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Harvard Forest Symposium Abstract 2005

  • Title: Eastern redback salamander (Plethodon cinereus) and juvenile eastern red-spotted newt (Notophthalmus viridescens viridescens) abundance in eastern hemlock-dominated stands and mixed deciduous stands
  • Primary Author: Brooks Mathewson (Harvard Forest)
  • Additional Authors: Betsy Colburn (Harvard Forest); David Foster (Harvard University)
  • Abstract:

    Eastern hemlock (Tsuga canadensis) is threatened in Massachusetts by the exotic pest hemlock woolly adelgid (Adelges tsugae) (Orwig et al. 2002). Although certain species of birds and mammals have been found to be associated with eastern hemlock-dominated stands (Yamasaki et al. 2000), little is known regarding salamander abundance in these stands (Brooks 2001). Wyman and Jancola (1992) found amphibian abundance to be lower in eastern hemlock stands than in beech stands in southcentral New York, and hypothesized that low pH may be the cause for this lower abundance.


    I have been studying the differences in eastern redback salamander (Plethodon cinereus) and juvenile eastern red-spotted newt (Notophthalmus viridescens viridescens) or “red eft” abundance in eastern hemlock-dominated stands and mixed deciduous stands at four tracts in Harvard Forest. This is the first research assessing salamander abundance in Harvard Forest. It is also the first attempt at determining whether the abundance of these two species is different in eastern hemlock-dominated stands and mixed deciduous stands within the Transition Hardwood – White pine – Hemlock forest region.


    Redback abundance was significantly greater in eastern hemlock-dominated stands than in mixed deciduous stands using searches of artificial cover objects over four seasons (Fall 2003 – Fall 2004 excluding winter) (ANOVA; p < 0.05; Figure 1). There was no significant difference in red eft abundance in eastern hemlock-dominated stands and mixed deciduous stands using visual surveys along 90m x 1m transects over five seasons (Summer 2003 – Fall 2004 excluding winter), although average abundance was higher in eastern hemlock-dominated stands (ANOVA; p = 0.18; Figure 2). Average forest floor surface temperature was lower in eastern hemlock-dominated stands in the spring (ANOVA; p < 0.001) and fall (ANOVA; p < 0.05). In addition, forest floor surface temperature was less variable in the spring in eastern hemlock-dominated stands (ANOVA; p < 0.001). Soil pH was lower in eastern hemlock-dominated stands (ANOVA; p < 0.01). However, soil pH was higher than the level at which redback abundance has been found to be negatively impacted (Wyman and Hawksley-Lescault 1987; Wyman 1988b).


    The focus of my future research will be on assessing redback abundance in eastern hemlock-dominated and mixed deciduous stands at sites throughout the upper Worcester Plateau of central Massachusetts using natural cover object searches. I will also continue to monitor differences in the biotic and abiotic factors affecting abundance in these forest types including soil temperature, soil pH, soil moisture, food availability, and volume of coarse woody debris. In addition, I plan on searching for nests in order to determine which species and decay classes of coarse woody debris are most commonly used as nest sites by redbacks.


    Brooks, R. T. (2001). Effects of the removal of overstory hemlock from hemlock dominated forests on eastern redback salamanders. Forest Ecology and Management 149: 197-204.


    Orwig, D. A., Foster, D.R., and Mausel, D. L. (2002). Landscape patterns of hemlock decline in New England due to the introduced hemlock woolly adelgid. Journal of Biogeography, 29, 1489-1503.


    Wyman, R. L. (1988b). Soil acidity and moisture and the distribution of amphibians in five forests of southcentral New York. Copeia 1988:394-399.


    Wyman, R.L. and Hawksley-Lescault, D. S. (1987). Soil acidity affects distribution, behavior, and physiology of the salamander Plethodon cinereus. Ecology 68: 1819-1827.


    Wyman, R.L. and Jancola, J., (1992). Degree and scale of terrestrial acidification and amphibian community structure. Journal of Herpetology, 26:392-401.


    Yamasaki, M., DeGraaf, W.B. and Lanier, J.W. (2000) Wildlife habitat associations in eastern hemlock – birds, smaller mammals and forest carnivores. Proceedings: symposium on sustainable management of hemlock ecosystems in eastern North America (eds K.A. McManus, K.S. Shields and D.R. Souto) pp. 135-143. USDA General Technical Report 267. Newtown Square, PA.


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