[Enviro-lunch] Enviro-lunch (2/28, M): Dr. Kate Heckman from USDA

[Kyungjin Min]

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Hello all,



Next Monday (2/28) Dr. Kate Heckman from USDA will present her research
about carbon cycling in forests and grasslands. Please join us between 12-1
pm (pacific) via zoom.



https://ucmerced.zoom.us/j/175736103



Title: Climate and physicochemical controls on C cycling in forests and
grasslands of the conterminous USA



Abstract: Mechanisms of soil organic matter (SOM) stabilization regulate
turnover of SOM by making biodegradation energetically or physically
unfavorable. Though similar mechanisms of SOM stabilization are at work
across a wide diversity of soils, which soil conditions determine their
relative importance is just beginning to be elucidated. We utilized soil
cores from 35 National Ecological Observatory Network (NEON) experimental
plots, covering a wide diversity of ecosystem and soil types, to examine
the influence of physicochemical parameters on soil C abundance and
turnover, and their relative importance in comparison to climatic
variables. Soils from three depths at each site were density fractionated
into free/light, occluded and heavy fractions. Carbon and radiocarbon
abundance were examined among fractions and in the context of climatic
variables (e.g. temperature, precipitation, moisture balance) and soil
physiochemical variables (e.g. texture, pH, exchangeable cations, reactive
metals). The abundance and persistence (i.e. stability or mean residence
time) of C differed among fractions and with depth, as expected. Organic
matter abundance in surface horizons was more closely associated with
climate variability than that of subsurface horizons. Perhaps the most
interesting result of this study is the strong bifurcation in soil organic
matter cycling characteristics in arid versus humid environments.

Bio:
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·       BA in Biology & Environmental Science in 2004 from Drury University
in Springfield, Missouri.

·       PhD in Soil, Water & Environmental Science in 2010 from University
of Arizona in Tucson, Arizona.

·       2011-2015: Postdoc focused on the application of radiocarbon to
earth system sciences with an emphasis on temperate mineral soils. Employed
by the USDA Forest Service and stationed remotely as a Visiting Scientist
at Lawrence Livermore National Laboratory.

·       2015-current: Research Scientist for the USDA Forest Service,
Northern Research Station, in Houghton, Michigan. Directs a radiocarbon
research program for the Forest Service, mostly focused on assisting and
leading research associated with the application of radiocarbon analysis to
C cycle and climate change questions. Personal research assignment focused
on the biogeochemistry of mineral soils, specifically regarding mechanisms
of soil organic carbon stabilization.



Sincerely,

co-host: KJ Min & Manisha Dolui

Faculty coordinator: Asmeret Asefaw Berhe

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Spring 2022 Enviro-Lunch Schedule

*date*

*speaker*

*title*

*1/31*

Mariela Garcia Arrendondo
@ Umass-Amherst

Root-mediated weathering

*2/7*

Michael Philben
@ Hope College

Rethinking carbon and nitrogen isotope fractionation during soil organic
matter decomposition

*2/14*

Alyssa Griffin*
@ UC Davis

The role of coastal marine sediments in carbon cycling from local to global
scales

*2/21*

Presidents’ day



*2/28*

Katherine Heckman
@ USDA

Density fractionation and soil carbon stabilization

*3/7*

Bhavna Arora
@ LBNL

Reactive transport modeling

*3/14*

Darian Smercina
@ PNNL

Free N fixing under switchgrass (Linking microbial scale processes to
ecosystem function)

*3/21*

spring break



*3/28*

Meng Zhao
@ Stanford U

Plant-water relationship (evapotranspiration) modeling

*4/4*

Hannah Naughton
@ LBNL

Root vs. topographic generation of redox anomalies on a subalpine hillslope
and floodplain

*4/11*

Michael Rowley
@ LBNL

Ca-mediated soil organic carbon stabilization

*4/18*

Weiyu Li*
@ Stanford U

Data-driven hydraulic modeling

*4/25*

Daniel Zuleta

@ Smithsonian Institute

Tree mortality in tropical ecosystems

*5/2*

Genevieve Noyce
@ Smithsonian Institute

Greenhouse gas emissions from wetland with climate change
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