Soil in our region include a sub-drain. I would expect this to be a common practice everywhere.

      • Elson Miller 11/30/2010 / 6:24 pm

        Forgive me Matt, but I understand the Silva Cell to which I was referring in my remarks, doubles as a storm water retention tank, which would suggest it is supposed to fill with water which would percolate away later.
        If there is a sub drain, how is it a dual storm water receptacle and sidewalk suspender?
        Do you have any thoughts on how the tank tangled roots might be replanted if the tree dies from other causes?

      • Matt Moore 11/30/2010 / 8:10 pm

        Sorry if I misunderstood your remark. The suspended pavement systems I have seen are not a tank, but more like a giant plastic milk crate. I don’t know what they do about drainage, but would expect something similar to a structural soil trench, meaning a drain system of some sort is part of the design. Structural soil has the available porosity to accept rapid runoff from parking lots, sidewalks, streetscapes, etc., filtering the water and allowing it to flow gradually into the stormwater system. Neither system is intended to be a sealed basin and I apologize if my “reservoir” remark gave that impression. They act as flow regulators in a manner of speaking.

        As you mention, it seems like replacing a tree in suspended pavement would be much like the utility access issue, but then again, replacing street trees is never a picnic.

  6. Scott Harris 11/24/2010 / 3:36 pm

    The use of Rootwell, a simple delivery device, providing Water, Oxygen and Nutrients to the planting pit is available and has shown great success in tree recovery and new plantings in compacted and clay soils.

    The problem with this product is its too simple. Assuming the installers prepare the planting pit, as designed, the part installs in seconds. The part sets 18″vertically into the pit equally spaced around the root ball; the tops are presented at the mulch line. The part is 3″wide and looks like a sprinkler head in the mulch.

    The product has a simple patented air convection cap that delivers oxygen and provides gas exchange in the critical root-zone. The same product allows for water, compost tea or other fertilizer directly into the root-zone delivered 18″ deep into the ground. Eliminating the need for a water bag that can exacerbate the compaction issue by adding weight with water to the root flair.

    The cost is minimal…under 30.00 delivered.

  7. Nick Kuhn City4ster 11/26/2010 / 6:53 pm

    Urban Forestry is not broken! I, and many others like me, have been advocating for these same advancements for longer than I have been thinking trees. Its no mirage when its really there and all of these recommendations and options have been available for years. The disconnect has been convincing the other aspects of municipal and private design, construction, and maintenance that rooting volume is important, that protecting large trees is better than replacement, and thinking long term is the basis for all tree management.

    Bartlett tree research is quoted but no mention that they and others like Davey Tree and the US Forest Service have been providing this information for decades. Uncompacted, more, and better rooting volume has been the basis of all urban tree design for many years and usually ignored in sidewalk, street, and home construction. How will urban forestry advance when trees are removed or not used for 3 car driveways, McMansions, and parking lots designed for ‘Black Friday’ shopping? Another disconnect is the planning and design for trees in the same category as flowers and turf. How can anyone compare something replaceable in 1-2 years with trees older than most cities? Why is the UF industry broken when its other people’s designs that ignore the needs of trees and cause the problems?

    The environmental values of trees is only part of the whole package. Trees provide social and economic benefits beyond value at installation. Trees creating places for people to walk that are safe from vehicles are more than temporary landscapes to be replaced when the concrete wears out and the tree still has over 100 years of life left. Those tree initiatives provide trees along streets and to homeowners who rely on trees for shade, property value, and an occasional apple pie. Are they the answer to carbon sequestration? Not now… but they do help change peoples attitudes that trees do belong in a city and then we can find the balance.

    Why is the nursery industry the problem when its LA’s setting standards and landscape contractors installing poor quality trees? I have tagged 1000’s of trees and planted 1000’s more each time having control over the quality and ensuring its planted correctly which prevents many of those girdling root problems. Tree planting and timing should not be decided by construction timelines and cheapest product but anyone will admit the landscape is not given priority over the ‘built environment’. Over many years we have devalued trees for HVAC, irrigation pipe, and food or building materials… trees became ornamental… and therefore optional. The design of the landscape has been more important than the function for too long.

