Inmates from the California Men’s Colony wielding pruning shears and chainsaws and a pair of wood-chewing tractors known as masticators began working their way through a 100-foot-wide, 4-mile-long swath of Cambria forest underbrush this week, leaving a shaded fire fuel break in their wake.

By removing a tangle of undergrowth and fallen limbs, Cal Fire is cutting off growth that could carry flames from grass up into the canopy of Cambria’s rare Monterey pine forest. Called crown fires, they can spread rapidly and burn intensely.

When the firebreak work is done, what’s left will be a woody carpet of chips, mature native shrubs such as toyon and manzanita and larger trees with diameters 10 inches or more about 4 feet above the ground — and even the piles of forest debris that dusky-footed wood rats use as nests.

“It ends up looking a lot like what you’d do in your backyard,” Cal Fire forester Alan Peters said. “I think people will like it.”

Ideally, Peters added, he’d like to see 100 percent tree canopy left. “We want as much shade as we can get.”

Work began along Bridge Street between Cambria’s East Village and the Cambria Cemetery partly because it’s the most accessible area of the firebreak, which will also run along the northeast side of Cambria Pines Road and the Pine Knolls and Happy Hill neighborhoods.

“That way, anyone with any curiosity can see what it looks like,” Peters said.

He expects the work to take three to four weeks to complete.

There are 32 to 34 state Department of Corrections Cuesta Fire Crew members on the job, aided by two masticators from Pacific Firewood & Lumber in Watsonville working on a contract basis. The masticator work will cost about $40,000.

Altogether, the fire fuel break area amounts to about 50 acres.

Peters said Cal Fire will inspect and maintain the firebreak in coming years as needed. He expects the clearing work will lead to a large number of pine seedlings coming up, which will be allowed to grow, as they don’t create a ladder fuel problem, he said.