In 1971 (prior to logging), vegetation plots were established along transects in both upland and riparian areas to get a baseline assessment of the watersheds. Measurements continued after logging through 1983 (another measurement may have been done in 1995). The study was resurrected in 2002 when a subset of the plots was relocated and measured. This subset of plots is now considered the full suite of permanent plots in Watersheds 6 and 7. WS06 has 17 upland plots and 5 riparian plots. WS07 has 19 upland plots and 5 riparian plots.
Upland plots are situated on transects that cross the watersheds in a SW- to NE-direction (i.e., along a compass azimuth that is approximately 225 (SW) to 45 (NE) degrees). The original plots were spaced 40-m apart, but the spacing of the plot subset varies. Upland plot centers are marked with fiberglass or PVC stakes and flagging. Riparian plots are situated along the creeks, with plot center directly in the creek bed and marked with a fiberglass stake and flagging. In WS06, riparian plots are numbered 65-69; in WS07 riparian plots are numbered 66-70.
Trees are sampled as part of the Permanent Sample Plots (TV010) protocol. Understory vegetation measurements are measured within 2 x 2-meter quadrats nested within tree plots and include surface cover estimates of specific surface cover types, total live tree foliage cover with the vertical projection of the quadrat, plot species cover, biomass measurements for particular species rooted in the quadrat, and a list of all species occurring within the plot.
Trees are sampled in a circular plot with a radius of 8.92 meters. In upland plots, there is one 2 x 2-meter understory vegetation quadrat nested within each tree plot. The center stake at plot center serves as one corner of the 2 x 2 quadrat, which is oriented at a 45-degree angle relative to North). The quadrat number in upland plots always = 1. In riparian plots there are two 2 x 2-m vegetation quadrats located on either side of the creek. The quadrat closest to the creek is #1; the one farthest from the creek is #2. One corner of each quadrat is aligned with the center stake in the creek. Quadrats are oriented at a 45-degree angle relative to North.
When the plots were resurrected in 2002, stump diameters were measured in each plot and tree cores were taken to estimate tree ages. Stumps that were rooted in the plot and a result of the 2001 thinning were measured approx. 28 cm above the ground with small diameter tapes or calipers. One increment core was taken at DBH for each tree of all tagged trees in the north half of each upland plot and the half of each riparian plot in the direction away from the gauging station. DBH was measured to the nearest 0.1 cm, tree core position was recorded (uphill, sidehill, downhill, flat) and bark thickness and sapwood thickness were measured with calipers to the nearest 0.1 cm. All cores were placed in straws labeled with watershed #, plot number, and tree tag number and saved for mounting and inspection in the lab.
In 2016, tree heights and crown volume estimates were taken to enable tracking over time, and to improve estimates of tree biomass. Heights were measured of 3 to 5 trees in each species and DBH class present. DBH classes were defined as 5-25 cm, 25-50 cm, 50-75 cm, 75-100 cm, and > 100 cm.
