Deserts globally are subject to significant anthropogenic pressure. Global change, agriculture, energy projects, urbanization, and other ongoing drivers introduce stressors on the resilience of arid and semi-arid ecosystems. The capacity to buffer against these changes in the environment and biodiversity are important considerations for ecosystem functioning and applied decision-making frameworks. Foundation species analyses can be a solution to rapidly assess ecological function for a specific region. A foundation species is defined as species that exerts and promotes a positive set of processes for the network of resident species. Shrubs and cacti in California are both candidate representative functional grouping of plant species that benefit other plants and often animals within a region. Herein, we sampled the effect of shrubs and cacti on other plant species through systematic plant surveys on environmental gradients. The hypothesis tested was that the direct effects of dominant plants lead to facilitation of other plant species and thereby function as buffers to undue change. Colloquially, this can be termed a patronus charm effect within facilitation ecology because regardless of the form of the protector, the species provides a talisman against local loss of function. From the northern extent of the San Joaquin Desert to the southernmost extent, we documented consistent positive effects of dominant plants including cacti on other plant species. Richness was not always increased and environmental context was important but this research suggests that using landmark species within an impact desert region accelerate identification of fundamental positive dynamics locally irrespective of species identity.
Supporting code: https://github.com/cjlortie/shrub.contrasts