Animal generation of green leaf litter in an arid shrubland enhances decomposition by altering litter quality and location

Abstract Soil carbon(C) and nutrients are derived largely from decomposition of plant biomass. Animals that generate greenfall, or green leaf litter, influence C and nutrient cyclingdynamics by altering the phenological condition, and therefore nutrient quality, of plant litterentering the soil, and transporting litteramong microsites. Micrositeeffects on decomposition rates are particularly pronounced in arid and semi-arid ecosystems where vegetation cover is often patchy. We investigated differences in decomposition of greenfall and senesced litterof three common Chihuahuan Desert plants from which animals frequently generate greenfall. A litterbag study was used to quantify differences in mass, C, and nitrogen (N) losses between green and senescedleaves in shrub intercanopy and subcanopy micrositesin desert shrublands. We found significant differences in nutrient concentration of green and senescedleaves, and that both littercondition (green or senesced) and micrositeaffected decomposition rate. For two of the three litterspecies, greenfall decomposed more rapidly than senesced litter; for all three species, litterdecomposed more rapidly in intercanopy than subcanopy microsites. These results support the idea that creation and translocation of greenfall by animals are important mechanisms regulating decomposition speed and C and nutrient transfer from plant biomass into the soil.