Maine Perspective Front Page
Scientists Studying Development of Old Growth Forests
A new view of the constant struggle in the Maine woods between trees, diseases and weather has emerged from years of painstaking research by a team of UMaine students and faculty.
Working in the Big Reed forest preserve in northern Piscataquis County, one of the largest remaining stands of old growth forest in New England, researchers have described patterns of life and death over the past 200 years with an unprecedented level of sophistication and detail.
Studies of old growth forests in Maine are about as rare as the forests themselves. The study cites only four previous projects from 1966-97.
The 5,000-acre Big Reed preserve, owned by the Maine Chapter of the Nature Conservancy, is north of Baxter State Park in the Reed Brook watershed. The research was funded by the Maine Agricultural and Forest Experiment Station.
"There are increasing public demands that forests be managed as naturally as possible," says Alan White, an advisor on the project and an associate professor in the Department of Forest Ecosystem Science. "This study provides some important background information regarding forest conditions and processes in the absence of direct intensive human intervention. The patterns and processes detected in this study may help in designing appropriate conservation and management strategies for similar forest types and landscapes."
The project was led by Unna Chokkalingam, a Ph.D. student and native of India. In her research, she worked with faculty in biological sciences and spatial information science and engineering. In addition, numerous UMaine undergraduate students worked with Chokkalingam to establish research plots and collect detailed information about every standing tree - dead and living - and fallen trunks. They also mapped the locations of every tree and obtained increment cores.
Dendroecology and geographic information system (GIS) technology were used to generate statistics about areas affected by natural disturbances such as severe winds, droughts and insects.
As a result, Chokkalingam was able to describe natural patterns of new growth and deaths of trees as far back as the late 18th century. Her thesis paints a picture of small but frequent forest disturbances, primarily the slow death and decay of standing trees, opening up sunny spots where small clusters of young trees grow quickly. Over the years, such clusters accumulate to dominate the forest community.
Landscape-level analysis of the preserve using GIS suggested that catastrophic disturbance was not a major sculpting force at the landscape scale. The predominantly small-scale single-tree disturbance regime resulted in an old-growth landscape of mature forests dominated by late-successional community types. The mostly shade-tolerant species included spruce, fir, beech, sugar maple and cedar. A very small proportion (0.2 percent) of the preserve was affected by fire in the recent past. Larger blowdowns occurred in spruce-fir forests but acted to maintain the same dominant species.
"This study confirms earlier hypotheses that there are long intervals between major stand-replacing disturbances and that small-scale gap dynamics play a prominent role in shaping forest structure in Maine," says White.
"However, the episodic and extensive nature of small-gap formation is an unexpected finding. Our results suggest silvicultural guidelines for species regeneration, optimal growth, harvesting, and other factors for forest managers interested in mimicking natural processes."