Sophie Franziska von Fromm

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von Fromm

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Sophie Franziska

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0000-0002-1820-1455

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Publications 1 - 10 of 15

An open-source database for the synthesis of soil radiocarbon data: International Soil Radiocarbon Database (ISRaD) version 1.0
Lawrence, Corey R.; Beem-Miller, Jeffrey; Hoyt, Alison M.; et al. (2020)
Earth System Science Data
Radiocarbon is a critical constraint on our estimates of the timescales of soil carbon cycling that can aid in identifying mechanisms of carbon stabilization and destabilization and improve the forecast of soil carbon response to management or environmental change. Despite the wealth of soil radiocarbon data that have been reported over the past 75 years, the ability to apply these data to global-scale questions is limited by our capacity to synthesize and compare measurements generated using a variety of methods. Here, we present the International Soil Radiocarbon Database (ISRaD; http://soilradiocarbon.org, last access: 16 December 2019), an open-source archive of soil data that include reported measurements from bulk soils, distinct soil carbon pools isolated in the laboratory by a variety of soil fractionation methods, samples of soil gas or water collected interstitially from within an intact soil profile, CO2 gas isolated from laboratory soil incubations, and fluxes collected in situ from a soil profile. The core of ISRaD is a relational database structured around individual datasets (entries) and organized hierarchically to report soil radiocarbon data, measured at different physical and temporal scales as well as other soil or environmental properties that may also be measured and may assist with interpretation and context. Anyone may contribute their own data to the database by entering it into the ISRaD template and subjecting it to quality assurance protocols. ISRaD can be accessed through (1) a web-based interface, (2) an R package (ISRaD), or (3) direct access to code and data through the GitHub repository, which hosts both code and data. The design of ISRaD allows for participants to become directly involved in the management, design, and application of ISRaD data. The synthesized dataset is available in two forms: the original data as reported by the authors of the datasets and an enhanced dataset that includes ancillary geospatial data calculated within the ISRaD framework. ISRaD also provides data management tools in the ISRaD-R package that provide a starting point for data analysis; as an open-source project, the broader soil community is invited and encouraged to add data, tools, and ideas for improvement. As a whole, ISRaD provides resources to aid our evaluation of soil dynamics across a range of spatial and temporal scales.
Reviews and syntheses: The promise of big diverse soil data, moving current practices towards future potential
Todd-Brown, Katherine E.O.; Abramoff, Rose Z.; Beem-Miller, Jeffrey; et al. (2022)
Biogeosciences
In the age of big data, soil data are more available and richer than ever, but-outside of a few large soil survey resources-they remain largely unusable for informing soil management and understanding Earth system processes beyond the original study. Data science has promised a fully reusable research pipeline where data from past studies are used to contextualize new findings and reanalyzed for new insight. Yet synthesis projects encounter challenges at all steps of the data reuse pipeline, including unavailable data, labor-intensive transcription of datasets, incomplete metadata, and a lack of communication between collaborators. Here, using insights from a diversity of soil, data, and climate scientists, we summarize current practices in soil data synthesis across all stages of database creation: availability, input, harmonization, curation, and publication. We then suggest new soil-focused semantic tools to improve existing data pipelines, such as ontologies, vocabulary lists, and community practices. Our goal is to provide the soil data community with an overview of current practices in soil data and where we need to go to fully leverage big data to solve soil problems in the next century.
Continental-scale controls on soil organic carbon across sub-Saharan Africa
von Fromm, Sophie Franziska; Hoyt, Alison M.; Acquah, Gifty E.; et al. (2020)
Soil Discussions
Earlier studies have demonstrated that soil texture and geochemistry strongly affect soil organic carbon (SOC) content. However, those findings primarily rely on data from temperate regions with soil mineralogy, weathering status and climatic conditions that generally differ from tropical and sub-tropical regions. We investigated soil properties and climate variables influencing SOC concentrations across sub-Saharan Africa. A total of 1,601 samples were analyzed, collected from two depths (0–20 cm and 20–50 cm) at 45 sentinel sites from 17 countries as part of the Africa Soil Information Service (AfSIS) project. The dataset spans climatic conditions from arid to humid and includes soils with a wide range of pHH20 values, weathering status, soil texture, exchangeable cations, extractable metals and a variety of important land cover types. The most important SOC predictors were identified by linear mixed effects models, regression trees and random forest models. Our results indicate that SOC is primarily controlled by aridity index (PET/MAP), exchangeable calcium (Caex) and oxalate-extractable aluminum (Alox); this was found across both depth intervals. Oxalate-extractable iron (Feox) emerged as the most important predictor for both depth intervals in the regression tree and random forest analyses. However, its influence on SOC concentrations was strong only below Feox concentrations of 0.25 wt %. This suggests that Feox can act as a pedogenic threshold – even on a continental scale. Across model-ling approaches, clay and fine silt content (< 8 µm) and land cover were not significant SOC pre-dictors, in contrast to common assumptions. Our findings indicate that the key controlling factors of SOC across sub-Saharan Africa are similar to what has been reported for temperate regions – except for soil texture and vegetation cover. However, the strength and importance of the controlling factors vary across the environmental gradient we studied.
