| 1. |
- Tao, Feng, et al.
(författare)
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Microbial carbon use efficiency promotes global soil carbon storage
- 2023
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 618:7967, s. 981-985
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Tidskriftsartikel (refereegranskat)abstract
- Soils store more carbon than other terrestrial ecosystems. How soil organic carbon (SOC) forms and persists remains uncertain, which makes it challenging to understand how it will respond to climatic change. It has been suggested that soil microorganisms play an important role in SOC formation, preservation and loss. Although microorganisms affect the accumulation and loss of soil organic matter through many pathways, microbial carbon use efficiency (CUE) is an integrative metric that can capture the balance of these processes. Although CUE has the potential to act as a predictor of variation in SOC storage, the role of CUE in SOC persistence remains unresolved. Here we examine the relationship between CUE and the preservation of SOC, and interactions with climate, vegetation and edaphic properties, using a combination of global-scale datasets, a microbial-process explicit model, data assimilation, deep learning and meta-analysis. We find that CUE is at least four times as important as other evaluated factors, such as carbon input, decomposition or vertical transport, in determining SOC storage and its spatial variation across the globe. In addition, CUE shows a positive correlation with SOC content. Our findings point to microbial CUE as a major determinant of global SOC storage. Understanding the microbial processes underlying CUE and their environmental dependence may help the prediction of SOC feedback to a changing climate.
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| 2. |
- Kamble, Pramod, et al.
(författare)
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Bacterial growth and growth-limiting nutrients following chronic nitrogen additions to a hardwood forest soil
- 2013
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Ingår i: Soil Biology & Biochemistry. - : Elsevier BV. - 0038-0717. ; 59, s. 32-37
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Tidskriftsartikel (refereegranskat)abstract
- Increasing nitrogen(N) deposition due to anthropogenic activities has become a significant global change threat to N-poor terrestrial ecosystems. We compared bacterial growth and nutrients limiting bacterial growth in one of the longest running experiments on increasing N-deposition to a temperate forest, the Chronic Nitrogen Amendment Study at Harvard Forest, USA. Soil samples were collected in fall 2009 from the organic and mineral horizons of plots treated annually since 1988 with 0 (unfertilized), 50(low N) or 150 (high N) kg N ha(-1) as NH4NO3. In the organic horizon, bacterial growth (leucine incorporation) decreased by 5 times in the high N plots compared to the unfertilized treatment, while no decrease was observed in the mineral horizon. Bacterial growth in all soils was primarily limited by lack of carbon (C), although adding only C (as glucose) resulted in only a minor increase in bacterial growth in the unfertilized soil compared to adding C in combination with N. The bacterial growth induced by adding only C increased with higher level of N fertilization, up to 7-8 times the level without any C addition in the high N treatment, suggesting increased availability of N for the bacteria with increasing N addition. (C) 2013 Elsevier Ltd. All rights reserved.
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| 3. |
- Rousk, Johannes, et al.
(författare)
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Revisiting the hypothesis that fungal-to-bacterial dominance characterizes turnover of soil organic matter and nutrients
- 2015
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Ingår i: Ecological Monographs. - : Wiley. - 0012-9615. ; 85:3, s. 457-472
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Tidskriftsartikel (refereegranskat)abstract
- Resolving fungal and bacterial groups within the microbial decomposer community is thought to capture disparate life strategies for soil microbial decomposers, associating bacteria with an r-selected strategy for carbon (C) and nutrient use, and fungi with a K-selected strategy. Additionally, food-web model-based work has established a widely held belief that the bacterial decomposer pathway in soil supports high turnover rates of easily available substrates, while the slower fungal-dominated decomposition pathway supports the decomposition of more complex organic material, thus characterizing the biogeochemistry of the ecosystem. We used a field experiment, the Detritus Input and Removal Treatments, or DIRT, experiment (Harvard Forest Long-Term Ecological Research Site, USA) where litter and root inputs (control, no litter, double litter, or no tree roots) have been experimentally manipulated during 23 years, generating differences in soil C quality. We hypothesized (1) that delta C-13 enrichment would decrease with higher soil C quality and that a higher C quality would favor bacterial decomposers, (2) that the C mineralized in fungal-dominated treatments would be of lower quality and also depleted in delta C-13 relative to bacterial-dominated high-quality soil C treatments, and (3) that higher C mineralization along with higher gross N mineralization rates would occur in bacterial-dominated treatments compared with more fungal-dominated treatments. The DIRT treatments resulted in a gradient of soil C quality, as shown by up to 4.5-fold differences between the respiration per soil C between treatments. High-quality C benefited fungal dominance, in direct contrast with our hypothesis. Further, there was no difference between the delta(CO2)-C-13 produced by a fungal compared with a bacterial-dominated decomposer community. There were differences in C and N mineralization between DIRT treatments, but these were not related to the relative dominance of fungal and bacterial decomposers. Thus we find no support for the hypothesized differences between detrital food webs dominated by bacteria compared to those dominated by fungi. Rather, an association between high-quality soil C and fungi emerges from our results. Consequently there is a need to revise our basic understanding for microbial communities and the processes they regulate in soil.
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| 4. |
- Rousk, Johannes, et al.
(författare)
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Temperature adaptation of bacterial communities in experimentally warmed forest soils
- 2012
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 18:10, s. 3252-3258
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Tidskriftsartikel (refereegranskat)abstract
- A detailed understanding of the influence of temperature on soil microbial activity is critical to predict future atmospheric CO2 concentrations and feedbacks to anthropogenic warming. We investigated soils exposed to 3-4 years of continuous 5 degrees C-warming in a field experiment in a temperate forest. We found that an index for the temperature adaptation of the microbial community, T-min for bacterial growth, increased by 0.19 degrees C per 1 degrees C rise in temperature, showing a community shift towards one adapted to higher temperature with a higher temperature sensitivity (Q(10(5-15 degrees C)) increased by 0.08 units per 1 degrees C). Using continuously measured temperature data from the field experiment we modelled in situ bacterial growth. Assuming that warming did not affect resource availability, bacterial growth was modelled to become 60% higher in warmed compared to the control plots, with the effect of temperature adaptation of the community only having a small effect on overall bacterial growth (<5%). However, 3 years of warming decreased bacterial growth, most likely due to substrate depletion because of the initially higher growth in warmed plots. When this was factored in, the result was similar rates of modelled in situ bacterial growth in warmed and control plots after 3 years, despite the temperature difference. We conclude that although temperature adaptation for bacterial growth to higher temperatures was detectable, its influence on annual bacterial growth was minor, and overshadowed by the direct temperature effect on growth rates.
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