Boston Today

The city of Boston covers roughly 31,000 acres of land. According to a 2014 study, 7,300 acres of that land, or approximately 24% of the city, is open space, and the number of documented trees averages out to about 6 trees per acre throughout the entire city.[1],[2] While over 30% of some cities, such as Atlanta, GA and Washington, DC, is green space, less than 10% of other cities like Denver, CO and New Orleans, LA are green space.[3]

Despite these numbers, the city of Boston can decrease fragmentation and increase biodiversity by assessing the quality and placement of its green spaces. It has been shown that natural parks with native flora are most beneficial to local fauna.[4] However, natural parks alone are not sufficient. Animals need a safe way to travel between green spaces, which can be provided by wildlife corridors. Strategically-placed, intermittent green spaces can create an effective wildlife corridor for city-dwelling animals to move between parks, promoting genetic and species diversity.[5]

Genetic diversity refers to diversity within a species. If a subset of a population is impacted by fragmentation—in other words, if infrastructure has eliminated their ability to interact with other individuals in their species—chances of inbreeding increase. This decreases genetic diversity, increasing the risks of species extinction due to disease or sudden habitat loss.[6] On the other hand, species diversity—more specifically, species richness—addresses the number of different species within a region.[7] Using the metrics of genetic and species diversity provide a broader picture that includes not only the resilience of each species but also the ecosystem in which they dwell.

To read more about the metrics Terrascope Class of 2024 has outlined to measure biodiversity, you can read our “What is Biodiversity?” page.

Past and Recent Updates

The Open Space and Recreation Plan 2015-2021 is a report released by the Boston City Government, which presents the analysis and goals involved in development of green spaces, and splits the benefits of parks into health, economic, environmental, and social benefits.[8] Three regional land trusts—the Trustees of Reservations, the Trust for Public Land, and the Massachusetts Audubon Society—are responsible for land protection and nature conservation throughout Boston, as well as the preservation and enhancement of several park areas within the city.[9]

Logos for The Trust for Public Land, Mass Audubon, and the trustees of reservations.
Figure 1. Regional land trusts throughout Massachusetts and the United States work to conserve natural parks.[10],[11], [12]

In evaluating the current state of biodiversity in Boston, it is important to establish an understanding of the native species and ecosystems within the city. Boston is crossed by five rivers (the Charles River, Muddy River, Neponset River, Chelsea River, and Mystic River) and also encompasses several key wetland areas, along with brooks, streams, and ponds.[13] The city is located in the Appalachian oak-hickory forest zone, and regions of this native woodland are still preserved in the Stony Brook Reservation in Hyde Park, along with others such as the Allandale and Hancock Wood.[14] However, even these existing forested areas have faced challenges due to the construction of roads, which result in habitat fragmentation and disruption of existing wildlife corridors.[15] Aside from forested areas, Boston is characterized by wetland vegetation, including both freshwater and coastal areas.[16] Currently, the City of Boston Climate Action Plan has a target of 35% tree canopy coverage by 2030, and agencies such as the Boston Urban Forest Council and the Parks Department are jointly working towards protection of native vegetation.[17] 

Within Boston’s existing open space, about 3,500 acres are comprised of important habitat lands for local wildlife.[18] Three Important Bird Areas (IBAs)—the Belle Isle Marsh, the Boston Harbor Islands National Recreation Area, and the Mystic River Watershed—fall partly within Boston city limits, and open spaces in these regions must specifically take into account IBA guidelines.[19] The continuation of urban sprawl has resulted in animals typically associated with remote wilderness areas being more commonly seen within city limits. Existing wildlife corridors in Boston are primarily associated with water bodies, such as rivers and bays.[20] However, there are several land-based wildlife corridors currently in existence, including the Emerald Necklace park system, the Arborway to the Arnold Arboretum, several cemeteries, and railroad corridors.[21] The Massachusetts Department of Conservation and Recreation has identified three Areas of Critical Environmental Concern (ACECs) within Boston, which are the Rumney Marshes, the Neponset Estuary, and the Fowl Meadow / Ponkapoag Bog.[22] The re-evaluation and design of new green spaces and wildlife corridors must take the needs of IBAs and ACECs into account, prioritizing methods that will best protect threatened wildlife. 

