| 1. |
- Niu, Shuli, et al.
(författare)
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Thermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms.
- 2012
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Ingår i: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 194:3, s. 775-783
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Tidskriftsartikel (refereegranskat)abstract
- • It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not been examined at broad spatial and temporal scales. • Here, we compiled data from 169 globally distributed sites of eddy covariance and quantified the temperature response functions of net ecosystem exchange (NEE), an ecosystem-level property, to determine whether NEE shows thermal optimality and to explore the underlying mechanisms. • We found that the temperature response of NEE followed a peak curve, with the optimum temperature (corresponding to the maximum magnitude of NEE) being positively correlated with annual mean temperature over years and across sites. Shifts of the optimum temperature of NEE were mostly a result of temperature acclimation of gross primary productivity (upward shift of optimum temperature) rather than changes in the temperature sensitivity of ecosystem respiration. • Ecosystem-level thermal optimality is a newly revealed ecosystem property, presumably reflecting associated evolutionary adaptation of organisms within ecosystems, and has the potential to significantly regulate ecosystem-climate change feedbacks. The thermal optimality of NEE has implications for understanding fundamental properties of ecosystems in changing environments and benchmarking global models.
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| 2. |
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| 3. |
- Soderlin, M. K., et al.
(författare)
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A more active treatment has profound effects on the health status of rheumatoid arthritis (RA) patients: results from a population-based RA register in Malmö, Sweden, 1997–2005
- 2010
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Ingår i: Scandinavian Journal of Rheumatology. - : Informa UK Limited. - 1502-7732 .- 0300-9742. ; 39:3, s. 206-211
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Tidskriftsartikel (refereegranskat)abstract
- Methods: A continuously updated population-based RA register was established in the city of Malmo, southern Sweden, in 1997. Self-completed postal questionnaires issued in 1997, 2002, and 2005 were used to collect information on demographics, medication, and health status. Cross-sectional comparisons were made between data from 1997, 2002, and 2005. Results: Between 1997 and 2005, the proportion of patients treated with any disease-modifying anti-rheumatic drug (DMARD) including biologics increased substantially (from 52% to 87%), as well as the proportion treated with methotrexate (from 23% to 52%) and biologics (almost exclusively tumour necrosis factor inhibitors) (from 0% to 20%). Twelve per cent of RA patients received biologics 5 years from disease onset in 2005. In parallel with changes in treatment, mean Health Assessment Questionnaire (HAQ) scores (1.19 vs. 0.89) and all Short Form 36 (SF-36) subscales improved from 1997 to 2005 (non-overlapping confidence intervals). Conclusion: Between 1997 and 2005, there was a substantial increase in the use of DMARDs, which was accompanied by improved mean HAQ and SF-36 scores in cross-sectional comparisons. These results support the concept that more intensive treatment with DMARDs and biologics can have profound effects on the overall health status in RA patients at the population level.
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| 4. |
- Yuan, Wenping, et al.
(författare)
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Redefinition and global estimation of basal ecosystem respiration rate
- 2011
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Ingår i: Global Biogeochemical Cycles. - 0886-6236. ; 25
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Tidskriftsartikel (refereegranskat)abstract
- Basal ecosystem respiration rate (BR), the ecosystem respiration rate at a given temperature, is a common and important parameter in empirical models for quantifying ecosystem respiration (ER) globally. Numerous studies have indicated that BR varies in space. However, many empirical ER models still use a global constant BR largely due to the lack of a functional description for BR. In this study, we redefined BR to be ecosystem respiration rate at the mean annual temperature. To test the validity of this concept, we conducted a synthesis analysis using 276 site-years of eddy covariance data, from 79 research sites located at latitudes ranging from similar to 3 degrees S to similar to 70 degrees N. Results showed that mean annual ER rate closely matches ER rate at mean annual temperature. Incorporation of site-specific BR into global ER model substantially improved simulated ER compared to an invariant BR at all sites. These results confirm that ER at the mean annual temperature can be considered as BR in empirical models. A strong correlation was found between the mean annual ER and mean annual gross primary production (GPP). Consequently, GPP, which is typically more accurately modeled, can be used to estimate BR. A light use efficiency GPP model (i.e., EC-LUE) was applied to estimate global GPP, BR and ER with input data from MERRA (Modern Era Retrospective-Analysis for Research and Applications) and MODIS (Moderate resolution Imaging Spectroradiometer). The global ER was 103 Pg C yr (-1), with the highest respiration rate over tropical forests and the lowest value in dry and high-latitude areas.
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| 5. |
- Yuan, W., et al.
(författare)
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Thermal adaptation of net ecosystem exchange
- 2011
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 8:6, s. 1453-1463
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Tidskriftsartikel (refereegranskat)abstract
- Thermal adaptation of gross primary production and ecosystem respiration has been well documented over broad thermal gradients. However, no study has examined their interaction as a function of temperature, i.e. the thermal responses of net ecosystem exchange of carbon (NEE). In this study, we constructed temperature response curves of NEE against temperature using 380 site-years of eddy covariance data at 72 forest, grassland and shrubland ecosystems located at latitudes ranging from similar to 29 degrees N to 64 degrees N. The response curves were used to define two critical temperatures: transition temperature (T-b) at which ecosystem transfer from carbon source to sink and optimal temperature (T-o) at which carbon uptake is maximized. T-b was strongly correlated with annual mean air temperature. T-o was strongly correlated with mean temperature during the net carbon uptake period across the study ecosystems. Our results imply that the net ecosystem exchange of carbon adapts to the temperature across the geographical range due to intrinsic connections between vegetation primary production and ecosystem respiration.
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