Mike R. Saunders, Shawn Fraver, Robert G. Wagner. (2011). Nutrient concentration of down woody debris in mixedwood forests in central Maine, USA. Silva Fennica vol. 45 no. 2 article id 112. https://doi.org/10.14214/sf.112

Keywords: Acadian Forest; hardwoods; softwoods; carbon-nitrogen ratios; decay classes; disturbance-based silviculture

Abstract | View details | Full text in PDF | Author Info

Both nutrient concentrations and pre- and post-harvest pool sizes were determined across down woody debris decay classes of several hardwood and softwood species in a long-term, natural disturbance based, silvicultural experiment in central Maine. Concentrations of N, P, Ca, Mg, Cu, Fe, and Zn generally increased 2- to 5-fold with increasing decay class. Concentrations of Mn, Al and B did not differ among decay classes, while K decreased by 20–44% from decay class 1 to class 4. C:N-ratios declined with increasing decay class, while N:P-ratios increased from decay class 1 to 2 and then plateaued with further decay. Within decay classes, softwoods generally had lower nutrient concentrations and higher C:N-ratios than hardwoods; N:P-ratios did not differ between hardwoods and softwoods. Although gap harvesting increased the size of the overall down woody debris nutrient pools, mostly through a large pulse of decay class 1 material, harvesting generally reduced the nutrients held in advanced decay classes. Pre-harvest down woody debris pools for N, P, K and Ca were 11.0, 0.6, 2.1 and 21.1 kg ha^–1, respectively, while postharvest were 20.0, 1.3, 6.2 and 46.2 kg ha^–1, respectively. While the gap-based silvicultural systems sampled in this study doubled the size of the pre-harvest, downed woody debris nutrient pools, the post-harvest pools were estimated to be only 3.2–9.1% of aboveground nutrients.

Saunders, Department of Forestry and Natural Resources, Purdue University, 715 State Street, West Lafayette, IN, USA E-mail: msaunder@purdue.edu
Fraver, USFS Northern Research Station, Grand Rapids, MN, USA E-mail: sf@nn.us
Wagner, School of Forest Resources, University of Maine, Orono, ME, USA E-mail: rgw@nn.us

article id 196, category Research article

Aaron R. Weiskittel, Laura S. Kenefic, Robert S. Seymour, Leah M. Phillips. (2009). Long-term effects of precommercial thinning on the stem dimensions, form and branch characteristics of red spruce and balsam fir crop trees in Maine, USA. Silva Fennica vol. 43 no. 3 article id 196. https://doi.org/10.14214/sf.196

Keywords: Acadian Forest; growth and yield; Abies balsamea; Picea rubens; precommercial thinning

Abstract | View details | Full text in PDF | Author Info

The effects of precommercial thinning (PCT) on stem dimensions, form, volume, and branch attributes of red spruce [Picea rubens Sarg.] and balsam fir [Abies balsamea (L.) Mill.] crop trees were assessed 25 years after treatment in an even-aged northern conifer stand. Treatments were a uniform 2.4 x 2.4-m spacing and a control (no PCT). The PCT treatment significantly increased individual tree diameter at breast height (DBH), height growth, crown ratio, and crown width, while it reduced the tree height to DBH ratio. PCT also significantly increased stem taper and consequently, regional volume equations overpredicted observed stem volume by 2 to 15%, particularly for the spaced trees. PCT also increased the number and maximum size of branches on the lower bole. The sizes of knots on half of the sampled spruce crop trees in the spaced plots precluded them from being used as select structural lumber; there were no other effects on log grade. Our findings indicate that PCT can have a long-term influence on the structural attributes of individual trees, and that improved stem-volume prediction equations are needed in the Acadian region of North America.

Weiskittel, School of Forest Resources, University of Maine, Orono, ME 04469, USA E-mail: aaron.weiskittel@umit.maine.edu
Kenefic, U.S. Forest Service, Northern Research Station, Bradley, ME 04411, USA E-mail: lsk@nn.us
Seymour, School of Forest Resources, University of Maine, Orono, ME 04469, USA E-mail: rss@nn.us
Phillips, School of Forest Resources, University of Maine, Orono, ME 04469, USA E-mail: lmp@nn.us

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