Amino sugars in native grassland soils along a climosequence in North America

Characterizing amino sugars is important for further understanding soil org anic matter (SOM) dynamics in terrestrial ecosystems. This study was design ed to evaluate the impart of climate on amino sugars in 18 surface soil (0- 10 cm) samples along a climosequence of native grasslands from central Sask atchewan, Canada, to Southern Texas, USA. Mean annual temperature (MAT) ran ged from 0.9 to 23.4 degrees C and mean annual precipitation (MAP) from 300 to 1308 mm, In all samples, the contents of soil organic C, glucosamine, m annosamine, galactosamine, and muramic acid were determined. Both the ratio s of glucosamine to galactosamine and of glucosamine to muramic acid were r elated to the moisture regime. With increasing MAP, increasing proportions of amino sugars were glucosamine, This glucosamine is possibly derived from the chitin of fungi. The proportion of bacterial-derived amino sugars, suc h as muramic acid, declined as MAP increased. The relationship between amin o sugar concentrations (mg kg(-1) soil organic C) and MAT followed a parabo lic regression model; the maximum of the amino sugar concentration occurrin g at the mesic temperature regime. On the basis of hierarchical cluster ana lysis the sites could be divided into two groups, which coincided with the Northern-central and Southern grasslands. We hypothesize that in the Northe rn-central grasslands frost limits amino sugar production whereas in the So uthern grasslands higher winter temperatures >0 degrees C favor amino sugar decomposition.