Last year in South Boston, a woman chased Vladimir Diaz down Old Colony Avenue with a knife after he took the chair she was using to reserve her shoveled-out parking spot.

On N Street, a guy tried to drag him out of his garbage truck, he said. Then there was the group of men who surrounded the truck.

“They just kept kicking it,’’ he said.

What’s most surprising about the stories is how Diaz tells them; it is not with anger, but with sympathy.

“They work hard to shovel their spot,’’ he said. “I feel sorry for them. But there’s nothing I can do. I’m just doing my job.’’

Diaz is a Boston trash collector. And, beginning yesterday, it again became one of the most treacherous jobs in the city. That’s when the mayor’s office ordered trash collectors, on their regular route, to begin taking all the space savers — cones, buckets, dining sets, whatever — that have become a post-snow tradition in many of the city’s neighborhoods.

If you put in the effort to shovel it, the ethic goes, you own it. At least for a little while.

But since 2005, when Mayor Thomas M. Menino decreed that space savers had to be removed 48 hours after a snow emergency ended, enforcement has become a dicey proposition, especially in South Boston, where the practice is rampant and militant.

As Diaz and his partner, Nilson Azevedo, made their way along East Third Street yesterday afternoon in their bright yellow Capitol Waste Services garbage truck, tossing busted beach chairs and broken baby toys into the compactor, their arrival was met with a mixed reaction.

Nick Provenzano politely moved his orange cones from the spots he’d shoveled for himself and his wife, and even chatted up Diaz and Azevedo.

“When they leave,’’ he said as the truck inched down the street, “I’m just going to put them right back.’’

Provenzano is a native of the neighborhood, and where residents stand on the practice of preserving parking spaces depends a lot on that distinction.

“I think it’s bogus,’’ said Colby Colarossi, a 26-year-old Connecticut native who lives on West Third Street. “You don’t own it. This is the city of Boston. It’s not your driveway.’’

Colarossi refuses to put out a saver on principle, even though it means she ends up having to park several blocks from her apartment.

“I don’t do it because it’s wrong, but then I leave and someone puts a chair in the spot I just left. And if I move it, my tires will get slashed,’’ she said. “It’s a lose-lose if you don’t go with the flow.’’