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Soil amino acid composition across a boreal forest successional sequence

TitleSoil amino acid composition across a boreal forest successional sequence
Publication TypeJournal Article
Year of Publication2009
AuthorsWerdin-Pfisterer, NR, Kielland, K, Boone, RD
JournalSoil Biology & Biochemistry

Soil amino acids are important sources of organic nitrogen for plant nutrition, yet few studies haveexamined which amino acids are most prevalent in the soil. In this study, we examined the composition,concentration, and seasonal patterns of soil amino acids across a primary successional sequenceencompassing a natural gradient of plant productivity and soil physicochemical characteristics. Soil wascollected from five stages (willow, alder, balsam poplar, white spruce, and black spruce) of the floodplainsuccessional sequence on the Tanana River in interior Alaska. Water-extractable amino acid compositionand concentration were determined by HPLC. Irrespective of successional stage, the amino acid pool wasdominated by glutamic acid, glutamine, aspartic acid, asparagine, alanine, and histidine. These six aminoacids accounted for approximately 80% of the total amino acid pool. Amino acid concentrations were anorder of magnitude higher in coniferous-dominated late successional stages than in early deciduousdominatedstages. The composition and concentration of amino acids were generally constantthroughout the growing season. The similar amino acid composition across the successional sequencesuggests that amino acids originate from a common source or through similar biochemical processes.These results demonstrate that amino acids are important components of the biogeochemical diversity ofnitrogen forms in boreal forests.