Extended Data Fig. 5: Calculating unit pore volume.
From: Forest vulnerability to drought controlled by bedrock composition
a, Idealized landscape with geophysical transects (black lines) at surface above weathered soil and saprolite with a vertical gradient in porosity. b, 1×1 m plot and underlying column of soil and saprolite spanned by the survey. c, Unit pore volume (φv) is calculated by integrating geophysics-based porosity (φ(z), gray shaded area) over depth (z) between the base of saprolite (zsap) and the surface (zsurf), where zsap is defined by a threshold VP = 1.1 km/s (see Methods). d, We define unit pore volume as the total pore volume per unit area at the surface. It therefore represents the depth of water required to fill all the void space in the column of soil and saprolite in panel b.
