Abstract
Forestry practitioners often need to identify old-growth stands because of their high conservation value. To identify the structural and compositional characteristics potentially unique to old-growth northern white-cedar (Thuja occidentalis L.) stands, we compared 16 old-growth stands and 17 partially harvested stands in Maine, USA and New Brunswick, Canada. Potential old-growth predictors included common structural metrics such as basal area (BA), quadratic mean diameter (QMD), large tree (≥40 cm diameter at breast height) density, and volumes of coarse woody debris (CWD), along with six structural indices. Using generalized linear mixed-models, we identified two significant structural predictors that differentiate old-growth from partially harvested stands when used in combination: Volume of advanced-decay CWD and live tree QMD. None of the structural indices were useful in distinguishing between old-growth and partially harvested stands, nor did the two types differ with respect to tree species composition. Our results demonstrate that two metrics easily derived from standard inventory data—decayed CWD volume and QMD—effectively characterize the old-growth white-cedar stands sampled in this study. Taken together, these results can improve management decision making for white-cedar, particularly in the context of certification, while also shedding light on the effects of past partial harvesting on current forest structure.
Highlights
Successful forest management often requires identifying areas suitable for silvicultural treatments, as well as areas to be set aside from harvest because of their high conservation value
The mixed-effects model that was best supported by the data included just two predictors that, when used in combination, allowed us to distinguish old-growth status: advanced-decay coarse woody debris (CWD) (p = 0.013) and quadratic mean diameter (QMD)
Our results may aid those interested in developing ecologically based silvicultural prescriptions for white-cedar stands by suggesting structural features on which to focus
Summary
Successful forest management often requires identifying areas suitable for silvicultural treatments, as well as areas to be set aside from harvest because of their high conservation value. One of the most challenging yet critical aspects of this process is determining which stands or communities have high conservation value. Such communities are often assumed to possess characteristics typical of old-growth, such as large live and dead trees [2,3,4], large volumes of coarse woody debris [2,5,6], and structural heterogeneity [4,7]. Though definitions of old-growth vary, the Forests 2018, 9, 376; doi:10.3390/f9070376 www.mdpi.com/journal/forests
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
