Litterfall, litter decomposition and associated nutrient fluxes in Pinus halepensis: influence of tree removal intensity in a Mediterranean forest

The online version of this article (doi:10.1007/s10342-015-0893-z) contains supplementary material, which is available to authorized users[EN] Our knowledge about the influence of silvicultural treatments on nutrient cycling processes in Mediterranean forests is still limited. Four levels of tree removal were compared in an Aleppo pine forest in eastern Spain to determine the effects on litterfall, litter decomposition and the associated nutrient fluxes after 12 years. Removal treatments included clearfelling, two shelterwood intensities (60 and 75 % of basal area removed) and untreated controls. Twelve years later, the basal area removed still explained 60 % of litterfall mass variance and 60 % of C, 52 % of N, 45 % of P, 17 % of K, 47 % of Ca and 60 % of Mg return variances. Litter decomposed somewhat more slowly in clearfellings compared to controls (p = 0.049), accumulated more Ca and released less K compared to the other three treatments. This was explained by contamination with mineral particles due to the poorly developed O horizon in clearfellings. We conclude that the management practices reduced the nutrient return via litterfall, but the nutrient release through decomposition seems poorly sensitive to canopy disturbance. In order to accurately quantify the harvesting impacts on nutrient cycling in this Mediterranean forest system, it is necessary to measure the litterfall of the understory layer.This work has been supported by a fellowship from the Generalitat Valenciana, Conselleria de Educacion, Formacion y Empleo awarded to L. Lado-Monserrat (BFPI/2008/041). Silvicultural treatments were carried out by the Mediterranean Centre for Environmental Studies (CEAM) through programme "I + D en relacion con la restauracion de la cubierta vegetal y otros aspectos de investigacion forestal". Dataloggers and probes were provided by the Generalitat Valenciana through Project "Efecto de diferentes sistemas de aclareo de masa forestal sobre la disponibilidad de agua, nutrientes y la regeneracion de la masa arborea y arbustiva en parcelas de pinar" (GV06/126). We acknowledge Joana Oliver, Ruth M. Tavera and Daniel Fortanet for their help in the laboratory and in the field. The authors wish to thank Francisco Galiana for his assistance, including help in fieldwork and providing information about the experimental design of the silvicultural treatments. Thanks also go to Rafael Herrera from the Centro de Ecologia, Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela and two anonymous reviewers for critically reviewing the manuscript.Lado Monserrat, L.; Lidón, A.; Bautista, I. (2015). Litterfall, litter decomposition and associated nutrient fluxes in Pinus halepensis: influence of tree removal intensity in a Mediterranean forest. 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Evaluating the Risk of Air Pollution to Forests in Central and Eastern Europe

Foliar damage to trees by air pollution in Central and Eastern Europe has been a major scientific and political issue. Emissions of toxic gases such as sulfur dioxide and nitrogen oxides can have wide-ranging effects on local and regional vegetation that can be compounded by other environmental stresses to plant growth. Since uptake and physiological effects of these gases on tree leaves are largely mediated by stomata, surrogate methods for estimating pollutant conductances into leaves and forest canopies may lead to risk assessments for major vegetation types that can then be used in regional planning. Management options to ameliorate or mitigate air pollutant damage to forests and losses in productivity are likely to be more difficult to widely implement than on-the-stack emissions abatement, Informed management and policy decisions regarding Central and Eastern European forests are dependent on the development of quantitative tools and models for risk assessment of the effects of atmospheric pollutants on ecosystem health and productivity

Teriparatide treatment exerts differential effects on the central and peripheral skeleton: results from the MOAT study

