Inoculation Response by Irrigation System Type for Desert Tree Establishment
Revegetation research offers the opportunity to test theories under difficult field conditions. These tests can help improve guidelines for establishing trees on arid and degraded sites. The borrow pit (surface mine) used for this study reflects the most difficult challenges of low fertility, extreme water stress, and harsh microclimate conditions. This set of conditions made it an ideal site to test interactions between irrigation system type and inoculation with rhizobial bacteria and mycorrhizal fungi. The tree chosen for the study, Prosopis glandulosa var. torreyana (L.D. Benson, M.C. Johnston), (mesquite, honey mesquite), is a small- to medium-sized leguminous tree with considerable value for ecosystem structure and function. It was once much more common in the low desert of California and was widely used as a food by indigenous people. The destruction of mesquite woodlands for fuel wood and agricultural and urban development has reduced once vast stands to isolated remnants. The California Department of Transportation supported research to mitigate mesquite habitat loss caused by ongoing highway construction. It was also expected this research would help nursery managers better prepare plants for difficult sites and assist restoration specialists and foresters in developing better techniques for restoration and agroforestry projects. The soil analyses showed that soil fertility was greatly reduced and inoculation potential was nearly absent in the borrow pit. Deep-pipe and buried-clay-pot irrigation each enhanced survival and growth. The steady moisture of buried clay pots appears to be more favorable for rhizobial inoculation, and deep-pipe irrigation with deeper wetting and greater aeration is better for mycorrhizal inoculation. Double inoculation provided increased survival and growth in the short term, but long-term effects were minimal.
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Author(s): David A. Bainbridge
Publication: Tree Planters' Notes - Volume 57, Number 2 (2014)
Volume: 57
Number: 2