CALIFORNIA Since 2015, the lab has been part of a large multi-stakeholder group investigating the impacts of mountain meadow restoration on soil carbon stocks and fluxes funded by the California Department of Fish and Wildlife. We have been measuring carbon fluxes prior to restoration, we are assessing the long-term change in carbon stocks and carbon chemistry in the first two decades after restoration, and we have been identifying C stocks and their associations with different vegetation communities from the meadow to the forest edge. We are also exploring iron-carbon interactions and their implications for meadow carbon stability, the temperature sensitivity of meadow soil respiration, and we are using remotely sensed products and a large field dataset to estimate long-term change in meadow carbon fluxes. This work is being led by Cody Reed (PhD) and Ryan Kasten (MS). We are about to embark on two new and related funded projects from the state of California to investigate the effects of meadow restoration on carbon stocks during two new meadow projects
NEVADA – new project! Questions: How do carbon stocks change as a result of decades of grazing pressure change and beaver activity in Nevada meadows? Does meadow restoration change the sign of the net soil carbon flux like it does in the Sierra? How do shifts in meadow carbon relate to changes in vegetation and sagegrouse habitat? This project was funded in 2018 by USDA-Hatch. We’ll be addressing this work in Maggie Creek (northeast Nevada) and Haypress meadows in central CA. Brian Morra is the PhD student leading this project.
NUTRIENTS – new project! Questions: where do meadow plants get the nitrogen to meet the demands of primary production? This project, funded by the USDA AFRI program, will use low and high productivity areas plus a long-term fertilization experiment in a meadow at the Sagehen Creek Experimental Station to identify how meadow plants can be so productive. Our previous work demonstrates that rates of gross primary productivity in Sierra meadows can be as high as a tropical rainforest. And yet there are few N fixing organisms, there are low rates of N losses (gaseous or hydrologic) from these ecosystems… do meadow plants mine organic N? This project will be led by Cody Reed as she starts her postdoc in the lab.
Rates and mechanisms of soil methane dynamics in arid environments
Methane is the second-most important greenhouse gas contributing to climate change. Anaerobic microbial activity in wet soils produces methane, but specialized microbes in well-drained soils actually consume it. Though arid and semiarid soils cover one-third of the Earth's land surface, we know very little about the mechanisms that control methane uptake in very dry soils. The goal of this research is to assess rates of methane uptake in dry soils, and identify the mechanisms that control methane uptake. We hope to peel back the surface of a very dark hole in aridland biogeochemistry by combining field and laboratory studies to assess methane fluxes in the Great Basin. This work was funded by USDA-Hatch in 2015 and is being led by Cordi Craig (MS student)
Tropical biogeochemistry: nitrogen fixation, secondary succession, and global change
Is this general enough? I'm fascinated by plant-soil feedbacks in tropical forest, and especially in secondary forest, which is becoming a major fraction of remaining tropical forest. Secondary forest isn't second-rate: in fact, it could be critical to the biogeochemical functioning of the remaining forested regions in the tropics. Understanding how these forests function and change is going to be a major concern for many developing countries in the years to come, as land use change intensifies.
Effects of forest management on soil carbon and nutrient stocks and fluxes
This is a new project in 2019! In an effort to reduce fire hazard, CalFire and the state of California are implementing large scale forest thinning efforts using a variety of techniques. This work will quantify the aboveground impacts of forest thinning on carbon stocks, project those changes out over decades, and then quantify the belowground carbon stocks and the effect forest management has on those. We will explore mechanisms of carbon change, such as the priming effect, and explore C-nutrient links. Finally, we will use the RHESSys model to project aboveground and belowground C change through time among many different treatment scenarios for a given forest unit. This work will be led by two incoming graduate students.
Plant-soil feedbacks and restoration of old fields in Nevada
Large swathes of low elevation land in Nevada has been used for alfalfa production since the turn of the 20th century. In some regions, this land is being taken out of production. Effectively reverting these former alfalfa fields to native vegetation may require understanding the dramatic changes a century of alfalfa production has had on the soil. In this research, we are attempting to identify the soil characteristics that are most likely to be associated with restoration success and identify what the effect of restoration is on the resistance and resilience of soil processes. This work was led by Stephanie Freund and Sarrah Dunham-Cheatham
Effect of piñon-juniper fuels management on vegetation and soils in the Great Basin
In the central Great Basin, an effort to improve sagebrush habitat has required the harvest of piñon and juniper trees. Typically, the tree material is either masticated or lopped and scattered on site. We seek to quantify the effects that these slash treatments have on the soil microenvironment and the success of existing and emergent vegetation. This work is funded by the Bureau of Land Managment and is being led by Jordin Jacobs (MS student).