[Enviro-lunch] Today at NOON: Rose Abramoff

[Nate Bogie]

[image: clip_image002]

Hello Everyone,

Please join us for a talk this *TODAY 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*





*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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