Asmeret Asefaw Berhe

University of California, Merced | UCM · Department of Life and Environmental Sciences

Soil organic matter (SOM) processes in dynamic landscapes are strongly influenced by soil erosion and sedimentation. We determined the contribution of physical isolation of organic matter (OM) inside aggregates, chemical interaction of OM with soil minerals, and molecular structure of SOM in controlling storage and persistence of SOM in different t...

In recent years, the role of soil erosion on terrestrial carbon sequestration had been the focus of a growing number of studies. However, relatively little attention has been paid so far to the role of erosion on the lateral distribution of soil nitrogen (N) and the role of geomorphic processes on soil N dynamics. Here, we present primary data on t...

In the next decades, the influence of wildfires in controlling the cycling and composition of soil organic matter (SOM) globally and in the Western US is expected to grow. While the impact of fires on bulk SOM has been extensively studied, the extent at which heating of soil affects the soluble component of SOM remains unclear. Here, we investigate...

Soil organic matter (SOM) often increases with the abundance of short-range-ordered iron (SRO Fe) mineral phases at local to global scales, implying a protective role for SRO Fe. However, less is known about how Fe phase composition and crystal order relate to SOM composition and turnover, which could be linked to redox alteration of Fe phases. We...

Landmines are one of the most environmentally destructive aftermaths of war facing the world today. The barely chronicled global landmine problem has transcended both humanitarian and sociological concerns to bring about environmental damage. Disruption of land's stability, pollution and loss of biodiversity constitute major ecological repercussion...

Purpose Rivers transfer eroded sediment with soil organic carbon (SOC) from terrestrial land to ocean basins, playing a key role in the global carbon cycle. During sediment delivery, the coarse particles can be preferentially settled and the fine particles may be transported to downstream depositional sinks. However, the size-specific quantificatio...

Hostile workplaces undermine efforts to make the ecological sciences more inclusive and welcoming. Survey responses by members of the Ecological Society of America (ESA) and subscribers to the ECOLOG‐L listserv provide a snapshot of a range of workplace experiences in ecology. The bottom line: identity matters. Although the majority of respondents...

Geosciences remain one of the least diverse fields. Efforts to diversify the discipline need to address the role of hostile and exclusionary work and learning environments. A workplace climate survey distributed to five professional organizations illustrates varied experiences of earth and space scientists over a 12‐month period (pre‐COVID). A majo...

Background Nitrogen (N) is an essential nutrient in soil that regulates plant growth, terrestrial sequestration of atmospheric carbon dioxide, and persistence of organic compounds. However, major knowledge gaps remain about how climate change may impact N accumulation and persistence, especially in deep soil and saprock (friable weakly weathered be...

Understanding potential response of forest carbon (C) and nutrient storage to warming is important for climate mitigation policies. Unfortunately, those responses are difficult to predict in seasonally dry forests, in part, because ecosystem processes are highly sensitive to both changes in temperature and precipitation. We investigated how warming...

In 2020, the combination of police killings of unarmed Black people, including George Floyd, Breonna Taylor, and Ahmaud Arbery, and the Coronavirus Disease 2019 (COVID-19) pandemic brought about public outrage over long-standing inequalities in society. The events of 2020 ignited global attention to systemic racism and racial inequalities, includin...

Interactions between soil organic matter and minerals largely govern the carbon sequestration capacity of soils. Yet, variations in the proportions of free light (unprotected) and mineral-associated (protected) carbon as soil develops in contrasting ecosystems are poorly constrained. Here, we studied 16 long-term chronosequences from six continents...

Pyrogenic organic carbon (PyC) is found in soils as a heterogeneous mixture of thermally altered plant residues that range in their susceptibility to losses via mineralization, leaching, and erosion. Leaching of PyC as DOC (DPyC) within the soil profile is likely influenced by the chemical composition of solid PyC and the dominant soil processes an...

Suspended sediment transport in montane headwaters is important to water quality and nutrient balances. However, predictions of sediment source and transport can be difficult, in part, because of a changing climate and increasing frequencies of disturbances. We used observations from ten headwater streams in Water Year (WY; starting on October 1st...

