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Fungal community characterization and colonization of added mineral substrates, Bartlett Experimental Forest, New Hampshire, USA.

Ritchie, Karen*,1, Fisk, Melany 1, 1 Appalachian State University, Boone, NC, USA

ABSTRACT- As acidic deposition and forest management alter the soil nutrient environment in forests of the northeastern US, there is increased interest in the potential for soil fungi to mobilize nutrients from primary mineral forms. To test affinity of different fungal species for calcium- and phosphorus-bearing minerals, we incubated mesh bags containing apatite (a Ca-phosphate mineral), wollastonite (a Ca-silicate mineral), and pure quartz (as a control) for one growing season in the B horizon of a 30-yr old northern hardwood stand at the Bartlett Experimental Forest, NH. We will compare species composition of mineral bags against soil samples taken from the same site to ascertain whether colonization of different mineral substrates is selective. We extracted DNA from B- and C-horizon soil samples as well as mineral bags and PCR-amplified the ITS region of the nuclear rDNA genes using the fungal-specific primers, ITS1f and ITS4. Subsequent terminal-restriction fragment length polymorphism (TRFLP) analysis yielded community profiles for each sample. Dominant fungi were identified by ITS sequence and species composition was estimated by frequency of occurrence among samples. In addition to significant fungal diversity, we found a shift in relative dominance towards mycorrhizal species at greater soil depths, possibly a function of their role in mineral nutrient mobilization for plant hosts. We are in the process of matching taxa found in soil samples with those colonizing mesh bags to evaluate any selective colonization of added mineral substrates. Analysis of mineral bags suggests preferential colonization of apatite over both wollastonite and control, and raises the interesting question of whether biotic demand for P is higher than that for Ca in this stand.

Key words: fungal community, ectomycorrhizal hyphae, apatite

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