Volcanic and hydrothermal processes produce disturbances by diverse mechanisms and ecological responses are varied. New and published pollen records from the Northern Rocky Mountains and Greater Yellowstone Ecosystem document the response of vegetation to three different types of volcanic and hydrothermal disturbances: (1) Pleistocene rhyolite lava flows in the central Greater Yellowstone Ecosystem created infertile landscapes that have shaped vegetation since rhyolite emplacement. Nutrient-poor, well-drained soils that developed on these flows supported low-diversity grassland during late-glacial time and Pinus contorta forests in interglacial periods. (2) Ash layers from eruptions of Pacific Northwest stratovolcanoes are commonly preserved in lake-sediment records in the Northern Rocky Mountains, and associated pollen records show enhancement of steppe vegetation for years to decades. (3) Local hydrothermal explosions have resulted in vegetation changes in hydrothermal areas that indicate tree mortality following deposition of explosion debris, followed by recovery in years. Thus, the type and duration of the vegetation response to volcanic and hydrothermal disturbances are highly contextual and governed by the antecedent plant communities and the magnitude and mechanism of the volcanic or hydrothermal disturbance. Vegetation resilience varied between disturbances, ranging from enduring ecosystem parameter changes to short-lived state changes in resilient plant communities.
Bibliographical noteFunding Information:
This work was supported by National Science Foundation (US), (NSF) Grant No. 1515353 to C. Whitlock and conducted under Yellowstone National Park Research Permits YELL-SCI-0009 and YELL-SCI-5054 . M.J. Power and A.D. Brunelle provided data and new samples from Foy Lake and Hoodoo Lake, respectively. We thank M. Baker, S.R. Brown, A. Carlson, D.J. Conley, S. Fritz, R.E. Gresswell, V. Iglesias, C. Linder, W.P. Nanavati, J. Mulder-Rosi, R. O'Grady, W.C. Shanks III, M. Shapley, R. Sohn, M. Weingart, and N. Zeibig-Kichas for their help with field work. Core analysis in the LacCore lab was facilitated by S. Brady, A. Stone, and M. Shapley. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
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- Hydrothermal explosions
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