High-intensity wildfires alter the chemical composition of organic matter, which is expected to be distinctly different from low-intensity prescribed fires. Herein, we used pyrolysis gas chromatography/mass spectrometry (Py-GC/ MS), in conjunction with solid-state 13 C nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectros...

Livestock are the largest source of anthropogenic methane (CH4) emissions, and in intensive dairy systems, manure management can contribute half of livestock CH4. Recent policies such as California's short-lived climate pollutant reduction law (SB 1383) and the Global Methane Pledge call for cuts to livestock CH4 by 2030. However, investments in CH...

With climate and land use changes, it is becoming increasingly important to understand not only how much carbon is and will be stored in soils, but also how long this C will remain in soils. Estimates of C age can provide useful information about the timescales on which C will respond to such changes. It is generally accepted that the interaction o...

Montane meadows are highly productive ecosystems that contain high densities of soil carbon (C) and nitrogen (N). However, anthropogenic disturbances that lead to channel incision and disconnected floodplain hydrology have altered the C balance of many meadows, converting them from net C sinks to net sources of C to the atmosphere. Restoration effo...

A central question in carbon research is how stabilization mechanisms in soil change over time with soil development and how this is reflected in qualitative changes in soil organic matter (SOM). To address this matter, we assessed the influence of soil geochemistry on bulk SOM composition along a soil chronosequence in California, USA, spanning 3...

Soils are the foundation of life on land and represent one of the largest global carbon (C) reservoirs. Because of the vast amount of C that they store and the continuous fluxes of C with the atmosphere, soil can either be part of the solution or problem with respect to climate change. Using a bank account analogy, the size and significance of the...

The terrestrial ecosystem is dominated by landscapes with considerable topographic variability. Soil carbon (C) storage and stabilization in dynamic landscapes are controlled by: (i) the magnitude and nature of soil erosion process that laterally distribute topsoil; and (ii) variability of soil properties and microenvironmental conditions across a...

Subsoil carbon (C) stocks are a prime target for efforts to increase soil C storage for climate change mitigation. However, subsoil C dynamics are not well understood, especially in soils under long-term intensive agricultural management. We compared subsoil C storage and soil organic matter (SOM) composition in tomato–corn rotations after 25 years...

Elucidating climatic impacts on stream nutrient export and stoichiometry will improve the understanding of forest carbon (C) storage in a warmer world. We analyzed C, nitrogen (N), and phosphorus (P) cycles in four watersheds within a rain-snow transition site and another four within a higher-elevation, snow-dominated site, in California's mixed-co...

Not only do soils provide 98.7% of the calories consumed by humans, they also provide numerous other functions upon which planetary survivability closely depends. However, our continuously increasing focus on soils for biomass provision (food, fiber, and energy) through intensive agriculture is rapidly degrading soils and diminishing their capacity...

Soil carbon losses to the atmosphere, via soil heterotrophic respiration, are expected to increase in response to global warming, resulting in a positive carbon-climate feedback. Despite the well-known suite of abiotic and biotic factors controlling soil respiration, much less is known about how the magnitude of soil respiration responses to temper...

Geoscience remains one of the least diverse disciplines in Science, Technology, Engineering, Mathematics and Medicine (STEMM), with persistent underrepresentation of Black, Indigenous and other people of colour (BIPOC) and other minoritized groups, in the United States and other countries. The exclusion and limited recruitment, retention and succes...

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 e...

Understanding the transport of dissolved organic carbon (DOC) and nitrogen (N) as water flows through headwater basins is important for predicting downstream water quality. With increased recognition of climatic impact on nutrient transport, more studies are needed in headwater basins experiencing a Mediterranean-type climate, such as those of the...

Large uncertainty remains in the spatial distribution of deep soil organic carbon (OC) storage and how climate controls belowground OC. This research aims to quantify OC stocks, characterize soil OC age and chemical composition, and evaluate climatic impacts on OC storage from the soil surface through the deep critical zone to bedrock. These object...

