Honors Theses (Environmental Studies Program)

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Browsing Honors Theses (Environmental Studies Program) by Author "Baach, Elizabeth"

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    Nitrogen Composition in Native and Invasive Plants in Relation to Ant Mounds in Serpentine Grasslands
    (2019-06) Baach, Elizabeth
    Serpentine grasslands are unique ecosystems that, due to their soil composition, prove to be areas where plant growth is difficult for most. With this particular soil composition having low levels of essential nutrients, and high levels of toxic minerals, plant endemism is particularly high in these ecosystems. However, there are processes in the ecosystem that make limiting nutrients, especially Nitrogen, more available, caused by ground dwelling organisms including ants. The particular organism of focus for this study is the harvester ant, Messor andrei, which creates mounds. These ant mounds are sites of nutrient upwelling, where nitrogen is made more available to plants growing on mound. Considering the ecosystem characteristics and processes occurring within, this project aimed to understand if there was a difference in nitrogen content in native and non-native plant species based on their on off mound condition. From this, two hypotheses were created that state there will be a significant difference between the different plant species based on their native/non-native status and functional group, and that there will be a significant difference between the on and off ant mound conditions. To test these, plant tissue samples were collected from seven species of different status and functional role from both on and off mounds at three different blocks in the Jasper Ridge Biological Preserve. The carbon to nitrogen ratios (C:N) were then calculated for these samples. Comparing the C:N of the different plant tissues there was found to be significant difference in C:N overall between the on and off ant mound condition. In addition there was found to be a significant difference between plant species with the lowest C:N being found in the native nitrogen-fixer and the non dominant forbs and a significantly higher C:N in the dominant forb and the non-native grasses.