Date of Award

2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Natural Resources

First Advisor

Anthony W. D'Amato

Abstract

Mixedwoods forests occur in temperate forests around the world, providing unique ecological, economic, and cultural benefits, but there are key knowledge gaps on their natural dynamics and development pathways. In northeastern North America, records and studies show that red spruce was once a common component of northern hardwoods in this region; however, historic selective harvesting has greatly reduced the preponderance of these mixedwood ecosystems. Given the narrow regeneration niche of red spruce and the various anthropogenic and natural disturbances that have reduced this species, significant challenges exist to the restoration of red spruce-northern hardwoods mixedwoods. To address this challenge, our study characterized the structure and composition of two old-growth mixedwoods stands, Township 40 of Adirondack Park in New York and the Bowl Natural Area of White Mountain National Forest in New Hampshire.We used dendroecological data from large, stem-mapped plots to reconstruct the natural disturbance pathways of these forests to inform techniques for restoring and sustaining red spruce-northern hardwood forests into the future. At Township 40, red spruce was the second most abundant species, occupied 58.1% of the dominant and codominant crown classes, and had an importance value (IV) of 22.5%. At the Bowl, red spruce was the most abundant species, occupied 81.4% of the dominant and codominant crown classes, and had an IV of 37.3%. Large trees (stems ≥50 cm DBH) made up 30–33% of the basal area at each site and were predominantly comprised of yellow birch and red spruce. Red spruce dominated the sapling layer (stems 2.54–9.9 cm DBH) at both sites. Snags (standing dead trees) and coarse woody material (CWM) were also abundant, with Township 40 having 237 snags/ha and average CWM volume of 94.5 m3/ha and the Bowl containing 110 snags/ha and average CWM volume of 99.1 m3/ha. There was no evidence of stand-replacing disturbance at either site. The mean decadal rate of canopy loss at both sites was 6.3% with decadal canopy loss <5% accounting for over half of each disturbance chronology. At Towship 40, red spruce median age was 116 years, with one-third of all spruce recruiting into the stand between 1870–1889, while at the Bowl the median age was 108 years, with less than 20% of all spruce recruiting into the stand from 1870–1889. Reconstructed disturbance histories and release patterns indicated that over half of all red spruce trees required only one release event to ascend to the canopy occurring at ages ranging from 19–103 years and diameters at breast height ranging from <1–15.3 cm. The developmental patterns observed in this work, in conjunction with the body of literature on the challenges of restoring conifer components to mixedwoods, argues for taking a tree-centric approach to sustaining these species over time. This includes focusing silvicultural activities on releasing red spruce stems from overtopping canopy trees to promote canopy ascension. Based on the structures and characteristics of our study sites, silvicultural practices should work toward developing multiple age classes, areas of retention, and deadwood for the successful, long-term recruitment of a mosaic of mixedwood species.

Language

en

Number of Pages

96 p.

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