Rainfall simulation sediment and nutrient dynamics in different forest types in the Lake Tahoe basin

Though human impacts are considered within the current efforts to model the water quality of the Lake Tahoe Watershed (CA-NV), vegetated land has been considered a uniform descriptor for much of the uplands within the Lake Tahoe Basin.  The objective of this study is to assess the effects of different forest types in the Lake Tahoe Basin on sediment and nutrient loss using rainfall simulation.  Among the four forest types studied (dense white fir-Abies concolor, open red fir-Abies magnifica, dense red fir, and dense white fir-red fir), dense white fir-red fir demonstrated the lowest amount of runoff and sediment in runoff.  There were marginal differences for organic matter in runoff between forest types, with dense white fir-red fir indicating the lowest amount.  Though dense white fir-red fir had the lowest amount of ammonium concentration in runoff, there were no significant differences for nitrate and phosphate concentrations.  All forest types demonstrated a nutrient (ammonium, nitrate, and phosphate) load reduction capacity (>85%).  Nutrient load reduction differences appear to be as variable between different plots as between different forest types.  This equivalency relates to the extent and replication of the experiment, which will be placed in the context of further watershed-scale studies.