Tree Benefits: Growing Arlington’s Urban Forest Presentation to Arlington County Civic Federation March 16, 2021

Karen Firehock – Executive Director

Research to inform this presentation was funded by the U.S. Forest Service. GREEN INFRASTRUCTURE CENTER INC.

The Green Infrastructure Center (GIC) is a nonprofit organization that helps communities evaluate green assets and manage them to maximize ecology, economy and culture. We do this by: Building landscape models and maps Teaching courses and workshops Researching new green infrastructure methods Helping communities create strategies

www.gicinc.org GIC has writtenGreen Infrastructurenumerous books, Center guides,GREEN INFRASTRUCTURE and case CENTER INC. studies on how to plan and implement green infrastructure strategies in your community. Additionally there are numerous free tools and other resources available through our website: www.gicinc.org

VA guide: $8.00 from GIC National guide: book sellers Advanced GIS users guide to mapping: book sellers GREEN INFRASTRUCTURE CENTER INC.

GIC’s Newest Project Resilient Coastal Forests: A study of all the factors that influence forest health, longevity, uses and extent! We are looking at Fire, Pests, Storm Surges, Zoning, Development Pressures etc. – what is happening to our forests and what can we do to better protect them for the future? In VA, SC, and GA! Two year project begun in 2019. Will develop a plan and model process that can be followed in the south and beyond! GREEN INFRASTRUCTURE CENTER INC. Our trees are at risk! In Virginia, we will develop more land in the next 40 years than the past 400! And, while total acreage is important, the quality and intactness of these forests also matters. Forest fragmentation remains the greatest threat to southern forests. Urban and suburban tree canopy cover is trending downwards nationwide at a rate of about 175,000 acres per year – around 36 million trees annually. (Nowak and Greenfield 2018) GREEN INFRASTRUCTURE CENTER INC. Urban Forests are Green Infrastructure!

Left shows the gray infrastructure including buildings and roads (left). Classified high-resolution satellite imagery (right) adds a green infrastructure data layer (trees and other vegetation). GREEN INFRASTRUCTURE CENTER INC. Benefits of Trees and Forests  Preserving biodiversity and wildlife habitat.  Conserving working lands such as farms and forests, that contribute to the economy.  Protecting and preserving water quality and supply.  Providing cost-effective stormwater management and hazard mitigation.  Improving public health, quality of life and recreation networks. GREEN INFRASTRUCTURE CENTER INC. Trees: the original green infrastructure!

Trees give us cleaner air, shade, beauty and stormwater benefits at a cost that is far cheaper than engineered systems!

Estimates for the amount of water a typical street tree can intercept in its crown, range from 760 gallons to 4000 gallons per tree per year, depending on species.

Estimate the value of a tree in your yard with itreemytree https://mytree.itreetools.org/#/ GREEN INFRASTRUCTURE CENTER INC. Trees: Create Healthy Communities

 Access to fitness opportunities. (addresses obesity, nature deficit disorders)  Clean air – trees absorb pollutants, VOCs, filter runoff, cool the city. (combat asthma)  Well being and mental health - -people heal faster when they can see or access green. (hospitals need this for patients, reduces absenteeism of workers)  Less crime occurs near trees. (issue especially for downtowns and public housing areas)  Employees will exercise if they can access green where they work and on the way to work. (addresses employee health) GREEN INFRASTRUCTURE CENTER INC.

Urban Tree Canopy Values

Trees provide more attractive areas for development, historic districts, commercial areas opportunities for people to interact with nature. A study by the University of Washington found that people shopped longer and more often in tree-lined retail areas and spent about 12 percent more money. Trees = more tax revenue even in developed commercial districts! GREEN INFRASTRUCTURE CENTER INC. Job Development Small companies, especially those that are have well paid and skilled workforce place a strong importance on the “green” of the local environment. Crompton Love and Moore, 1997 The creative class: artists, media, lawyers, analysts, make up 30 percent of the U.S. workforce and they place a premium on outdoor recreation and access to nature. Florida, 2002 Trees and parks attract better paid jobs and thus a better tax base = $ GREEN INFRASTRUCTURE CENTER INC. What is an urban heat island? Urban heat islands occur when a metro area is significantly warmer than its surrounding rural areas due to human activities. Temperature differences are usually larger at night than during the day, and is most apparent when winds are weak. Paved areas in cities absorb and re-radiate tremendous heat!

