Russian Olive Invasion
A Case Study at Aztec Ruins National Monument
The purpose of this case study was to investigate the impact of ecological and historical factors on the Russian olive invasion in the Animas River Watershed in Aztec, New Mexico. Russian olive is a prominent invasive species found in many riparian corridors in the southwestern United States. Though its success can be inhibited by the flow fluctuations of unregulated rivers, the banks of the Animas River in and around Aztec are heavily infested with this species. Data collected from treated, untreated, and recently infested areas of land at Aztec Ruins National Monument showed significant differences in understory composition and retention of Russian olive seeds in the soil. Regression analyses of tree size vs. tree ring number allowed for the calculation of average tree age as well as variance in age distribution in untreated and agricultural areas. Ground water wells revealed that proximity to ground water is not a limiting factor in Russian olive growth rate. Examination of historical aerial photos provided some evidence that all areas were used for agricultural purposes and may contribute to why this and surrounding areas are uniquely affected by Russian olive. The complete removal of Russian olive is still a controversial topic in the southwest. Land managers must make decisions on a case by case basis, as the success of Russian olive establishment and the rate of succession into previously uninfected areas is likely linked to several biotic and abiotic variables.