The proportion of xylem was not affected by bulk density or soil
type (Table 2). However, the proportion of xylem cross section area
(CSA) dedicated to vessels, which is related to percentage area for
water conduction, showed a decrease with soil compaction (Fig. 1c)
and was not affected by soil type (Table 2). The number of xylem
vessels per unit area of xylem CSA was not affected by bulk density
or soil type, but the xylem vessel diameter was negatively affected
by soil compaction in sandy-loam soil (Table 2). Visually we can see
how soil compaction affects the xylem vessel diameter (Fig. 3).