Worlds apart: location above- or belowground determines plant litter decomposition in a semiarid Patagonian steppe

1. While considerable attention has been devoted to how precipitation modulates net primary productivity in arid and semiarid ecosystems, the emergence of multi-faceted controls on carbon (C) turnover suggests that there is much to be understood with respect to the mechanistic controls on plant litter decomposition. 

2. In the Patagonian steppe, we conducted a long-term factorial experiment, evaluating the importance of position, litter quality, tissue origin and soil resources on rates of C turnover under natural field conditions. Leaf and root litter of dominant grass species were placed in litterbags in different positions, on the soil surface and buried at 5 cm depth, with soil treatments of labile C, nitrogen (N) and their combination (C+N) over a three-year period.  

3. As predicted, leaf litter decomposed significantly (nearly six-fold) faster aboveground than did root litter belowground (P < 0.001). Surprisingly, root litter decomposed significantly faster than leaf lit...