VICKSBURG, Miss. - Working for the city of Cambridge, Massachusetts, the U.S. Army Engineer Research and Development Center (ERDC) Environmental Laboratory (EL) Risk and Decision Sciences (RaDS) team explored extreme climate-related scenarios over the next 50-100 years which could challenge the integrity of the city’s urban forests. Study results indicated the most tolerant tree species and locations in Cambridge with an informative vulnerability assessment for effectively managing this beneficial resource.
Cambridge city officials approached the ERDC RaDS team based on past history with Dr. Igor Linkov, EL research scientist, who had served as an adviser on past projects.
This Planning Assistance to States (PAS) agreement was developed to supplement the city’s current evaluation efforts and was executed through the Corps’ New England District in January 2013.
The PAS program allows the Corps of Engineers to assist states, local governments, and other non-federal entities in preparing comprehensive plans for the developing and conserving water and related land resources.
“This agreement allowed the RaDS team to assess the potential impact to the urban forest of different, increasing likely, climatic events,” said Dr. Christy Foran, EL research scientists and RaDS project coordinator. “A matrix of scenarios and sensitivities were developed in order to evaluate the relative impact on each tree species in the city.”
“The team was assisted by Michael Narcisi, environmental scientist from the New England District, who mapped the anticipated outcome of each scenario utilizing a GIS layer of all the individual trees in Cambridge developed by the city,” Foran said.
Numerous trees assets
Once standing for their childhood climbs and hide-and-seek games, scientists now seriously value trees as tremendous assets in air quality, lower wind speeds, aesthetics, energy conservation, noise pollution, habitat, decreased runoff, and bolstering of local businesses and property values.
However, these versatile assets are at the mercy of the weather.
“The vulnerability of Cambridge’s urban forest to climate change has been assessed by evaluating the effects of possible scenarios on the composition and abundance of trees. The scenarios focused on a category one (is Category One capitalized? I don’t know) hurricane, increase in heat stress, an early or late snow or ice event with loss of tree limbs, two different pest infestations, the Asian longhorn beetle (ALB) and the emerald ash borer, and the cumulative effect of all these possible scenarios,” Foran said.
Assessment results revealed reasonable indications of the most tolerant tree species in Cambridge and their locations.
Infestation impact most severe
“The loss of trees and tree species in response to climate-associated extreme events showed the most severe impact was the culling of trees following an ALB infestation.
“Tree mortality following an ice storm or a heavy snow event is scattered across the city, but impacts a smaller percentage of trees than an infestation. Recommendations for individual tree species which are tolerant to many of these conditions can be developed and vetted by the city’s arborist and development division,” Foran said.
The assessments pointed out other impacts are limited to a specific area, such as the FEMA 100-year flood zone.
“Because the scenarios in our RaDS team study are expected over the next 100 years, effective management is the key to minimizing the impact of any extreme event,” Foran said.