Ubiquitous mycorrhiza: friendly partner in ecological restoration and ecosystem sustainability

Professorial Chair Lecture

United Coconut Planters Bank Professorial Chair Lecture

Abstract

Three ecosystems: Eucalyptus urophylla-Shorea contorta mix (ECO-1), La Mesa Dam Watershed (ECO-2), and P-fertilized E. globolus stand (ECO-3) were prepared to quantify functions of mycorrhiza in restoring degraded forest lands in the Philippines and sustaining plantations in Western Australia.. Rooted cuttings of S. contorta (RCSC) were either inoculated (with fumigated and unfumigated soil from Makiling and Subic dipterocarps forests) or uninoculated, following RCBD experiment. RCSC were interplanted in ECO-1 and monitored growth, survival and ectomycorrhizal (ECM) dynamics in 6-18 months after outplanting. In ECO-2, emergence of indigenous wildlings under five plantations was evaluated in terms of endomycorrhizal association. In the last study, superphosphate (P0=0, P1=100, P2=1000 kg ha-1) was applied in ECO-3 to assess effects in below (ECMF hyphal biomass, root production, nutrient turnover) and above-ground (tree, litter, ECMF diversity and production, nutrient accumulation) biomass.

Inoculated RCSC in ECO-1 were taller by 40-46% with biomass 2-3x higher than uninfected control before outplanting. Soil inoculation increased RCSC height by 26-46% after 18 months of outplanting. ECM root colonization improved RCSC survival by 33-48% relative to control. This developed 7 and 11 root morphotypes in E. urophylla and RCSC, respectively. ECM roots were short, monopodial, thickened by fungal mantle, and contained Hartig net in epidermal cell walls. ECM diversity consisted of 4 genera (Scleroderma, Thelephora, Cortinarius, Boletellis) and 8 species, with biomass (gm-2) in the order: Co (5.3+8.9) < fumigated (45.8 + 10.5 < unfumigated (70.9 + 0.2). In ECO-2, the emergence of 57 indigenous species of wildlings could be linked to endomycorrhizal (4 genera and 18 species) fungi (21-198 spores 100g dry soil-1) that infect 42-95% of fine roots. In ECO-3, the number of taxa and abundance were unaffected by P application; however, biomass production was reduced by 26-40% after 12 months. By comparison, P addition decreased hyphal growth by 17-36% with root biomass (kg ha-1) of: P0 (118.9) < P1 (181.9) < P2 (122.0). P supplement increased accumulation in Lacccaria was significantly higher in Scleroderma and Pisolithus by 35% (N), 76% (P), 54% (K), and 75% (Cu).

Overall, mycorrhizal association contributes about 45% to growth and survival of cuttings. Their presence suggests potential in diversifying indigenous flora for watershed. Mycorrhizal function in nutrient cycling is sensitive to high inorganic P application that limits sustainability of plantation. Restoration of dipterocarp forests should consider nursery inoculation of best ECM strains to assure greater success. Role of endomycorrhiza in maintaining biodiversity in watershed needs further studies. P application should weigh the consequences in mycorrhizal activities to sustain nutrient cycling in plantation ecosystem. The national forest management of terrestrial ecosystems should incorporate underground ecosystem in biodiversity assessment and carbon sequestration studies.

Location

UPLB Main Library Special Collections Section (USCS)

College

College of Forestry and Natural Resources (CFNR)

Language

English

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