Demographics of E. californica and exotic grass species in the San Joaquin Desert: a field survey and greenhouse experiment

Shrubs facilitate the abundance and productive of annual plants in desert ecosystems.However, these shrub microhabitats favour plant species with competitive life histories. Ephedra californica is a dominant shrub in the San Joaquin desert that has been identified as a facilitator. Here, we explore the factors that limit the Ephedra californica recruitment into the San Joaquin desert including substrate, water availability, and herbivory. We also explore the role of the invasive grass Bromus madritensis on limiting establishment of E. californica. Vegetation surveys were conducted in the field during 2013 and collected seed was then used to conduct two greenhouse trials. The first explore germination and establishment techniques for E. california and the optimal substrate. The second examined E. californica establishment in present of the invasive B. madritensis responding to different water levels and herbivory. These results can have implications for land managers in the San Joaquin Valley to maintain native shrub biodiversity in the region.