What We Can Learn From the Street Trees of Baltimore

“She said the prettiest place on earth was Baltimore at night…”
(“Streets of Baltimore,” Tompall Glaser and Harland Howard, 1966) 

The classic country song “Streets of Baltimore” wasn’t originally penned about trees but maybe it’s time to consider a rewrite. These days, street trees in Baltimore are looking better than ever and, between 2007 and 2015, the city experienced a 1% increase in urban tree canopy (UTC). This occurred while most cities in the US were losing tree canopy according to a 2012 USDA Forest Service study which also found that Baltimore had lost nearly 2% of its tree canopy between 2001 and 2005. 

Baltimore City Hall

The 2012 study determined UTC loss or gain by looking at pairs of aerial photographs from cities during various time periods. The UTC increase in Baltimore between 2007 and 2015 was detected using high-resolution aerial imagery and 3D airborne LiDAR data.  

Baltimore’s increase in UTC may be partially due to the city’s 2007 goal to increase UTC to 40% by 2036 and their efforts on multiple fronts to reach that goal: 

  • In 2007, TreeBaltimore was created as a mayoral initiative to serve as a co-ordinating organization for tree planting, establishment, maintenance and preservation. The partnership includes governmental agencies, non-profits, private companies and citizens of Baltimore. Initially,  TreeBaltimore focused exclusively on mass tree plantings in open spaces like parks and schoolyards.
  • In 2011, the Priority Planting Map was released which utilizes a set of UTC Prioritization Tools including public health, water quality and environmental justice. High-priority planting areas in the city were identified and targeted for tree planting.
  • In 2013, the Baltimore City Street Tree Species List was updated with emphasis placed on matching appropriate species to sites.
  • Recently, the city began its “Proactive Pruning Program” which encourages structural pruning of every street tree five inches or greater in diameter, neighborhood by neighborhood. Proper structural pruning focuses on creating a tree with a single central leader and a strong framework of well-attached, well-spaced scaffold branches. A structurally trained tree generally suffers less breakage and has a longer useful life in the landscape. In my opinion, this program may have the most positive long-term impact on Baltimore’s tree canopy, although what would be necessary to prove this is unknown.
  • Tree replacement standards for parks and rights-of-way were tightened. 
  • Pruning standards were improved based on current Best Management Practices (BMPs) set forth by the International Society of Arboriculture (ISA).
  • A comprehensive tree inventory of all street trees and developed parkland trees was initiated in 2017 with completion expected in summer 2018. The inventory, which is tied to the city’s real-time work order system, will serve as the primary management tool for prioritizing maintenance and identifying future planting locations. 

White oak (Quercus alba) is the state tree of Maryland

The road to improvement is seldom straight or simple. An increase from 27% to 28% UTC represents a net increase of 200 acres in tree canopy cover within Baltimore. However, more than 1000 acres were lost during the 2007-2015 time period. Managing tree canopy can be likened to managing our own health – we must perform a myriad of positive actions in the present while staying vigilant to identify problems looming on the horizon. Living things take time to develop, improvement often occurs incrementally, and a destructive event such as illness or an accident (or for a tree, a storm or construction) may produce a sudden and dramatic setback. 

Blank Lot Project on Carey Street, by the Franklin Square Community Association

What can we learn from Baltimore? 

  • Attack the problem on many fronts. Tree planting, maintenance, preservation, and invasive species removal all should be addressed.
  • Keep looking ahead. TreeBaltimore started with mass plantings in open spaces. Knowing that soon those easily planted areas would be filled, they simultaneously worked on prioritizing planting in various neighborhoods around the city.
  • Involve diverse allies. The list of governmental and non-profit partners on TreeBaltimore’s website is impressive and includes more than just the tree-huggers: clean water, sustainability, clean energy , transport and education organizations are all part of the effort. Countless neighborhood and community groups are also helpful to the cause.
  • There will be ups and downs. When asked about the future, Baltimore’s City Arborist and Chief of Urban Forestry Erik Dihle says:  

“I suspect [UTC] has slightly increased since 2015, due in part to our intensive planting program coupled with a lack of hurricanes or other major storms. Emerald ash borer is beginning to hit us hard, though. The city has approximately 8% ash throughout its canopy – including public and private lands. So all bets are off – whether we can increase or even hold steady – over the next five to ten years.” 

 Despite the challenges ahead, Dihle – and the rest of the city – won’t stop their continual efforts to get more, bigger, and better trees onto the streets of Baltimore. 

Ellyn Shea is a consulting arborist and country singer in San Francisco. Thanks to Erik Dihle for his assistance with this article. 

Image 1: SmallbonesCCO 1.0
Image 2: Mbell1975 / CC BY-SA 3.0
Image 3: Pierre Joseph Redouté / PD-1923
Image 4: Photo courtesy of Scott Kashnow

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