Field work was conducted on Hog Island from May 2015 to March 2016. In order to quantify the effect of the shrub thicket on microclimate, three transects were established on Hog Island that traverse the edge of three shrub thickets. The first transect was located at 37-deg 22min 46.37sec N, 75-deg 42min 49.28sec W and the second at 37-deg 22min 47.04sec N, 75-deg 42min 52.58sec W. These two transects ran east to west, perpendicularly through the thicket edge, with the eastern side of the transect inside the thicket and the western side of the transect outside of the thicket. The second transect was 85 m west of the first transect, and had a partially opened canopy due to recent shrub mortality. The third transect was located 180 m north of the first two transects, at 37-deg 22min 51.00sec N, 75-deg 42min 45.06sec W. It ran north to south, with the northern side of the transect inside the thicket. Each transect began 10 m inside the shrub thicket, crossed perpendicularly through the thicket edge, and ended in the open canopy grassland, 10 m away from the thicket edge. Along these 20 m transects were sampling points every 5 m such that a point existed 10 m inside the thicket, 5 m inside the thicket, at the thicket edge, 5 m outside the thicket, and 10 m outside the thicket. The midpoint of each transect which coincided with the edge of the thicket was defined as the location where shrub cover overcame grass cover. The thickets were chosen because they were at least 20 m wide, roughly level elevation and same age, and the adjacent grassland was free of shrubs that may influence the grassland plots. There were also three sampling points 500 m south of the transects, inside free-standing, grassland shrubs which were beyond influence of the thicket. Three temperature sensors (T Buttons, Thermodata) set at different heights, ground level, 20 cm, and 1 m, recorded bihourly measurements at each of the six plots along each transect (n=3) including the free-standing shrubs.