Questions: • Will there be a relationship between the average size of Ephedra californica individuals and their overall density in a given area? • If there is a relationship, then will shrubs found at higher densities have a lower size or higher size, and vice versa? • Will the overall health of Ephedra californica individuals be impacted by varying densities? • Will the relationship between shrub health and density follow the - 3/2 self-thinning law?
Hypothesis: • Density-dependent interactions between Ephedra californica individuals will result in a decrease in overall size, cover, and will significantly influence the overall health of these shrubs.
Predictions: 1. Ephedra californica size will decrease with increasing densities of individuals in an established area. 2. Ephedra californica shrub cover will follow a similar trend as shrub size where there will be a decreasing in cover in higher density areas. 3. Health of Ephedra californica individuals will be higher in areas with a lower chance of intraspecific interactions.
Methodology: • Select 6 sites previously listed • Establish plots within site containing a variety of Ephedra densities • Measure Ephedra individuals size • Determine Ephedra density from measured shrub within a 10m radius • Quantify overall Ephedra individual health via a Likert scale
Foundational Shrub Species Purpose: • To determine if varying densities of foundational shrub species, primarily Ephedra californica, impact the abundance of invasive annual species under their canopy, in particular Bromus rubens.
Foundational Shrub Species Questions: • Do Ephedra californica individuals facilitate high levels of Bromus rubens? • Do higher densities of Ephedra californica individuals facilitate the growth of Bromus rubens at higher rates than lone shrub individuals? • Does canopy cover of Ephedra californica influence the total dry matter of annuals underneath their canopies?
Foundational Shrub Species Hypothesis: • Density-dependent interactions between Ephedra californica and Bromus rubens will increase at higher densities of shrub species, and will significantly differ based on canopy cover. Predictions: 1. Higher Ephedra californica densities will have a larger abundance of Bromus rubens than lone Ephedra individuals. 2. Larger Ephedra canopies will result in larger abundances of dry matter and Bromus rubens individuals.
Foundational Shrub Species Proposed Methodology: • Establish 10 (or more), 10m plots ranging in Ephedra density (5-8 individuals) per plot. • Establish several lone individual shrubs outside of the established plots. • Measure dimensions of all shrub individuals (As seen in Chapter 1). • Plant Bromus rubens seeds both in established plots and with lone shrub individuals • Record total Dry Matter underneath canopies and in open areas.
Questions: • Will local vertebrate species respond to the reduction and removal of Ephedra individuals? If so to what extent? • Will vertebrate species relocate to areas where removed shrubs are replanted? If yes then which vertebrate species? • How will the complete removal of shrub individuals impact vertebrate species abundance and richness?
Hypothesis: • A higher vertebrate species abundance will be associated with an increasing density of Ephedra californica individuals both at the natural and artificially made plots because these plots provide positive benefits associated with these foundational shrub species.
Predictions: 1. Vertebrate species not previously present in areas absent of Ephedra will display higher association to these new artificially established areas. 2. Vertebrate species abundance will be higher in areas with a high Ephedra density both in natural and artificial plots. 3. Vertebrate species richness will be higher in previously established Ephedra plots. 4. Vertebrate species will prefer interacting with Ephedra californica individuals than in open areas. 5. Vertebrate species will have a decreased association with artificially open plots.
Proposed Methods: • Establish 10m radius “Natural plots” and “Artificial plots” • Artificial plots will either have shrub individuals removed or planted • Camera Trapping • 100m Transect • Focal Observations
Goals 1 Density-dependent Intraspecific Interactions in a Desert Shrub Species Field Season to start May 2021 Data analysis by September/October 2021 Second field season May/June 2022? 2 Intraspecific Association of Invasive Plant Species with a Foundational Shrub Species Field Season February/March 2022 and subsequent return May/June 2022 Data Analysis by July/August 2022 Second field Season February/March 2023? 3 Intraspecific Interaction of Vertebrates with Foundation Shrubs Species Field Season May/June 2023 Data Analysis begin by September/October 2023 Second Field Season 2024?