    Considering the carbon efficiency of tree planting… saying that bringing in soil and craning in large trees is not carbon efficient ignores the fact the removal of all trees and stripping topsoil is standard protocol for almost every construction project in the country. Don’t subtract from tree value for fixing someone else’s design that stripped a site bare or helps offset the problems of a parking rooftop. I see very little problems for tree replacement with these options if trees suffer from ‘other urban stress’ but they should not be designed to fail. Even saying ‘its just costly urban art’ seems very narrow-minded since the same could be said for any wall that gets graffiti, any road where an accident might occur, or any playground where someone might get hurt. Any reasonable value engineer should learn what trees and vegetation provides and how trees appreciate in value as they grow instead of depreciate like everything else in the city.

    Many resources are available from http://www.treesaregood.comhttp://www.fs.fed.us/ucfhttp://www.urban-forestry.com The tree people are out there! This problem is real and can be fixed by LA’s and Engineers, working with Arborists, using standards already established. You have more influence on design and installation of landscapes than most Arborists could ever dream… use it!

    • Melissa Gildea 12/06/2010 / 8:15 am

      These are all good arguments and accurate. As LA’s we have to start referencing the research if we are going to use it. To state as fact that trees require a certain amount of rooting volume should also require the reference of the fact. I believe that the research has not been done on all tree species, and is a rule of thumb. All of the work is well intentioned and moving in a good direction. It would be appropriate and more accurate to acknowledge all of the good work done by foresters, researchers, and private industry who are doing this research for similar purposes and on which all of these assertions are based.

  8. John Melvin 11/26/2010 / 7:55 pm

    I heartily agree with Mr. Kuhn. The technology spoken of above is certainly another tool in the toolbox. That does not mean, however, that tried and true practices and other technologies are not also useful. The important take home is that urban forestry is well worth the investment in the long term using any currently accepted techniques including those advocated by Mr. Urban and friends above. The problem that needs to be elevated is the need to see vegetative infrastructure (trees etc…) elevated in importance to where it is seen just as importantly as are sidewalks, streets, lights, etc…. all of which provide needed services that make people’s lives better.

  9. Bob Moore 11/29/2010 / 9:08 am

    I agree that many problems plague understanding of trees in city environments, and that Mr. Urban’s education efforts is part of shocking planners and builders out of an outdated mentality. I am saddened that the article seems to toss the whole nursery industry under the bus in the effort to make his point. I have worked with some really great vendors that have high quality standards above the norm. but that level of costs are out bid on projects where price and price alone are considered. In the low bid environment, common for cities, how are nurseries able to adapt to what is seen as being needed when the standards that accept poor trees is so low? You get what you pay for really.

  10. Domenico D'Alessandro 12/02/2010 / 12:01 pm

    All the comments are worthy of note. Peter Schaudt and Peter McDonaugh offer a plausable engineering solution, however I don’t believe they offer a visionary one that is needed to overcome our urban environmental problems.
    There are those of us that have been working on holistic, regenerative solutions that go far beyong the McDonaugh-Schaudt scenarios.
    Perhaps it is time for the profession to allow new voices in the discussion that are willing to break some moulds.
    I have offered to present some innovative concepts and approaches for the urban environment only to be rejected time and again by the landscape committees, whereas I had great feedback from the WEF, SER and other ecologically minded groups. Landscape architecture is still catching up after years of sleep, can we jump some loops to get caught up by bypassing the old guard?

  11. Scott 12/02/2010 / 12:47 pm

    Preserving existing trees and understanding the economic, ecological and aesthetic values of these large plants are critical in many urban centers’ goals of increasing canopy coverage. If Chicago, for instance, is to acheive an improvement from 17% to 20% coverage they must work as hard at preserving large tree canopies as they do planting trees. It is not either or equation, it is an “and” equation. Development and design practices are doing a much better job these days at working with the existing resource and real sustainability is seen when large trees are preserved and enhanced.

  12. solloway.chris@epa.gov 12/02/2010 / 12:54 pm


  13. gordon 12/02/2010 / 2:11 pm

    What a great discussion. However, saying urban forestry is broken is saying that all the things we are talking about aren’t working, including the innovations and increased demand for soil volume, the topics of this article.

