title: Soil, vegetation, and seed bank of a Sonoran Desert ecosystem along an exotic plant (Pennisetum ciliare) treatment gradient.
abstract: Ecological conditions following removal of exotic plants are a key part of comprehensive environmental management strategies to combat exotic plant invasions. We examined ecological conditions following removal of the management-priority buffelgrass (Pennisetum ciliare) in Saguaro National Park of the North American Sonoran Desert. We assessed soil, vegetation, and soil seed banks on seven buffelgrass site types: five different frequencies of buffelgrass herbicide plus hand removal treatments (ranging from 5 years of annual treatment to a single year of treatment), untreated sites, and non-invaded sites, with three replicates for each of the seven site types. The 22 measured soil properties (e.g., pH) differed little among sites. Regarding vegetation, buffelgrass cover was low (≤1% median cover), or absent, across all treated sites but was high (10-70%) in untreated sites. Native vegetation cover, diversity, and composition were indistinguishable across site types. Species composition was dominated by native species (>93% relative cover) across all sites except untreated buffelgrass sites. Most (38 species, 93%) of the 41 species detected in soil seed banks were native, and native seed density did not differ significantly across sites. Results suggest that: (1) buffelgrass cover was minimal across treated sites; (2) aside from high buffelgrass cover in untreated sites, ecological conditions were largely indistinguishable across sites; (3) soil seed banks harbored ≥12 species that were frequent in the aboveground vegetation; and (4) native species dominated post-treatment vegetation composition, and removing buffelgrass did not result in replacement by other exotic species.
authors.affiliation: National Park Service, Washington Office, Natural Resource Stewardship and Science Directorate, Biological Resource Management Division, 1201 Oakridge Dr., Fort Collins, CO, 80525, USA, scott_abella@nps.gov.
authors.forename: Scott R
authors.initials: SR
authors.lastname: Abella
authors.forename: Lindsay P
authors.initials: LP
authors.lastname: Chiquoine
authors.forename: Dana M
authors.initials: DM
authors.lastname: Backer
mesh_terms: D001130:Arizona; D003889:Desert Climate; D052918:Environmental Restoration and Remediation; D006540:Herbicides; D058865:Introduced Species; D031782:Pennisetum; D012639:Seeds; D012987:Soil
chemical_list: D006540:Herbicides; D012987:Soil