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ISMC News 19 August 2022

Announcements + Featured Paper + Featured Soil Modeller
New Working Group: Machine Learning for Soil Modeling
ISMC will start up a working group focusing on Machine Learning Approaches and their applicability for soil modeling. If you are interested to participate, please send an email to:
Do you want your paper featured? Please share your recent paper if you want to be featured in the ISMC newsletter. With your contributions, we will select one paper to be featured in every newsletter. Below is the link to google form
Featured Paper
Soil hydrology in the Earth system
Soil hydrological processes (SHP) support ecosystems, modulate the impact of climate change on terrestrial systems and control feedback mechanisms between water, energy and biogeochemical cycles. However, land- use changes and extreme events are increasingly impacting these processes. In this Review, we describe SHP across scales and examine their links with soil properties, ecosystem processes and climate. Soil structure influences SHP such as infiltration, soil water redistribution and root water uptake on small scales. On local scales, SHP are driven by root water uptake, vegetation and groundwater dynamics. Regionally, SHP are impacted by extreme events such as droughts, floods, heatwaves and land- use change; however, antecedent and current SHP partially determine the broader effects of extreme events. Emerging technologies such as wireless and automated sensing, soil moisture observation through novel synthetic aperture radars satellites, big data analysis and machine learning approaches offer unique opportunities to advance soil hydrology. These advances, in tandem with the inclusion of more key soil types and properties in models, will be pivotal in predicting the role of SHP during global change.
Pedotransfer functions (PTF) are used to predict soil hydraulic properties from soil properties, which can then serve as a basis for estimating large-scale soil hydrological processes, such as water storage, infiltration, evapotranspiration, drainage and run-off. This process is demonstrated here for soils from Europe, based on the mean sand content (far left panel). The hydraulic conductivity (middle lower panel), K, indicates the ease with which water can flow in the soil: the value of this parameter will decrease rapidly with decreasing θ. Together with the gradient in hydraulic potential (∇(h + z), with h being determined by the water retention curve and z the vertical coordinate), K determines the flow of water in the soil, thereby affecting the processes of infiltration, redistribution, drainage, root water uptake and evaporation. The information contained in the water retention curve (middle upper panel) also provides the models with parameters that determine how much water a certain soil can hold in its pore system (the available volumetric water content (AWC), as shown in the far right panel) and how easy it is for the roots to take up this water (that is, how tightly the water is being held in the pores).
Featured Soil Modeller
Kathe Todd-Brown
I make computer models of how soil breaths and link up data to support these models. I’m an Assistant Professor at the University of Florida in the Environmental Engineering Sciences since 2019. I’ve held several post-doc positions including the Linus Pauling Distinguished Fellowship from the Pacific Northwest National Lab (a US Department of Energy research lab), as well as post-docs at the University of Oklahoma and Wilfrid Laurier University. My PhD is in Earth System Science from University of California Irvine (2013) and I hold a BS in Mathematics from Harvey Mudd College (2004).
- Please tell us briefly about yourself and your research interest.
I want to understand how carbon moves through soils and how that flux is affected by climate. I use mathematical models to tell stories about the processes that we think govern this dynamic and extrapolate what the implications of this might be in climates different from where we are now. These models are often data hungry and linking data from different sources in ways that are useful beyond a single project is another major focus of my research. I’m becoming more and more interested in building collaborative communities of researchers across background and disciplines.
On a more personal note. I live in a 5-adult communal household where we try to balance having too many meetings with collective decision making. I’m an avid cyclist and have biked most of the Pacific Coast of the US (would recommend if you are looking for a long holiday!). I love reading and try to spend some time with two cups of coffee and a couple of books every morning. I have recently expanded my love for classic science fiction and urban fantasy to include natural history, governance models, and philosophy.
-  How did you first become interested in soil modelling and learn about ISMC?
My first job out of my undergraduate was working at Oak Ridge National Lab implementing CENTURY, a classical soil carbon model, to help look at the effects of increasing plant lignin content on soil carbon stocks. I got very excited when I noticed that models of cancer cells fundamentally showed similar processes (cell colonies growing on media) but in a very different way. I thought that there might be a new development for soil carbon models to incorporate more features of these cancer models. This evolved into an interest in microbial explicit soil carbon models and has remained a fundamental direction to my research program over the past 15+ years.
As a graduate student I attended the first ISMC conference in Texas and was amazed that there were so many math-y soil folks! I remember being delighted to run into folks using non-homogenous meshes to simulate water flow, fractal indices for aggregate formation, and other folks using mathematics and models in different ways to tease appart soils. It is still really exciting to be surrounded by folks who use my kind of tools to look at the best system in the world.
-Can you share with us your current research focus?
My research focuses on process-based model development and data harmonization to support those models. Currently I’m working with several models that represent carbon age in a few different ways and how that interacts with the distribution of that carbon across depth or lability. I’m also working on workflows and vocabularies to knit together data from different research groups.
- Please tell us briefly how your research could contribute to ISMC Science Panel’s activities? Or the other way around, how do you wish ISMC science panels help/support your research activities?
I help chair two manuscript-driven working groups. The first is on Soil Carbon Potential where we are asking: what if both the machine learning models and process models are ‘right’, how can we reconcile their different distributions of soil carbon stocks? The second is just getting started and has a tentative title of “The Math of Soil Processes” where we will identify key mathematical representations use in soil water, energy, carbon, and nutrient models that we can then use down the road to try to tease apart what’s driving model differences. The power of ISMC is in its community, what are the kinds of questions that really leverage broad expertise and how can we effectively come together to answer those questions.
- What resources or skills would you recommend that early career members of ISMC should acquire? And how can ISMC help and support early career members in this regard?
How to run different kinds of meetings, structure long term collaborations, and develop community strategies. After several years of trying to figure out how to work a group conversation into a collaborative conversation, I think I might be getting closer to actually doing it. From the rhythm of different meeting agendas, to letting the group know when we are talking around a problem vs making a decision, to what to do when someone just wants to do something different. Navigating collaborations is hard, especially when you are trying to make inclusive equitable decisions as a collective.
ISMC could explicitly experiment with different collaborative styles and decision making models or run training workshops. I’ve found sociocracy or dynamic governance resources to be a unexpected source of inspiration in my own collaborations and lab group.
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