Lessons Learned 5+ Years After Transplanting and Seeding Restoration Sites in the Sonoran Desert, U.S.A.

Abstract

Recovery of degraded lands in arid environments is especially challenging due to difficulty of matching ideal conditions to seed germination requirements and reduced native soil seed banks. Restoration practitioners try to overcome these challenges through seeding and site preparation treatments. In the McDowell Sonoran Preserve, Scottsdale, Arizona, the focus for restoring old roads was on seeding, cactus transplants, and soil treatments (either ripping or adding soil from nearby construction areas). Here we evaluated the success of these restoration sites 5–8 y after project completion. We compared vegetation and ground cover on eight roads that received a combination of these restoration treatments with adjacent reference areas. Plant cover was similar between the restoration and reference plots, but plant composition was different. The restoration plots contained more cacti due to cactus transplants, whereas the reference areas contained more shrub cover. The number of native plant species was greater in the reference areas than in the restoration plots. Seeding treatment had little effect, with only five of 11 seeded species appearing in plots, and only one species, Bouteloua aristidoides, appeared in both treatments that included seeding. Although cacti may have contributed to overall plant cover, they did not appear to aid establishment of other plants. Our findings suggest more interventions are likely required for the restoration and reference plant communities to converge in arid environments. We suggest considering multiple seeding treatments that will maximize the potential for ideal germination conditions and additional local interventions that may help accumulate litter and protect seeds.