Root dynamics of southern Ohio oak-hickory forests: influences of prescribed fire and landscape position

This study compares standing root biomass from sequential root cores and new root production in ingrowth cores in three watersheds: an unburned control watershed, a watershed burned once in 1996, and a watershed burned for three consecutive years (1996-1998). Based on root cores collected on six sampling dates from April through November 1998, maximum standing live root biomass occurred approximately 1 month earlier in the growing season in the site burned three times, presumably because of increased soil temperature after the fires. Standing live fine root biomass was significantly lower in the site burned three times in three of the six sampling dates (April, June, and November) and when averaged over the whole growing season. Most of this effect was due to lesser root biomass in the most mesic landscape position. New root production was measured during three ingrowth core intervals: April to August 1998, August to November 1998, and August 1998 to November 1999. Net production was significantly greater in sample plots in xeric landscape positions during each sampling interval. Overall, differences in standing root biomass were inversely correlated with fire-induced changes in N mineralization and increased soil temperature after burning shifted the phenology of root biomass accumulation earlier in the growing season.