The monumental copper beech tree that provides a graceful canopy over part of the front lawn of the Eugene O’Neill Theater Center in Waterford has, over the decades, become an image deeply connected with that theater.

The O’Neill play-development model was born under its branches, notes Preston Whiteway, O’Neill’s executive director.

Dramatist John Guare was part of the first playwrights conference at the O’Neill in 1966, and he only had the first act of his “House of Blue Leaves,” which would eventually become an Obie-winning, Tony-nominated piece.

During the playwrights conference, “Blue Leaves” was still in the early stages and in need of development.

At that point, the O’Neill was doing full productions in the amphitheater. The problem was, O’Neill leaders realized it ended up being all about sets, costumes and lights and not focusing enough on helping the writer.

“John asked if he could use some of the actors who were here on the other projects and do a reading with music stands under the tree,” Whiteway says. “That was a revelation, that this is what we should be doing — that by stripping away sets, costumes and lights and just bringing top professionals in to work with the writers in front of an audience, that the play could become better. The stage-reading model — the O’Neill model — was born. Then it grew like wildfire all across the country. Every theater in America has a play-reading series now, but it was all born under this tree.”

Before this coming winter, the iconic tree will be cut down.

The behemoth — which is upwards of 83 feet tall and is more than 180 years old — has to be taken down because of a fungus and water rot that has damaged it. It is like several trees in one, and as it started growing more horizontally than vertically, it created a funnel bringing water into the core of the trunk, rotting it.

The O’Neill tried to save the tree and its twin, which is located about 20 feet away on the lawn and is slightly smaller. The O’Neill brought in SavATree, an Old Saybrook-based tree care and lawn service company, to help out. They have been doing intensive care on the trees for about eight years. The main one, which is closest to the stage of the outdoor Edith Oliver Theater, was just too rotted to save, and it will not be replaced, but the other is responding well to treatment and is very healthy, Whiteway says.

The treatment, by the way, involves injecting kelp into the tree roots, and the roots draw nutrients from that.

The O’Neill is working with the town of Waterford on the details of taking down the tree. It’s not certain yet how long it will take. Another copper beech that grew near the O’Neill’s cafeteria was cut down two years ago over the course of two days, but that was a simpler tree; it had a single trunk instead of multiple ones.

SUBHEAD: Like ‘The Giving Tree’

The plays that have been developed on the stage under the soon-to-disappear copper beech are many, varied and impressive. They include August Wilson’s “Joe Turner’s Come and Gone” in 1984 and, more recently, Jennifer Haley’s “The Nether,” which moved from the O’Neill in 2011 to the West End in 2015, along with plays by Beth Henley and Sam Hunter.

Raquel Davis, who is resident lighting designer for the O’Neill’s National Playwrights Conference, says that when she first worked in the Edith Oliver Theater space as an assistant lighting designer, “I remember the tree, there was no way to light it wrong … It wouldn’t let you fail.”

She compares it to the tree in the Shel Silverstein book “The Giving Tree,” as if the copper beech “embraces the work that’s being done underneath it and protects it and encourages it and has given its life.”

“That tree is the soul of the theater to me,” Davis says. “As much as a tree can be a literal thing in the background of a play that’s set in an exterior location, it can also be an energetic field totally abstracted that is about the shadows you create or the negative space in the branches or the way that you change the color of the tree to speak to an emotional moment in the play that has nothing to do with an actual tree. It’s just about the emotional reaction you’re having to the shape and the color and the mass that’s standing behind the actors onstage.”

As for what will be done with the wood once the copper beech is felled, Whiteway says a lot of the core of the tree is rotted through and no good, which is why it has to come down, but there are branches they want to preserve or make into something, whether it’s furniture, tables or perhaps smaller pieces “that folks who feel a connection to the tree might be able to take home.”

SUBHEAD: A farewell party

The copper beech is going out in style, with a party on Aug. 3 — dubbed the “Beech Party” — at the O’Neill. It will serve as the O’Neill’s summer gala and is open to the public. It will feature live music, cocktails, food, an oyster bar, silent auction, dancing and entertainment.

Davis says that, while she realizes all things have a life span, knowing that the copper beech is coming down “is devastating … I’m so grateful for that tree, and it will be incredibly sad to come back to campus and have there be a hole.”

If you go

What: Beech Party

Where: Eugene O’Neill Theater Center, 305 Great Neck Road, Waterford

When: 7 p.m. Aug. 3

Includes: Live music, cocktails, food, an oyster bar, silent auction, dancing and entertainment

Tickets: Start at $75

Visit: www.theoneill.org/gala