These methods, instrumentation and/or protocols apply to all data in this dataset:| Methods and protocols used in the collection of this data package |
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PLOT LAYOUT
Square 0.1 hectare plots were located near the center of each treatment unit. The plots were oriented so that the upper and lower plot boundary lines were roughly parallel to the contours of the slope in each unit. Distance from plot center to the center point of each boundary line (52.8 feet or 16.1 meters) was measured horizontally with a tape. The corners of the plots were located at the intersection point of the compass bearings corresponding to the two adjoining plot boundary lines.
The three square 0.025 hectare control plots were oriented so that the corners are at the cardinal points of the compass from plot center. Distance from plot center to each corner was again measured horizontally with a tape.
Plot center and the four corners were each marked with rebar capped with an easily visible 3-foot blue-tipped length of white PVC pipe. Where a plot corner was located beneath a deep pile of slash, the corner marker was moved to the nearest location where it could be set in the ground and would be easily visible. In these cases, the location of the actual plot corner was recorded and still used as the point of reference for establishing which trees were “in” or “out” of the plot.
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TREE MARKING AND MEASUREMENTS
Almost all the trees in the were tagged with a number and marked as close to breast height (4.5 feet, measured from the uphill side) as possible with blue tree marking paint. Only trees with damaged crowns or small stems growing out of the upturned rootballs of fallen old-growth trees – those which will likely exhibit atypical growth patterns -- were not marked or tagged and thus excluded from the experiment. A number was affixed to each tree by looping a plastic cable tie through a metal number tag and stapling the end of the cable tie to the bole of the tree at or as close to DBH as possible. The number tags face plot center unless it is impractical to approach a particular tree from that direction to read its number and measure its DBH. Because of the user’s control over the precise placement of the staple, a staple gun worked better than a staple hammer for fastening the cable ties to the trees. The long cable ties were used instead of nailing the number tags to the trees because it was thought that the number tags would be less likely to “grow into the trees” over the course of the experiment’s duration, which is expected to coincide with a period of rapid diameter growth for the trees.
In each plot, the numbering sequence (i.e. the lowest number) began with the tree closest to true north from plot center and continued in a clockwise direction around the plot back to true north, so that the lowest- and highest-numbered trees are usually quite close to each other. The intention was to keep trees tagged in numerical sequence as close together as possible, so that researchers measuring the trees can proceed around the plot as quickly as possible.
The species and five measurements were recorded for each marked tree at the time the plots were established:
• DBH to the nearest 0.1 inch
• total and live crown height (using a Haglof Vertex Laser instrument and transponder). The base of the live crown was defined as the lowest live branch along the bole not separated by a large gap from the rest of the crown. Measurements were recorded to the nearest foot in the first few plots and, after discussion, to the nearest 1/10 foot in the remaining ones.
• crown width on the north and south side of the tree, estimated to the nearest 0.5 foot (note: these measurements were the most subjective of the empirical data collected)
Although only one quarter the size of the thinned plots, the control plots still contained many more trees. Thus, control plots measurements included all trees in the plot greater than 4.5 inches DBH but only a subsample of smaller trees. This subsample took the form of a nested plot within the larger one, comprising all live trees within 4 meters of plot center. All trees greater than 4.5” DBH were marked with blue paint, as in the thinned plots, and trees less than 4.5” DBH in the nested plot were marked with yellow paint. Trees in the control plots were numbered in the same manner as those in the thinned plots, except that all the larger blue trees were tagged with numbers preceding those on the smaller yellow trees.
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GROUND VEGETATION TRANSECTS
In each treatment unit, transects for sampling woody ground vegetation were established along the four cardinal points of the compass (north, south, east, west) from plot center to 11.3 meters. The ends of these four transects were marked with rebar capped with a 1.5-foot length of blue-tipped white PVC pipe. Since the plot corner markers serve as the ends of the vegetation transects in the control plots, no additional transect markers were needed in these three plots.
Vegetation was sampled by extending a metric measuring tape along the transect. The species, precise location, and extent of woody vegetation and ferns falling directly under the transect line were recorded. Measurements were rounded to the nearest 0.1 meter in the first few plots and, after discussion, recorded to the nearest 0.01 meter in the remaining ones. Plants were identified by known recognizance, verified by Plants of the Pacfic Northwest Coast (Pojar and Mackinnon, 1994) when necessary. Data was recorded beginning at plot center and extending to the end of each transect, so all measurements are from plot center.
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Plot Layout for Control Units (E)
Locate a 0.025 hectare square plot in the center of the control unit with homogeneous and representative tree distribution. Establish plot center and four plot corners (tape and compass, rebar and PVC pipe). The side of the square is 15.81m long, distance from plot center to side is 7.91m, and distance from plot center to corner post is 11.18m. All plot distances are slope corrected.
Tag all trees in the plot using cable ties; mark the trees with blue paint at breast height (1.37m above ground); measure and record DBH (0.1 inch, diameter tape or caliper), species, height and base of the live crown (0.1 ft., Haglof Hypsometer), and two crown radii (south and north, 0.5 ft., tape).
If the number of trees in a plot exceeds 50 trees, sub-sample tree heights and crown radii of smaller diameter trees by diameter classes (0.5, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0 inch …) and species. The dominant trees should still be completely sampled; smaller overtopped and intermediate trees can be sub-sampled for heights and crown radii with 3-5 trees per diameter class. All trees in the plot should be marked, tagged, and species and DBH should be recorded.
Vegetation transect sampling follows the protocol of the thinned experimental units: Line intercept sampling (start, end, or distance to 0.01m) along 16.1 m transect, corrected for slope.
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