Greenhouse gases trap that heat and re- radiate it back to Earth. GREEN INFRASTRUCTURE CENTER INC. Cost of Urban Heating… “Heat island” effect can contribute significantly to energy consumption during hot summer days—about $100 million dollars annually just in Los Angeles. Electricity demand for air conditioning increases approximately 1–9% for each 2°F increase in temperature. (U.S. EPA). Power generated from oil fuel/coal then generates more greenhouse gases = more climate change impacts! GREEN INFRASTRUCTURE CENTER INC.

Micro-climates Urban areas change weather patterns .. By increasing heat = more evaporation and more rain = more flooding

Stream in Arlington overtops its banks

https://www.arlingtonmagazine.com/is-arlington-ready-for-the-next-flood/ GREEN INFRASTRUCTURE CENTER INC.

Consequences of Emissions on Hot Days…

https://www.climatecentral.org/news/hot-summers-cities-climate-change-21676 GREEN INFRASTRUCTURE CENTER INC. But we can combat this problem with new trees!

Global Temperatures “Restoring forests is the only thing on Earth that can reverse the emissions that drive global warming,” Conservation International CEO M. Sanjayan GREEN INFRASTRUCTURE CENTER INC. Trees combat heat & add value to neighborhoods Trees add value to properties, in improved real estate values, savings on air conditioning costs, lower heat island and even sequestering carbon!

Decreases in tree canopy correlate to increased urban heating. Areas under trees are often 12 degrees cooler and neighborhoods are cooler too! GREEN INFRASTRUCTURE CENTER INC. As land cover changes, so does stormwater runoff and infiltration …

Infiltration GREEN INFRASTRUCTURE CENTER INC. Urban Tree Canopy and Water

• 20%+ of annual rainfall retained in crown (Xiao et al., 2000)

• Delays runoff up to 3.7 hours

• infiltration capacity of soils

• One tree can soak up 700 to 4000 gallons water annually depending on the age and species! GREEN INFRASTRUCTURE CENTER INC.

Water flow strategies How do we make this… function like this? GREEN INFRASTRUCTURE CENTER INC.

This parking lot could be retrofitted so we get less of this …

One acre of pavement releases 36 times more runoff than a forest. During a rainfall event of one inch, one acre of forest will release 750 gallons of runoff, while a parking lot will release 27,000 gallons.

(PennState Extension). Arlington Flooding GREEN INFRASTRUCTURE CENTER INC.

Link and use trees as stormwater infrastructure.

• Establish city trees’ role as infrastructure to receive federal aid for post-storm clean up efforts.

• Credit urban trees in a stormwater utility fee to promote more urban tree plantings.

• One large tree can soak up thousands of gallons of stormwater annually! GREEN INFRASTRUCTURE CENTER INC.

USDA Forest Service funded GIC to partner with 6 states to demonstrate how cities can utilize trees for stormwater management. Urban flooding A partnership between USDA Forest Service, 6 southern states: state forestry agencies and the GIC developed to implement the project. SC, NC, GA, FL, AL, VA Virginia: Norfolk, Harrisonburg and Lynchburg GREEN INFRASTRUCTURE CENTER INC. Project Goals

This project’s purpose what to show the role that trees play in soaking up stormwater. GIC helped each city with strategies to map, evaluate, protect and restore its urban forests for improved stormwater management and clean water.

Flooding on Greenwood Drive in Lynchburg, VA

Urban forests are a vital tool in managing and reducing runoff. GREEN INFRASTRUCTURE CENTER INC. Forestry Work Group Study

Tree canopy works to reduce the proportion of precipitation that becomes stream and surface flow, also known as water yield. We used a modified water yield equation that changes the SCS model by adding a canopy interception term (Ci), as suggested by Hynicka and Divers resulting in:

= +2 𝑃𝑃 − 𝐶𝐶𝑖𝑖 − 𝐼𝐼𝑎𝑎 Where R is runoff 𝑅𝑅 𝑃𝑃 − 𝐶𝐶𝑖𝑖 − 𝐼𝐼𝑎𝑎 𝑆𝑆 P is precipitation

Ia is the initial abstraction, S is the potential maximum retention after runoff begins for subject land cover. (S = 1000/CN – 10) GREEN INFRASTRUCTURE CENTER INC.

