ACADIA NAT’L PARK — Acadia’s forests are thriving.
They have a healthy understory and a good rate of regeneration. And there are very few problems with invasive plants, insect pests or deer browse.
Forest ecologist Kate Miller knows all that because each of 176 forest monitoring plots in Acadia gets a check-up every four years on a rotating basis. Those plots, each of which measures 50-by-50 feet, contain a total of about 8,000 trees.
Miller works with the Northeast Temperate Inventory & Monitoring Network, a program of the National Park Service that keeps tabs on the condition of natural resources in 12 NPS units from Maine to New Jersey, plus the Appalachian Trail. The network’s headquarters is in Vermont, but Miller and a few other staff members are based in Acadia.
“This program has been collecting immense amounts of data about the health of forests in national parks in this region for 12 years,” said Rebecca Cole-Will, Acadia’s chief of resource management.
“And what we know is that Acadia’s forests are super healthy. We have the best forest health conditions anywhere in this part of the park service.”
Miller said one measure of forest health is the degree to which native species have been choked out by invasive plants such as glossy buckthorn, purple loosestrife, Japanese barberry and bush honeysuckle
“The parks [we monitor] in New York, New Jersey and eastern Pennsylvania have really bad invasive problems, and what’s interesting is that they are the same species we have in Acadia,” she said. “It’s just that they never really got a stronghold here because the exotic plant management program here is so strong, and it’s been managing these species for so long.
“Those other parks just haven’t had the resources to do what Acadia has been able to do.”
Friends of Acadia has been supporting the park’s invasive species eradication program since 2009 as part of its Wild Acadia initiatives, giving as much as $85,000 a year.
“There are whole wetlands in Acadia that used to have a lot of purple loosestrife, and now they have none,” Miller said. “That’s pretty amazing.”
The only insect pest that has caused noticeable damage in Acadia is red pine scale, which has killed most of the red pine trees in the park over the past few years. Fortunately, only a tiny percentage of trees in Acadia were red pine.
Emerald ash borer and winter moth are invasive insects that have been attacking and killing trees in parts of the northeast, and they have been detected in some places of Maine. But so far, Acadia’s forests have been spared.
About 40 percent of the trees in Acadia are red spruce.
“It’s the dominant plant species from the ground to the canopy,” Miller said. “So, if something were to start affecting the red spruce, we would be really concerned.”
But no known threat to red spruce trees is currently on anyone’s radar.
Despite the apparent abundance — some would say over-abundance — of deer in residential neighborhoods and areas bordering Acadia, “Deer are not a problem in the park,” Miller said.
“We see very low impacts from deer or no sign of deer in most of our [forest monitoring] plots. And we know what deer impact looks like because of the other parks where we sample.”
One example, Miller said, is Morristown National Historical Park in New Jersey.
“In that park, there is a stark [horizontal] deer browse line, and everything under that is either bare or things that deer don’t eat,” she said. “You see that every seedling that does exist is completely browsed.”
On Mount Desert Island, residential areas are “a really good habitat for deer,” Miller said. “But they’re not really at high densities in the park. They don’t do well in interior forests.”
Because of that and other factors, including the virtual lack of invasive species, “Regeneration of our forests is really good,” Cole-Will said.
“We have a really healthy ecosystem, and we want to keep it that way.”