Ectomycorrhizal Fungi of Salix Rotundifolia Trautv. II. Impact of Surface Applied Prudhoe Bay Crude Oil on Mycorrhizal Root Respiration and Cold Acclimation

Ectomycorrhizal root tips of Salix rotundifolia Trautv. removed from Barrow, Alaska tundra treated with 5 or 12 l/m² Prudhoe Bay crude oil on 1 July 1975 showed decreased respiration rates within 48 hr after surface application of oil. Oil treated roots continued to have depressed respiration rates throughout the summer. The following summer, respiration rates of the 5 l/m² oil treated roots were higher than controls. With respiration of the 12 l/m² treated roots only 20% below controls. However, during the summer, respiration rates declined very rapidly, probably due to water stress caused by drought conditions. The third summer, respiration rates of all root samples were quite similar, with all rates low, probably due to continued water stress. Viable root biomass declined from year to year in the oiled soils. Analysis of cold acclimation by Arrhenius plots of respiration rates shows losses in cold acclimation after oil treatment. Ectomycorrhizal roots of S. rotundifolia from the oil impregnated soils of a natural oil seep at Cape Simpson, Alaska showed a minimum loss in respiration rates and cold acclimation after exposure to fresh crude oil

Ectomycorrhizal Fungi of Salix Rotundifolia Trautv. I. Impact of Surface Applied Prudhoe Bay Crude Oil on Mycorrhizal Structure and Composition

The effects of exposure to crude oil on the structure and quantity of viable mycorrhizae of the dwarf deciduous shrub, Salix rotundifolia Trautv., have been investigated at Barrow and Cape Simpson, Alaska over a three year period on experimental plots treated with 5 and 12 l/m² of Prudhoe Bay crude oil. Salix rotundifolia populations growing adjacent to the Cape Simpson natural oil seep were examined for possible changes which may have occurred as the result of long term exposure to oil. Structural examination of mycorrhizae was accomplished by light and scanning electron microscopy. Structural difference in viable mycorrhizae were observed between control and oil treated plots one year after the application of oil. Ectomoycorrhizae with smooth mantle surfaces were found to predominate on the Barrow control plot. The predominant viable mycorrhizae on the oil treated plots demonstrated a marked proliferation of mantle hyphae, presumably a result of the altered soil environment. Prudhoe Bay crude oil applied at 12 l/m² caused a large reduction in the number of viable willow mycorrhizae within one week at Barrow. After this rapid initial response, the rate of destruction of mycorrhizae appeared to proceed at a slower rate throughout the remainder of the growing season. The effect of oil in depressing the number of viable mycorrhizae was still apparent three growing seasons after the application of oil. Salix rotundifolia growing adjacent to the Cape Simpson oil seep demonstrated greater numbers of viable mycorrhizae and a higher percentage of Cenococcum graniforme (Sow.) Ferd and Winge. mycorrhizae than did plants at Barrow