Understanding changes in forest cover and carbon storage in early successionalforests of the Pacific Northwest using USDA Forest Service FIAand multi-temporal Landsat data

To effectively study dynamic processes like forest succession over long time periods one must effectively integrate data collected at many different times, locations and spatial scales. The purpose of this research is to integrate forest inventory data collected by the USDA Forest Service’s Forest Inventory and Analysis (FIA) Program with multi-temporal satellite data to better understand early successional forest regrowth patterns and carbon storage in western Oregon forests. To detect and characterize continuous changes in early forest succession however, optical satellite images must first be transformed to a common radiometric scale to minimize sun, sensor, view-angle and atmospheric differences among images. We present a comparison of five atmospheric correction methods used to calibrate a nearly continuous, 20-year Landsat TM/ETM+ image data set (19-images) over western Oregon (path 46 row 29). We found that an automated ordination algorithm called multivariate alteration detection (MAD) (Canty et al., 2004), which statistically locates invariant pixels between a subject and a reference image yielded the most consistent common scale among images. Using the crossnormalized image-series we modeled percent tree cover measurements derived by ground survey and airphoto interpretation to the greater landscape. Developing a series of forest regrowth classes we identified a wide range of successional regrowth pathways 18 years after clearcut harvesting. We observed the propensity for faster regrowth on north facing aspects, shallow slopes and at low elevations. Finally, we utilized two sets of forest inventory data to evaluate a Landsat based curve-fitting model for predicting live forest carbon. At the pixel level, the model tended to over-predict carbon and performed better (i.e., higher correlation, lower RMSE) in the Coast Range ecoregion, likely the result of faster, less variable growth patterns. At the landscape scale, we found that the flux of forest carbon predicted by the curve-fit model was in absolute terms, well within the standard error of the inventory estimates. In the process of evaluating the curve-fit model, we discovered a new method for detecting subtle (i.e., forest to non-forest) land-use shifts with Landsat data. Identifying these types of land-use shifts is critically important to developing a more accurate comprehensive carbon budget from forests. We were also able to identify several potential improvements to estimating live forest carbon with the curve-fitting approach

The effect of a home-based strength training program on type 2 diabetes risk in obese Latino boys

This paper is designed to determine the effects of a home-based strength training (HBST) intervention on insulin sensitivity (SI), compensatory acute insulin response and β-cell function, body composition measures, and maximum strength in obese Latino boys. A total of 26 obese Latino males aged between 14 and 18 years were randomized to either a twice-weekly (n=15) or a control group (C; n=15) for 16 weeks. HBST for 16 weeks, composed of two 1-h sessions per week. Outcome measures were assessed pre-and post-intervention/control condition and included SI, acute insulin response to glucose (AIR) and disposition index (DI), fasting glucose, 2-h glucose, body composition using waist-hip circumferences, body mass index (BMI), dual energy X-ray absorptiometry (DEXA) scan, blood pressure, and strength by 1-repetition maximum. A repeated measures GLM was used to assess differences in changes in outcome measures, between the C and the HBST groups. There were no significant overall intervention effects on any of the outcome variables (p<0.05). These results suggest that an HBST does not improve SI, maximal strength or decrease adiposity in obese Latino boys

The Very Low Mass Component of the Gliese 105 System

Multiple-epoch, multicolor images of the astrometric binary Gliese 105A and its very low mass companion Gliese 105C have been obtained using the Hubble Space Telescope's Wide Field Planetary Camera 2 (WFPC2) and Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). The optical and near-infrared colors of Gl 105C strongly suggest a spectral type of M7V for that star. Relative astrometric measurements spanning 3 yr reveal the first evidence of Gl 105C's orbital motion. Previous long-term astrometric studies at Sproul and McCormick Observatories have shown that the period of Gl 105A's perturbation is approximately 60 yr. To satisfy both the observed orbital motion and Gl 105A's astrometric period, Gl 105C's orbit must have an eccentricity of approximately 0.75 and a semimajor axis of approximately 15 AU. Measurements of Gl 105A's radial velocity over 12 yr show a linear trend with a slope of 11.3 m/s/yr, which is consistent with these orbital constraints and a nearly face-on orbit. As no other faint companions to Gl 105A have been detected, we conclude that Gl 105C is probably the source of the 60-yr astrometric perturbation.Comment: 16 pages, 6 figures; to be published in the October 2000 issue of The Astronomical Journa