Looking Ahead

Map of Boston showing the location of parks, parkways, Urban Wilds, Cemeteries, and Malls.
Figure 2. The Emerald Necklace is a chain of open spaces within Boston, highlighted in this image in green.[27] The key includes malls, or public areas “often set with shade trees and designed as a promenade or pedestrian walk.”[28]

In addressing the biodiversity crisis within urban and suburban areas, it is critical not only to develop sustainable plans for future cities, but also to analyze and improve upon the conditions of current cities. This analysis can highlight places that can be reasonably altered to mitigate the negative environmental effects of urban sprawl.

To address Boston specifically, the city government launched a plan in 2018 called Imagine Boston 2030, a multi-faceted project to improve the city as a whole. Included within this framework are nine goals regarding the expansion and conservation of open spaces.[23],[24] Uniquely, the city of Boston has a chain of natural parks and open spaces, nicknamed the Emerald Necklace.[25] In addition to investing in the city’s largest park, Franklin Park, the Imagine Boston 2030 plan suggests improvements to the Emerald Necklace network.[26]

Open spaces are not necessarily designed for wildlife. The map below identifies the Emerald Necklace as a chain including athletic fields, parkways, and cemeteries (Figure 2), some of which are not beneficial to local flora and fauna. Parkways, for example, and other large, high-traffic roadways, can kill animals. Moreover, these areas become sparser closer to the city’s center, providing animals in those areas with few safe options to move within or through the city.

Current City Funding

Boston’s FY21 budget plan includes a new $3 million Climate Resilience Reserve, a $500,000 investment in the urban forestry plan, and $1 million increase in the annual street trees capital project.[29] This increase in investment towards green spaces is indicative of the Boston city government’s prioritization of environmental issues, as well as the potential increase in investment over time towards green space and wildlife corridor projects. Furthermore, the Boston FY21-FY25 Capital Plan dedicates over $3.5 million to urban wilds renovation under the Parks and Recreation Department, alongside over $10 million towards projected park renovations.[30] These next five years are an optimal time to reevaluate the design and placement of green spaces and wildlife corridors, in order to utilize the projected budget impactfully. 


[1] Boston Maps Analytics Team. (2018, November 7). Open Space. Analyze Boston. 

[2] Boston Maps Analytics Team. (2019, January 10). Trees. Analyze Boston. 

[3] Geotab. (2019, April). Urban footprint: The allocation of space in US cities. Geotab. 

[4] Goddard, M. A., Dougill, A. J., & Benton, T. G. (2010, February). Scaling up from gardens: biodiversity conservation in urban environments. Trends in Ecology & Evolution, 25(2), 90-98. ScienceDirect. 

[5] Lepczyk, C. A., Aronson, M. F.J., Evans, K. L., Goddard, M. A., Lerman, S. B., & MacIvor, J. S. (2017, August 9). Biodiversity in the city: fundamental questions for understanding the ecology of urban green spaces for biodiversity conservation. BioScience, 67(9), 799-807. 

[6] Hughes, A. R., Inouye, B. D., Johnson, M. T.J., Underwood, N., & Vellend, M. (2008, April 8). Ecological consequences of genetic diversity. Ecology Letters, 11(6). 

[7] Williams, P. (1991). Measuring biodiversity: Taxonomic relatedness for conservation priorities. Australian Systematic Botany, 4(4), 665-679. 

[8] Boston Parks & Recreation. (2015, January). Open space & recreation plan 2015-2021. City of Boston. 

[9] Ibid.

[10] Mass Audubon. (n.d.). 

[11] The Trust for Public Land. (n.d.). 

[12] CISA. (2013, May 1). The Trustees of Reservations. 

[13] Boston Parks & Recreation. (2015, January). Open space & recreation plan 2015-2021. City of Boston. 

[14] Ibid.

[15] Ibid.

[16] Ibid.

[17] Ibid.

[18] Ibid.

[19] Ibid.

[20] Ibid.

[21] Ibid.

[22] Ibid.

[23] Boston Mayor’s Office. (2017, July). Imagine Boston 2030. City of Boston. 

[24] Ibid.

[25] Ibid.

[26] Ibid.

[27] Ibid.

[28] Merriam-Webster. (2020, October 26). Mall definition.,grassy%20strip%20between%20two%20roadways 

[29] Boston Mayor’s Office. (2020). FY21 climate and open space priorities. City of Boston. 

[30] Boston Mayor’s Office. (2020). FY 21 Capital Budget. City of Boston.