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Results for “Precipitation legacy effects”

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3 recordsLinked to original sources
PubMed2026

Reduced legacy precipitation decreases microbial community growth efficiency and alters soil organic carbon in a California grassland.

BACKGROUND: Changes in global patterns can leave a lasting legacy in semiarid grasslands by reshaping microbial growth dynamics and carbon cycling during the first wet-up in the autumn-a period known for intense microbial activity and significant carbon emissions. To study the lasting impacts of decreased winter rain, we implemented two precipitation regimes (100% vs. 50% mean annual precipitation) in California Mediterranean-climate grassland field plots. After the dry season, soils were rewetted in the laboratory with H218O and sampled at 0 h, 3 h, 24 h, 48 h, 72 h, and 168 h post rewet. We quantified CO2 efflux, measured microbial growth and mortality via quantitative 18O stable isotope probing and 16S rRNA gene amplicon sequencing, and characterized the soil organic carbon chemical composition, metagenomes, and metatranscriptomes. RESULTS: We found that reduced winter precipitation imposed a strong legacy effect on microbial turnover; despite maintaining similar respiration rates, microbial growth declined by ~1 order of magnitude, yielding decreased community growth efficiency (CGE = new biomass growth/respiration), and microbial mortality declined by ~2 orders of magnitude. Soil organic carbon also shifted from lipid-like, amino-sugar-like, and protein-like compounds (indicative of microbial necromass) to more oxidized lignin-like and tannin-like compounds (indicative of decomposing plant-derived compounds). Meta-omics revealed distinct metabolic strategies linked to CGE. At high-CGE, microbes appeared to consume more energetically favorable N-rich necromass (released via high microbial turnover); this allowed for increased amino acids and peptidoglycan biosynthesis and greater aromatic compound degradation, fueling further energy production and growth efficiency. At low CGE, communities had elevated carbohydrate metabolism and lipid turnover, consistent with increased investment in plant detritus degradation and membrane repair and maintenance rather than growth. CONCLUSIONS: Together, our findings demonstrate that reduced winter rainfall decreases microbial turnover following rewetting without a concurrent reduction in CO2 emissions. This shift results in persistently lower CGE, which has the potential to increase soil carbon loss as CO2. If such conditions are maintained over multiple years, these changes could reshape soil organic carbon stocks and alter the balance of grassland ecosystems under future climate scenarios. While our data suggest that sustained reductions in CGE may drive SOC decline, the magnitude and persistence of these effects depend on long-term environmental dynamics and warrant further investigation. Video Abstract.

Soil Microbiology↗
PubMed2026

Extreme climatic events drive consistent and predictable shifts in soil antibiotic resistance genes.

Antimicrobial resistance (AMR) is a growing One Health challenge, and as climate warming intensifies extreme events, it remains unclear how these disturbances affect soil antibiotic resistance genes (ARGs). Here we analyzed the data from a controlled experiment using soils from 30 grassland sites across ten European countries, which simulated drought, flooding, freeze-thaw, and heatwaves to explore ARG dynamics. Overall, ARGs exhibited relatively small but highly consistent shifts across treatments. Heatwaves caused the strongest reductions in ARG abundance and in their linkages with mobile genetic elements (MGEs), a pattern that may reflect a hypothesized metabolic-genetic trade-off, in which microbial investment may shift from core metabolism toward stress signaling and structural maintenance. ARG dynamics during and after disturbance were governed by distinct soil physicochemical properties, with temperature and nutrient status determining acute responses, whereas soil moisture and seasonal variability in temperature and precipitation shaped longer-term legacy effects. Cross-validated random-forest models showed positive predictive performance for Bray-Curtis-based compositional responses within the environmental range represented by the 30 grassland sites. Our findings enhance the understanding of how soil ARGs respond to extreme climatic events and provide a step toward predicting extreme-event impacts on soil resistomes with relevance to One Health.

Soil Microbiology↗
PubMed1999

After the bombing: public scenarios and the construction of meaning.

In both our folk psychology and mental health practice, we adhere to the modernist view that a crisis is something that an individual has. A crisis is either something that happens to people or which people bring on themselves because of character pathology. On the other hand, postmodern theorists now draw our attention to how processes of interaction provide opportunities for certain characterizations to emerge and disipate. Both the conceptualization of an event as a crisis and the scenarios of how it is best understood arise within a community and emerge out of the communal construction of meaning. In this process in Oklahoma City, bystanders, politicians, pilgrims and news media played a role of great significance. Whether local or from afar, they became a community of observers who interacted with one another and looked to one another for verification as to what counted as a crisis and what behavior was appropriate. Lindy has observed that traumatized individuals are often surrounded quickly by a small network of trusted people who serve to buffer and protect them and who define what is helpful and what constitutes further trauma. Here, in Oklahoma, however, a wider public defined the event as a crisis, elaborated on it, and have gradually transformed it into almost mythic proportions, a process now exemplified in the construction of the Oklahoma City National Monument. However, they have also endorsed diverse other scenarios, not all of which have facilitated appropriate grieving, repair of life-disruption, or moving on. All, however, seem to have given a sense of meaning to the event. In this rich matrix, some survivors and their families have felt helped. Others have felt exploited. Still others have wanted to forget the whole thing and to avoid anything that reminded them of it. Of the would-be helpers, some felt unjustly rejected and unappreciated. Others felt appreciated, useful, and even enriched. However, a true legacy of the bombing may well be the metalogue it can precipitate and advance about the relationship between individuals and society, and especially the relationship between our individual life-stories and larger public scenarios, and the effects these scenarios have on the questions we can ask, what we can perceive and what solutions we can create.

Crime Victims↗