Date of Award
Bachelor of Science
invasive species, nitrogen fixation, soil carbon, soil chemistry, carbon to nitrogen ratio
Invasive plant species can have dramatic and pervasive impacts on ecosystems, from species interactions, to resource availability, to biodiversity. One such invasive plant, the nitrogen-fixing black locust tree (Robinia pseudoacacia), has had significant effects on the soil chemistry in the globally rare inland pine barren ecosystem of the Albany Pine Bush. We have documented a loss of soil carbon following invasion by black locust, one that persists long after locusts are removed. We hypothesize that the nitrogen added through fixation by the black locust increases the carbon flux from soil to the atmosphere. Because decomposition rates are dependent on leaf litter quality and carbon:nitrogen ratio, addition of the nitrogen-rich locust leaves may accelerate the release of CO2. To test this, we added exotic locust or native scrub oak leaf litter to barren soil or locust soil in a factorial design and conducted a 16 week lab incubation. The carbon flux of the soil was monitored every 1-2 weeks using a LiCor 6400 portable photosynthesis analyzer. The invasion simulation treatment had a higher soil flux than the native simulation and treatments designed to control for the amount of carbon added and the original amount of carbon in the soil. These results indicate that adding nitrogen to the soil by nitrogen fixation accelerated the rate of decomposition and the release of CO2 from the soil. Future measurements will determine whether there is less stored soil carbon in the soil. If more CO2 is released to the atmosphere and stored soil carbon is lost because of species invasion, this may indicate another mechanism of carbon emissions and may provide more incentive for management of nitrogen fixing invasive species.
Sharry, Jacqueline, "Can an invasive species burn soil carbon? Black locust invasion and soil carbon in the Albany Pine Bush" (2018). Honors Theses. 1624.