Cover was estimated as the actual percentage of the quadrat covered by vegetation rooted within the quadrat, without rounding or filling in areas between leaves or vegetative parts.
The analysis used 877 large quadrats 10 mm×10 mm (actual size 100 km×100 km), which covered about 8.77 million km2.
Cobble/boulder typically covered at least 50% of the quadrat at both sites (mean rank at MI = 2.8; GI = 2.7), whereas algae cover was slightly lower than cobble/boulder (MI = 2.3; GI = 1.9).
To generate a cumulative estimate of number of eggs within each quadrat, percent cover of loose eggs and attached eggs were converted to number of eggs using an egg radius (r = 0.74 mm) from Alderdice and Hourston [ 46], which was similar to our egg radius measurement made on site in Quatsino Sound (r = 0.83 mm, n = 20).
However, current widely used traditional survey techniques such as destructive harvests, pin frame quadrats and visual cover estimates can be very time consuming and are prone to subjective variations.
A 16 × 16-cm quadrat was prepared with a mesh net to randomly cover a portion of the Chaetomorpha sp. community, and all thalli inside the quadrat were collected with scissors.
Cover crop biomass was determined by clipping the plants at the soil surface within a 5.4-ft2 (0.5-m2) quadrat, oven-drying the vegetation at 122°F for one week, and then weighing the dried samples.
The transects were further divided into five separate quadrats and the dimension of each quadrat was maintained as per decided standard (i.e., 10 m × 100 m), although in some places the standard was adapted to cover the desired transect area due to geomorphological constraints such as escarpments in the field.
Cover for each species was expressed as a percentage of the summed total of species maximum cover values in each quadrat in each year.
Remarkably, visual inspection of PCA revealed that in the first two represented ordinations, quadrats showing the presence of L. multiflorum individuals were highly correlated with rock formation (variable 'RockForm') and non-correlated with high coverage (variable 'vegetation cover') (Fig. 5).
