Vegetation Cover in the Clearcut Site at Harvard Forest 2010-2013

Five 50-m transect lines were established, radiating from the flux tower into the surrounding clear-cut area. Both ends of each transect line were marked with permanent rebar poles for repeatability. The locations of the transect start and end points are as follows: Transect 1 (72°10”25.58” W 42°32’45.23” N to 72°10”25.39” W 42°32’46.82” N), Transect 2 (72°10”25.69” W 42°32’45.14” N to 72°10”27.11” W 42°32’46.34” N), Transect 3 part 1 (72°10”25.65” W 42°32’44.97” N to 72°10”26.81” W 42°32’45.22” N), Transect 3 part 2 (72°10”27.67” W 42°32’45.38” N to 72°10”28.78” W 42°32’45.55” N), Transect 4 (72°10”26.28” W 42°32’44.49” N to 72°10”28.13” W 42°32’43.67” N), Transect 5 part 1 (72°10”25.54” W 42°32’44.14” N to 72°10”25.55” W 42°32’43.33” N), and Transect 5 part 2 (72°10”25.59” W 42°32’42.98” N to 72°10”25.73” W 42°32’42.15” N). Vegetation cover surveys were conducted twice annually from 2010 till present, 1) at the beginning of June and 2) in July. A measuring tape was extended along each transect. We used a wooden stake to identify vegetation along an infinitely thin line immediately adjacent to the tape measure. All ground cover was identified based on species and form, and the starting point and end point of the identified cover was recorded, as noted on the measuring tape. The width was then calculated as the difference between the two points (start and end). All layers of vegetation were included, for example: when a shrub has grass below it, both were identified and recorded. Bare soil, rocks, stumps, and coarse woody debris were also recorded when no vegetation was present. The ground cover of each object i (i.e. vegetation, bare soil, rocks, woody debris, stumps) was calculated as: Eq. 1: % ground cover i = (width i (cm)/25000 (cm)) x 100% where width is the total sum of measured widths of i occurring along all five transects (5 x 50 m). Note that overlap of vegetative strata allows the sum of all ground cover to exceed 100%. Data analysis involved aggregation into cover-type groups, including vegetation types (i.e. herbs, shrubs and trees), bare soil, rocks stumps and debris. Each group’s relative contribution to total ground cover was calculated as the ratio of the group’s ground cover to the overall site’s ground cover within a given year. Furthermore, the percent of total vegetation cover for any species j crossing the line-intercept, analogous to species relative abundance, was calculated as follows: Eq. 2: % vegetation cover j = (width j (cm)/∑ width j (cm)) x 100% where width is the total width of the jth species from all five transects. Data from June and July surveys in each year were combined to provide annual statistics.