Subsoil microbiomes play important roles in soil carbon and nutrient cycling, yet our understanding of the controls on subsoil microbial communities is limited. Here, we investigated the direct (mean annual temperature and precipitation) and indirect (soil chemistry) effects of climate on microbiome composition and extracellular enzyme activity thr...

A central question in carbon research is how stabilization mechanisms in soil change over time with soil development and how this is reflected in qualitative changes of soil organic matter (SOM). To address this matter, we assessed the influence of soil geochemistry on bulk SOM composition along a soil chronosequence in California, USA spanning 3 m...

The storage and cycling of soil organic carbon (SOC) are governed by multiple co-varying factors, including climate, plant productivity, edaphic properties, and disturbance history. Yet, it remains unclear which of these factors are the dominant predictors of observed SOC stocks, globally and within biomes, and how the role of these predictors vari...

Perennial bioenergy crops with deep (>1 m) rooting systems, such as switchgrass (Panicum virgatum L.), are hypothesized to increase carbon storage in deep soil. Deeply rooted plants may also affect soil hydrology by accessing deep soil water for transpiration, which can affect soil water content and infiltration in deep soil layers, thereby affecti...

Subsoil microbiomes play important roles in soil carbon and nutrient cycling, yet our understanding of the controls on microbial communities in the subsoil is limited. Here, we investigate the direct (mean annual temperature and precipitation) and indirect (soil chemistry) effects of climate on microbiome composition and activity throughout the soi...

Climate-smart land management practices that replace shallow-rooted annual crop systems with deeply-rooted perennial plants can contribute to soil carbon sequestration. However, deep soil carbon accrual may be influenced by active microbial biomass and their capacity to assimilate fresh carbon at depth. Incorporating active microbial biomass, dorma...

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, w...

Data collected from research networks present opportunities to test theories and develop models about factors responsible for the long-term persistence and vulnerability of soil organic matter (SOM). Synthesizing datasets collected by different research networks presents opportunities to expand the ecological gradients and scientific breadth of inf...

A bstract Climate-smart land management practices that replace shallow-rooted annual crop systems with deeply-rooted perennial plants can contribute to soil carbon sequestration. However, deep soil carbon accrual may be influenced by active microbial biomass and their capacity to assimilate fresh carbon at depth. Incorporating active microbial biom...

Recent compilations of global soil radiocarbon data suggest that current Earth System Models underestimate the mean age of soil carbon (C). The discrepancy between data-derived estimates and model calculations might be due to an inadequate representation of processes that control C persistence in soils-especially in understudied regions. Here, we i...

Subsurface carbon stocks are a prime target for efforts to increase soil carbon storage for climate change mitigation and improving soil health. However, subsurface carbon (C) dynamics are not well understood, especially in soils under long term intensive agricultural management. We compared subsurface C dynamics in tomato-corn rotations after 25 y...

Pyrogenic organic carbon (PyC) is a complex, heterogeneous class of thermally altered organic substrates, but its dynamics and how its behavior changes with soil depth remain poorly understood. We conducted a laboratory incubation study to investigate the interactive effects of pyrolysis temperature and soil depth on the turnover of PyC compared to...

Pyrogenic carbon (PyC) is produced by the incomplete combustion of vegetation during wildfires and is a major and persistent pool of the global carbon (C) cycle. However, its redistribution in the landscape after fires remains largely unknown. Therefore, we conducted rainfall simulation experiments on 0.25 m2 plots with two distinct Swiss forest so...

You can find the full paper in the following link: https://rdcu.be/cdwqD

Soil organic carbon (SOC) regulates terrestrial ecosystem functioning, provides diverse energy sources for soil microorganisms, governs soil structure, and regulates the availability of organically‐bound nutrients. Investigators in increasingly diverse disciplines recognize how quantifying SOC attributes can provide insight about ecological states...

Soil science is one of the least diverse fields within science, technology, engineering and mathematics (STEM). Because demographics of groups and institutions provide a window into the culture, climate, equity and inclusion of minoritized scholars, we discuss how lack of diversity continues to affect our science and the scientific community, and i...

Soil science is one of the least diverse subdisciplines within the agricultural, earth, and natural sciences. Representation within soil science does not currently reflect demographic trends in the U.S. We synthesize available data on the representation of historically marginalized groups in soil science in the U.S. and identify historical mechanis...

