Resource enhancement techniques to aid shrub transplant success in an arid shrubland restoration

For vegetation restoration in arid environments, where low and unpredictable rainfall is typical, establishment of perennial vegetation can be improved with modest increases in soil moisture availability. We evaluated the efficacy of techniques that can increase water availability to enhance success transplanting perennial shrub seedlings in an arid environment. We applied treatments of (a) mycorrhizae inocula to the rooting zone, (b) polyacrylamide gel to the rooting zone, and (c) an aboveground obstruction (a piece of wood) in a full factorial design, and measured survivorship of three species of native shrubs. These amendments may increase available soil moisture by increasing the volume of soil exploited for water uptake, by increasing the amount and time of water availability within the root zone, and/or by altering the microclimate and decreasing evaporation rates. We transplanted 888 seedlings in April 2005: 281 Atriplex canescens, 352 Artemisia tridentata, and 255 Chrysothamnus nauseosus. Overall survivorship after the first growing season was 17.5%, with the highest level for A. tridentata (29.4%), followed by A. canescens (20.3%), and C. nauseosus (6.5%). Overall, the addition of the aboveground obstruction, in combination with the other techniques, led to the highest survivorship. Averaged over the other treatments, survivoship was significantly higher with the addition of the aboveground obstruction for A. tridentata and A. canescens. Addition of the polyacrylamide gel enhanced survivorship for both A. canescens and C. nauseosus, while mycorrhizae inocula did not have a significant impact on survivorship for any species.