Nutrient cycling in New England spruce-fir forests

From July to August of 1987 and 1988, a regional sampling of spruce-fir forests across New England was conducted. Forest floors and foliage were sampled from 161 sites, in 11 areas from Maine to New York. Potential net N mineralization, nitrification, pH and analysis of total concentration for selected elements were measured on forest floor samples. Foliar lignin, N, cellulose and elemental concentration were determined for red spruce and balsam fir. Using National Atmospheric Deposition Program N deposition data, a isopleth map of New England wet only N deposition was produced. Estimated N deposition was correlated with longitude (R = 0.87, P $\u3c$ 0.001), forest floor nitrification (R = 0.89, P $\u3c$ 0.0001), the fraction of forest floor net N mineralization which nitrified (R = 0.82, P $\u3c$ 0.001), forest floor net potential N mineralization (R = 0.66, P $\u3c$ 0.5), forest floor C:N (R = $-$0.81, P $\u3c$ 0.001), forest floor Mg concentration (R = $-$0.64, P $\u3c$ 0.05), red spruce foliar lignin Concentration (R $-$0.61, P $\u3c$ 0.05), lignin:N (R = $-$0.79, P $\u3c$ 0.01), and red spruce foliar Mg:N (R = $-$0.57, P $\u3c$ 0.05). The research supported the theory of a nutrient imbalance between foliar N and Mg as a possible cause for forest decline. The second half of the research established a series of fertilization additions to spruce-fir plots on Mt. Ascutney Vermont. Four paired plots were amended with NH\sb4-N and/or NO\sb3-N, over the course of three growing seasons. Combined age class red spruce foliar N, lignin, and cellulose chemistry were measured in June, July and August of each year. Litter mass and chemistry were monitored for two years. Forest floor mass, net N mineralization, nitrification, pH, and elemental concentration were measured. Additions of N fertilizer were correlated with increased foliar %N (R\sp2 = 0.78, P = 0.0003) and litter %N (R\sp2 = 0.73, P = 0.0006), increased net N mineralization (R\sp2 = 0.59, P = 0.005), and decreased red spruce foliar lignin:N ratio (R\sp2 = 0.49, P = 0.01). No correlations were found between type of fertilizer applied and measured variables. Increases in net N mineralization stabilized or decreased during the second year of N applications, suggesting a limitation of available C

Characteristic Mechanisms and Outcome of Cardiopulmonary Arrest in Congestive Heart Failure Patients

Recent studies suggest the mechanism of sudden death in congestive heart failure (CHF) patients is less frequently VT/VF than previously believed. In order to further understand the characteristics and mechanisms of death in CHF patients, we evaluated 146 patients who underwent cardiopulmonary resuscitation during hospitalization for congestive heart failure, ischemic heart disease, and noncardiac causes. Clinical characteristics and outcomes are described below:CHF/CardiacnonCHF/CardiacnoncardiacN302690Age63 (49.71)67 (60.72)63 (29.71)Sex (% male)375860Initial Rhythm N(%)VT/VF7 (25)11 (44)24 (27)Asystole6 (21.4)6 (24)33 (37.5)Bradycardia5 (17.9)2 (8)6 (6.8)EMD6 (21.4)1 (4)13 (148)Other4 (14.3)5 (20)12 (136)ROSC21 (70)13 (50)51 (56.7)Survival to D/C1 (3.3)4 (15.4)2 (2.2)Patients with nonCHF/Cardiac disease had a higher ROSC than patients with CHF and noncardiac diseases (p=0.016). In summary, patients with CHF often experience cardiopulmonary arrest with bradycardic or EMD arrests. Although patients with CHF are resuscitated with a high degree of success their in-hospital survival was low. Furthermore, the high rate of bradycardic and EMD arrests may explain the low in-hospital survival rates

Predicting watershed erosion production and over-land sediment transport using a GIS, in: Carrying the Torch for Erosion Control: An Olympic Task

ABSTRACT Soil erosion from forested lands can seriously degrade stream water quality. Sediment production and over-land sediment transport models have been developed which predict ecosystem management impacts on soil erosion and movement across watersheds. The predictions of soil erosion are for whole watersheds, not for points within the watershed. Soil erosion and transport models are usually run independently. From a spatial perspective, the models are difficult to define and the output is difficult to interpret. Our research utilizes a user friendly, modular based, Geographic Information System (GIS) for predicting soil erosion and over-land sediment transport under a variety of management practices including road building, timber harvesting, burning, and creation of wildlife food plots, given a range of storm intensities broken into four seasons (i.e., spring, summer, fall, winter). Through the use of a GIS, model predictions of sediment can be spatially distributed across the watershed and displayed as map outputs of eroded soil deposition. The major objective of this paper is to demonstrate how a GIS and a modular modeling approach can be used by land managers to develop alternative management scenarios for cumulative effects assessment in forested watersheds. As improved soil erosion and transport models are developed, new models can be easily exchanged with current models using a GIS as an integrating database tool. &apos

Upscaling key ecosystem functions across the conterminous United States by a water-centric ecosystem model

