Document: EDI-3-64-32

Mycorrhizae and restoration in seasonal tropical forests in Mexico.

ALLEN, E.B.*, M.F.ALLEN, L.CORKIDI, L.EGERTON-WARBURTON and A.GOMEZ-POMPA

University of California Riverside, Riverside, CA 92521 ¹

Abstract:
Forest remnants in Quintana Roo, Mexico are subject to frequent fires that escape from shifting cultivation, and will require restoration to break the fire cycle. In September 1997 we planted 756 seedlings of six species of early and late successional trees. We propagated the seedlings in the greenhouse using inoculum collected from a mature forest that has no history of soil disturbance, a two year old forest resprouting from a wildfire, and uninoculated controls. The seedlings were planted into an experimental burn dating from June, the end of the 1997 dry season. Spore densities were greatly reduced after the fire, and root infection was sparse in resprouts three months after the fire. Soils were high in P, with an average of 50 ppm bicarbonate extractable P. The most effective inoculum in promoting plant growth was from the early seral forest, which produced the tallest seedlings with the greatest biomass (P < 0.001). The late seral inoculum caused either the second highest growth or the poorest growth, depending on the host tree species. All uninoculated seedlings became infected from remnant field inoculum by December 1997, but the growth effect of inoculating seedlings is persisting into the third growing season. The different growth responses may be related to the high density of Gigasporaceae in late seral inoculum, as some species of this family are known to be less effective in promoting growth responses than other species of mycorrhizal fungi. The results show that the species of mycorrhizal fungi are not limiting the regrowth of secondary forests, but the dense, flammable regrowth promotes a continual rapid fire cycle.

Keywords: fire, phosphorus, succession, inoculum

This abstract is being presented at: 8:30 AM in session:
Oral Session #60: Forest Restoration.