Patterns of belowground productivity in oak-hickory forests in southern Ohio in relation to prescribed fire and landscape position

This study examines patterns in belowground productivity in southern Ohio oak-hickory forests within the context of a large-scale ecosystem management project using prescribed burning to restore these degraded oak-hickory ecosystems. Three watersheds were assigned to a different prescribed burning regime: frequent burn (annually-burned), infrequent burn (periodically-burned every 3–4 years) and unburned control and each watershed was broken into xeric, intermediate and mesic landscape positions. Specifically, I examined root biomass and productivity, root nitrogen (N) concentration, root decomposition and microarthropod abundance in relation to prescribed burning and landscape position.; A combination of sequential and in-growth coring techniques was used to sample root biomass and root production. 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. Root production measured with in-growth cores was significantly greater in the xeric landscape positions.; Samples collected to determine standing root biomass and root production were also analyzed for N content. Prescribed burning had no effect on live or dead root N concentration. Root N concentration was significantly lower in the xeric landscape positions only during the driest sampling dates. There was little evidence for N resorption from roots.; Root decomposition and N release were quantified using root litterbags. Overall, 70% of original mass was lost and 80% of total N was released over one year, with no significant differences among the treatment watersheds in the instantaneous decay rate (k) or rate of N release. During the first 3 months of decomposition (June–September 1999), there was significantly greater proportion mass loss and significantly lower N release in root litter from the control watershed than from the two burned watersheds.; Microarthropod abundance (with the exception of immature mites) was significantly lower in the annually-burned watershed than the periodically-burned and control watersheds. Since both the periodically-burned and annually-burned watersheds were burned in April 1999, the reduction in microarthropod abundance was not simply an immediate effect of burning. The abundance of oribatid and immature mites was significantly greater in the xeric landscape position.