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Dendrochronologia 22 (2004) 3142 ORIGINAL ARTICLE

Summary: Dendrochronologia 22 (2004) 31≠42
Development and application of boundary-line release criteria
Bryan A. Black√, Marc D. Abrams
203 Forest Resources Laboratory, Penn State University, University Park, PA 16802, USA
Received 26 November 2003; accepted 10 May 2004
Identifying releases from suppression represents one of the most fundamental dendroecological procedures for
quantifying forest disturbance histories. In this study we evaluate boundary-line release criteria, which incorporates the
effects of growth history on release response. In eastern hemlock (Tsuga canadensis L.) the maximum possible value of
a pulse in percent-growth change is dependent on growth decline immediately prior to the pulse. Maximum values of
percent-growth-change decline exponentially as prior growth rate increases. This negative exponential rate is
quantified as a boundary line, which is used to scale each percent-growth change pulse by the maximum possible value
predicted by prior growth rate. The consistency of the relationship between radial growth prior to a release and the
magnitude of the release is evaluated in multiple eastern hemlock data sets. Trees from diverse sites show large releases
that approach the maximum value predicted by the prior-growth rates. These sites tend to have a history of
disturbance, suggesting that disturbance is the most influential variable determining the magnitude of release response.
Possible exceptions are sites on the northern and western borders of eastern hemlock's range, which consistently fall
short of the boundary line and may be exhibiting unique relationships between prior growth and percent-growth
change. Yet overall the relationship between prior growth and percent-growth change appears to be consistent across


Source: Abrams, Marc David - School of Forest Resources, Pennsylvania State University
Black, Bryan.- Hatfield Marine Science Center, Oregon State University


Collections: Environmental Sciences and Ecology