    What urban forestry has not done historically well is transferred the needs and requirements of trees to the other industries, disciplines, and practices that affect trees during design and construction. Two examples: (1) most trees aren’t even considered until after the building and parking lots are designed for the property. Sometimes they aren’t considered until after grading and construction begins! Any existing trees are just considered demolition costs; and new trees, amenity costs (2) tree protection is often removed when the landscape contractors come on site. They cut roots to install irrigation lines that other contractors have avoided, and compact soils.

    Tree quality? Where are our quality specifications? If the specifications are written correctly, substandard plant material should not be delivered, or if delivered – sent back. Of course we can’t check each tree, but a reasonable sampling will determine if the specifications are being met. Most construction projects take a couple years to plan, design, and build. At the planning/design stage, the trees could be contract grown to quality specifications; and after a couple of years of nurseries getting it better, such as following the new California nursery standards and practices, http://www.fs.fed.us/ccrc/topics/urban-forests/docs/Nursery_Trees_Quality_specs10-13.pdf , maybe this advance nursery planning won’t be as necessary.

    Finally, urban trees have been growing in urban soils for over 150 years. Yes more stress has been placed on trees as construction practices strip soil, compact soil, and and site designs squeeze the room for trees. However, the trees still are providing benefits and are being recognized for their contributions besides looking nice. We need to improve their growing space and soils as much as possible.

    If we design the perfect tree sites, and perfect tree preservation requirements, less trees will be planted and more trees will be removed because perfection will not be achieved in most designs; the economics don’t usually work. However, through innovations, planning and improved site designs, and tree protection specifications, we can make improved growing sites and preserve existing trees that have good useful life left. Add to that increased species diversity and increased age diversity, and urban forestry will continue to move in the right direction toward sustainable urban trees.

  14. Bob Brennan 12/02/2010 / 10:02 pm

    We need to enforce the rules that work and ignore and vote out the people who want to give small root space and tall westerly walls to protect.

    The the large trees that break up the large rain drops which makes mist that is absorbed into the tree and other plant life under the large tree. We have large ficus with leaves that are six to eight inches long and will stop all rain for the first few minuets but then everything becomes wet with very fine mist.

    More root space is what we need!

    You are all working at fixing the problem! Rock on!

  15. i.a. smildzins 12/03/2010 / 4:02 pm

    So I’m watching some program and there is this plea to the public to help support planting of a million trees by sending in some money. I turn to me wife and say…what we need to do is to SAVE a million trees. Typical of the USA to throw $$$$ at the problem rather than asking the question of why?
    Don’t get me wrong as there are needs for more reforestation, but, as some have said the real planning is done at time of site analysis. Too bad I have to deal with setbacks, zones and land use rules developed and still on the books from the 60’s. We need to dump those “standards” and get on board with the new planning goals…and that is NOT protecting economic land values based on building assesements…if you know.

  16. M. D. Vaden of Oregon 12/06/2010 / 12:10 am

    New approaches to soil like loam for trees in the landscape may not be close to enough. Maybe in established areas for replacements.

    I suspect a grander approach may be needed, like sacrificing every other one-way street for more root growth area. Like long skinny park blocks. And then increase every other street for more traffic.

    But that may need to be for from-scratch planning.

    MDV – Oregon

  17. Len Phillips 12/14/2010 / 9:30 am

    A word of caution about grow-bag trees. Grow-bags small volume makes these trees easier to handle but because the root ball is smaller, there is less water storage capacity. Combined with a dense root system, this lesser reserve makes trees produced in grow-bags more sensitive to desiccation immediately after digging than trees grown directly in field soil. Landscape architects should make provisions for delivering the irrigation needed to prevent desiccation before, during, and after planting.

    Because grow-bag trees require more frequent irrigation and require staking to hold them up, grow-bag trees are rarely planted directly into the landscape because of the likelihood of mishandling and poor understanding of the product. Soil inside the ball can become loose from just a moderate disturbance. A drop of the root ball will cause the roots to lose contact with the soil and the tree may go into shock and be more likely to die quickly.