Pyrogenic carbon (PyC) is produced by the incomplete combustion of vegetation during wildfires and is a major and persistent pool of the global carbon (C) cycle. However, its redistribution in the landscape after fires remains largely unknown. Therefore, we conducted rainfall simulation experiments on 0.25-m 2 plots with two distinct Swiss forest s...

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 subtropical regions. We investigated soil properties and...

Soil carbon losses to the atmosphere, via soil heterotrophic respiration, are expected to increase in response to global warming, resulting in a positive carbon-climate feedback. Despite the well-known suite of abiotic and biotic factors controlling soil respiration, much less is known about how the magnitude of soil respiration responses to temper...

Demographics of the science, technology, engineering, and mathematics (STEM) workforce and student body in the US and Europe continue to show severe underrepresentation of Black, Indigenous, and people of color (BIPOC). Among the documented causes of the persistent lack of diversity in STEM are bias, discrimination, and harassment of members of und...

The lasting influence humans have on Earth’s critical zone—and how geologic forces have mediated those influences—is revealed in studies of soil and carbon migration.

The importance of soil age as an ecosystem driver across biomes remains largely unresolved. By combining a cross-biome global field survey, including data for 32 soil, plant, and microbial properties in 16 soil chronosequences, with a global meta-analysis, we show that soil age is a significant ecosystem driver, but only accounts for a relatively s...

The Science, Technology, Engineering, and Math (STEM) workforce has long suffered from a lack of diversity. In addition to unequal representation of all members of the public during recruitment, the prevalence of bias, discrimination, and harassment continue to affect success and retention of women and members of underserved communities in the STEM...

Data collected from research networks present opportunities to test theories and develop models about factors responsible for the long-term persistence and vulnerability of soil organic matter (SOM). Synthesizing datasets collected by different research networks presents opportunities to expand the ecological gradients and scientific breadth of inf...

The geosciences are one of the least diverse disciplines in the United States, despite the field's relevance to livelihoods and local and global economies. Bias, discrimination, and harassment present serious hurdles to diversifying the field. These behaviors persist due to historical structures of exclusion, severe power imbalances, unique challen...

Demographics of the Science, Technology, Engineering, and Mathematics (STEM) workforce and student body in the U.S. and Europe continue to show severe underrepresentation of Black, Latinx, and Indigenous people. Among the documented causes of the persistent lack of diversity in STEM include bias, discrimination, and harassment of members of underre...

Fires produce an aromatic particulate residue commonly referred to as pyrogenic carbon (PyC). Particulate PyC is low density, high porosity, and is predominantly deposited on the soil surface in post‐fire landscapes. These characteristics create a material that is prone to mobility, both vertically down the soil profile and laterally across the lan...

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 subtropical regions. He...

Ascertaining the fate of eroded OM is critical for our understanding of the role of soil erosion in global and local carbon cycles on earth's system. In this review, we compiled critical information on isotopes and molecular biomarker approaches that are widely applied to identify sources of eroded OM. We highlight the benefits and shortcomings of...

Soil stores over 2500 Pg carbon (C), with the majority of C stored in deep soil layers (> 30 cm). Soil C can be lost to the atmosphere when organic compounds are mineralized to carbon dioxide (CO2, via oxidative decay or respiration) and moved upward through the soil profile (via diffusion). Soil moisture status can influence the balance between re...

Modelling essential drivers of lateral redistribution of pyrogenic carbon under a controlled condition experiment

Chemical forms of P in airborne particulate matter (PM) are poorly known and do not correlate with solubility or extraction measurements commonly used to infer speciation. We used P X-ray absorption near-edge structure (XANES) and 31-P nuclear magnetic resonance (NMR) to determine P species in PM collected at four mountain sites (Colorado and Calif...

The role of soil biodiversity in regulating multiple ecosystem functions is poorly understood, limiting our ability to predict how soil biodiversity loss might affect human wellbeing and ecosystem sustainability. Here, combining a global observational study with an experimental microcosm study, we provide evidence that soil biodiversity (bacteria,...