"Smart" trees? PSU's Digital City Testbed Center is working on it.

Portland State University's Digital City Testbed Center (DCTC) is partnering with researchers inside and outside the university to track the health of urban trees using ground, aircraft, and satellite-based sensor technology. 

The tiny sensors placed high up in the canopy combined with remote sensors will soon monitor everything from temperature and humidity to air quality to help track the health of urban trees in an effort to better preserve it. Researchers will begin monitoring trees as soon as next month.

"We see a lot of opportunities here," said DCTC director and PSU professor Jonathan Fink.

"Smart cities usually refers to techniques that can monitor the built environment—like houses, cars, sewers, and power lines. Research in Portland by the DCTC and our partners is extending this approach to the natural environment."

PSU professor Vivek Shandas is one of the faculty researchers leading the effort. He is known for his work mapping and analyzing urban heat islands, areas in cities that retain heat due to everything from design or lack of shade to choice of building materials. Shandas has conducted heat island mapping in over a dozen cities using car-mounted instruments that monitor temperature and humidity throughout the day.

Now this work is branching off in a new direction - urban forests.

Trees play a critical role in reducing temperatures in cities as well as providing other benefits, so researchers, including Shandas, want to know how to best monitor and protect them. 

Shandas and PSU faculty, including Biology professor Todd Rosenstiel, are working with colleagues at Reed College, Washington State University-Vancouver, The Nature Conservancy, and the U.S. Forest Service see how the health of trees in cities varies with temperature, humidity, shade, elevation, and proximity to roads.

"We are working on the final design of the canopy sampling plan for this season and plan to deploy as soon as possible. Some of our approach and thinking will complement the effort to "wire" large wildland trees with sensors as the OSU team has done at HJ Andrews," Rosenstiel said.

This team is also interested in the impacts of inequity in tree distribution. In a recent study, Shandas found that dangerously high temperatures disproportionately impact neighborhoods today that were ‘redlined’ from the 1930s on and deliberately denied public investment. These neighborhoods commonly have fewer trees and less green space and as a result experience higher temperatures than historically more privileged areas. 

The team will also use technology to examine whether the benefits of tree canopies will endure even during the hottest summers, year after year. Results of their work could help cities better preserve their urban forests in the face of accelerating climate change and lead to greater tree density and more resilient canopies throughout cities. DCTC researchers are pursuing several NSF grants to help grow this under-studied field.

DCTC is also partnering with The Nature Conservancy to hire a postdoctoral fellow to help research urban forests including using remote-sensing techniques to assess the distribution and characteristics of urban trees, conducting spatial and statistical analyses to see how urban trees affect human and ecological health, and engaging with community groups in the Portland metropolitan region to find out how different tree conservation strategies can result in better health for residents.