The central and peripheral skeleton was characterised using imaging techniques during 104 weeks of teriparatide treatment. Teriparatide exerts differential effects on the central and the peripheral skeleton. Overall, we did not observe a change in total body bone mineral. Our conclusions are constrained by the study limitations. INTRODUCTION: Teriparatide stimulates bone formation and resorption and therefore can cause bone gain and loss. We simultaneously characterised the central and peripheral skeleton using imaging techniques to better understand the mechanism of action of teriparatide. METHODS: Postmenopausal, osteoporotic women (n = 20, 65.4 ± 5.5 years) were recruited into a 104-week study of teriparatide. Imaging techniques included DXA, quantitative computed tomography (QCT), and high-resolution peripheral quantitative computed tomography (HR-pQCT). RESULTS: Total lumbar spine areal bone mineral content (aBMC) (+ 11.2%), total lumbar spine areal bone mineral density (aBMD) (+ 8.1%), subregional thoracic spine aBMD (+ 7.5%), lumbar spine aBMC (+ 23.5%), lumbar spine aBMD (+ 11.9%), pelvis aBMC (+ 9.3%), and pelvis aBMD (+ 4.3%) increased. However, skull aBMC (- 5.0%), arms aBMC (- 5.1%), legs aBMC (- 2.9%), and legs aBMD (- 2.5%) decreased. Overall, we did not observe a change in total body bone mineral. Increases in L1-L3 volumetric BMD (vBMD) (+ 28.5%) occurred but there was no change in total proximal femur vBMD. Radius and tibia cortical vBMD (- 3.3 and - 3.4%) and tissue mineral density (- 3.2 and - 3.8%) decreased and there was an increase in porosity (+ 21.2 and + 10.3%). Tibia, but not radius, trabecular inhomogeneity (+ 3.2%), and failure load (+ 0.2%) increased, but cortical thickness (- 3.1%), area (- 2.9%), and pore volume (- 1.6%) decreased. CONCLUSIONS: Teriparatide exerts differential effects on the central and the peripheral skeleton. Central trabecular vBMD (L1-L3) is improved, but there is a concomitant decrease in peripheral cortical vBMD and an increase in porosity. Overall, we did not observe a change in total body bone mineral. We acknowledge that our conclusions may be speculative and are constrained by the technical limitations of the imaging techniques used, the lack of a control group, and the small sample size studied

An assessment of RELAP5 MOD3.1.1 condensation heat transfer modeling with GIRAFFE heat transfer tests

RELAP5 MOD3.1.1 is being used to simulate Loss of Coolant Accidents (LOCA) for the Simplified Boiling Water Reactor (SBWR) being proposed by General Electric (GE). One of the major components associated with the SBWR is the Passive Containment Cooling System (PCCS) which provides the long-term heat sink to reject decay heat. The RELAP5 MOD3.1.1 code is being assessed for its ability to represent accurately the PCCS. Data from the Phase 1, Step 1 Heat Transfer Tests performed at Toshiba`s Gravity-Driven Integral Full-Height Test for Passive Heat Removal (GIRAFFE) facility will be used for assessing the ability of RELAP5 to model condensation in the presence of noncondensables. The RELAP5 MOD3.1.1 condensation model uses the University of California at Berkeley (UCB) correlation developed by Vierow and Schrock. The RELAP5 code uses this heat transfer coefficient with the gas velocity effect multiplier being limited to 2. This heat transfer option was used to analyze the condensation heat transfer in the GIRAFFE PCCS heat exchanger tubes in the Phase 1, Step 1 Heat Transfer Tests which were at a pressure of 3 bar and had a range of nitrogen partial pressure fractions from 0.0 to 0.10. The results of a set of RELAP5 calculations al these conditions were compared with the GIRAFFE data. The effects of PCCS cell nodings on the heat transfer process were also studied. The UCB correlation, as implemented in RELAP5, predicted the heat transfer to {+-}5% of the data with a three-node model. The three-node model has a large cell in the entrance region which smeared out the entrance effects on the heat transfer, which tend to overpredict the condensation. Hence, the UCB correlation predicts condensation heat transfer in the presence of noncondensable gases with only a coarse mesh. The cell length term in the condensation heat transfer correlation implemented in the code must be removed to allow for accurate calculations with smaller cell sizes

A comparison between the balance method and radiotracer methods for measuring calcium absorption in treated and untreated patients with osteoporosis

Measurements of calcium absorption by the balance method and by the double tracer, multiple blood sampling radiocalcium tracer method were synchronized in 48 studies in 35 patients with osteoporosis. In the patients who were studied twice, results were obtained before and during treatment. Significant correlations were obtained between fractional dietary calcium absorption and three measures of the rate of 47Ca absorption : the maximum rate of absorption (M.A.R.) and mean rate of absorption (AR), both calculated by deconvolution analysis from the results of the double tracer study ; and the mean rate of absorption calculated from the oral tracer appearance curve using Marshall and Nordin's (1969) method (L.A.R.). None of these correlations were sufficiently good for the radiocalcium absorption test to be able to replace the expensive and time-consuming balance technique in the detailed study of absorption of calcium from the diet or calcium balance in individual patients with osteoporosis. Only a small part of this lack of correspondence could be accounted for by methodological uncertainties. The most sensitive radiocalcium absorption tests appear to be those which measure rates of absorption and they appear best suited to studying patients in homogeneous groups rather than individually. © 1980