Elaeagnus angustifolia (Russian Olive) is an invasive tree in many landscapes in western North America. In these landscapes, E. angustifolia invasion impacts native plant biodiversity and soil nitrogen levels. E. angustifolia grows within close proximity of other trees and is shade tolerant, therefore dense stands can form. E. angustifolia is able to fix nitrogen via a relationship with Frankia bacteria. However, little research has examined if these impacts of E. angustifolia invasion manifest in the mixed grass prairie of South Dakota. Our main objective was to assess the effect of E. angustifolia on plant communities and on soil nitrogen across the state. To meet this objective, two transects per tree were sampled. On each transect, plots were located under the canopy, at the canopy, 1.5 m and 5 m outside the canopy. At each plot, plant community structure was recorded in 0.5 m X 1 m quadrat and two soil cores were taken and composited. Soil samples were analyzed for total N. Following this, total nitrogen data was standardized to eliminate location affects. Soil and vegetation data were analyzed using ANOVA and Students-T tests.
Results/Conclusions
E. angustifolia has an effect on South Dakota’s plant communities and soil nitrogen. The results indicate that total nitrogen was significantly higher (p < 0.0001, F - Test = 46.7807, DF = 3) under the canopy of the E. angustifolia than outside the canopy. Also, underneath the canopy of the E. angustifolia there was less native plant richness than 5 m outside the canopy (p < 0.0447, F- Test = 2.7112, DF = 3). E. angustifolia effects the plants and soils of South Dakota by changing soil nitrogen levels and by having lower native richness in the area within 5 m of the tree. With the results in South Dakota being similar to other invaded regions it is likely many of the same affects, like lower native plant diversity and monotypic stands of E. angustifolia, are also found in South Dakota.