Urban Forestry Archives

These are the Champions: Our biggest trees

December 14, 2017
By Vincent Verweij

What are Champion trees?

Measuring Champion trees (Source: Mississippi Champion trees)

Champion trees are the largest of its kind, in that species. Some species, like oaks and maples, get much larger than species like dogwoods and serviceberries, so we measure each species in its own class.

Measurement is done by professionals and volunteers all over the state. They involve three key measurements:

Height of the tree from the base to the top
Circumference of the trunk at 4.5 feet (also known as circumference at breast height, CBH)
The average width of the crown.

One adds the height, the circumference, and 1/4 of the canopy spread. This gives you a number, which you can compare with other large trees, to see if it’s the largest in the county, state, or nation.

State Champion Dawn Redwood

Does Arlington have Champion trees?

Because we have such dedicated volunteers, and a strong history in preserving trees, Arlington has some amazing champion trees, including state champions and one national champion! One tree we recently re-measured is the state champion Dawn Redwood (http://bigtree.cnre.vt.edu/detail.cfm?AutofieldforPrimaryKey=1838), which is a whopping 114 ft tall, and has a giant trunk. This tree is native to China, but finds our soil to be as suitable as its home country. Like our native baldcypress, it’s a deciduous conifer, and loses its leaves in the winter. Check out the picture on the left for this beauty, which can’t even fit in a single picture.

Where can I find them?

We have 1 National Co-champion (a Dwarf Hackberry), 49 State Champions, and 59 County champion trees. While some trees are on private property, and you need permission to view them, many of them are on county land. Check out the maps and registers below, for locations and more information:

http://gis.arlingtonva.us/gallery/index.html – GIS Gallery of all our maps, including Champion trees.

http://bigtree.cnre.vt.edu/ – State register of Virginia big trees.

http://www.americanforests.org/explore-forests/americas-biggest-trees/champion-trees-national-register/ National register of champion trees.

For Your Health: How Trees Can Save Your Life

August 8, 2017
By Vincent Verweij

Health benefits of trees

Recent studies have shown that sometimes, going to a park, or even looking a single tree can significantly improve a person’s health and stress levels. Some doctors have started prescribing parks as a remedy to patients’ health issues, and our tree values have been expanded to include mental and physical health benefits. While this is intuitive to tree lovers, seeing these studies can help us communicate the value of trees more.

Air quality and climate mitigation

Our trees are critical in filtering our air, removing harmful pollutants, such as Carbon Monoxide (toxic at high levels), particulate matter (causes asthma), and Ground-level Ozone (various respiratory impacts). See the image on the right.

Trees Improve Air Quality (Source: Nature Conservancy)

Water quality

As previously discussed in our stormwater post, trees filter drinking water for us and the creatures with which we share the world.

Mental health

A less-reported value of trees are their mental health benefits, but these can outweigh many of the others, shown through many studies (links below):

Improved memory
Reduced hospital time and improved recovery, from a view of green or treed space
Increased attention level in children
Increase social cohesion of communities

Trees and health (Source: ACTrees)

Shade

Heat is one of the greatest impact on urban health, and trees, through shade and transpiration, can greatly reduce heat-related illness and comfort. Trees can reduce ambient heat by up to 9 degrees Fahrenheit, compared to exposed areas.

Crime

The folklore of trees providing hiding spots for crime is largely negated by modern research, which shows trees can greatly improve crime statistics in neighborhoods. Controlled for social background, areas with vegetation and healthy trees performed much better than unvegetated areas. In one study, vegetated areas had 7 to 8 percent less gun-related incidents than the control area. This most likely links with the mental health benefits of trees, but is good to take into account when planning a city.

Our community’s trees overall health benefits

Our i-Tree study provides us with actual number values of some of these benefits, and in Arlington, our trees provide us with the following health benefits:

Number of trees: 755,400 (45 trees/acre, a healthy natural forest has 40-60 trees/acre)
Pollution removal: 235 tons/year ($3.59 million/year)
Carbon storage: 204,000 tons ($27.1 million)
Carbon sequestration: 9,630 tons/year ($1.28 million/year)
Avoided stormwater runoff: 10,730,168 cubic feet/year ($717 thousand/year)
Building energy savings: $1,020,000/year
Avoided carbon emissions: 2,210 tons/year ( $294,000/year)

These numbers take into account avoided hospital visits, illness, and death, and show how trees can really improve ourselves and our community!

How Our Trees Clean Our Water

July 14, 2017
By Vincent Verweij

Trees as a Filter

Bluemont Forest Buffer

Arlington County recently installed its first forest buffer as a stormwater Best Management Practice (BMP) at Bluemont Park’s new baseball field. This forest buffer not only looks great, but also serves an important function for this park and our community.

To help improve the Chesapeake Bay Watershed, and the water we depend on, trees are being used on larger projects that allow water to flow into a forest or forest buffer. The trees improve our water in many ways, along with providing other benefits of air pollution control, shade, beauty and wildlife benefit.

The First Rain: Interception and Evaporation

Every tree catches the rain as it comes down, but did you know a mature White Oak (Quercus alba) can intercept up to 12,010 Gallons of water every year? That’s just a single tree! This water stays in the leaves until it’s absorbed by the tree or evaporates to cool our air. This is the first line of defense, as this prevents this water from needing to be piped or treated by other stormwater infrastructure. According to our i-Tree Eco study, our trees in Arlington alone capture 80,267,230 gallons every year!

Stormwater Benefits of Trees: Source: Deeproot

Keeping it in the Soil and Filtering: Infiltration and Storage

Trees are designed by evolution to make the best use of every drop that falls on their canopy. Their leaves and branches act like a giant capturing device to get precious water to the tree’s roots. This helps trees provide one of the greatest stormwater benefits: infiltration and storage. Through filtering the water with their roots and soil, pollutants get trapped and diluted which reduces the impact of water pollution.

Additionally, storing all this water makes it available for the tree and other plants around it. This stored water can then be used to grow the tree and evaporate this water back into the air, once more preventing it from impacting our stormwater system.

Forest Buffers as a Stormwater Device

In the case of Bluemont’s baseball field, there were some restrictions to using this tool, but it was perfect for this project. These are some of the restrictions to using forest buffers for stormwater credit:

You need a fairly flat slope and space to accommodate the water to slowly flow through
- Very flat slopes (1-4%) can use a 35 ft buffer
- Moderately flat slopes (4-6%) need 50 ft
- Steeper slopes (6-8%) need 65 ft
Soils must be able to drain and store the water

Wider Benefits

These solutions can have a great positive impact on our community and has many benefits over traditional stormwater infrastructure:

This technique is a non-engineered, nature-based solution to stormwater
Near streamsides, forest buffers can significantly improve tree canopy and our natural habitat
Lower cost than engineered solutions, in most cases

Learn More

How Trees Tame Stormwater by the Arbor Day Foundation

Benefits of Forest Buffers by the Chesapeake Bay Foundation

Forest Buffers presentation to the Urban Forestry Commission:

The Streamside Forest Buffer. Source: USFS