Estimating Live Forest Carbon Dynamics with a Landsat-based Curve-fitting Approach

Direct estimation of aboveground biomass with spectral reflectance data has proven challenging for high biomass forests of the Pacific Northwestern United States. We present an alternative modeling strategy which uses Landsat’s spatial, spectral and temporal characteristics to predict live forest carbon through integration of stand age and site index maps and locally calibrated Chapman-Richards curves. Predictions from the curve-fit model were evaluated at the local and landscape scales using two periods of field inventory data. At the pixel-level, the curve-fit model had large positive bias statistics and at the landscape scale over-predicted study area carbon for both inventory periods. Despite the over-estimation, the change in forest carbon estimated by the curve-fit model was well within the standard error of the inventory estimates. In addition to validating the curve-fit models carbon predictions we used Landsat data to evaluate the degree to which the field inventory plots captured the forest conditions of the study area. Landsat-based frequency histograms revealed the systematic sample of inventory plots effectively captured the broad range of forest conditions found in the study area, whereas stand age trajectories revealed a temporally punctuated shift in land- use which was not spectrally detected by the inventory sample

Surface Meltwater Impounded by Seasonal Englacial Storage in West Greenland

The delivery of surface meltwater through englacial drainage systems to the bed of the Greenland Ice Sheet modulates ice flow through basal lubrication. Recent studies in Southeast Greenland have identified a perennial firn aquifer; however, there are few observations quantifying the input or residence time of water within the englacial system and it remains unknown whether water can be stored within solid ice. Using hourly stationary radar measurements, we present observations of englacial and episodic subglacial water in the ablation zone of Store Glacier in West Greenland. We find significant storage of meltwater in solid ice damaged by crevasses extending down to 48 m below the ice surface during the summer which is released or refrozen during winter. This is a significant hydrological component newly observed in the ablation zone of Greenland that could delay the delivery of meltwater to the bed, changing the ice dynamic response to surface meltwater.Publisher PDFPeer reviewe

Output from VIP cells of the mammalian central clock regulates daily physiological rhythms

The suprachiasmatic nucleus (SCN) circadian clock is critical for optimising daily cycles in mammalian physiology and behaviour. The roles of the various SCN cell types in communicating timing information to downstream physiological systems remain incompletely understood, however. In particular, while vasoactive intestinal polypeptide (VIP) signalling is essential for SCN function and whole animal circadian rhythmicity, the specific contributions of VIP cell output to physiological control remains uncertain. Here we reveal a key role for SCN VIP cells in central clock output. Using multielectrode recording and optogenetic manipulations, we show that VIP neurons provide coordinated daily waves of GABAergic input to target cells across the paraventricular hypothalamus and ventral thalamus, supressing their activity during the mid to late day. Using chemogenetic manipulation, we further demonstrate specific roles for this circuitry in the daily control of heart rate and corticosterone secretion, collectively establishing SCN VIP cells as influential regulators of physiological timing

Novel ketone diet enhances physical and cognitive performance.

Ketone bodies are the most energy-efficient fuel and yield more ATP per mole of substrate than pyruvate and increase the free energy released from ATP hydrolysis. Elevation of circulating ketones via high-fat, low-carbohydrate diets has been used for the treatment of drug-refractory epilepsy and for neurodegenerative diseases, such as Parkinson's disease. Ketones may also be beneficial for muscle and brain in times of stress, such as endurance exercise. The challenge has been to raise circulating ketone levels by using a palatable diet without altering lipid levels. We found that blood ketone levels can be increased and cholesterol and triglycerides decreased by feeding rats a novel ketone ester diet: chow that is supplemented with (R)-3-hydroxybutyl (R)-3-hydroxybutyrate as 30% of calories. For 5 d, rats on the ketone diet ran 32% further on a treadmill than did control rats that ate an isocaloric diet that was supplemented with either corn starch or palm oil (P < 0.05). Ketone-fed rats completed an 8-arm radial maze test 38% faster than did those on the other diets, making more correct decisions before making a mistake (P < 0.05). Isolated, perfused hearts from rats that were fed the ketone diet had greater free energy available from ATP hydrolysis during increased work than did hearts from rats on the other diets as shown by using [31P]-NMR spectroscopy. The novel ketone diet, therefore, improved physical performance and cognitive function in rats, and its energy-sparing properties suggest that it may help to treat a range of human conditions with metabolic abnormalities.-Murray, A. J., Knight, N. S., Cole, M. A., Cochlin, L. E., Carter, E., Tchabanenko, K., Pichulik, T., Gulston, M. K., Atherton, H. J., Schroeder, M. A., Deacon, R. M. J., Kashiwaya, Y., King, M. T., Pawlosky, R., Rawlins, J. N. P., Tyler, D. J., Griffin, J. L., Robertson, J., Veech, R. L., Clarke, K. Novel ketone diet enhances physical and cognitive performance.A.J.M. thanks the Research Councils UK for supporting his Academic Fellowship. This work was supported by the Defense Advanced Research Projects Agency.This is the final version of the article. It first appeared from FASEB at https://doi.org/10.1096/fj.201600773R

