Ecology / Ecologie (CBA/ABC)
Robertson, Susan J. , Rutherford, Michael , Massicotte, Hugues .
Interactions between petroleum hydrocarbon contaminants and ecto- and ericoid mycorrhizal communities in sub-boreal forest soils.
The dynamics of petroleum hydrocarbon (PHC) biodegradation in boreal forest soils are not well understood. We used a bioassay approach to determine whether differences in ecto- (ECM) and ericoid (ERM) mycorrhizal fungal communities corresponded to differences in PHC biodegradation patterns. Surface-sterilized seeds (Pinus contorta, lodgepole pine; Betula papyrifera, paper birch) or seedlings (Vaccinium vitis-idaea, lingonberry) were planted into ConetainerTM pots containing reconstructed soils: an organic layer (mor humus, coarse woody debris, or previously contaminated humus) overlying sandy mineral horizons (Ae and Bf) of field-collected forest soils obtained from central BC, Canada. After 4 months, BC light crude oil (219 mg cm-2) was applied to the soil surface around the seedling stem; systems were destructively sampled at 1 and 16 weeks following treatment. Concentrations of PHCs in 4 fractions were determined using acetone-hexane extraction followed by gas chromatography – flame ionization detection analysis. ECM communities (composition, relative abundance and spatial distribution) were assessed on pine and birch roots using light microscopy and fungal community profiles were generated for all root systems using length heterogeneity PCR and primers targeted at the ITS region of rDNA. In addition, selected mycorrhizal root tips (ECM and ERM) were tested for oxidative enzyme (laccase) activity in assays with 2,2’-azinobis-3-ethylbenzthiazoline-6-sulfonate (ABTS). An inherent capacity for biodegradation of nC10-nC16 fraction PHCs was found in all plant – soil combinations from 1 to 16 weeks. However, total PHC (nC10-nC50) concentrations declined significantly in only pine-woody debris and birch-humus systems. Laccase activity was observed for some mycorrhizas, indicating potential for biodegradation of aromatic PHCs. The mycorrhizosphere appears to play an indirect role in PHC biodegradation through support of heterotrophic microbial communities. The level of PHC contamination used in this study (~22 tonne oil ha-1) appeared to have minimal impact on the development and metabolic capacity of ECM and ERM communities.
Log in to add this item to your schedule
1 - University of Northern British Columbia, Natural Resources and Environmental Studies Program, 3333 University Way, Prince George, BC, V2N 4Z9, Canada
2 - University of Northern British Columbia, Environmental Science and Engineering Program, 3333 University Way, Prince George, BC, V2N 4Z9, Canada
3 - University of Northern British Columbia, Ecosystem Science and Management, 3333 University Way, Prince George, BC, V2N 4Z9, Canada
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 28th, 2008
Time: 10:15 AM