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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.
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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.
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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.
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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.
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Past Research Projects |