Current and future biomass carbon uptake in Boston's urban forest

Andrew Trlica; Lucy R Hutyra; Luca L Morreale; Ian A Smith; Andrew B Reinmann

doi:10.1016/j.scitotenv.2019.136196

Current and future biomass carbon uptake in Boston's urban forest

Sci Total Environ. 2020 Mar 20:709:136196. doi: 10.1016/j.scitotenv.2019.136196. Epub 2019 Dec 19.

Authors

Andrew Trlica¹, Lucy R Hutyra², Luca L Morreale³, Ian A Smith⁴, Andrew B Reinmann⁵

Affiliations

¹ Boston University, Department of Earth & Environment, 685 Commonwealth Ave., Boston, MA, USA. Electronic address: atrlica@bu.edu.
² Boston University, Department of Earth & Environment, 685 Commonwealth Ave., Boston, MA, USA. Electronic address: lrhutyra@bu.edu.
³ Boston University, Department of Earth & Environment, 685 Commonwealth Ave., Boston, MA, USA. Electronic address: lmorreal@bu.edu.
⁴ Boston University, Department of Earth & Environment, 685 Commonwealth Ave., Boston, MA, USA. Electronic address: iasmith@bu.edu.
⁵ Environmental Sciences Initiative, CUNY Advanced Science Research Center, 85 Saint Nicholas Terr., New York, NY, USA; PhD Program in Earth and Environmental Science, The Graduate Center, CUNY, 365 First Ave., Room 4306, New York, NY, USA; Department of Geography and Environmental Science, Hunter College, 695 Park Ave., Room 1006 HN, New York, NY, USA. Electronic address: areinmann@gc.cuny.edu.

PMID: 31887518
DOI: 10.1016/j.scitotenv.2019.136196

Abstract

Ecosystem services provided by urban forests are increasingly included in municipal-level responses to climate change. However, the ecosystem functions that generate these services, such as biomass carbon (C) uptake, can differ substantially from nearby rural forest. In particular, the scaled effect of canopy spatial configuration on tree growth in cities is uncertain, as is the scope for medium-term policy intervention. This study integrates high spatial resolution data on tree canopy and biomass in the city of Boston, Massachusetts, with local measurements of tree growth rates to estimate the magnitude and distribution of annual biomass C uptake. We further project C uptake, biomass, and canopy cover change to 2040 under alternative policy scenarios affecting the planting and preservation of urban trees. Our analysis shows that 85% of tree canopy area was within 10 m of an edge, indicating essentially open growing conditions. Using growth models accounting for canopy edge effects and growth context, Boston's current biomass C uptake may be approximately double (median 10.9 GgC yr^-¹, 0.5 MgC ha^-¹ yr^-¹) the estimates based on rural forest growth, much of it occurring in high-density residential areas. Total annual C uptake to long-term biomass storage was equivalent to <1% of estimated annual fossil CO₂ emissions for the city. In built-up areas, reducing mortality in larger trees resulted in the highest predicted increase in canopy cover (+25%) and biomass C stocks (236 GgC) by 2040, while planting trees in available road margins resulted in the greatest predicted annual C uptake (7.1 GgC yr^-¹). This study highlights the importance of accounting for the altered ecosystem structure and function in urban areas in evaluating ecosystem services. Effective municipal climate responses should consider the substantial fraction of total services performed by trees in developed areas, which may produce strong but localized atmospheric C sinks.

Keywords: Canopy fragmentation; Carbon uptake; Climate adaptation; Ecosystem services; Street trees; Urban forest.

MeSH terms

Biomass*
Boston
Carbon
Cities
Forests
Massachusetts
Trees

Substances

Carbon