Root soil sampling and competition in Mojave Desert shrubs

This thesis is a collection of experiments attempting to characterize the root extension architecture and competitive processes of several Mojave Desert perennial shrubs. The first experiment looks at the belowground interspecific and intraspecific competitive relationships between Larrea tridentata and Ambrosia dumosa, and the possibility of root territory defense. The results show that Larrea tridentata does not completely defend a root zone territory. The second experiment uses 32P as a radioisotope marker to characterize the horizontal root extension patterns of Larrea tridentata, Ambrosia dumosa, Lycium palladum, and Lycium andersonii. This study shows that each shrub utilizes a unique root architecture strategy. The final experiment uses the same methods to characterize vertical root extension patterns of Larrea tridentata, Ambrosia dumosa, and Lycium palladum under different irrigation types, and shows that there are significant differences among shrub species as well as irrigation type.