Establishment of Tamarix ramosissima under different conditions of salinity and water availability: Implications for its management as an invasive species

The spontaneous spread of Tamarix represents a threat for biodiversity conservation. Tamarix ramosissima has been identified as an invader of arid and semi-arid environments in Argentina. The effects of salinity and water availability on vegetative reproduction and germination were evaluated in this study in order to determine ecological conditions that are appropriate for the species, and to identify areas of potential invasion in Argentina. Seeds and cuttings were grown in different concentrations of NaCl and PEG-6000 and under of soil saturation conditions. Percentages of seed germination and establishment and survival of cuttings were measured. The tolerance limits for germination reached values of -0.4 MPa (PEG-6000) and -0.8 MPa (NaCl). Cutting survival was significantly reduced at concentrations above 8.8 g/lt NaCl (-0.6 MPa) and under saturated soil conditions. Any cuttings survived under drought conditions. We concluded that soils with an EC less than 15 dS/m were adequate for germination, whereas cuttings tolerated values below 6 dS/m. Consequently, temperate, semi-arid and arid zones of Argentina are under risk of invasion by T. ramosissima even though the species is not resistant to local conditions of extreme drought or prolonged flooding. (C) 2010 Elsevier Ltd. All rights reserved.