    For more information read “Planting Grow-Bag Trees” in the March/April 2010 Seminar at Online Seminars for Arborists Archive 31. http://www.on-line-seminars.com/index.php?p=1_24_Archive-31

  18. Richard Boase 02/01/2011 / 2:05 pm

    Here in the Salish Sea basin we are struggling with a myriad of very significant issues regarding urban watershed restoration. High growth rates, more densification and EIA combined with less resources to effect restoration have led us to look at nature first for the tools we need.

    We completed a thesis in 2010 that quantified rainfall interception of a number of our more common urban trees. The results we hope will lead us to developing policy towards maintaining a certain threshold of tree canopy cover in our urban watersheds (even on private property). A copy of the thesis can be found via ftp here;


    The other component is the soil. Maintaining healthy urban soil for rainwater management is cheaper, more effective and offers many ancilliary benefits compared to other engineered solutions. Here is a link to a doccument we use to promote urban soil restoration for ecological benefit.


    I believe that we need many more trees throughout the urban environment than we presently feel we need. Parks, forest land and rural natural forests are very important but are not as effective a tool to help mitigate the consequences of urbanization. I have now come to believe that the lack of forest cover and good soil throughout an urban watershed is most likley a more limiting factor to stream health than the strings of riparian land so overzealoulsy protected.

    Provide me a mature healthy Western red Cedar that overhangs portions of the driveway, house footprint and deck on each residential lot and stream health will probably improve.

  19. Stephen Boos BCMA 02/01/2011 / 10:19 pm

    Very good article and I believe Mr. Urban is definately on the right track. I disagree with assigning cubic feet of soil to the square feet of the canopy; that kind of cookie cutter thinking is what LA’s clamor for and are wrong about. I understand they have a job to do but ‘one size fits all’ doesn’t work when it comes to diverse tree species. Suppose you place enough soil for that 700 sq ft canopy but the trees canopy will actually want to reach 1400 sq ft? Why not just a plant smaller species but more of them unless you actually have the space to grow a large conopy tree? Why fight the very nature of the tree, why not just plant the right sized species?

    As far as urban forestry being broken, I couldn’t disagree more. We are definately headed in the right direction; just look at the great work that Jim Urban and others are doing. Are things perfect, no but we’ve come so far and good things are on the horizon. We just need to work with the trees not against them.

  20. Rich Regan 02/04/2011 / 11:13 am

    Nice and accurate article, but a little too idealistic for most urban tree planting situations. My landscaping company does business in two cities that have done a nice job in planting and protecting trees (Greenville and Spartanburg, SC). There are an abundance of urban trees and agressive tree ordinances in order to protect them.
    In the real world, when a new tree planting project is implemented, cost becomes a major factor. Municipalities might hire a brilliant landscape architect to create a beautiful plan, but when it comes to the work they will ask people like me to submit bids. Wholesale tree growers don’t grow the quality of trees you desire because doing so would make them lose money. Landscaping companies like mine could never include something like ‘1400 cubic foot of high quality soil’…. simply because if we did figure that into our costs – we would never get the bid.
    An analogy might be your automobile. Sure manufacturers could design and build a much better automobile….. but at what cost?

    Rich Regan
    Blue Dot Landscaping

  21. Mark Johnson 02/16/2011 / 3:47 pm

    Sounds like Greenville needs to require some type of verification system to make sure contractors are bidding on the actual documents. Yes, quality costs. And projects seldom have an installation verification system that has teeth to insure that good bids aren’t undercut by the intention to “do what we always do”. I’m not saying any of it is easy.

    On another note… If we really want to sequester carbon and do a lot of other good things, I’d argue that codes (and aesthetically brilliant design) often require trees to be planted in poor spaces and don’t provide for areas where healthy trees can naturally excel. We also need to realize that trees are major habitat for all manner of beneficial species that live in and around them. Parks, large bioswales, constructed wetlands, etc. can bring a variety of “life” to a busy (but largely lifeless) urban environment. Using technologies to support trees in stressful locations is a great thing; but providing a more natural setting for trees is really the best option for life.

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