Environmental Change Research Group - University of Oregon Geography

Paleoecology Lab - University of Oregon

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Current Research

	Paleoenvironmental reconstructions to understand historical range of variability in geomorphic and ecological processes The historical record of weather, climate, and landscape change, usually less than 100 years long, is too brief to constrain the types of conditions expected under climate change, even in the near future. The paleoecological record is an essential component to observe functional responses of natural systems to changes in climate much greater than recently experienced. We collaborate with earth scientists and taxonomic specialists to tap the range of information available in the Quaternary sediment record Reconstructing summer temperature in the Oregon High Cascades since deglaciation from chironomid insect remains, a method that uses the stenothermic temperature niches of this diverse assemblage of taxa. PhD research of Jamila Baig. Flood histories in dynamic alluvial river settings. Lakes that receive sediment pulses from adjacent rivers are a natural archive of the history of sediment flows in these rivers. We have interpreted these records in the context of the multiple factors that affect river history, sometimes revealing the magnitude of human-caused erosion or the occurrence of massive past floods and dynamic river channels, or the progression of deltas into lakes affecting the detrital mineral component of lakes.
	Aquatic system response to climate change and pollution history Lake sediments preserve records of both upland and aquatic ecosystems. In most lakes, sediment mass is mainly aquatic productivity. We assay the composition of limnic sediment to assess aquatic productivity history via diatom content, organic content and its stable isotopes and C:N ratio, detrital mineral content, etc. Coeur d'Alene Lake in north Idaho has been severely polluted by over a century of mining for metals such as Pb and Zn. We are updating past sediment studies of this lake to understand pre-mining ecosystem composition, mining impacts, and degree of recovery following remediation.
	Fire ecology of the western Oregon Cascade Range The massive fires of Labor Day weekend in 2020 changed the forest landscape of western Oregon, due to extremely high winds causing power-line ignitions and subsequent high fire severity. While the recent historical record provides some precedent for these fires the trajectory the landscape takes during succession (outside of plantation areas on most private land) is largely speculative, including the rapid return of high fire hazard as shrubs colonize these previously dense forested areas. With funding from Pacific Northwest Climate Adaptation Center and collaborators at OSU, PSU, and Cal State Humboldt, we are surveying burned areas for the fuel and plant diversity returning to these areas.
	Tropical peatland history Peatlands are massive carbon reservoirs that are at risk of loss; much has been lost already to development and agriculture. Peatlands also are a paleoenvironmental archive in the tropics where lake sediments are absent. With Indonesian collaborators I am interested in inferring what we can learn from the climate history of the tropics and the geomorphic and climate factors that have led to the formation of tropical forested peatlands.

Past Research Projects

	Forest responses to climate change Species will shift their ranges in response to future climate change but the mode and tempo of such changes is largely speculative. The duration of migrational lags depends upon dispersal rates dispersal distances (existence of refugial or disjunct populations) and colonization success. We address these biogeographical questions using a retrospective approach involving statistical treatment of pollen and macrofossil data and quantitative climate reconstruction using a variety of paleoclimate proxies from lake sediments. Specific projects under this theme include: The Clearwater Refugium of northern Idaho. Was this area of disjunctions and endemism in the "inland temperate rainforest" established by long-distance dispersal from coastal populations or in situ persistence in refugia? Funding from the National Science Foundation. Fire-mediated forest compositional change in infrequent-fire ecosystems on the Olympic Peninsula, Washington State.
	Forest disturbance regimes: a long-term perspective The historical range of variability of disturbance regimes is an important baseline to guide ecosystem management and to aid studies of ecosystem dynamics and species coexistence. For forest disturbances the observational record does not adequately characterize this variability over time spans relevant to tree life cycles. Paleoecological methods provide unique long-term data for reconstructing disturbance regimes. Precedent for fire in primary dipterocarp forests and forest peatlands of West Kalimantan, Indonesia, using radiocarbon dating of soil charcoal across several habitat types. Funding by the NSF. Climate Change, Fire History and Redwood Abundance across Space and Time. Methods focus on soil-charcoal dating in Humboldt County. Funding by the Bureau of Land Management. A research-coordination-network, the Novus RCN focuses on reconstructing ecosystem processes with respect to past disturbances. Led by Kendra McLauchlan at Kansas State University. Mountain pine beetle outbreaks linked to forest governance and climate change. Co-PI on an NSF Coupled Human and Natural Systems grant. Erosion history and variability: Sediment buried in Oregon Coast Range points to a frosty past. Fire frequency and severity of the late Holocene in the Siskiyou Mountains of southwest Oregon. Other projects and collaborations: On a wet British Columbia island, historical fires likely were human products Coastal Oregon aquatic responses to late Holocene climate change. Oregon Sea Grant co-PI with David Sutherland and Josh Roering.
	Tree-ring records of forest growth and disturbance dynamics A persistent challenge to the study of growth rates of tree species is attributing causal factors to long-term growth trends. Factors affecting growth rates vary from simple mechanisms such as stand dynamics and the natural growth trends of trees to insect outbreaks, soil nutrition, climate, and interactions of all these factors. Interactive effects of insects fire and climate on fuel loads and fire behavior in mixed conifer forest. Past funding from the Joint Fire Science Program. Detecting growth declines using novel dendroclimatic analytical approaches. Paper in CJFR.