FIG. 2.

Effect of initial sterilization treatments of Terschelling dune soil on temporal dynamics of hyphal extension ability of several soil-borne fungi (A to D), soil respiration (E), and bacterial plate counts (F). Hyphal extension from potato dextrose agar disks into soil was measured at all indicated time intervals and is given as a percentage of the extension measured into acid-purified beach sand. *, mean extension, respiration, or bacterial number is significantly higher (two-sample t test, P < 0.05) than that of the nonsterilized dune soil. Bar patterns (from left to right within each group): solid black bar, untreated soil; checkerboard bar, microwaved; checked bar, autoclaved plus 1% nonsterile dune soil inoculum; trellis bar, autoclaved and open incubation; and hatched bar, autoclaved and closed incubation.