Beyond bulk: Density fractions explain heterogeneity in global soil carbon abundance and persistence
Heckman, Katherine; Hicks Pries, Caitlin E.; Lawrence, Corey R.; et al. (2021)
Global Change Biology
Understanding the controls on the amount and persistence of soil organic carbon (C) is essential for predicting its sensitivity to global change. The response may depend on whether C is unprotected, isolated within aggregates, or protected from decomposition by mineral associations. Here, we present a global synthesis of the relative influence of environmental factors on soil organic C partitioning among pools, abundance in each pool (mg C g−1 soil), and persistence (as approximated by radiocarbon abundance) in relatively unprotected particulate and protected mineral-bound pools. We show that C within particulate and mineral-associated pools consistently differed from one another in degree of persistence and relationship to environmental factors. Soil depth was the best predictor of C abundance and persistence, though it accounted for more variance in persistence. Persistence of all C pools decreased with increasing mean annual temperature (MAT) throughout the soil profile, whereas persistence increased with increasing wetness index (MAP/PET) in subsurface soils (30–176 cm). The relationship of C abundance (mg C g−1 soil) to climate varied among pools and with depth. Mineral-associated C in surface soils (<30 cm) increased more strongly with increasing wetness index than the free particulate C, but both pools showed attenuated responses to the wetness index at depth. Overall, these relationships suggest a strong influence of climate on soil C properties, and a potential loss of soil C from protected pools in areas with decreasing wetness. Relative persistence and abundance of C pools varied significantly among land cover types and soil parent material lithologies. This variability in each pool's relationship to environmental factors suggests that not all soil organic C is equally vulnerable to global change. Therefore, projections of future soil organic C based on patterns and responses of bulk soil organic C may be misleading. © 2021 John Wiley & Sons Ltd.
Controls on timescales of soil organic carbon persistence across sub-Saharan Africa
von Fromm, Sophie Franziska; Doetterl, Sebastian; Butler, Benjamin M.; et al. (2024)
Global Change Biology
Given the importance of soil for the global carbon cycle, it is essential to understand not only how much carbon soil stores but also how long this carbon persists. Previous studies have shown that the amount and age of soil carbon are strongly affected by the interaction of climate, vegetation, and mineralogy. However, these findings are primarily based on studies from temperate regions and from fine-scale studies, leaving large knowledge gaps for soils from understudied regions such as sub-Saharan Africa. In addition, there is a lack of data to validate modeled soil C dynamics at broad scales. Here, we present insights into organic carbon cycling, based on a new broad-scale radiocarbon and mineral dataset for sub-Saharan Africa. We found that in moderately weathered soils in seasonal climate zones with poorly crystalline and reactive clay minerals, organic carbon persists longer on average (topsoil: 201 ± 130 years; subsoil: 645 ± 385 years) than in highly weathered soils in humid regions (topsoil: 140 ± 46 years; subsoil: 454 ± 247 years) with less reactive minerals. Soils in arid climate zones (topsoil: 396 ± 339 years; subsoil: 963 ± 669 years) store organic carbon for periods more similar to those in seasonal climate zones, likely reflecting climatic constraints on weathering, carbon inputs and microbial decomposition. These insights into the timescales of organic carbon persistence in soils of sub-Saharan Africa suggest that a process-oriented grouping of soils based on pedo-climatic conditions may be useful to improve predictions of soil responses to climate change at broader scales.
