Urban Forestry

Introduction

As climate change, resiliency, and smart growth begin to take the foreground in many of today’s urban planning policies, city officials nationwide are speedily looking for ways to make “green” cities. Two of my favorite initiatives include Paris’ unbroken strides towards becoming car-independent and the state of Arizona looking to reduce urban heat island (UHI) effect. Among these ambitious projects, it can be easy to forget one of our greatest tools to combat climate change while also improving the public spaces of our cities: planting trees. Unfortunately, not all urbanists are arborists. In the book “Walkable City: How Downtown Can Save America, One Step At A Time”, Jeff Speck writes “[M]ost cities know that trees are good, but few are willing to pay properly for them”. I would not consider planting urban forestry within a city without the necessary efforts to preserve it as “paying properly”. Since Speck provides adequate evidence for planting trees in cities, I will opt in this article to write about their preservation. More specifically, I will write about the numerous benefits of painting trees white in urban, suburban, and rural cities and communities.

I admittedly first learned about this while watching Studio Ghibli’s “Kiki’s Delivery Service”. If you are somewhat familiar with popular Studio Ghibli director, Hayao Miyazaki, you would know he is also a very determined and forthright environmentalist, so it doesn’t come as a surprise to see Miyazaki incorporating horticulture into his city-based movie. When I saw the white painted lines on the trees lining the city, the urbanist inside of me was immediately curious and began to scour Google for answers. I have come to realize this “white paint” (more specifically a mixture of iron oxide, limestone, mica clay, milk, silica, menthol cellulose, and diatomaceous earth) has several benefits to trees and, by association, cities. The benefits to painting trees I will briefly cover include its overall health, pest control, and pedestrian visibility, all of which lead to even more improvements towards their city.

Healthier Trees = Healthier Cities

I am not a gardener, but it does not take a gardener to know plants need water and sunlight to thrive. However, too much of one resource can lead the plant to wilt, underproduce, and eventually die (kind of like cities and overdependence on cars). To ensure the trees of our urban forestry are maintained to be as efficient and healthy as possible, we will need to be innovative and creative than ever for the benefit of cities and people living in them. Luckily, painting trees can remedy this.

Trees absorb nutrients from the soil through fibrous pathways known as xylem. Extremely hot or cold temperatures can influence the xylem in trees through summer and winter sunscald. Sunscald is especially catastrophic for orchardists who maintain fruit tress in the hundreds. For orchardists in unpredictable climates, white paint on their trunks is a must. Not only has white paint been known to prevent sunscald, but it also helps protect the bark from shattering due to the alternating temperatures of the night and day. Trees with protected bark are less likely to decay from infectious organisms and rodents and have a prolonged lifespan. Whether the city is more urban or rural, older trees can provide numerous advantages in the forms of increased canopy, larger fruit return, and a deeper sense of city culture.

White Trees in Urban Areas

The emergence of apps and websites like FallingFruit.org has sparked an interest from many citizens about how urban forestry can help feed the homeless and potentially lead us towards ending world hunger. Cities like Seattle, WA are starting to realize fruit trees do not have to be a burden, eyesore, or hassle for cities thanks to taking a second look at urban foraging. I personally can see urban foraging initiatives help the public reconnect with nature, provide excellent volunteering opportunities, and even give the homeless population opportunities to obtain income in addition to healthy food.

Usually when people advocate for planting more trees in urban areas nowadays, the topic of urban heat island effect, or UHI effect, is mentioned extensively. The concise city hall definition of UHI effect can be summarized as increased temperatures in urban areas caused by dark building footprints including off-street parking lots and a lack of green areas. This problem, while seemingly small at first, is quickly becoming a rising issue and a “hot” topic (pun intended). as climate change inevitably endangers cities and people realize the small change in temperature can be what determines whether grandma or a child will collapse from heatstroke while crossing the street or not.

