Cycling of Carbon and Nutrients

Soils are the foundation of terrestrial ecosystems. They provide critical services including supplying a substrate and the nutrients necessary for plant growth, retaining moisture from precipitation, filtering contaminants from percolating waters, and acting as a sink of carbon. Healthy soils are key to sustaining both human and ecosystem health. However, global- and regional-scale disturbances...

California is experiencing changes in precipitation and wildfire regimes. Longer, hotter fire seasons along with extremes in precipitation are expected to continue. Not only do these disturbances affect the productivity and resilience of ecosystems, they also directly impact human health and wellbeing. Soils hold an immense amount of our terrestrial carbon pool, and the microorganisms and minerals...

This project focuses on development of new interdisciplinary modeling capabilities of long-term time series that capture interactions among climate, land use, water use, and water availability. Research builds on expanding the USGS Forecasting Scenarios of Land Use (FORE-SCE) model and integrating with spatially explicit models from other disciplines. Interdisciplinary models will be co-developed...

Warming and thawing of permafrost soils in the Arctic is expected to become widespread over the coming decades. Permafrost thaw changes ecosystem structure and function, affects resource availability for wildlife and society, and decreases ground stability which affects human infrastructure. Since permafrost soils contain about half of the global soil carbon (C) pool, the magnitude of C losses...

Drought and fire are powerful disturbance agents that can trigger rapid and lasting changes in the forests of western North America. Over the last decade, increases in fire size and severity coincided with warming, drought, and earlier snowmelt, factors that projected climatic changes are likely to exacerbate. However, recent observations are brief relative to the lifespans of trees and include...

In the intermountain west, seasonal precipitation extremes, combined with population growth, are creating new challenges for the management of water resources, ecosystems, and geologic hazards. This research contributes a comprehensive long-term context for a deeper understanding of past hydrologic variability, including the magnitude and frequency of drought and flood extremes and ecosystem...

Estuaries and their surrounding wetlands are coastal transition zones where freshwater rivers meet tidal seawater. As sea levels rise, tidal forces move saltier water farther upstream, extending into freshwater wetland areas. Human changes to the surrounding landscape may amplify the effects of this tidal extension, impacting the resiliency and function of the upper estuarine wetlands. One visible...

This project integrates soil and ecosystem data to impute important soil properties for hydric soils and wetlands. The work hopes to answer the questions: How have historical changes in biogeochemical processes affected present-day and potential future interactions among land, water, and ecosystem resources? How can improved understanding of historical and present-day biogeochemical interactions...

Wetlands accumulate organic-rich sediment or peat stratigraphically, making them great archives of past environmental change. Wetlands also act as hydrologic buffers on the landscape and are important to global biogeochemical cycling. This project uses wetland archives from a range of environments to better understand how vegetation, hydrology, and hydroclimate has changed on decadal to multi...

While research into eutrophication has been a cornerstone of limnology for more than 100 years, only recently has it become a topic for the remote alpine lakes that are icons of protected national parks and wilderness areas. National park lakes in the western U.S. are threatened by global change, specifically air pollution, warming, and their interactions, and the problem is quickly worsening...

Land cover and land use (LC/LU), climate, and biogeochemical processing are significant drivers of water quality in streams and rivers over broad scales of space and time. As LC/LU and climate continue to change we can expect changes in water quality. This project seeks to understand the drivers of spatial and temporal variability in water quality across scales using new and existing data to...

Stream transport (lateral transfer) of carbon remains a poorly understood flux within the global carbon budget. This research addresses the need to refine our knowledge of both provenance and transformations of Dissolved Organic Matter (DOM) as it moves from mountains to sea. Interpreting shifts in carbon quality with increasing stream order, and how these patterns change with variation in...