Some Thoughts on Trees
by Frank Robinson, Executive Director, Lewis Ginter Botanical Garden
You may have noticed an article in the Richmond Times-Dispatch on October 28, about a moratorium on cutting down trees in the City while City Council reviews its current policy on tree removal.
I stepped into this issue last week when I was asked to assist in saving an old Willow Oak on Seminary Avenue. It is a stately tree, but is has a problem – a crack down its trunk. I spoke with some passionate folks who want to save the tree, and I spoke with the City arborists, who were professional, informed and patient in answering my questions. I went home feeling there were no bad guys in this, but that something was amiss.
Much of the explanation about the tree’s removal was about lack of adequate funds and the liability a compromised tree is, once identified, to the City and its taxpayers. Basically, if a tree is compromised – in this case by maturity, a full canopy and the weight of an abundant acorn crop – it becomes a hazard. And, even if treated, should it fall and do property damage or kill someone, the City clearly has a problem. The tree needed to go because of risk management. Inadequate funds will be an issue we are all going to deal with in the near future, but the impact here is that the City arborists are stretched too thin to go back to monitor a doctored tree to see if it is improving or getting worse. Thus, once recognized as a potential risk, it has to go.
What I have been stewing about is the conflict of values between the risk management argument, which has merit, and the tree lovers, who are doing the City a favor by advocating for the trees.
The problem is that there is no discussion about the benefits trees bring to our environment. The policies are about removing trees, not about keeping them. This is the challenge to City leadership – to articulate and measure the value of trees to the City, and to communicate to the community why we want to keep as many as we can, and plant more.
A quick review – trees are important because:
1. They save utility costs and the use of fossil fuels. The air temperature within the shade of a tree can be 10 degrees cooler than ambient air temperature. The shade cast by a mature tree saves air conditioning costs and the demands on the power company to provide electricity. Shade also reduces the amount of absorbed heat on the earth’s surface, thus reducing overall temperature, and re-radiation of the absorbed heat after the sun sets.
2. Trees clean our air. They absorb carbon dioxide (greenhouse gases) and other air pollutants and expel clean oxygen – oxygen we need to breath.
3. Trees save water. They absorb rain water through their roots, and transpire water vapor through their leaves. They are a critical part of the rain cycle, and the creation of rain clouds. Where trees disappear, rain disappears as well. Moreover, the soils under trees are generally more permeable than lawns, and certainly pavement, allowing water to percolate into the local water table, thus restoring our wells, streams, lakes and rivers. Water not percolated into the soil is flushed through storm sewers into our major rivers, full of pollutants, and bypassing the critical process of filling local aquifers.
4. Trees clean our environment. They absorb and metabolize excess nutrients we spread on our lawns and gardens, and they mitigate other chemicals we routinely spread on our lawns, gardens and public spaces.
5. Trees save soils. Their root systems stabilize soils, preventing erosion and particle pollutants in our rivers and bays.
6. Trees are habitats and food supply for entire ecosystems we barely see – birds, insects, mammals, and amphibians.
7. Trees are ecologically efficient. They return their biomass to the earth each fall as they shed their leaves, (and older needles and leaves on evergreens). This material has values in restoring the tilth and nutrient of soils, though we generally fail to use these well.
8. Trees humanize the built environment.
9. Trees are beautiful, and we need beauty in our lives.
I hope there is someone who has measured the output and positive impact of trees, because if we could calculate the oxygen production of the oak on Seminary Avenue, we would probably be stunned.
Risks! Ah, we have so many risks we need to manage! We have all seen the damage caused by trees falling in hurricanes and ice storms. However, this is really the result of another causal agent – wind and heavy ice – rather than caused by trees themselves. And, such storms take both the compromised trees and the apparent healthy ones.
I couldn’t help but do a little research. According to the CDC and the National Vital Statistics Report the leading cause of death in the U.S. is cardiovascular disease – 650,000 people a year – a reflection on our diet and life styles. Influenza kills 65,000 people. Motor vehicle accidents kill 43,000. Firearms kill 28,000. Falls kill about 13,000. Aspirin, ibuprofen, etc. kill 7,600 people and hospitalize 76,000. Deer cause 1.5 million accidents per year, killing 150 people and injuring 10,000.
When it comes to trees, there is almost no data cited. Apparently trees are most dangerous to the arborists who care for them. The Bureau of Labor Statistics says there were 156 fatal accidents in the ornamental shrub and tree service industry in 2003. These were three major – parts of trees falling on coworkers as trees were being removed, workers falling from tree canopies, and contact with electrical current. I found a citation stating 150 people are killed annually around the globe by falling coconuts. Luckily, coconut trees don’t survive in Richmond.
Like everything else, trees age and die – they have a limited life span. They can be hazardous when they are weakened by weather, infested with insects, diseased or genetically inferior, and they should be removed. However, whenever possible, if they can be cabled, have their crowns thinned out, or treated with chemicals, they should be saved, for all the good things they provide.
I found the tree on Seminary to be particularly significant, as just a few blocks to the east we have the lower part of Chamberlayne Avenue, where all the trees have been lost. It is a subjective observation, but I can’t imagine most people wouldn’t prefer the environment on Seminary.
I know if a tree fell and injured someone I love, or crushed my car, I would be asking why. But, I also know that we expose ourselves to much greater risk everyday by driving, overeating, and using firearms.
I hope we will never perceive trees as terrorists lurking along a shaded lane ready to take us out. And, I hope even more that we can objectively identify why we want trees in our environment, and how we can afford and join together to keep them healthy and strong.