Cities in the United States are more at risk of facing the consequences of UHI effect than other countries due to over-dependence on automobiles and land area dedicated to asphalt. Thus, cities in the drier climates of the west including Salt Lake City, UT have been aggressively adding more trees to their urban forestry. Being from Utah myself, I know much of the new trees planted there will be given abundant supply of irrigation water through sprinklers shared with grass turf. Depending on the trees planted, painting the trunks of these trees can help them become healthier and grow to be denser, resulting in more urban tree canopy which not only helps pedestrians while walking, but also decreases the water necessary to feed the grass and tree itself. If this is incorporated city-wide, slightly more secondary water can be conserved for other purposes like watering agriculture or cooling during the summer.

White Trees in Rural and Suburban Areas

So white paint on tree trunks has numerous benefits on health for both the trees and citizens living in urban areas, but what about rural communities and suburban areas? Most of these benefits apply to them as well, but issues like UHI effect might not be the first issues on their agenda. Besides the two or three trees increasing property value of their property and greenery provided by trees at parks, many suburbanites might find little reason to prioritize more trees over an additional lane to a stroad. Plus, many rural communities often have too many trees to keep track of, so suddenly putting intense care into trees might come off as random and even a waste of tax dollars.

Regardless of the arbitrary distinction between urban, suburban, and rural trees, nobody wants to crash their car into one. Luckily, white paint does a very good job of being bright and noticeable. This can be beneficial for rural communities who are opposed to fast development and would prefer white trees over streetlights. In urban and suburban areas, planners have been trying to line streets with trees as a natural barrier to protect pedestrians from cars and force drivers to be more attentive in populous areas. However, some citizens and traffic engineers have reservations about the relationship between streets and trees because of the possibility of crashing and shun the idea of painting trees white due to nervousness of being blinded and lower visibility. This is a familiar argument to reflective off-white asphalt combatting UHI effect, which has been proven incorrect through multiple studies. If cities have reservations about a completely white paint on tree trunks, they can opt for an off-white color, or alternative colors like yellow or green. These paints on trees can also be conveniently used for festive events within a city.

Reasoning Against White Paint?

Numerous countries like China, Mexico, Panama, El Salvador, Germany, Greece, Turkey, and Ukraine have already been painting trees in their cities white for decades and have seen their benefits. Besides New Mexico and orchard communities in the east, white paint on trees is arguably a topic not often brought up as a method to improve the health of a city until recently; why is that? Many zoning codes do not mention altering the appearance of landscaped trees, so perhaps planners put the idea on the back of their agenda of regulations needed to be changed. Maybe government officials are skeptical about the economic results brought by purchasing large amounts of special tree paint, increased labor required from the city for maintenance, or underlying myths mentioned previously about street visibility. From a political perspective, many cities might be hesitant because painting trees white has history with the Soviet Union and want to refrain from possible correlations. Similarly, cities might oppose painting trees white to avoid possible accusations of promoting a “white agenda”. It is also possible these supposed reasons against white-painted trees are not considered at all because of officials being oblivious to the idea entirely. Because this idea of combatting UHI effect among other things is relatively new, it is difficult to find sour es of cities who adamantly oppose the idea of white paint on trees.

Conclusion

Regardless of the reasons against painting trees white in cities, the underlying issue many of us face is finding ways to fight back against the increasing effects of climate change. Trees, urban tree canopy, and public health are all important resources cities will need to preserve. This article attempted to show how white paint on trees can help with all these concerns, but I understand many cities will opt for other strategies more pertinent for their communities (hopefully involving trees). The most vital takeaways from this are the importance of trees in our communities, the necessity of their preservation for our physical and mental health, and how the added attention to our urban forestry can benefit all of us in the future. Whether you are in the planning field or not, get in touch with your local government to learn what is being done to preserve and increase the trees in your area.

If you found this information useful or interesting, check out a previous blog about environmental planning. I am also curious to hear about the initiatives being done worldwide to help trees; message us or leave a comment on our Instagram with your cool ideas. If you have any further questions about this topic do not hesitate to reach out to your Friendly Neighborhood Planner.