Tree Over Parking Lot

Tree Over Street Trees take up more or less water depending on their settings so GIC created high resolution 1 meter x 1 meter maps to account for conditions of the urban forest.

Tree Over Lawn Tree Over Natural Forest Cover GREEN INFRASTRUCTURE CENTER INC. The GIC’s stormwater calculator uses land cover and soils to model the benefit of maintaining or increasing urban canopy. GREEN INFRASTRUCTURE CENTER INC. The GIC’s stormwater calculator also calculates changes in pollution loading from one land use to the next. GREEN INFRASTRUCTURE CENTER INC.

Data can be translated into maps~

All planting areas are not created equal.

Optimal Tree Planting Location GREEN INFRASTRUCTURE CENTER INC.

Optimal places to retain canopy GREEN INFRASTRUCTURE CENTER INC.

What can you do?

Remember that most decisions affecting trees happen at the local level.

GIC has a spreadsheet that covers all the ordinances you should have in place to: 1) Reduce Impervious surfaces and

2) Improve, expand and enhance urban forest management GREEN INFRASTRUCTURE CENTER INC.

What to Look For! TSW Codes, Ordinances & Practices Tool GREEN INFRASTRUCTURE CENTER INC. What does a tree need? • Air (circulation) • Light (photosynthesis) • Water (growth) • Nutrients (from soil and even the air) Urban trees also need watering the first few years to help them get established. • Space (roots and canopy They should have some attention to pruning to need to spread out) ensure proper and safe form, to avoid issues like this one below. • Free from pests and diseases (watch out for these and treat as needed)

Check out Trees VA for more! https://treesvirginia.org/education/tree-planting GREEN INFRASTRUCTURE CENTER INC. Accommodate Large Trees

Avoid this!

Larger trees offer greater benefits – so think carefully when setting planting goals for streets! Consider using suspended pavement systems, rather than just choosing small trees! Trees will pay back your investment! GREEN INFRASTRUCTURE CENTER INC. Save trees! Work with developers to shrink the footprint.

• Look for opportunities to minimize impervious surfaces by meeting with Does your community encourage pre- developers BEFORE plans are finalized development meetings with builders to and INCLUDE the urban discuss tree saving – before site plans are final? Remember by the time a public forester/arborist on staff. hearing occurs, a lot of money has already been spent on development planning and • Build taller not wider! engineering. So have conversations about site layout sooner! GREEN INFRASTRUCTURE CENTER INC. Variable Space Sizing

Not all of us drive this

Some of us drive this.

. Some parking lots have excess spaces, resulting in greater impervious surfaces and more stormwater runoff. Use variable spaces and parking maximums. . Green up parking lots with trees and bioswales to increase parking lot perviousness, provide more shade, and increase attractiveness. . Shaded pavement lasts longer, so trees save us money in paving repairs. GREEN INFRASTRUCTURE CENTER INC. Trees as Best Management Practices (BMPs) Trees can be used in concert with existing Best Management Practices, such as this bioswale with a tree planted in it.

A bioswale is a stormwater cleaning practice using stone and amended soils and plants to capture and clean rainwater runoff before it enters drains and creeks. Trees as Best Management Practices (BMPs)

Background: Individual trees not currently considered a best management practice (BMP) for managing stormwater in Virginia. DEQ is to convene a study group to report on options for using tree as BMPs (delayed due to Covid – was to be last fall) Benefits: Trees reduce the amount of stormwater runoff by capturing precipitation and infiltrating it onsite & evapotranspiration, thus reducing flooding and recharging groundwater. Challenges:  Quantifying standard volume for credits is difficult: variables include tree species, size, location/soils where tree is planted, etc.  Time lag for compliance if new, young trees planted for credit (versus mature tree) benefits.

