Expanding DC’s Extraordinary Urban Tree Canopy

by David Jonas Bardin

In July 2011, Mayor Vincent C. Gray announced Sustainable DC – a planning effort to make the District of Columbia the greenest, healthiest, and most livable city in the nation. One of Sustainable DC’s major initiatives is to increase the District’s urban tree canopy…. The District’s tree canopy provides many environmental and social benefits, including reduced stormwater runoff and carbon footprint, improved air quality, additional wildlife habitat, savings on energy bills, increased property values, and enhanced quality of life. The District’s tree canopy also fosters social and educational opportunities and provides aesthetic benefits to residents.

District Department of the Environment and District Department of
Transportation Urban Forestry Administration,
District of Columbia Urban Tree Canopy Plan (January 2013)

Aerial photo of Rock Creek Park, with nearby streets and private homes. (National Park Service photo)

DC’s urban tree canopy includes natural forests and landscaped areas as well as about 145,000 street trees managed by the District Department of Transportation’s (DDOT) Urban Forestry Administration (UFA). The number of all trees in DC – federal, DC and private – are estimated to exceed 2.6 million.

Living trees add to canopy until they decline from age, pests, or disease or are cut to clear space for other land uses. UFA believes half of canopy expansion comes from growth of existing trees and half from new tree plantings.

Urban tree canopy (UTC) covers more of DC’s land area – 35% – than of most densely-populated cities, according to The Trust for Public Lands. Public parks and private homes account for most of our canopy. And the federal government provides more citywide canopy than its proportionate share of DC’s land area. National Park Service (NPS) trees thrive in designed park areas like the National Mall, where NPS policy is to replace all trees that die, and natural forest areas like much of Rock Creek Park and its satellites, Fort Dupont Park, and the C&O Canal.

Tree canopy shades carousel on the National Mall. (photo by Casey McAdams, Smithsonian Institution)

DC benefits from trees on other federal lands, such as the Arboretum and U.S. Capitol grounds, and on institutional lands like the Hillwood Museum & Gardens and Peruvian Embassy, and at many, many private homes. And valuable DC-owned street trees in the transportation right of way (ROW) shade our sidewalks, homes and roads. Shade trees are large trees with widespread, dense canopy. A shade tree is taller than 25 feet at maturity.

Connecticut Avenue street trees canopy (photo by the author)

The Mayor’s Sustainable DC Plan would expand citywide tree canopy from 35 to 40 percent of land area by 2032 – three years earlier than called for by the U.S. Environmental Protection Agency (EPA). That would be a gain of about 2,000 acres of tree canopy in the course of 20 years.

Based on 2006 data, estimated DC tree canopy extends over 13,673 acres out of 39,283 land acres. (DC is almost 90 percent land and just over 10 percent water.)

How can the Plan succeed? This article addresses challenges and responsibilities; it starts to discuss budgets and resources; the next article will turn to measuring success. “As we progress,” writes Mayor Gray, “we must constantly assess our efforts to determine whether or not they are working to improve the quality of life, increase economic prosperity, and ensure everyone is sharing in the benefits.”

Lead Responsibility and Partnering

To reach big goals requires sustained efforts. According to the Sustainable DC Plan (pages 114-115), the Mayor assigns lead responsibility to DDOT’s UFA, which has most of DC’s tree budgets, partnering with three listed DC agencies – District Department of the Environment (DDOE), Department of General Services (DGS), DC Public Schools (DCPS) – and one non-governmental organization – Casey Trees.

DDOT Urban Forestry Administration

UFA has cradle-to-grave responsibility for DC’s street tree assets. UFA plants, prunes, controls pests and disease, and removes street trees when ravaged by storms, vehicular collisions, or natural debilitation. It also has limited regulatory and removal duties for some trees on private lands.

UFA has focused on its street trees. They range in size from 2 inches to 65 inches diameter at breast height (DBH), with average sizes between 10 and 20 inches – making for considerable growth potential. Only 3 percent exceed 35 inches DBH. Maples make up 38 percent of the street trees; oaks, 31 percent; elms, 10 percent; over 150 species all told. UFA has about 11,000 empty planting spaces it is working to fill. It seeks to expand existing tree boxes and create new ones by removal of impervious paving. UFA contracts to plant new trees to replace dead and dying street trees and to fill empty tree spaces, generally with saplings of at least 2 inches caliper, warranted to survive at least a year.

