Title

A systematic review of species performance and treatment effectiveness for revegetation in the Mojave Desert, USA

Document Type

Chapter

Abstract

Land managers need ecologically and cost-effective strategies for revegetating arid lands, such as the Mojave Desert in the southwestern United States. Many disturbances – failed agricultural attempts, grazing by exotic herbivores (e.g., burros, cattle), creating roads, land clearing for military or mining activities, off-road vehicle use, and wildfires fueled by exotic grasses – have modified or eradicated native vegetation. Natural revegetation often is slow, or consists of exotic species that do not meet management objectives. As a result, active revegetation using native species may be required to accomplish ecological and utilitarian objectives, such as enhancing native plant communities, curtailing fugitive dust that poses a human health hazard, or establishing non-flammable vegetation for reducing wildfires. We evaluated the following questions by systematically reviewing published revegetation studies in the Mojave Desert: (1) Which species have been most commonly and effectively planted or seeded? (2) Which treatments have increased plant establishment? (3) What are the relative performances of planting and seeding, and are these species specific? Fifteen planting studies assessed a total of 41 species, 33 of them shrubs. None of the nine species planted in ≥ 3 studies avoided a complete failure (0% survival) in one or more treatments in one or more studies, but several species (e.g., Larrea tridentata, Atriplex spp.) consistently exhibited high (> 50%) survival. Fencing, shelters, and irrigation increased survival of some species, but these treatments require cost/benefit analyses. Though seeding frequently has been discouraged relative to planting, seeding success is species and situational specific. For example, Baileya multiradiata, Phacelia parishii, Atriplex polycarpa, Penstemon palmeri, and Penstemon bicolor became established at densities ranging from 3-9 plants/m2 in individual seeding studies. Based on published data, seeding should not be discounted and warrants additional research as a revegetation option. Our review focused on the Mojave Desert, but our method of systematic, evidence-based synthesis may be useful for assessing revegetation options in other arid lands.

Disciplines

Desert Ecology