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1 April 2009 Twenty Five Years of Change in a Disjunct Tsuga canadensis Forest in Southern Wisconsin
Thomas F. Grittinger
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A 1.44 ha plot in a disjunct Tsuga canadensis-dominated forest in southern Wisconsin was mapped and examined for 25 y. Every 5 y between 1981 and 2006, all of the trees ≥ 2.54 cm dbh were measured and mortalities and additions were noted. The stand had a 27.6% overall decline in density and a 5.8% decline in basal area. Tsuga remained the dominant species though it had a 28.2% decline in density and a loss in basal area of 12.6%. It still made up almost half the relative density and relative dominance throughout the study. Diameter distributions for the six leading species were all bell-shaped or skewed unimodal with the exception of Acer saccharum which had an inverse J-shaped curve. Tsuga presented bell-shaped curves due to the lack of recruitment from the seedling stage. Nearly 32% of the original Tsuga trees ≥ 2.54 cm dbh died throughout the study, giving an annual mortality rate of 1.53%/year. The annual mortality rate for Tsuga stems ≥ 30 cm dbh was 0.71%/year, which is higher than a Michigan study using the same sized stems. The long-term outlook for the Tsuga in this isolated stand is uncertain due to its sporadic regeneration, high mortality rate, possible deer browsing effects combined with future potential threats such as land development, climate warming and the hemlock woolly adelgid.

Thomas F. Grittinger "Twenty Five Years of Change in a Disjunct Tsuga canadensis Forest in Southern Wisconsin," The American Midland Naturalist 161(2), 251-263, (1 April 2009).
Received: 17 September 2007; Accepted: 1 May 2008; Published: 1 April 2009

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