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story + photos by Catherine Schmitt

The long-running effort to restore the summits of Cadillac and other mountains continues. Decades of footsteps have eroded soil and vegetation down to bare granite. Every bit of damage leaves remaining plants, mosses, and lichens–part of Acadia’s unique sub-alpine communities–more exposed and vulnerable to the intensifying rain storms, freeze-thaw cycles, and prolonged periods of hot, dry weather on mountaintops.

Park managers have been evaluating different ways to bring plants back to the mountain, in partnership with Friends of Acadia, Native Plant Trust, and Schoodic Institute. Beginning in 2016, Bill Brumback and Jill Weber of Native Plant Trust led a series of experiments on the summit of Cadillac. Over the next five years, the partners set up 79 plots, outlined with rope and sandbags, in eroded areas of the summit. Each received a different combination of soil, erosion fabric, seeds (collected from Cadillac plants), and/or seedlings (grown from the collected seeds). Other plots received no treatment to serve as controls.

Measurements of plant growth and survival revealed mixed success, but a main conclusion is that “soil helps,” said Weber, who reported on the results with Brumback in March. Growth was better in the plots with deep layers of compost or loam–even in plots without any seeds or plants, as seeds from neighboring areas arrived on their own. Of the species planted, three-toothed cinquefoil and green alder were the most successful.

Planting nursery-grown seedlings (as opposed to seeds) was the most time and energy-intensive treatment and only resulted in high plant cover in some plots. This method also isn’t feasible on other summits where erosion is occuring, such as South Bubble, Penobscot, and Sargent, which don’t have the road access and water supply of Cadillac.

It is also too early to draw any conclusions, said Brumback. “Continued monitoring is essential.”

Additional monitoring and data analysis by Schoodic Institute scientists, ongoing since 2017, has confirmed these results.

Acadia National Park biologist Jesse Wheeler agrees. “There’s still so many questions, including what does successful restoration look like in 20 years, and what do we need to know?” Wheeler said that answering these questions will require inviting more voices into restoration decisions.

Three people stand around an area of bare ground on the foggy summit of Cadillac Mountain.
Chris Nadeau, Jesse Wheeler, and Peter Nelson discuss how to restore soil and plants to eroded areas on the Cadillac summit.

To help the park identify summit restoration goals and adaptive management approaches, in 2022 Chris Nadeau facilitated a series of workshops to incorporate diverse expertise and user groups. For example, the Science Advisory Committee will include Scott Abella of University of Nevada Las Vegas. Abella is the restoration expert with both hands-on and theoretical experience in restoration, including with desert soil crusts, which are not unlike the moss and lichen that are the first to become established on bare rock and gravel and help build soil on Acadia’s granite peaks.

“Our monitoring of the experimental plots on Cadillac documented new growth of soil-forming mosses and lichens,” said Peter Nelson, who worked with Nadeau and Wheeler on the summit. “We want the restoration to follow nature’s lead and mimic these processes.

Ongoing experiments involve the use of crust organisms to stabilize gravel beds or partially eroded patchy vegetation, in combination with methods from the first phase of the project, such as the use of mesh netting (coir) to hold soil in place and potentially selective planting and soil amendments.

They will also continue to monitor the previously planted areas, and survey other summits to learn more about natural processes of soil and plant regeneration. The hope is that with more voices, more information, and more preparation, they can be more successful in protecting Acadia’s unique and wild mountain summits.


A version of this article appeared in the Summer 2022 issue of Acadia Magazine.

Three people kneel, stand, and squat on the edge of an area where soil and plants have eroded away from the Cadillac summit.