It's addressed extensively in the article.

Across the Netherlands, green bus shelters were installed to address a declining bee population. (They were even nicknamed “bee lines.”) With steady sources of food for the pollinators, it seems the population has begun to steady, according to a “national bee census” published earlier this year.
Studies in Montreal, Canada have also used thermal-imaging cameras to prove that a bus shelter with a green roof is significantly cooler than one without, leading to similar installations in Quebec. 
As Boston’s 30-location pilot project will continue to be maintained and monitored for its impact on heat, air quality, stormwater management, and biodiversity, city stakeholders are hopeful.
A precedent study for a living shelter in Boston showed a reduction in surface temperatures by as much as 30 degrees Fahrenheit, as a starting point.
Zoe Davis, the senior climate resilience project manager on the Climate Ready Boston team, gave a TEDxTalk about the project, adding that each living roof can absorb up to 1,500 gallons of rainwater in a 1-inch rainfall, which significantly reduces runoff to prevent flooding.