UFA aims to raise plantings to 7,000 in FY 2013 and 2014. UFA is principally an asset management agency. It also regulates removals of certain special protected trees on private lands. UFA administers the District’s Special Purpose Revenue Tree Fund, which receives payments when developers cut down private trees. UFA has drawn operating revenues from the Tree Fund in some years to pay for part of its street tree plantings. But most of UFA’s funding comes (desirably) from capital budgets. The FY2014 budget, would add $12.5 million of local funds to UFA capital projects, including $3 million for planting trees.

Department of General Services

DGS, another asset management agency, is landlord to DC Public Schools, DC Department of Parks & Recreation, and others, with respect to District lands outside the transportation rights-of-way. It has construction and maintenance responsibilities for assets including trees. DGS may enter into agreements or understandings with UFA to take over some tree responsibilities on such District lands. Budgets do not distinguish trees.

District Department of the Environment

DDOE, a planning and regulatory agency, also manages incentive programs such as RiverSmart Homes, part of which includes planting canopy shade trees on private lands, where the landowner co-pays $50 per tree and commits to maintain the tree, and tree rebate programs which gives out $50 for smaller tree species, $100 for larger ones.

These subsidies, for planting only, recently incentivized over 1,000 trees a year via contracts with Casey Trees. DC operating budgets have not identified DDOE tree dollars separately but they have been far less than UFA’s. DDOE expects that its $156,000 grant to Casey Trees in 2013 will result in 2,100 trees – plantings or rebates for private plantings. DDOE has waiting lists for canopy shade tree plantings, but not for rebates.

DDOE is DC’s Storm Water Administrator. DC storm water fees, collected by DC Water for DDOE, now fetch over $12 million a year for the District’s Storm Water Permit Compliance (MS4) Special Purpose Revenue Enterprise Fund, but only a small fraction goes for tree planting. DDOE uses Clean Water State Revolving Fund money from EPA and some other national funding sources for its programs and those of other agencies. DDOE was budgeted $384,000 of Sustainable DC funds (not yet committed) in FY2013 for DCPS/DPR tree plantings.

Ironically, DDOE has been allocating $300,000 annually of the MS4 storm water funds for planting street trees despite its RiverSmart Homes tree planting waiting list.

Casey Trees

Casey Trees plants just over 2,000 trees a year, mainly on private lands, with self-generated funds and through contracts with DDOE. Casey also collects and publishes information on tree plantings and tree canopy in DC and on what drives changes in tree canopy. Each year, Casey surveys principal government and private tree planters in DC and publishes how many trees they planted.

Casey Trees has also portrayed recent clear-cutting of many trees for the sake of development as negatively impacting canopy. Tree Report Card 2012 (2013).

Not a tree was left (top photo, in June 2012) of canopy covering 40 acres (bottom, April 2010). UFA says trees removed were invasive and undesirable species which grew after previous clear cuttings. (photo courtesy of Casey Trees)

Strategy and Coordination

Paralleling its Sustainable DC Plan, DC committed to EPA to do three things:
(a) develop a strategy for reducing discharge of storm water pollutants “by expanding tree canopy throughout the city”;
(b) plant at least 4,150 net trees a year in the part of DC served by separate storm and sanitary sewers (“MS4” ¹); and
(c) report progress annually.

DDOE and DDOT jointly submitted their citywide strategy as required. The draft District of Columbia Urban Tree Canopy Plan submitted to EPA in January 2013 includes the “Plan for Achieving the District’s Forty Percent Canopy Goal” (Section V, pages 19-22). They are confident of exceeding 4,150 net trees annually.

DDOT and DDOE’s joint plan for achieving 40 percent canopy includes two “potential” tracking items:
(a) Perform a tree mortality study targeting DC, federal, and private lands and
(b) perform a District canopy analysis every 5 years.

UFA expects to release a tree mortality study late this summer and a new five-year canopy analysis jointly with Metropolitan Washington Council of Governments early this summer based on 2011 data. Its last study, based on 2006 data, indicated a city-wide canopy of 35% of total land area. It also sliced and diced canopy data for sub-areas, such as:

• 90% tree canopy for Rock Creek Park; and
• 11% to 69% range for the various advisory neighborhood commission (ANC) areas.

