Last month, 193 trees along Van Ness Avenue were served death warrants when the city plastic-wrapped removal notices to their trunks.

Construction of San Francisco’s first bus rapid transit system begins next year, and the trees will have to go to make way for the line. In their place 401 new trees will be planted along the busy corridor.

But some neighbors are protesting what they say are halfhearted attempts by the city to save the street’s urban forest. Others say they were never informed of the construction and don’t understand why the trees need to be chopped down.

“This has just been a nightmare,” neighbor Mary Anne Kayiatos said. “It is a devastatingly awful thing to do to the San Francisco community. Trees make urban living a little more tolerable. Oh my God, this is so bad. I can’t even believe it.”

The buses will run on Van Ness between Lombard and Mission streets, one of the busiest corridors in the city. If approved by the Department of Public Works Monday, the trees’ removal would coincide with construction next year of the $158.8 million system.

“The buses are literally going to run through some of the medians that currently have trees in them,” said Carla Short, an urban forester for the city. “The trees are going to have to be in different configurations now. There was no way to save these trees, and it wouldn’t have been worth the cost.”

Currently, Muni routes 47 and 49 and Golden Gate Transit cover the area, and bus stops are in the curb lanes. In the new configuration, bus lanes and boarding platforms will replace the medians — many planted with trees — that run up the middle of the road. The new system is projected to reduce transit travel times by 32 percent, according to an MTA study.

San Francisco’s tree canopy is at 13.7 percent, but most cities peg desirable tree canopy coverage closer to 25 percent, said Dan Flanagan, executive director of Friends of the Urban Forest, a nonprofit that has planted more than 49,000 trees since 1981. These benefits are hard to replace, he said.

"We're always very disappointed when mature trees are cut down,” Flanagan said. “Friends of the Urban Forest did register its concern for the loss of those trees. It's our understanding that the plan calls for more trees to be planted than are being cut down, which in the long run is good for our urban forest but still a huge loss in terms of the greater benefits provided by mature trees."

Phillip Ambers, who regularly babysits for a friend who lives near Van Ness, said the community was blindsided and that the information provided by the city has been unclear.

“A lot of people are upset and don’t even know what’s going on,” he said. “The city says the trees are diseased, but I don’t see how 200 of them could all be sick. We already don’t have enough trees in this city, and they keep cutting them down. How is this OK?”

San Francisco Municipal Transportation Agency spokesman Paul Rose maintains that the trees are unhealthy. The agency did a tree removal evaluation and analysis in 2012, and it showed a grim future for the trees, he said.

“A certified arborist evaluated the maturity of tree health and condition of all the median trees,” Rose said. “The preservation of the existing trees was proved nearly impossible. A lot of them are unhealthy or would be impossible or expensive to move.”

City officials considered replanting the trees in a different location, but that wasn’t feasible because of their maturity. Larger trees need to maintain a certain percentage of their root mass to survive transplantation

In their place, hundreds of new lemon-scented gum, Brisbane box and London plane saplings will be planted along the sidewalks and the new medians. Besides the 193 trees being removed, another 12 trees will be preserved in their current locations, and one cork oak dedicated to Rosa Parks — in the median between Jackson and Pacific streets — will be relocated.

“It’s not that we don’t want to spend the money,” Short said. “It’s about investing the money in something that will survive, versus something that won’t. Most people are concerned about losing mature trees, and we get that. But there’s no way, and we’re hoping the 401 new trees will make up for it.”

For some neighbors, that still won’t be enough.

“This is just going to be so tough,” Kayiatos said, sighing. “The project has passed through so many stages of approval, so it’s going to be an uphill battle. But we are fighting for our trees.”

Lizzie Johnson is a San Francisco Chronicle staff writer. E-mail: ljohnson@sfchronicle.com Twitter: @lizziejohnsonnn

Public hearing

A public hearing is scheduled for 5:30 to 7:30 p.m. Monday in Room 146 of City Hall.