Abstract
The effects of anthropogenic nitrogen deposition are being studied worldwide; yet the consequences of nitrogen deposition in semi-arid ecosystems such as the Mediterranean-type shrublands of southern California are not fully understood.  Furthermore, semi-arid ecosystems of southern California are subjected to periodic fire, and increased nutrient inputs can alter ecosystem recovery.  This three-year study compared the recovery from fire of three chaparral sites in southern California located along an anthropogenic nitrogen deposition gradient.  Aboveground biomass was measured using non-destructive dimensional analysis four times each year seasonally.  Total biomass, shrub biomass and average shrub biomass were compared as a function of months post fire.  Shrub biomass was also examined as a function of shrub density.  The results of this study suggest that nitrogen deposition leads to greater aboveground biomass, average shrub biomass and increased shrub biomass as a function of density.