ANC area canopies ranged from 69% for 3G (Chevy Chase) and 66% for 3F (Forest Hills) to 11% for 1B (Columbia Heights / LeDroit Park / U Street) and 12% for both 6C (Union Station) and 2F (Logan Circle / Thomas Circle). Studies used old boundaries (before redistricting in light of the 2010 Census), and included park trees in ANCs.

DDOT and DDOE estimated it would take an average of 10,800 tree plantings each year and 108 acres of net canopy growth each year to reach 40 percent canopy over 20 years. ² UFA sees these numbers as uncertain and changeable and believes there is no way to provide a solid number. Also, canopy is always changing and growth is largely unpredictable. UFA would rely on 5-year canopy reports and adjust as needed.

The Sustainable DC Plan promises regulatory changes which will require new developments to incorporate trees and green space as a matter of course. Presumably, 5-year canopy reviews will examine whether such new trees and growth of older trees sufficiently exceed natural canopy attrition and private removals of healthy trees to achieve net canopy expansion.

DC has offered no estimate of costs of expanding canopy cover from 35 percent to 40 percent. UFA believes it would be difficult to predict those costs in long-term city budgets: If most canopy expansion happens on private lands, where most canopy losses took place and the only place where most replacements are possible, will private landowners bear all costs without a budgeted city contribution (via RiverSmart Homes and like programs)? Yet Sustainable DC Plan also promises:

The [UFA] will review prime planting locations for trees across all neighborhoods. Planting may take place on either public or private land and through the successful RiverSmart Homes program and other initiatives.

The Mayor’s Office will decide whether to freeze or expand incentivizing of tree plantings on private lands through RiverSmart Homes. The Tree Fund offers potential support for more incentivizing. It actually receives revenues when developers cut down trees on private land. And DC Law would allow use of Tree Fund to incentivize more plantings on private lands. Although UFA has used Tree Fund dollars (so far) to pay for planting additional street trees, the Tree Fund is subject to clumsy rules and inferior to capital funding for UFA’s tree planting program: Ups and downs in development and, therefore, of tree cutting on private lands make for irregular Tree Fund revenues:

During 8 years, FY2005-2012, Tree Fund revenues totaled $1.8 million, but UFA used revenues in only 5 years, totaling $1.1 million. UFA used those revenues as operating funds for part of its street tree planting in place of capital funds. Frozen in FY2010, $627,937.83 was diverted from Tree Fund to the General Fund in FY2011.

Locations of incentivized DDOE/Casey tree plantings (courtesy of Casey Trees; click the map to download the PDF)

DC’s extraordinary tree canopy means competitive, quality of life advantages over other big cities. As other cities try to catch up, Sustainable DC challenges us to hold on to DC’s advantages and add to them – enhancing asset values and creating green jobs.

This article was submitted to Forest Hills Connection on June 20th, 2013, and is current through that date. My next article will discuss forthcoming analyses as well as margins of error, uses (e.g., tools for planning and canopy management), costs of preparation, more transparency, and policy options.

Acknowledgements: Many good people in UFA, DDOE, Casey Trees, USFS, the Office of the Chief Financial Officer, DGS, UDC, and the trees and parks communities, helped me try to understand complicated, often confusing matters. John P. Thomas, David Allen Clark and Mark Buscaino were particularly generous with time and attention to walk me through facts and undo misconceptions. However I am solely responsible, of course, for any errors or critical omissions.

References:
Sustainability DC, Sustainable DC Plan (2013)
The Trust for Public Land, 2012 City Park Facts (PDF, 2013)
O’Neil-Dunne, A Report on Washington, D.C.’s Existing and Possible Tree Canopy (PDF, U. of VT 2010)
UFA/DDOT, District of Columbia Assessment of Urban Forest Resources and Strategy (PDF, June 2010)
Corletta, Washington DC’s GIS Based Street Tree Inventory & Work Management System (large PDF, UFA Oct 2010)
DDOE/DDOT, Draft District of Columbia Tree Canopy Plan< (PDF, 2013)
DDOE, 2011 and 2012 DC MS4 Annual Report (2013)
Casey Trees, Tree Report Card 2012 (2013)