[Enviro-lunch] This THURSDAY 4/12: Rose Abramoff
Jing Yan
jyan235 at ucmerced.edu
Mon Apr 9 13:31:55 PDT 2018
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Hello Everyone,
Please join us for a talk this THURSDAY 4/12 by Rose Abramoff, 12-1pm in Room SE2-302.
A tale of four models, or Spatial gradients can hide the temperature sensitivity of soil organic matter to warming
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Abstract:
Modelers and empiricists often use spatial data to characterize soil organic carbon (SOC) stock responses to warming and to test climate predictions in the absence of long-term warming measurements. This "space-for-time" approach assumes that decadal-scale SOC stock warming responses are similar to the steady-state relationship between temperature and SOC stocks at spatially distributed sites; however, this assumption has never been tested for soil models. Here, we use a theoretical soil model to demonstrate that while multiple temperature response assumptions can make identical steady-state SOC stock predictions, the transient SOC stock responses to warming differ greatly.
We developed four variants of the Reaction-network-based model of Soil Organic Matter and microbes (ReSOM) using measured SOC stocks from a large latitudinal transect. Each model embedded different assumptions about the temperature sensitivity of microbial activity and mineral sorption. Assuming that microbes were acclimated to the mean annual temperature at each site, model variants made identical SOC stock predictions at steady state but predicted transient warming responses that differed in sign and magnitude. We compared SOC stock predictions at steady state and with warming to two large observational datasets (one spatial gradient at assumed steady state and one meta-analysis of warming experiments). The two model variants best matching observations assumed either that (a) microbial and mineral activity is not temperature sensitive or that (b) microbial activity is temperature sensitive and adsorption to minerals is favored at higher temperatures. We evaluated the four model variants and found that direct temperature effects on mineral-associated C are not needed to predict a large (-0.3 to +0.1 kg C m-2 °C-1 yr-1) SOC stock warming response. When only microbial activity is temperature sensitive, mineral-associated C can still be lost due to dynamic interactions between mineral surfaces and aqueous C, implying that mineral-associated C is vulnerable to warming.
Bio:
Rose Abramoff is interested in the effect of global change on biogeochemical cycling in plants and soil. She did her doctorate research at Boston University with Adrien Finzi, studying root growth and turnover at the Harvard Forest Long Term Ecological Research site using a combination of field, lab, and modeling work. As a postdoc at Lawrence Berkeley National Laboratory, Rose primarily works with theoretical models of soil organic matter (SOM) decomposition, site-level models (using field data from Margaret Torn's deep warming experiment at Blodgett Experimental Forest in the Sierra Nevada foothills), and Earth System models. She is most interested in mechanisms that determine the rate of SOM turnover, such as sorption of SOM to mineral surfaces, aggregate formation, and microbial activity. In her spare time, Rose likes to go to the theater, play with her rare earth magnets, and jog very slowly.
When: Apr., 12 Thursday, 12pm - 1pm
Where: SE2-302
Coffee and treats will be provided, please bring your own mugs.
We look forward to seeing you,
Nate & Jing
Organizers for Spring 2018: Nate Bogie and Jing Yan
Faculty coordinator: Asmeret Asefaw Berhe
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