Boxplots of (left) isoprene flux rates on a log scale (negative value represents consumption) and (right) the percentage of the provided isoprene consumed in soils incubated under varying mixing ratios of isoprene. Boxes represent the interquartile range, lines within boxes are medians, and whiskers extend to minimum and maximum values. Soil was collected from beneath the deciduous Populus tremuloides (A) and the evergreen Pinus contorta (B).