Salt dynamics in Tamarix ramosissima in the lower Virgin River floodplain, Nevada

Tamarisk (Tamarix spp.) is a halophyte with salt glands on its leaves and is an invasive riparian plant in the US. To increase our understanding of the effects of Tamarix on soil salinity, we conducted a year-long field investigation to evaluate the salt dynamics of a stand of Tamarix ramosissima along the lower Virgin River floodplain, NV, USA. We examined salt accumulation in the biomass and studied salt return to the soil by litter fall, throughfall and stemflow from September 2009 to September 2010. We also investigated soil salinity concentrations inside and outside of the stand where native shrub species was sparsely distributed. The average Na⁺ accumulated in the plant biomass was estimated at 23.4 g m^-2. The Na⁺ returned to the soil through litter fall, throughfall and stemflow during the investigation was similar with that accumulated in the plant biomass. More than 90 % of Na⁺ leached to the soil was from throughfall and stemflow. Soil salinity was significantly lower inside than outside of the stand. Salt secretion from Tamarix is generally expected to increase soil salinity in stands. However, our results suggest that surface soil salinity does not necessarily increase in the Tamarix stand along the lower Virgin River floodplain that is subjected to occasional flooding.