Aboveground decomposition in arid environments: Results of a long-term study in central New Mexico

The literature on aboveground litter decomposition in arid environments, which is dominated by short-term studies (one- to three-year duration), shows no consistent relationship between mass loss rates and factors controlling decomposition in mesic environments. For ten years, we repeated a decomposition study of five species in four arid to semi-arid biomes in central New Mexico. Annual precipitation during the study ranged from 60% to 150% of the long-term mean. Mass remaining after one year of decomposition varied widely between species: Bouteloua eriopoda (47-85%), Bouteloua gracilis (31-87%), Juniperus monosperma (62-85%), Larrea tridentata (14-67%), and Oryzopsis hymenoides (22-88%). No consistent results were found relating percent mass change during several intra-annual intervals with initial litter C:N or current, cumulative or antecedent precipitation for any species at any site. The relative rates of decomposition were L. tridentata⪢O. hymenoides>B. eriopoda=J. monosperma>B. gracilis. Except for percent lignin, litter quality measures were not good predictors of relative mass loss rates among species. Although a few significant relationships between decomposition and precipitation and litter quality were found, our study results were overwhelmingly unsupportive of these factors having major impacts on litter decomposition processes in central New Mexico.