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Full-Text Articles in Life Sciences
Changes In Microbial Communities Along Redox Gradients In Polygonized Arctic Wet Tundra Soils, David A. Lipson, Ted K. Raab, Melanie Parker, Scott T. Kelley, Colin J. Brislawn, Janet Jansson
Changes In Microbial Communities Along Redox Gradients In Polygonized Arctic Wet Tundra Soils, David A. Lipson, Ted K. Raab, Melanie Parker, Scott T. Kelley, Colin J. Brislawn, Janet Jansson
Ted K. Raab
This study investigated how microbial community structure and diversity varied with depth and topography in ice wedge polygons of wet tundra of the Arctic Coastal Plain in northern Alaska, and what soil variables explain these patterns. We observed strong changes in community structure and diversity with depth, and more subtle changes between areas of high and low topography, with the largest differences apparent near the soil surface. These patterns are most strongly correlated with redox gradients (measured using the ratio of reduced Fe to total Fe in acid extracts as a proxy): conditions grew more reducing with depth and were …
Effects Of Willows (Salix Brachycarpa) On Populations Of Salicylate-Mineralizing Microorganisms In Alpine Soils, Steven K. Schmidt, David A. Lipson, Ted K. Raab
Effects Of Willows (Salix Brachycarpa) On Populations Of Salicylate-Mineralizing Microorganisms In Alpine Soils, Steven K. Schmidt, David A. Lipson, Ted K. Raab
Ted K. Raab
We used the substrate-induced growth-response (SIGR) method to quantify salicylate-mineralizing microbes and total microbial biomass in soils from under willows (Salix brachycarpa) and in surrounding meadows dominated by the sedge Kobresia myosuroides. Willows had a strong effect on the biomass of salicylate-mineralizing microbes in both years of this study. There were always higher biomass levels of salicylate mineralizers in soils from under Salix (4.6–10.1 ug C/ g) than under Kobresia (0.23–0.76 ug/ g). In contrast, total microbial biomass was not significantly different under these plant species in 1996 and was only higher under Salix on one date in 1997. These …
Variation In Competitive Abilities Of Plants And Microbes For Specific Amino Acids, David A. Lipson, Ted K. Raab, Steven K. Schmidt, Russ K. Monson
Variation In Competitive Abilities Of Plants And Microbes For Specific Amino Acids, David A. Lipson, Ted K. Raab, Steven K. Schmidt, Russ K. Monson
Ted K. Raab
Microbes are assumed to possess strong competitive advantages over plants for uptake of nutrients from the soil. The finding that non-mycorrhizal plants can obtain a significant fraction of their N requirement from soil amino acids contradicts this assumption. The amino acid glycine (Gly) has been used as a model amino acid in many recent studies. Our preliminary studies showed that Gly was a poor substrate for microbial growth compared to other amino acids. We tested the hypothesis that the alpine sedge Kobresia myosuroides competes better for Gly than for other amino acids because of decreased microbial demand for this compound. …