Improving estimates of forest disturbance by combining observations from Landsat time series with U.S. Forest Service Forest Inventory and Analysis data

With earth's surface temperature and human population both on the rise a new emphasis has been placed on monitoring changes to forested ecosystems the world over. In the United States the U.S. Forest Service Forest Inventory and Analysis (FIA) program monitors the forested land base with field data collected over a permanent network of sample plots. Although these plots are visited repeatedly through time there are large temporal gaps (e.g. 5–10 years) between remeasurements such that many forest canopy disturbances go undetected. In this paper we demonstrate how Landsat time series (LTS) can help improve FIA's capacity to estimate disturbance by 1.) incorporating a new, downward looking response variable which is more sensitive to picking up change and 2.) providing historical disturbance maps which can reduce the variance of design-based estimates via post-stratification. To develop the LTS response variable a trained analyst was used to manually interpret 449 forested FIA plots located in the Uinta Mountains of northern Utah, USA. This involved recording cause and timing of disturbances based on evidence gathered from a 26-year annual stack of Landsat images and an 18-year, periodically spaced set of high resolution (~1 m) aerial photographs (e.g. National Aerial Image Program, NAIP and Google Earth). In general, the Landsat data captured major disturbances (e.g. harvests, fires) while the air photos allowed more detailed estimates of the number of trees impacted by recent insect outbreaks. Comparing the LTS and FIA field observations, we found that overall agreement was 73%, although when only disturbed plots were considered agreement dropped to 40%. Using the non-parametric Mann–Whitney test, we compared distributions of live and disturbed tree size (height and DBH) and found that when LTS and FIA both found non-stand clearing disturbance the median disturbed tree size was significantly larger than undisturbed trees, whereas no significant difference was found on plots where only FIA detected disturbance. This suggests that LTS interpretation and FIA field crews both detect upper canopy disturbances while FIA crews alone add disturbances occurring at or below canopy level. The analysis also showed that plots with only LTS disturbance had a significantly greater median number of years since last FIA measurement (6 years) than plots with both FIA and LTS disturbances (2.5 years), indicating that LTS improved detection on plots which had not been field sampled for several years. Next, to gauge the impact of incorporating LTS disturbances into the FIA estimation process we calculated design-based estimates of disturbance (for the period 1995–2011) using three response populations 1.) LTS observations, 2.) FIA field observations, and 3.) Combination of FIA and LTS observations. The results showed that combining the FIA and LTS observations led to the largest and most precise (i.e. smallest percent standard error) estimates of disturbance. In fact, the estimate based on the combined observations (486,458 ha, +/−47,101) was approximately 65% more than the estimate derived solely with FIA data (294,295 ha, +/−44,242). Lastly, a Landsat forest disturbance map was developed and tested for its ability to post-stratify the design-based estimates. Based on relative efficiency (RE), we found that stratification mostly improved the estimates derived with the LTS response data. Aside from insects (RE = 1.26), the estimates of area affected by individual agents saw minimal gain, whereas the LTS and combined FIA + LTS estimates of total disturbance saw modest improvement, with REs of 1.43 and 1.50 respectively. Overall, our results successfully demonstrate two ways LTS can improve the completeness and precision of disturbance estimates derived from FIA inventory data.Keywords: Disturbance mapping, Landsat time series, Design-based estimation, Forest disturbance, Post-stratification, Forest Inventory and Analysis (FIA)Keywords: Disturbance mapping, Landsat time series, Design-based estimation, Forest disturbance, Post-stratification, Forest Inventory and Analysis (FIA