A Mojave Desert shrub community was experimentally burned to understand changes in seed bank of desert annual plant species in response to wildfire. Seed mortality ranged from 55 to 80%, and fire caused significant losses of native and alien annual seeds. Schismus arabicus, Schismus barbatus, Bromus madritensis, Bromus tectorum, Erodium cicutarium and Plantago spp. made up >95% of the seed bank...

Land managers are concerned about the negative effects of alien annual plants on native plants, threatened and endangered species such as the desert tortoise (Gopherus agassizii), and ecosystem integrity in the Mojave Desert. Management of alien plants is hampered by a lack of information regarding the dominance and environmental correlates of these species. The results of this study indicate t...

New combinations and names are here validated for ten grass (Poaceae) taxa in California for the forthcoming revision of The Jepson Manual. In addition, guided by recent molecular phylogenetic studies, ten non-California grass species are here transferred to Muhlenbergia (Chloridoideae: Cynodonteae) to achieve monophyly of the genus. Lolium, long known to be phylogenetically nested within Festu...

Increased livestock densities near artificial watering sites create disturbance gradients called piospheres. We studied responses of alien and native annual plants and native perennial plants within 9 piospheres in the Mojave Desert of North America. Absolute and proportional cover of alien annual plants increased with proximity to watering sites, whereas cover and species richness of native an...

We quantified seed dispersal in a guild of Sonoran Desert winter desert annuals at a protected natural field site in Tucson, Arizona, USA. Seed production was suppressed under shrub canopies, in the open areas between shrubs, or both by applying an herbicide prior to seed set in large, randomly assigned removal plots (10-30 m diameter). Seedlings were censused along transects crossing the repro...

The North American tortoise Xerobates agassizii (synonym: Gopherus agassizii) consumes herbage and grasses produced from low and variable desert rains. Utilization of Sphaeralcea ambigua foliage and the grass Schismus barbatus were studied in 8 adult tortoises (2.3 kg body mass). The herbage contained more N but less fiber than the grass. Tortoises ingested and digested more dry matter and ener...

Novel fire regimes are an important cause and consequence of global environmental change that involve interactions among biotic, climatic, and human components of ecosystems. Plant flammability is key to these interactions, yet few studies directly measure flammability or consider how multiple species with different flammabilities interact to produce novel fire regimes. Deserts of the southwest...