We developed a water-centric monthly scale simulation model (WaSSI-C) by integrating empirical water and carbon flux measurements from the FLUXNET network and an existing water supply and demand accounting model (WaSSI). The WaSSI-C model was evaluated with basin-scale evapotranspiration (ET), gross ecosystem productivity (GEP), and net ecosystem exchange (NEE) estimates by multiple independent methods across 2103 eight-digit Hydrologic Unit Code watersheds in the conterminous United States from 2001 to 2006. Our results indicate that WaSSI-C captured the spatial and temporal variability and the effects of large droughts on key ecosystem fluxes. Our modeled mean (±standard deviation in space) ET (556 ± 228 mm yr−1) compared well to Moderate Resolution Imaging Spectroradiometer (MODIS) based (527 ± 251 mm yr−1) and watershed water balance based ET (571 ± 242 mm yr−1). Our mean annual GEP estimates (1362 ± 688 g C m−2 yr−1) compared well (R2 = 0.83) to estimates (1194 ± 649 g C m−2 yr−1) by eddy flux-based EC-MOD model, but both methods led significantly higher (25–30%) values than the standard MODIS product (904 ± 467 g C m−2 yr−1). Among the 18 water resource regions, the southeast ranked the highest in terms of its water yield and carbon sequestration capacity. When all ecosystems were considered, the mean NEE (−353 ± 298 g C m−2 yr−1) predicted by this study was 60% higher than EC-MOD\u27s estimate (−220 ± 225 g C m−2 yr−1) in absolute magnitude, suggesting overall high uncertainty in quantifying NEE at a large scale. Our water-centric model offers a new tool for examining the trade-offs between regional water and carbon resources under a changing environment

Unprecedented phase transition sequence in the perovskite Li0.2Na0.8NbO3

Funding for this research was provided by: EPSRC (award No. EP/L505079/1).We demonstrate the existence of a novel phase transition sequence in the perovskite Li0.2Na0.8NbO3 at elevated temperature. The rare Glazer tilt system, a+a+c-, is observed in both polar and centrosymmetric polymorphs. The perovskite Li0.2Na0.8NbO3 is shown, by powder neutron diffraction, to display a unique sequence of phase transitions at elevated temperature. The ambient temperature polar phase (rhombohedral, space group R3c) transforms via a first-order transition to a polar tetragonal phase (space group P42mc) in the region 150 – 300 °C; these two phases correspond to Glazer tilt systems a-a-a- and a+a+c-, respectively. At 500 °C a ferroelectric – paraelectric transition takes place from P42mc to P42/nmc, retaining the a+a+c- tilt. Transformation to a single-tilt system, a0a0c+ (space group P4/mbm), occurs at 750 °C, with the final transition to the aristotype cubic phase at 850 °C. The P42mc and P42/nmc phases have each been seen only once previously in perovskite crystallography, in both cases in compositions prepared at high pressure.Publisher PDFPeer reviewe

Effect of Oral Iron Repletion on Exercise Capacity in Patients With Heart Failure With Reduced Ejection Fraction and Iron Deficiency: The IRONOUT HF Randomized Clinical Trial.

Importance: Iron deficiency is present in approximately 50% of patients with heart failure with reduced left ventricular ejection fraction (HFrEF) and is an independent predictor of reduced functional capacity and mortality. However, the efficacy of inexpensive readily available oral iron supplementation in heart failure is unknown. Objective: To test whether therapy with oral iron improves peak exercise capacity in patients with HFrEF and iron deficiency. Design, Setting, and Participants: Phase 2, double-blind, placebo-controlled randomized clinical trial of patients with HFrEF ( Interventions: Oral iron polysaccharide (n = 111) or placebo (n = 114), 150 mg twice daily for 16 weeks. Main Outcomes and Measures: The primary end point was a change in peak oxygen uptake (V̇o2) from baseline to 16 weeks. Secondary end points were change in 6-minute walk distance, plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, and health status as assessed by Kansas City Cardiomyopathy Questionnaire (KCCQ, range 0-100, higher scores reflect better quality of life). Results: Among 225 randomized participants (median age, 63 years; 36% women) 203 completed the study. The median baseline peak V̇o2 was 1196 mL/min (interquartile range [IQR], 887-1448 mL/min) in the oral iron group and 1167 mL/min (IQR, 887-1449 mL/min) in the placebo group. The primary end point, change in peak V̇o2 at 16 weeks, did not significantly differ between the oral iron and placebo groups (+23 mL/min vs -2 mL/min; difference, 21 mL/min [95% CI, -34 to +76 mL/min]; P = .46). Similarly, at 16 weeks, there were no significant differences between treatment groups in changes in 6-minute walk distance (-13 m; 95% CI, -32 to 6 m), NT-proBNP levels (159; 95% CI, -280 to 599 pg/mL), or KCCQ score (1; 95% CI, -2.4 to 4.4), all P \u3e .05. Conclusions and Relevance: Among participants with HFrEF with iron deficiency, high-dose oral iron did not improve exercise capacity over 16 weeks. These results do not support use of oral iron supplementation in patients with HFrEF. Trial Registration: clinicaltrials.gov Identifier: NCT02188784