STAND DYNAMICS AND SPATIO-TEMPORAL PATTERNS OF NATURAL DISTURBANCE IN AN ACADIAN OLD-GROWTH RESERVE

STAND DYNAMICS AND SPATIO-TEMPORAL PATTERNS OF NATURAL DISTURBANCE IN AN ACADIAN OLD-GROWTH RESERVE

By Stacy J. Birch

Thesis Advisor: Dr. Alan S. White

An Abstract of the Thesis Presented

in Partial Fulfillment of the Requirements for the

Degree of Master of Science

(in Forestry)

August, 2010

Old-growth forests are rare in New England given the regions extensive history of land clearing for agriculture and timber harvesting. Old-growth forests are important in that they exhibit a unique set of qualities and provide us with a benchmark to which short and long term biological and environmental change can be compared.The structural complexity and rarity of old-growth forests make them valuable resources on the landscape in helping to conserve biodiversity. The main objective of this project was to provide useful quantitative information on old-growth attributes to forest managers for future biodiversity conservation efforts and to inform developing silvicultural systems based on the ecology of natural reserves.

In this study we identified multiple old-growth forest community types (cedar swamps, northern hardwood, spruce forest, hemlock forest, cedar seepage forests, and mixed wood forests) in the 430 acre Boody Brook Natural Area in northern Piscataquis County, Maine. This array of community types in close proximity to one another reflects the area’s location between the boreal forests of the north and the temperate northern hardwoods to the south and west. In each of the forest types we investigated the species composition and age and size of canopy trees, regeneration, and wood material decaying on the forest floor. All attributes led us to the conclusion that the BBNA was in fact a valuable natural old-growth resource in the state of Maine where such areas are typically much smaller in size.

In the second portion of this research we used dendroecology (the study of tree ring growth patterns) to investigate the natural disturbance history of the area. We found that trees had been responding to many factors including native defoliating insects such as spruce budworm, introduced pathogens like those that cause beech bark disease, and severe weather events. Through the last 150 years this area had never experienced a stand replacing disturbance event like fire or widespread hurricane-driven windthrow. Instead, canopy turnover seems to be occurring little by little with the formation of small gaps caused by the mortality of unhealthy and/or old trees.