Dynamics of ectomycorrhizal fungi in a Eucalypus urophylla S.T.Blake plantation in the Philippines: Effect of phospohorus fertilization

Commercial plantations in the Philippines may benefit from fertilization and mycorrhizal application. Work in temperate forestry suggests that phosphorus (P) addition can alter dynamics of ectomycorrhizal (ECM) fungi in eucalypt [Eucalyptus spp.] plantations. To investigate P effects on fungal dynamics, P (0, 100, and 1000 kg P ha-1) was applied to a 19-month E. urophylla plantation in Mindanao and the following quantified: biomass of basidiocarps, soil hyphae, fine roots, tree and litter, and their NPK content. Diversity of ECM fungi was low and biomass production was in the order: Scleroderma>Thelephora>Cortinarius. Hyphal growth decreased with increasing P supply. There was no response in tree growth or litter production to P. The soil hyphae were significant reservoirs of below-ground N, P and K. The nutrient content of trees above-ground was approx. equal to the sum of the nutrient load in roots, litter and ECM fungi. It was estimated that the ECM basidiomes and soil hyphae accounted for only 1-2% of the inorganic nutrients in the whole tree. The response of mycorrhizal fungi to fertilizer should be investigated in longer-term studies in the Philippines. The low fungal biodiversity and basidiome biomass were probably due to previous land use and the introduction of an exotic tree. The eucalypt plantation was established on an Imperata grassland, formerly a rainforest dominated by dipterocarps