Amino acid dynamics across a grassland altitudinal gradient

Amino acids (AAs) have been the focus of an increasing amount of research in relation to nitrogen fluxes in soils. We use five temperate grassland sites across an altitudinal gradient to establish relationships between soil properties and the size of individual AA pools and their mineralisation rate. Soil and soil solution chemistry, vegetation and microbial community structure, and standing concentrations of free- and peptide-AAs, were quantified. Mineralisation of AAs was universally rapid (t1/2 < 5 h). We found no relationship between standing AA pool chemistry and rate of AA mineralisation. Instead, soil pH and total microbial biomass, and vegetation community structure were most strongly related to AA turnover rate, highlighting the regulatory role of pH on soil microbial function.