Structural attributes, disturbance dynamics, and ecosystem properties of old-growth forests in western Massachusetts

2007 2007

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Abstract (summary)

Natural disturbance patterns, forest structural attributes, patterns of nitrogen availability, and the abundance and composition of understory vegetation were studied in eighteen old-growth stands in western Massachusetts. Dendroecological analyses indicated that disturbance regimes for these systems were dominated by relatively frequent, low intensity disturbances (average of 5.0% canopy area disturbed per decade) operating randomly on the landscape. Comparisons of dendroecological patterns with model simulations of past hurricane events and historical documents suggested that broad-scale disturbances, such as hurricanes and ice storms, resulted in common disturbance peaks in the 1790s, 1820s, and 1920s at several study areas separated by over 50 km. No stand-replacing disturbances were detected at any old-growth area during the period examined (1700-1989).

Comparisons of structural characteristics in old-growth and second-growth hemlock forests illustrated that old-growth stands exhibit a higher degree of structural complexity compared to second-growth hemlock forests. In particular, old-growth stands had larger overstory trees and a greater abundance of downed coarse woody debris (135.2 versus 33.2 m3/ha) and snags (21.2 versus 10.7 m3/ha) compared to second-growth systems. The range in variation of structural attributes within my old-growth study areas was similar to those in other old-growth eastern hemlock forests located on more moderate terrain in the Upper Midwest and New York. This range in variation was related to differences in disturbance history and site productivity among old-growth stands.

Soil measurements indicated that there were no detectable differences in soil characteristics, such as total C and N, between old-growth and second-growth hemlock stands; however, inorganic N (NO3-N and NH4-N) availability was much greater in old-growth stands. In contrast, differences existed in soil characteristics and N availability between old-growth hemlock and old-growth northern hardwood forests, with hardwood dominated systems exhibiting lower forest floor C:N ratios and greater amounts of inorganic N.

Old-growth hemlock stands had higher species richness and diversity, as well as a greater abundance of understory herbs and shrubs, and tree seedlings and saplings compared to second-growth forests. In addition, several common understory plants, including Aralia nudicaulis, Dryopteris intermedia , and Viburnum alnifolia, were more abundant in old-growth stands.

Indexing (details)

0478: Forestry
Identifier / keyword
Biological sciences; Disturbance; Ecosystem; Forests; Massachusetts; Old-growth
Structural attributes, disturbance dynamics, and ecosystem properties of old-growth forests in western Massachusetts
D'Amato, Anthony William
Number of pages
Publication year
Degree date
School code
DAI-B 68/03, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Orwig, David A.
University of Massachusetts Amherst
University location
United States -- Massachusetts
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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