After coming from Nantucket to the Vineyard on Wednesday, Cormac Collier first noticed the trees lining the roads that wind through Chilmark.

“We took a little tour on the western side of the Island, and the one thing I was most amazed about was . . . the forests that are here. We definitely have some similarities in terms of geological formations and vegetation, but the amount of mature forests that are here is pretty remarkable. It’s definitely nice to come here, because we don’t have forests like you,” he said.

cormac collier
Cormac Collier says Vineyard has more mature forests. — Katie Ruppel

Mr. Collier, executive director of the Nantucket Land Council, was welcomed at the Polly Hill Arboretum for the annual David Smith lecture last week, where he spoke about conservation efforts taking place on Nantucket, including the protection of plant communities, downtown trees and watersheds.

The two Islands face similar conservation challenges, said Polly Hill executive director Tim Boland who introduced the speaker.

In addition to the Land Council, the two other main conservation organizations are the Nantucket Conservation Foundation and the Nantucket Land Bank. Together the organizations have conserved 45 to 50 per cent of the land on Nantucket, Mr. Collier said.

Absent thick patches of forest, the Nantucket landscape is predominantly sandplain grasslands, coastal heathlands and shrublands.

As on the Vineyard, the sandplain grasslands and heathlands are managed typically by burning and mowing. Fire controls the spread of wooded plant species while at the same time increasing plant biodiversity, Mr. Collier said.

But he said Nantucket lacks a native seed collection program to replenish the areas after management.

“What we have is all these areas — not conservation areas — but other areas that are so ripe for restoration, but just mowing and fire is not going to do anything,” said Mr. Collier. “You actually really need to put some seeds out there as well.”

Nantucket shares many of the same native plants as the Vineyard, including beach plum and Beetlebungs, which on Nantucket are called by their more common name, tupelo trees.

Unique to Nantucket is its downtown tree tour, featuring silver maples, redwoods, sycamores, elms and more, shading the streets with their grand canopies. One elm is estimated to be around 200 years old, with a circumference of 18 feet.

“The elm trees particularly are gems of the downtown area,” said Mr. Collier.

He said the town has allocated money to the downtown tree program since the 1800s.

“It’s important to understand how valuable trees are in suburban landscapes,” he said. “Not just the look and feel, but how it makes the community alive.”

Outside town on the western side of Nantucket is the 104-acre Bartlett’s farm — one of only two main working farms on the island. The farm lies in a watershed area and the Land Council holds a conservation restriction on it which prevents development.

“We do a lot of conservation and advocacy work based on watersheds, not just plant communities,” said Mr. Collier.

He said the council also purchased a conservation restriction for a 240-acre area for $14 million.

“It was important to us because it prevented a 60-to-70-lot subdivision in the northern part of the watershed, which is already a degraded water system.”

He said above all, the council focuses on advocacy.

“It is so key to conservation,” said Mr. Collier. “You can have land protection, education, preservation — those are all vital and fundamental. But you need conservation beyond a permitting agency.”

He described a number of issues the council is tackling, including erosion control projects, fertilizer regulations and septic system inspections.

Mr. Collier said the Nantucket harbor is one of the few remaining vibrant bay scalloping areas in the Northeast, and the council has focused on keeping the harbor healthy by monitoring septic systems around the harbor and watershed.

“We better do something now that we can,” he said.

He spoke about Hummuck Pond, which has been experiencing toxic blue-green algae blooms for several summers due to nutrient overload, seeping into the water through fertilizers and septic systems.

The council helped put in place fertilizer regulations that focus on limiting phosphorus and nitrogen nutrients in the soil.

“In Nantucket, you don’t have these woods blocking houses like you do here,” Mr. Collier said. “You drive down one of the roads and you have this gigantic Nantucket bluegrass lawn with hydrangeas and other things that are fertilized out of the wazoo.”

He added: “I didn’t see that many landscaped lawns and areas [on the Vineyard] like I do in other places. But there are a lot of farms, and a lot of farms put fertilizer down. And you do have watersheds. And if that bleeds into one of those coastal plain ponds it definitely is going to have some sort of nutrient overloading at some point, if not already.”

He stressed the importance of soil testing in gardens and lawns to show nutrient or micronutrient levels that need controlling.

“When you go to the doctor and you have something wrong with you, conditionally the doctor does a blood test to determine what the problems are. The same goes for a soil test,” Mr. Collier said.