Gisele Bundchen: 'Have You Already Planted Your Tree?'

Gisele Bundchen takes her adorable son Benjamin on a bike ride along the Charles River on Sunday (September 23) in Boston, Mass.

The day before, the 32-year-old pregnant supermodel went strolling through the park with little Benjamin and their pup Lua!

PHOTOS: Check out the latest pics of Gisele Bundchen

“Let’s do our part and take care of trees in the way they deserve!” Gisele recently tweeted, along with a link to an educational editorial from Gisele titled “Have You Already Planted Your Tree?”

“Studies show that ten trees would need to be planted to ensure enough oxygen for a person to breathe for one year,” Gisele wrote.

FYI: Gisele is using her Trek bike.