Effects of Volcanogenic SO2 on Leaf Stomata and Isotopic Composition of Vegetation on Hawaii

Commonwealth University Of Pennsylvania, Bloomsburg PA

Investigators

Abstract

It is the purpose of the proposed research to examine in detail the effects on vegetation of SO2 released by the ongoing eruption of Kilauea volcano on Hawaii. Specifically, this project will compare the stomatal index (a ratio derived from the number of stomata compared to the number of epithelial cells) and the carbon isotope composition of leaves on plants growing in the path of the volcanic plume with plants growing in other areas of the island. This research will serve as a test of the hypothesis that loading of the atmosphere by SO2 emitted during basaltic volcanic eruptions constitutes a significant disturbance of the atmosphere that causes changes in the number of leaf stomata and in the fractionation of carbon by leaves during photosynthesis. This hypothesis challenges the current paradigm that all variations in stomatal indices can be explained by variations in atmospheric CO2 levels. Statistically significant results of this one-year study will permit design of a rigorous multi-year experimental study to quantify the effects of SO2 exposure. The broader implications of this research relate to mechanisms of biotic extinction. Large eruptions of flood basalts have been linked to several episodes of mass extinction. This project will help to determine if volcanogenic SO2 leaves an identifiable record on vegetation that may be identified from the fossil record. Additionally, this proposal creates research experiences for undergraduate students who will be involved directly in the collection and evaluation of the data.