Invasion by the C3 annual grass Bromus tectorum has significantly increased the amount of relatively low quality (high lignin:nitrogen) plant litter deposited in arid Colorado Plateau grasslands. Our objectives were to determine what effects these changes have on microbial utilization of carbon (C) and nitrogen (N). We measured net C and N mineralization, and the ?13C of bulk organic matter, mineralized C, and bacterial fatty acids from soils of invaded and non-invaded C3 (Stipa hymenoides) and C4 (Hilaria jamesii) native grasslands. Carbon mineralization was greater in invaded compared to non-invaded sites (1.25 +/- 0.09 and 1.52 +/- 0.18 g CO2-C kg-1 soil h-1 respectively). Rates of net inorganic N mineralization were lower in invaded [...]
