The problem is that as the arboretum puts up more buildings, the land devoted to woods, meadows and the public necessarily shrinks. Since its inception in 1872, the arboretum has always worked to balance the research and recreational uses of its property.

Harvard has a thousand-year, $1-per-year lease on some parts of the land that the City of Boston owns.

The arboretum is also a link in Frederick Law Olmsted’s “Emerald Necklace,” a string of public parks that wind their way around the city.

Many residents of Roslindale and Jamaica Plain see the arboretum’s 265 acres—one of the largest open spaces in Boston—as a natural resource for their community.

In addition to the three buildings, the arboretum’s plans call for fences around the nursery as well as an access road—both of which will cut into the public access to the park.

Evans, the neighbor, said she first heard rumors about the proposed expansion three days before she closed on her house this past August. She thought she was purchasing views of a rustic landscape, but if the arboretum’s plans go through she will be directly across from a fenced-off nursery.

Even more troubling to her, she said, is the location of the much-touted research facilities. Greenhouses, growth chambers and research laboratories will take up between 15,000 and 20,000 square feet on the crest of Weld hill, while administrative offices will occupy another 10,000 to 15,000 square feet.

The building will have expansive views of the woods below it, but Evans says she wishes it could be sited less conspicuously.

“Hundreds of people who come to the arboretum every day enjoy the park part of it and the beauty,” she said. “I wish the research side was more invisible.”

Some neighbors are worried less about aesthetics and more about the logistics of adding more activity to the arboretum’s grounds.

“Who is going to police it?” asked Walter Michalik, a Roslindale resident who professes “four decades of love” for the arboretum. “It was promised to be open ground for decades, but if they’re going to keep it open and increase the traffic there’s going to be a commensurate security risk.”

Michalik’s concerns range from the dangers of the access road, which will empty onto a portion of Walter Street frequented by “kamikaze drivers,” to the hazard posed by animals driven from their habitats.

Michalik said he has been attacked by rabid gray foxes on his own lawn, and that the construction threatens to exacerbate the animal menace.

“If you’ve ever spent any times in the woods, you know, they see you, they hear you, they smell you. I know there are animals in there. Where are they going to go?”

But the larger anxiety among neighbors like Evans and Michalik is that these expansion plans will not be the end.