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Go to:57. Regeneration and Growth After Thinning in Hemlock-Hardwood Stands

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Catalog of Long Term Research Conducted by the Northeastern Research Station

Catalog #58

Crop Tree Versus Area-Wide Thinning
1) To compare the effects of growth and yield of various crop tree treatments with standard area-wide thinning. 
2) To define the optimum number of crop trees per acre to maximize the value yield of non-crop trees. 
3) To determine whether or not regulation of stand density is important and if so, how to achieve it under the crop-tree approach to gain maximum growth and yield.
Allegheny National Forest
Completely random design. 
Block 1 contains 4 0.6-acre measurement plots surrounded by a 1.4-acre buffer containing the same treatment isolation strip). 
Block 2 contains 5 2-acre plots each of which contain a 0.6-acre measurement plot. Isolation strips were laid between treatment applications. Each 0.6-acre plot was subdivided and inventoried by 0.1-acre subplots to facilitate exact control on number of crop trees/acre.

3 additional blocks (Blocks 3,4 and 5) were established at Rock Run during 1992. Marked trees had a minimum of 0.5" diameter.

Block 1: applied 1988 
1. 40 crop trees/acre with all trees whose crowns touch the crop tree being cut unless that tree was another crop tree. 
2. Area-wide thinning with a residual density of 40%. 
3. Standard 60% relative density area-wide thinning. 
4. Control plot having 40 crop trees/acre.

Block 2: applied 1989 
1. Crowns touching cut with 60% crop trees/acre. 
2. Crowns touching cut with 40% crop trees/acre. 
3. Merchantable cut. 
4. Standard thinning. 
5. Control plot having 60 crop trees/acre.

Block 3: applied 1992 
1. Crowns touching cut with 80 crop trees/acre. 
2. Crowns touching cut with 120 crop trees/acre. 
3. Crowns touching cut with 160 crop trees/acre. 
4. Uncut control.

For comparison, 60 crop trees/acre were selected to be followed in both the control and the standard area-wide thinning. 
Additional variables were measured in accordance with standards set for the Northeast Model. The sample was modified from the standard procedure due to the small number and condition of the sample trees required that were below the QSD. The net result was that only crop trees were included in the sample and that more trees than were required were sampled. All crop trees were evaluated in each plot according to the standards outlined in the working group guidelines dated Jan. 29, 1990.
Independent: species, competitive position, age, and treatment. 
Dependent: Individual tree-diameter growth, merchantable sawlog height, volume growth, value increment, total stand-cubic foot volume, board foot volume, and value. Quality is assessed as height to 1st live limb, number of epicormic branches, height to first fork, and butt log grade.

Block 1: 100% inventory: 1988. d.b.h.: 1989. Post-logging inventory: 1990. Measured sample trees: 1990, 1993, 1994.
Block 2: 100% initial overstory inventory: 1988. Post logging inventory: 1989. Measured sample trees: 1989, 1993, 1994.
Blocks 3, 4 and 5: 1993 d.b.h., total height, base of crown height, height to 1st live branch, number of live and dead branches on 1st log, number of epicormics on 1st log, crown length and width, and tree coordinates.

Data were field checked and data-entry into computer was 100% cross checked with field sheets.
Raw data by plot reside on DG and tally sheets are kept with written instructions and detailed maps to each stand. Annually, the raw data are transformed using the REGEN1 program in DG Info. System. Summarized data by plot and by stand reside in a DG-based program that can output to ASCII text files.
Studies of Ecosystem Processes
Study plan. 1990. David Marquis. 
Establishment report for Block 2. 1991. James Redding. 
Establishment report for Block 1. 1992. James Redding. 
Establishment report for Blocks 3, 4 and 5. 1994. James Redding and Chris Nowak. 

The above are office reports of U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station, Warren, PA.

Nowak, C.A. 1995. Individual tree- versus stand-level approaches to thinning: is it a choice of one or the other or a combination of both? In: Gottschalk, K.W.; Fosbroke, S.L.C., eds. Proceedings, 10th central hardwood conference; 1995 March 5-8; Morgantown, WV. Gen Tech. Rep. NE-197. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 577p.

Susan Stout, USDA, Forest Service, P.O. Box 267, Irvine PA 16329. (814) 563-1040
Allegheny National Forest, PA.



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