Litter quality of C_3 perennial grasses and soil inorganic nitrogen in a semiarid rangeland of central Argentina

摘要

The study was undertaken to quantify litter quality of six C_3 perennial grasses and species effects on soil inorganic nitrogen (N) in a semiarid rangeland of central Argentina. Leaf litter and roots were analyzed for N, carbon, phosphorus and lignin concentrations. Field measurements and laboratory experiments compared inorganic N content and potential net N mineralization in the soil under selected grasses. Species were represented by two palatable late-seral grasses (Poa ligularis and Stipa clarazii), two unpalatable late-seral grasses that increase in abundance under heavy grazing (Stipa ambigua and Stipa gynerioides) and two palatable mid-seral grasses (Piptochaetium napostaense and Stipa tenuis). Species exhibited relatively little variation in the chemical composition of leaf litter and roots. The soils associated with these species did not differ in inorganic N content in field or potential net N mineralization. Furthermore, amending soils with roots of these species had no consistent impact on inorganic N content. Our results suggest C_3 perennial grasses that differ in their palatability to grazers do not differentially influence soil inorganic N dynamic in semiarid rangelands of central Argentina.