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- Elberling, Bo, et al.
(författare)
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Soil and Plant Community Characteristics and Dynamics at Zackenberg
- 2008
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Ingår i: High-arctic ecosystem dynamics in a changing climate - Ten years of monitoring and research at Zackenberg Research Station, Northeast Greenland (Advances in Ecological Research). - 0065-2504. - 9780123736659 ; 40, s. 223-248
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Arctic soils hold large amounts of nutrients in the weatherable minerals and the soil organic matter, which slowly decompose. The decomposition processes release nutrients to the plant-available nutrient pool as well as greenhouse gases to the atmosphere. Changes in climatic conditions, for example, changes in the distribution of snow, water balance and the length of the growing season, are likely to affect the complex interactions between plants, abiotic and biotic soil processes as well as the composition of soil micro- and macro-fauna and thereby the overall decomposition rates. These interactions, in turn, will influence soil-plant functioning and vegetation composition in the short as well as in the long term. In this chapter, we report on soils and. plant communities and their distribution patterns in the valley Zackenbergdalen and focus on the detailed investigations within five dominating plant communities. These five communities are located along an ecological gradient in the landscape and are closely related to differences in water availability. They are therefore indirectly formed as a result of the distribution of landforms, redistribution of snow and drainage conditions. Each of the plant communities is closely related to specific nutrient levels and degree of soil development including soil element accumulation and translocation, for example, organic carbon. Results presented here show that different parts of the landscape have responded quite differently to the same overall climate changes the last 10 years and thus, most likely in the future too. Fens represent the wettest sites holding large reactive buried carbon stocks. A warmer climate will cause a permafrost degradation, which most likely will result in anoxic decomposition and increasing methane emissions. However, the net gas emissions at fen sites are sensitive to long-term changes in the water table level. Indeed, increasing maximum active layer depth at fen sites has been recorded together with a decreasing water level at Zackenberg. This is in line with the first signs of increasing extension of grasslands at the expense of fens. In contrast, the most exposed and dry areas have less soil carbon, and decomposition processes are periodically water limited. Here, an increase in air temperatures may increase active layer depth more than at fen sites, but water availability will be critical in determining nutrient cycling and plant production. Field manipulation experiments of increasing temperature, water supply and nutrient addition show that soil-plant interactions are sensitive to these variables. However, additional plant-specific investigations are needed before net effects of climate changes on different landscape and plant communities can be integrated in a landscape context and used to assess the net ecosystem effect of future climate scenarios.
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| 2. |
- Smedby, Karin Ekström, et al.
(författare)
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Ultraviolet radiation exposure and risk of malignant lymphomas
- 2005
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Ingår i: Journal of the National Cancer Institute. - : Oxford University Press (OUP). - 0027-8874 .- 1460-2105. ; 97:3, s. 199-209
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The incidence of malignant lymphomas has been increasing rapidly, but the causes of these malignancies remain poorly understood. One hypothesis holds that exposure to ultraviolet (UV) radiation increases lymphoma risk. We tested this hypothesis in a population-based case-control study in Denmark and Sweden. METHODS: A total of 3740 patients diagnosed between October 1, 1999, and August 30, 2002, with incident malignant lymphomas, including non-Hodgkin lymphoma, chronic lymphocytic leukemia, and Hodgkin lymphoma, and 3187 population controls provided detailed information on history of UV exposure and skin cancer and information on other possible risk factors for lymphomas. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated by logistic regression. Statistical tests were two-sided. RESULTS: Multivariable-adjusted analyses revealed consistent, statistically significant negative associations between various measures of UV light exposure and risk of non-Hodgkin lymphoma. A high frequency of sun bathing and sunburns at age 20 years and 5-10 years before the interview and sun vacations abroad were associated with 30%-40% reduced risks of non-Hodgkin lymphoma (e.g., for sunbathing four times a week or more at age 20 versus never sunbathing, OR = 0.7, 95% CI = 0.6 to 0.9; for two or more sunburns a year at age 20 versus no sunburns, OR = 0.6, 95% CI = 0.5 to 0.8). These inverse associations increased in strength with increasing levels of exposure (all P(trend)< or =.01). Similar, albeit weaker, associations were observed for Hodgkin lymphoma. There were no clear differences among non-Hodgkin lymphoma subtypes, although associations were stronger for B-cell than for T-cell lymphomas. A history of skin cancer was associated with a doubling in risks of both non-Hodgkin and Hodgkin lymphoma. CONCLUSIONS: A history of high UV exposure was associated with reduced risk of non-Hodgkin lymphoma. The positive association between skin cancer and malignant lymphomas is, therefore, unlikely to be mediated by UV exposure.
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| 3. |
- Hansen, Bjarne H, et al.
(författare)
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The Scandinavian Sarcoma Group Skeletal Metastasis Registry Functional outcome and pain after surgery for bone metastases in the pelvis and extremities
- 2009
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Ingår i: ACTA ORTHOPAEDICA. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 80, s. 85-90
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Tidskriftsartikel (refereegranskat)abstract
- Background Few authors have investigated function and pain after surgical treatment of patients with bone metastases. In 1999 the Scandinavian Sarcoma Group (SSG) initiated the Skeletal Metastasis Registry as a multi-centric, prospective study to provide a scientific basis for recommendations of treatment. Patients and methods We have analyzed function and pain in 530 patients (mean age 65 yr) operated on (599 operations) for non-spinal skeletal metastases at 9 SSG centres. 7% were operated for more than 1 metastasis. Carcinoma of the breast, prostate, kidney, and lung were the dominating sites for primary tumors. Results 25% of the patients died within 6 weeks after operation. 11% of the patients had complications. 6% had reoperation. In patients surviving more than 1 year the reoperation rate was 12%. 92% of the patients had no, light or moderate pain from metastasis at 6 weeks (first control) and 6 months follow-up. Patients using opioids were reduced from 40% preoperative to 30% at 6 months after surgery. In patients with metastases in pelvis or lower extremity 79% were walking with or without crutches, 6 weeks and 88%, 6 months after surgery. More patients with metastases; in proximal femur were mobile at 6 weeks and 6 months when treated with prosthetic replacement compared to internal fixation. Interpretation Palliative surgery for bone metastases improves function and reduce pain. Mobility is improved by surgery in patients with metastases in the pelvis or lower extremity. Prosthetic replacement seems to do better than internal fixation for metastases in the proximal femur. We need to analyze function and pain earlier than 6 weeks postoperative to investigate the benefit of surgery in patients with short time survival.
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