Large-scale controls of soil organic carbon in (sub)tropical soils
von Fromm, Sophie Franziska; Hoyt, Alison M.; Asefaw Berhe, Asmeret; et al. (2020)
EGUsphere
Soil organic carbon (SOC) is a key component of terrestrial ecosystems. Experimental studies have shown that soil texture and geochemistry have a strong effect on carbon stocks. However, those findings primarily rely on data from temperate regions or use model approaches that are often based on limited data from tropical and sub-tropical regions. Here, we evaluate the controls on soil carbon stocks in Africa, using a dataset of 1,580 samples. These were collected across Sub-Saharan Africa (SSA) within the framework of the Africa Soil Information Service (AfSIS) project, which was built on the well-established Land Degradation Surveillance Framework (LDSF). Samples were taken from two depths (0–20 cm and 20–50 cm) at 46 LDSF sites that were stratified according to Koeppen-Geiger climate zones. The different pH-values, clay content, exchangeable cations and extractable elements across various soils of the different climatic zones (i.e. from arid to humid (sub)tropical) allow us to identify different soil and climate parameters that best explain SOC variance across SSA. We tested if these SOC predictors differed across climatological conditions, using the ratio of potential evapotranspiration (PET) to mean annual precipitation (MAP) as indicator. For water-limited regions (PET/MAP > 1), the best predictors were climatic variables, likely because of their effect on the quantity of carbon inputs. Geochemistry dominated SOC storage in energy-limited systems (PET/MAP < 1), reflecting its effect on carbon protection. On a continental scale, climate (e.g. PET) is key to predicting SOC content in topsoil, whereas geochemistry, particularly iron-oxyhydroxides and aluminum-oxides, is more important in subsoil. Clay content had little influence on SOC at both depths. These findings contribute to an improved understanding of the controls on SOC stocks in tropical and sub-tropical regions.
Continental-scale controls on soil organic carbon across sub-Saharan Africa
von Fromm, Sophie Franziska; Hoyt, Alison M.; Lange, Markus; et al. (2021)
Soil
Soil organic carbon (SOC) stabilization and destabilization has been studied intensively. Yet, the factors which control SOC content across scales remain unclear. Earlier studies demonstrated that soil texture and geochemistry strongly affect SOC content. However, those findings primarily rely on data from temperate regions where soil mineralogy, weathering status and climatic conditions generally differ from tropical and subtropical regions. We investigated soil properties and climate variables influencing SOC concentrations across sub-Saharan Africa. A total of 1601 samples were analyzed, collected from two depths (0-20 and 20-50gcm) from 17 countries as part of the Africa Soil Information Service project (AfSIS). The data set spans arid to humid climates and includes soils with a wide range of pH values, weathering status, soil texture, exchangeable cations, extractable metals and land cover types. The most important SOC predictors were identified by linear mixed-effects models, regression trees and random forest models. Our results indicate that geochemical properties, mainly oxalate-extractable metals (Al and Fe) and exchangeable Ca, are equally important compared to climatic variables (mean annual temperature and aridity index). Together, they explain approximately two-thirds of SOC variation across sub-Saharan Africa. Oxalate-extractable metals were most important in wet regions with acidic and highly weathered soils, whereas exchangeable Ca was more important in alkaline and less weathered soils in drier regions. In contrast, land cover and soil texture were not significant SOC predictors on this large scale. Our findings indicate that key factors controlling SOC across sub-Saharan Africa are broadly similar to those in temperate regions, despite differences in soil development history.
Reviews and syntheses: The promise of big soil data, moving current practices towards future potential
Todd-Brown, Katherine E. O.; Abramoff, Rose Z.; Beem-Miller, Jeffrey; et al. (2021)
Biogeosciences Discussions
In the age of big data, soil data are more available than ever, but -outside of a few large soil survey resources- remain largely unusable for informing soil management and understanding Earth system processes outside of the original study. Data science has promised a fully reusable research pipeline where data from past studies are used to contextualize new findings and reanalyzed for global relevance. Yet synthesis projects encounter challenges at all steps of the data reuse pipeline, including unavailable data, labor-intensive transcription of datasets, incomplete metadata, and a lack of communication between collaborators. Here, using insights from a diversity of soil, data and climate scientists, we summarize current practices in soil data synthesis across all stages of database creation: data discovery, input, harmonization, curation, and publication. We then suggest new soil-focused semantic tools to improve existing data pipelines, such as ontologies, vocabulary lists, and community practices. Our goal is to provide the soil data community with an overview of current practices in soil data and where we need to go to fully leverage big data to solve soil problems in the next century.
