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- Abbott, Benjamin W., et al.
(author)
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Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire : an expert assessment
- 2016
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In: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 11:3
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Journal article (peer-reviewed)abstract
- As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced.
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- Capek, P. T., et al.
(author)
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A plant-microbe interaction framework explaining nutrient effects on primary production
- 2018
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In: Nature Ecology & Evolution. - : Springer Science and Business Media LLC. - 2397-334X. ; 2:10, s. 1588-1596
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Journal article (peer-reviewed)abstract
- In most terrestrial ecosystems, plant growth is limited by nitrogen and phosphorus. Adding either nutrient to soil usually affects primary production, but their effects can be positive or negative. Here we provide a general stoichiometric framework for interpreting these contrasting effects. First, we identify nitrogen and phosphorus limitations on plants and soil microorganisms using their respective nitrogen to phosphorus critical ratios. Second, we use these ratios to show how soil microorganisms mediate the response of primary production to limiting and non-limiting nutrient addition along a wide gradient of soil nutrient availability. Using a meta-analysis of 51 factorial nitrogen-phosphorus fertilization experiments conducted across multiple ecosystems, we demonstrate that the response of primary production to nitrogen and phosphorus additions is accurately predicted by our stoichiometric framework. The only pattern that could not be predicted by our original framework suggests that nitrogen has not only a structural function in growing organisms, but also a key role in promoting plant and microbial nutrient acquisition. We conclude that this stoichiometric framework offers the most parsimonious way to interpret contrasting and, until now, unresolved responses of primary production to nutrient addition in terrestrial ecosystems.
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| 8. |
- Gadeyne, S, et al.
(author)
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The turn of the gradient? Educational differences in breast cancer mortality in 18 European populations during the 2000s
- 2017
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In: International Journal of Cancer. - : John Wiley & Sons. - 0020-7136 .- 1097-0215. ; 141:1, s. 33-44
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Journal article (peer-reviewed)abstract
- This study aims to investigate the association between educational level and breast cancer mortality in Europe in the 2000s. Unlike most other causes of death, breast cancer mortality tends to be positively related to education, with higher educated women showing higher mortality rates. Research has however shown that the association is changing from being positive over non-existent to negative in some countries. To investigate these patterns, data from national mortality registers and censuses were collected and harmonized for 18 European populations. The study population included all women aged 30-74. Age-standardized mortality rates, mortality rate ratios, and slope and relative indexes of inequality were computed by education. The population was stratified according to age (women aged 30-49 and women aged 50-74). The relation between educational level and breast cancer mortality was predominantly negative in women aged 30-49, mortality rates being lower among highly educated women and higher among low educated women, although few outcomes were statistically significant. Among women aged 50-74, the association was mostly positive and statistically significant in some populations. A comparison with earlier research in the 1990s revealed a changing pattern of breast cancer mortality. Positive educational differences that used to be significant in the 1990s were no longer significant in the 2000s, indicating that inequalities have decreased or disappeared. This evolution is in line with the "fundamental causes" theory which stipulates that whenever medical insights and treatment become available to combat a disease, a negative association with socio-economic position will arise, independently of the underlying risk factors.
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- Kilpi, F, et al.
(author)
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The Authors Respond
- 2018
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In: Epidemiology (Cambridge, Mass.). - 1531-5487. ; 29:4, s. E37-E37
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Journal article (other academic/artistic)
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