Saltgrass revegetation of saline soils

2010 Summer.Includes bibliographic references.Saltcedar (Tamarix spp.) invasion into riparian areas in southwestern US, including Colorado, is threatening native biodiversity and riparian geomorphic and hydrologic processes. Great effort and resources have been invested to eliminate and control saltcedar invasion. However, due to salt redistributions, saltcedar-affected sites typically have high salts content at the soil surface. Ecological restoration of sites impacted by invasion ( and subsequent control) of saltcedar presents technical and conceptual challenges. Inland saltgrass (Distichlis spicata L. Greene) is a warm-season, rhizomatous, perennial, halophyte with worldwide distributions. It may have potential to use as a revegetation species for salinity affected soil, including saltcedar cleared areas. Therefore, the objectives of my first study are to: 1) Collect native saltgrass germplasms on riparian sites with saltcedar present along major river systems in the western US; 2) Evaluate the collections for establishment and long-term persistence in Colorado climate by determining coverage, vigor, density, and biomass over 3-4 year period. We collected saltgrass ecotypes along major rivers in the western U.S. from 2004 to 2006. Ninety-two ecotypes were planted in 2006 and 2007 for field observation. Data obtained for this study were: establishment as indicated by saltgrass coverage, density, height, yield, and spring green-up. Data showed significant differences among saltgrass ecotypes. Vegetative coverage was correlated to plant height and density in both years' plantings. From ecotypes planted in 2006, C30, C35, C25, C32, and C2 had the fastest establishment with good persistence. In considering all data collected, ecotype C30 is best suited for revegetation purposes; C30 exhibited the fastest establishment, and it was among the ecotypes that exhibited the highest density and yield. The growth and coverage of C30 persisted over the duration of this experiment (from 2006 to 2009). From ecotypes planted in year 2007, C51, C52, C62, C70, C115, C117, C133, C134, C135, and C137 have the best promise for revegetation purposes. Information from this study can be used to further develop saltgrass for revegetation purposes. Two experiments were conducted in the field with the objective to determine saltgrass seed germination and establishment as affected by salinity and seed treatment chemicals (Proxy and/or Thiourea). As the average soil EC salinity increased from 3.5 to 7.6 dS m- 1, saltgrass seed germination was not affected. However, lower germination and plot coverage were observed in plots with soil salinity at 12.4 dS m- 1 than the control plots. Our results indicate that Proxy solution at 5 mM a.i. enhanced saltgrass seed germination better than the other treatments at all salinity levels. The ecotypes selected in this study can be valuable to further develop saltgrass for revegetation purposes. The information on saltgrass germination as affected by salinity and proxy treatment can be integrated into development of protocols for revegetation of saline areas