Thu, Aug 18, 2022: 8:30 AM-8:45 AM
513E
Background/Question/MethodsThe rise in atmospheric CO2 caused by human emissions has a direct effect on plants due to the role of CO2 in photosynthesis. When CO2 levels rise, the photosynthetic process is stimulated, leading to an increased production of the carbohydrates that make up plant structures. The result is a trend towards increasing plant growth over time. To better understand this phenomenon, my question is, how is plant nutrient concentration impacted by CO2 levels rising over time? I hypothesize the increased plant growth from CO2 stimulated photosynthesis will lead to larger plants whose nitrogen concentration has been diluted by carbohydrates. I have designed an observational study that uses herbarium specimens from the last 140 years to obtain carbon and nitrogen concentration data. I destructively sampled a small amount of tissue from herbarium specimens of false indigo bush (Amorpha fruticosa) to be run through an elemental analyzer. I then obtained records from both ice core (pre-1969) and Mauna Loa (post-1969) CO2 data for the dates of specimen collections. Using this data, I compared plant nutrient concentrations to atmospheric CO2 concentrations.
Results/ConclusionsMy preliminary data has shown an increase in carbon concentration for all plant tissues in correlation with increasing atmospheric CO2. For nitrogen, the data suggest tissues involved in photosynthesis maintain their nitrogen concentration, while tissues primarily involved in other plant functions decline in nitrogen concentration as CO2 increases. More specifically, leaves of Amorpha fruticosa maintain a nitrogen concentration of around 2.7% while the flowers decline in nitrogen concentration at a rate of -0.026% per 1 ppm increase of CO2. While these results are not statistically significant, this limited preliminary dataset shows trends that support my hypothesis. Over the next few months, I will be able to collect much more extensive data from a broader geographic range, multiple plant species, and more plant tissue types. Given more data, the results will contribute to our understanding of how rising atmospheric CO2 may affect the nutritional quality of primary producers, and therefore the nutritional quality of higher trophic levels in the food chain.
Results/ConclusionsMy preliminary data has shown an increase in carbon concentration for all plant tissues in correlation with increasing atmospheric CO2. For nitrogen, the data suggest tissues involved in photosynthesis maintain their nitrogen concentration, while tissues primarily involved in other plant functions decline in nitrogen concentration as CO2 increases. More specifically, leaves of Amorpha fruticosa maintain a nitrogen concentration of around 2.7% while the flowers decline in nitrogen concentration at a rate of -0.026% per 1 ppm increase of CO2. While these results are not statistically significant, this limited preliminary dataset shows trends that support my hypothesis. Over the next few months, I will be able to collect much more extensive data from a broader geographic range, multiple plant species, and more plant tissue types. Given more data, the results will contribute to our understanding of how rising atmospheric CO2 may affect the nutritional quality of primary producers, and therefore the nutritional quality of higher trophic levels in the food chain.