PARENT SESSION
Oral Session #43: Soil Ecology: Mycorrhizae and Roots. Presiding: W. Stock.
Wednesday, August 8, 2001. 8:00 AM to 12:15 PM. Hall of Ideas F.

Burning slash has no long-term effect on AM inoculum potential but does affect quality of revegetation.

HASKINS, KRISTIN¹, GEHRING, CATHERINE¹, ¹

ABSTRACT- Studies have shown that fire reduces arbuscular mycorrhizal (AM) inoculum potential. Reductions in the quantity or quality of available inoculum may decrease plant diversity or inhibit desirable plants from re-colonizing following fire. Because burning is a common management practice, we investigated whether or not burning slash in a pinyon-juniper woodland negatively affected AM inoculum potential five years following burning. Plant surveys revealed that vegetation in burned areas generally consisted of weedy species. We hypothesized that inoculum potential would be lower near burned patches than in non-burned interspaces. We conducted a corn bioassay to determine the inoculum potential of soil cores from four areas: 1) burned slash sites, 2) interspace sites between burned slash, 3) non-burned canopy sites, and 4) non-burned interspace sites. Corn was grown in 10cm soil cores for 5 weeks and examined for AM colonization. We also examined the mycorrhizal status of dominant plants in burned and control areas. There were no differences in inoculum potential among the 4 treatments (n=25) in the bioassay. The dominant plants from both burned and control areas showed few differences in mycorrhizal colonization. This suggests that either the fire did not reduce inoculum potential, or that it has recovered in the 5 years since burning. The increase in weedy plant species following burning may be due to other soil changes (e.g., nutrients) or to reductions of native species in the seed bank.

KEY WORDS: AM mycorrhizae, slash, fire