Date of Graduation

1999

Document Type

Thesis

Degree Type

MS

Committee Chair

Jonathan R. Cumming

Committee Member

William T. Peterjohn

Committee Member

Richard C. Thomas

Abstract

Elevated levels of acidic deposition are leading to higher concentrations of aluminum (Al) in the soil solutions of some forest ecosystems. For this thesis, I performed a suite of experiments to investigate the effects of four interconnected factors on the growth and nutrition of Liriodendron tulipifera L. (tulip poplar): 1. Al exposure in solution; 2. mycorrhizal presence and percent colonization; 3. N source ratio; and 4. N level. My studies of L. tulipifera demonstrate a sensitivity to Al at concentrations as low as 100 µM, ranking it among the most Al sensitive tree species ever studied. Selected Al tolerant species of mycorrhizal fungi appear to confer Al tolerance to this species, but when inoculated with a community of mycorrhizal fungi trapped from the field, tulip poplar seedlings displayed symptoms of Al toxicity. N source ratio and N level affected the extent of mycorrhizal colonization and also cation accumulation, with reductions in nutrient cations observed primarily under ammonium nutrition. Tulip poplar is highly mycorrhizal, and the negative effects of forest acidification may be mitigated by acid and Al tolerant species of fungi.

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