Understanding soil organic carbon dynamics at larger scales
Doetterl, Sebastian; Abramoff, Rose; Cornelis, Jean-Thomas; et al. (2023)
Burleigh Dodds Series in Agricultural Science ~ Understanding and fostering soil carbon sequestration
Understanding soil organic carbon abundance and persistence at continental to global scales
von Fromm, Sophie Franziska (2023)
Given the importance of soils in the global carbon (C) cycle, it is important to understand not only how much C soils store, but also how long this C persists. Climate change is rapidly altering the C cycle, yet information on the drivers of soil organic carbon (SOC) abundance (C storage) and persistence (retention of stored C) across continental regions and at the global scale is still limited. Previous studies have shown that the amount and age of soil SOC are strongly influenced by the interaction of climate, vegetation and mineralogy. However, these findings are based primarily on studies from temperate regions and on fine-scale studies, leaving large knowledge gaps for soils from understudied continental regions such as sub-Saharan Africa. In addition, there is a lack of data to validate modeled SOC dynamics at large scales. This thesis presents insights into large-scale SOC cycling based on a (sub-)continental radiocarbon and mineral dataset for sub-Saharan Africa and a synthesized global radiocarbon dataset. The key drivers of SOC abundance and persistence found at the continental scale confirm results of small-scale studies and work from other regions – this has not previously been demonstrated across the wide range of soil types found in sub-Saharan Africa. To explain the spatial variation in SOC abundance (chapter 2), oxalate-extractable metals (Alox + ½ Feox) were most important in humid regions with acidic and highly weathered soils, whereas exchangeable Ca dominated in alkaline and less weathered soils in drier regions. In contrast, land cover and soil texture were not significant predictors of SOC abundance at this large scale. The analyses of SOC persistence (chapter 3) showed that SOC abundance and persistence are explained by similar controls. However, they probably represent different mechanisms. Moderately weathered soils in seasonal climates with poorly-crystalline (Alox + ½ Feox) and reactive 2:1 clay minerals result in more persistent organic C than highly weathered soils in humid regions with less reactive minerals. Soils in arid climates store organic C for periods similar to those in seasonal climates, but likely reflect climatic constraints on soil weathering, C inputs, and microbial decomposition. This work further shows that patterns of SOC abundance and persistence are related to common soil development stages, which can be grouped into broad pedo-climatic zones at the (sub-)continental scale for sub-Saharan Africa. To test whether such grouping holds at the global scale, synthesized soil radiocarbon data from the International Soil Radiocarbon Database (ISRaD) were used (chapter 4). Applying both statistical and depth-resolved compartment models, it could be shown that the controls on SOC abundance and persistence differ greatly between the major pedo-climatic regions at the global scale. For example, high SOC abundance associated with longer timescales of C persistence may be due to climatic constraints on soils (e.g., in tundra/polar regions) or high mineral adsorption (e.g., in soils dominated by reactive minerals). In contrast, lower SOC abundance may be associated with lower SOC persistence (e.g., in highly weathered tropical soils) or with higher SOC persistence (e.g., in drier and less productive regions). The large variation in SOC abundance and persistence is thus causally related to variation in the strength and combination of factors constraining plant C input, microbial decomposition, vertical C transport, and mineral SOC stabilization potential. This thesis identified unique controls on SOC abundance and persistence for different pedo-climatic zones at the (sub-)continental to global scale. This has implications for our understanding of large-scale SOC dynamics in general and for modeling efforts. The unique controls on SOC abundance and persistence in the identified pedo-climatic regions limit the ability to extrapolate outside of these regions and should be used to constrain statistical models for global soil mapping products and for benchmarking global C models. Furthermore, while the individual importance of the identified controls on SOC abundance and persistence has been demonstrated previously, understanding the varying importance of these controls on SOC dynamics at larger scales may allow us to better predict how soils will respond to climate change. Current soil conditions, which are important in controlling SOC abundance and persistence at larger scales, may largely determine how soils respond to climate change.

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