He helps put the emerald in the Emerald Necklace

Boston’s arborist has 40,000 trees in his portfolio to keep green and strong -- and upright

Max Ford-Diamond is Boston's tree warden.David L. Ryan/Globe Staff

He’s in the green business, a man whose professional life is devoted to keeping Boston’s 40,000 street trees alive and well — green and growing — and forever climbing for the sky.

So, when Max Ford-Diamond pulled his city truck to the curb on Dent Street in West Roxbury the other morning, he paused as if in a silent, solemn salute.

His body language said it all: This is not good.

“It’s an emergency,” he told me, squinting into the late-morning spring sun. “The tree is split in half.”

Then he pointed down, where a tall, 60-year-old linden tree poked through a 3-by-7-foot tree pit.

Carpenter ants scampered at the base of the tree, whose trunk was clearly wounded by decay. The split was visible just where the tree’s lowest branches began to diverge.

“Anytime you see mushrooms growing off the base of a tree, that’s a sign of decay,” he said. “That tree was definitely healthy and wonderful at one time. But that split has been there for a while. If it’s a split, you take it down the next day.”

A somber verdict issued by Boston’s arborist and tree warden, who is dedicated to preserving a variety of species to ensure a healthy and robust leaf canopy from Charlestown to Jamaica Plain.

This is a guy who helps put the emerald in the Emerald Necklace.

Boston has some 40,000 street trees, and plants at least 1,200 new ones annually. And that keeps Ford-Diamond, 32, busy at a job that, it seems, he was born to do.

He was born in Boston, but spent most weekends on a 200-acre farm in Warren, Vt., that belonged to his mother’s family and became his beloved weekend retreat where he rode tractors, watched deer scamper through the woods, and helped make maple syrup on weekends.

“My grandfather taught me as a kid growing up. Everything,” he said. “How to cut down a tree. How to use a chainsaw. How to drive a tractor. How to identify trees. So, quickly I realized that farming wasn’t for me. And maybe I wanted to be a tree guy.”

So that’s what he did.

His other passion? To keep Boston green. And growing.

The city’s overall tree canopy has been relatively stable. From 2014 to 2019, it was measured at about 8,200 acres.

As we talked the other morning at Franklin Park, Ford-Diamond — the son of a Boston public school teacher — taught a lesson like the ones he used to listen to as a kid at Norfolk County Agricultural High School in Walpole, identifying the nearby trees.

“Cherry tree. Cherry tree. Cherry tree. That’s a red maple, the big one. Those are white pines. That thing that’s just blooming right there, that looks like a Norway maple.

“You’ve got a bunch of oak trees up on that hill. Those large trees down there — the big, big trunk diameters — are oaks. That tree right there is one of my favorites. The Kentucky coffee tree. Such a random place for a Kentucky coffee tree to be growing.”

Soon, Ford-Diamond and Boston’s other tree lovers will know precisely how many trees the city has and where they are located.

“For the last 11 years,” he said, “I’ve been flying blind. I don’t have a tree inventory. I don’t know where all our trees are.’’

That’s why a company called PlanIT Geo is at work on an urban forestry master plan for Boston. Five arborists are walking every city street, measuring trees, assessing their condition, and plotting them on a map.

Ford-Diamond suspects that survey will indicate that Boston has a lot more honey locust trees than anything else.

“My guess is that 30, 40 years ago there was a big push to plant honey locusts,” he said. “I don’t know if there was a movement by landscape architects or if this was the nurseries going, ‘Oh, my God. We can plant this street tree anywhere and it will survive.’ They don’t seem to have that high of a mortality rate.”

The guy is serious about what he does. Currently, he and two others are doing the work that used to be performed by five people. “We’re missing two arborists,” he said.

But he knows he’s doing something he was born to do.

“Going to a normal school wasn’t something I was into,” he said. “Someone with a little ADD and wanting to be outside all the time was not someone who wanted to be sitting in a classroom learning about the Ottoman Empire. I was like: How do I get outside and do something?”

So, he plotted a course that would take him where he wanted to be.

And he’s got some advice for homeowners who are the guardians of that tree that helps shade your street.

“The most common mistake is people putting too much mulch up against the base of a tree,” he told me. “We don’t want what they call a ‘mulch volcano.’ . . . That’s not good. You want the root flare of the tree to be visible and at the ground level.”

Want a quick primer? Here it is: Water. Mulch reasonably. And keep debris, trash, and dogs away from the trees.

Nature will pretty much do the rest.

“Each year, we plant between 1,000 and 1,600 trees,” he said. “This year, we’re hoping to plant 2,000 trees. We got a very large increase in our budget thanks to the City Council. We went from $750,000 to $1.7 million.”

That’s a lot of trees.

Arbor Day is coming up. It’s April 30.

Ford-Diamond plans to spend it in Easton with other local arborists at the 36-acre estate that was once the home of Governor Oliver Ames. The property has been acquired by the Sharon-based Trustees of Reservations.

It’ll be quite the green holiday. Think: trimming, pruning. removing hazardous trees.

Maybe someone will ask Max Ford-Diamond about the work he’s been doing most of his life.

“It always prompts a conversation,” he said. “They say, ‘What do you do? And I say, ‘I’m an arborist.’ And they go, ‘What? What do you even mean? Why? Huh?’

“They’ll say, ‘You grew up here, but you’re into trees?’ That always sparks people’s imagination. They have so many questions. Why? Because they have a home and they have trees and they want to know information about their trees.’'

And if they happen to bump into Ford-Diamond on Arbor Day, and they ask questions like that, they’d better be ready to put the pruning shears down, lean against the trunk of the nearest tree, and listen to the guy who fell in love with the trees.

And then found a way to make a sturdy living out of it.