Limitations: Only existing forest cover can be counted as stormwater management. GREEN INFRASTRUCTURE CENTER INC. So do other places use trees as a BMP? Sure!  Center for Watershed Protection has tools to calculate vol. benefits per tree: https://www.cwp.org/making-urban-trees-count/  Pine Lake, GA: 10 gallons of water credit per inch of the diameter at breast height (DBH) for preserving existing trees under 12” DBH, and 20 gallons of credit per inch of DBH for preserving existing trees over 12” DBH.  Washington D.C.: 20 cubic feet for each preserved tree, and 10 cubic feet for each planted tree. Trees planted as part of BMP, e.g. bioswale get 10 cubic feet water credit. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6134866/  Portland: ‘tree credit’ can be used to offset 10 percent of a site’s impervious surface as stormwater management and they also use trees in BMPs. https://www.portlandoregon.gov/bes/article/582102> GREEN INFRASTRUCTURE CENTER INC.

Develop a forestry emergency response plan.

Municipalities typically plan well for the removal of vegetation and debris directly following a storm. However, much less foresight is typically put into replanting after a storm.

A forestry emergency response plan addresses funding and timelines for replanting following a storm. Contracts can be set up ahead of time – before a hurricane – to save on delays and get better pricing too! This is a goal for Arlington County VA http://www.gicinc.org/PDFs/Comm%20Forest%20Storm %20Mitigation%20Workbook%20_National%20Final.pdf GREEN INFRASTRUCTURE CENTER INC. Plant a forested buffer!

A 100 foot buffer can remove more than 90% of nitrogen, phosphorus and sediment!

Although the Chesapeake Bay Act requires 100’ buffers be maintained (with some exceptions for urban areas and agriculture) many areas lack buffers.

Chesapeake Bay BMPs for Trees to meet watershed implementation plans: https://www.chesapeakebay.net/docu ments/WIP_Forestry_BMP_Packet_No vember_2018_Update.pdf GREEN INFRASTRUCTURE CENTER INC. Once you enter your codes: A summary shows what to improve! Trees and Stormwater Codes, Ordinances, and Practices Audit Summary Sample City 100%

90%

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Reducing Tree Care and Plans and Implementation Monitoring Emergency Elements Integration Impervious Protection Goals Capacity Progress Response Surfaces Each municipality gets a score by priority and topic. GREEN INFRASTRUCTURE CENTER INC. Key Strategy: Plant trees on private lands

In a study GIC did looking at 31,000 parcels in a city, if everyone planted a single tree, they would intercept 62 million gallons of rainwater every year (1.5 million bathtubs!) 80% of planting areas are on private property!

. The Arlington County Tree Canopy Assessment found that approximately 2,890 acres were identified as preferred planting areas, with most of that acreage coming from residential zoning (2,088 acres).

. So organize plantings in your community and Each tree icon represents a possible tree planting location that avoids buildings, encourage them in HOA lands, yards, streets underground utilities, and other infrastructure. Tree spacing is 30 feet. …everywhere! GREEN INFRASTRUCTURE CENTER INC. Products you can use Trees and Stormwater …http://www.gicinc.org/trees_stormwater.htm

 Trees and Stormwater Codes Ordinances and Practices Audit Tool: Anyone can fill it out and can self-score!  Trees and Stormwater Calculator Tool: Requires tree canopy map and adding in data such as roads, buildings etc. Then plantable area can be calculated and data can be added to the calculator spreadsheet. Technical instructions for GIS on line! Arlington could do this analysis or hire GIC!  Case Studies – get them on line!  A final summary report, on line too, provides key findings. Local Resources for Arlington Tree Canopy Report https://arlingtonva.s3.dualstack.us-east-1.amazonaws.com/wp- content/uploads/sites/13/2018/01/Arlington-County-Tree-Canopy- Report-2016-.pdf

Arlington’s Ecosystem Services Report for its Trees: https://environment.arlingtonva.us/wp- content/uploads/sites/13/2017/02/iTree-2016-Written-report.pdf

Arlington’s Urban Forest Master Plan (to be updated): https://projects.arlingtonva.us/fnrp-overview-and-timeline/

Apply to plant trees in your Arlington Community! https://www.ecoactionarlington.org/community-programs/trees/ GIC Inc. End 320 Valley St. Scottsville, VA, 24590 434-286-3119

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