There has been an increase in the frequency and size of wildfires in deserts of North America due to invasive annual grasses. Rodent consumers can have strong top down effects on regulating these invasions. However, there is much that still needs to be understood about how fire and consumers interact in the outcome of invasions and in the establishment of invasive grass fire cycles. We researched the interaction between fire and consumers on the establishment of invasive plants and their competitive interactions. The five-year study used a full factorial design in five replicated blocks to test the effects of fire and rodent exclusion on the invasive and native plant communities in the Mojave Desert. Measurements of density, biomass, and plant cover were taken during April and May for five years.
Results/Conclusions
In the burned plots, Bromus rubens was the first prominent invasive grass, later followed by Schismus arabicus. Once both grasses were established in the plots, niche differentiation was apparent. Bromus rubens was more abundant in the fertile islands created by shrubs whereas Schismus arabicus was more abundant and frequent in the inter-shrub spaces. The diversity and abundance of native plants was low in the burned plots. Invasion was stronger in plots where rodents were excluded, and the rodent effect was larger for Bromus rubens than for Schismus arabicus.