Acadia From Above, 1949–1980: Turning 700,000 Old Aerial Photos Into Maps of Forest Change

To model how Acadia National Park's forests will change, researchers need to know how they have changed — and the data usually used, from remote sensing, reaches back only 20 to 30 years. The forests of Acadia have been shaped by land use, climate and more over the 400 years since European colonization. Two or three decades is a short window on that.

A much longer one exists, on paper.

700,000 photographs nobody could use

Beginning in the 1930s, aerial photography was used across the region for land management and urban planning, and it continued for decades. The Sewall Company, one of New England's historic surveying and engineering firms, built up a collection of 700,000 remarkably detailed aerial photographs, many of them of Acadia, and in 2019 donated it to the University of Maine. But the collection was never digitized, so researchers, land managers and the public could not use it.

Stitching the past together

Peter Howe, a University of Maine graduate student and Acadia Science Fellow, is using photogrammetry — the science of taking precise measurements within photographs, so that many can be combined into one spatially accurate composite — to change that.

1. Select images dated 1949 to 1980 from the archive.
2. Digitize and process them.
3. Stitch them into landscape-scale mosaics of the historical landscape.
4. Publish the mosaics and their data for researchers, park staff and the public.

Seeing forest change over that longer span should give a fuller picture of the past and help park managers decide how to respond to change ahead.

Why the park wants it

"This timely project will support the park's ongoing efforts to restore ecosystems at Great Meadow, Bass Harbor Marsh, and on our mountain summits," said Rebecca Cole-Will, the park's resource management program manager. "We cannot have a thriving ecosystem in the future if we don't understand how the ecosystem has evolved."

Howe sees the research value — a longer record of Acadia and the Northern Forest — but argues that the photographs' greatest value is the stories they can tell, and he hopes the finished work will reach a broad audience.

Sources

Based on "Research Brief: Exploring landscape change in Acadia with historical aerial imagery and modern photogrammetry," National Park Service, Acadia National Park; a work of the United States government in the public domain; rewritten in hubnx's own words.