PARENT SESSION
Symposium #31: Ecological Restoration in a Future Altered Climate .

Organized by: ME Loik and KD Holl
Thursday, August 8. 1:00 PM to 3:45 PM. Leo Rich Theatre.

Mycorrhizae and tropical forest: restoration and carbon sequestration.

Allen, Michael^*,1, Allen, Edith¹, Gomez-Pompaa, Arturo¹, Egerton-Warburton, Louise¹, Rotenberg, James, ¹ University of California, Riverside, CA

ABSTRACT- Tropical ecosystems play a critical role in the balance of carbon release versus sequestration. Deforestation and fire associated with land transformation destabilizes soils, causes a loss in mycorrhizal fungi, and results in C release to the atmosphere. Succession in many areas is limited by an ever-increasing fire frequency. We initiated restoration of a seasonal tropical forest in Quintana Roo, Mexico by manipulating mycorrhizal fungi (early versus late seral fungi). Both AM and EM fungi are present in late seral stands. Late seral AMf established immediately when part of the soil mix, but took several years to invade naturally. EM fungi have not yet re-established. In other studies, glomalin, a glycoprotein formed by arbuscular mycorrhizal (AM) fungi, increases with succession and with elevated CO2. In addition, Scutellospora spp., late seral AMf, decline with disturbance and high N. This fungus correlates with higher concentrations of glomalin. If N is limiting, AMf and glomalin increase. When N is added, AMf shift composition, and EMf longevity increases, but the total of mycorrhizae decline. These dynamics regulate not only the plants ability to grow and fix CO2, but also to sequester C in soils. Since the tropics are a major global sink of C, the ability to manage global C may reside in our ability to shift the predominant activity from deforestation to restoration.

KEY WORDS: mycorrhizae, tropical forest, carbon sequestration, nitrogen