BACKGROUND Members of the University of Maine’s Cooperative Forestry Research Unit (CFRU) have identified a better understanding about how forest stands respond to commercial thinning as a top research priority for As a result, the CFRU Commercial Thinning Research Network was established in A primary objective of this network is to establish a set of long-term commercial thinning study sites across the state of Maine. Initial efforts are directed at the spruce-fir forest type. Research installations in mature spruce-fir stands that have been previously pre-commercially thinned are answering two key questions: What is the influence of: (1) timing of commercial thinning? (2) residual density on subsequent stand response? EXPERIMENTAL DESIGN 1.Randomized complete block design with 6 sites or replications 2.Seven 0.92 A (200 x 200 ft) treatment plots containing 0.20 A (100 x 87.2 ft) measurement plot installed per site (see diagram) 3.Pre-treatment tree measurements include tree species, DBH, height, and location in plot (summer 2000) 4.Pre-treatment data were used to develop treatment specifications for each plot 5.Plots were thinned using a single-grip processor with forwarder and ghost trails (see diagram) in Merchantable volume removed was measured 7.Residual trees are numbered with aluminum tag, location within plot recorded, and DBH, height, and live crown monitored over long-term 8.Data collected from this site are being combined with data from other sites across state to determine tree- and stand-level responses to commercial thinning treatments STUDY PLOT DESIGN 200 ft 30 ft 100’ 87.2’ 200 ft 30 ft 100 ft 87.2 ft Ghost trails Forwarder trails - approx. 12 ft wide and 100 ft apart 12 ft Wood zone – logs stacked here STAND HISTORY ~1966—Overstory removal, naturally regenerated ~1982—Herbicide treatment ~1985—Pre-commercially thinned to a target density of 850 trees/acre February 2002—Plots 7 and 3 were commercially thinned to remove 33 and 50 percent respectively of the relative density TREATMENT PRESCRIPTIONS THEORETICAL AND ACTUAL TREATMENT EFFECTS AS SHOWN ON STAND DENSITY MANAGEMENT DIAGRAM Actual treatment effect following first thinning at 33% and 50% at this site Log tree density (TPA) Log tree volume (ft 3 ) Average stand trajectory line Max. self- thinning line 33% 50% Control Theoretical effect of thinning intensity on residual relative density Control Maximum self-thinning line (RD=1.0) Log tree density Log tree volume Start RD reduction 33%50% Time of entry Robert G. Wagner, Robert S. Seymour, and Daniel J. McConville Maine's Commercial Thinning Research Network Irving Woodlands, LLC, Weeks Brook Installation

For more information about this study site contact: Cooperative Forestry Research Unit Bob Wagner, Director and Professor of Forest Ecosystem Science University of Maine, Orono, Maine ; Phone: (207) ; Irving Woodlands, LLC Hugh Crammond: (207) CFRU COOPERATORS Major Cooperators Baskahegan Corporation Clayton Lake Woodlands Nexfor Fraser Papers, Inc. Hancock Timber Resource Group Huber Resources Corporation International Paper Company Irving Woodlands, LLC Maine Bureau of Parks and Lands Maine Timberlands Company MeadWestvaco Corporation Plum Creek Timber Company, Inc. Prentiss & Carlisle Company, Inc. Ste. Aurelie Timberlands Company Seven Islands Land Company The Nature Conservancy Other Cooperators Bethel Furniture Stock, Inc. H.O. Bouchard, Inc. Field Timberlands Finestkind Tree Farms Hancock Lumber Company, Inc. Huber Wood Products Landvest F. A. Madden, Inc. Peavey Manufacturing Company Pride Manufacturing Company Robbins Lumber Company Western Maine Nurseries The following organizations have supported this research through the Cooperative Forestry Research Unit at the University of Maine PLOT CONDITIONS BEFORE AND AFTER THINNING Total stand volume (VOL/A) in cords/acre, stand density (TPA) in trees per acre, mean volume per tree (VOL/TREE) in ft 3 per tree, and relative density (RD), before thinning and immediately after thinning for plots that had received a thinning. THINNING EQUIPMENT USED 12’ WIDE FORWARDER TRAILS WERE CUT ON 100’ INTERVALS Valmet single-grip processor used in the thinning operation PLOTTREATMENT VOL/ATPAVOL/TREERD BeforeAfterBeforeAfterBeforeAfterBeforeAfter % % % % % % CONTROL STUDY SITES PEF Comp. 23A IP Macwahoc Irving Weeks Brook Rd. Plum Creek Ronco Cove Plum Creek Lazy Tom IP Alder Stream