scholarly journals Uncovering Dryland Woody Dynamics Using Optical, Microwave, and Field Data—Prolonged Above-Average Rainfall Paradoxically Contributes to Woody Plant Die-Off in the Western Sahel

2020 ◽  
Vol 12 (14) ◽  
pp. 2332 ◽  
Author(s):  
Paulo N. Bernardino ◽  
Martin Brandt ◽  
Wanda De Keersmaecker ◽  
Stéphanie Horion ◽  
Rasmus Fensholt ◽  
...  
Keyword(s):  
Vegetation Dynamics ◽  
Field Data ◽  
Large Scale ◽  
Biomass Accumulation ◽  
Severity Index ◽  
Important Variable ◽  
Woody Vegetation ◽  
Sudden Increase ◽  
Ecosystem Recovery ◽  
Normal Rainfall

Dryland ecosystems are frequently struck by droughts. Yet, woody vegetation is often able to recover from mortality events once precipitation returns to pre-drought conditions. Climate change, however, may impact woody vegetation resilience due to more extreme and frequent droughts. Thus, better understanding how woody vegetation responds to drought events is essential. We used a phenology-based remote sensing approach coupled with field data to estimate the severity and recovery rates of a large scale die-off event that occurred in 2014–2015 in Senegal. Novel low (L-band) and high-frequency (Ku-band) passive microwave vegetation optical depth (VOD), and optical MODIS data, were used to estimate woody vegetation dynamics. The relative importance of soil, human-pressure, and before-drought vegetation dynamics influencing the woody vegetation response to the drought were assessed. The die-off in 2014–2015 represented the highest dry season VOD drop for the studied period (1989–2017), even though the 2014 drought was not as severe as the droughts in the 1980s and 1990s. The spatially explicit Die-off Severity Index derived in this study, at 500 m resolution, highlights woody plants mortality in the study area. Soil physical characteristics highly affected die-off severity and post-disturbance recovery, but pre-drought biomass accumulation (i.e., in areas that benefited from above-normal rainfall conditions before the 2014 drought) was the most important variable in explaining die-off severity. This study provides new evidence supporting a better understanding of the “greening Sahel”, suggesting that a sudden increase in woody vegetation biomass does not necessarily imply a stable ecosystem recovery from the droughts in the 1980s. Instead, prolonged above-normal rainfall conditions prior to a drought may result in the accumulation of woody biomass, creating the basis for potentially large-scale woody vegetation die-off events due to even moderate dry spells.

scholarly journals Confocal laser endomicroscopy reveals alterations in duodenal permeability in patients with acute pancreatitis

2019 ◽  
Vol 47 (3) ◽  
pp. 1279-1287
Author(s):  
Lingjia Sun ◽  
Min Yue ◽  
Yining Dai ◽  
Chaohui Yu ◽  
Chunxiao Chen
Keyword(s):  
Acute Pancreatitis ◽  
Large Scale ◽  
Duodenal Bulb ◽  
Severity Index ◽  
Duodenal Mucosa ◽  
Confocal Laser Endomicroscopy ◽  
Confocal Laser ◽  
Mucosal Permeability ◽  
Reactive Protein ◽  
Severity Index Score

Objective Intestinal permeability increases during the course of acute pancreatitis (AP). We assessed duodenal permeability alterations in patients with AP by confocal laser endomicroscopy (CLE). Methods Thirty patients with AP underwent CLE evaluation of the antral and duodenal mucosa. Images were graded based on the appearance of capillaries and the degree of fluorescein leakage. Results Patients with AP had increased duodenal mucosal permeability that could be detected by CLE. The mucosal permeability progressively increased in the gastric antrum, duodenal bulb, and descending duodenum. The CLE parameters in the antrum and duodenal bulb were not significantly different between patients with mild and severe AP. The CLE grades in the descending duodenum were higher in patients with severe than mild AP. The C-reactive protein level in AP was positively correlated with the permeability in the duodenal bulb and descending duodenum, while the computed tomography severity index score was positively correlated with the mucosal permeability in the duodenal bulb and descending duodenum. Conclusion CLE revealed increased duodenal permeability in patients with AP. Higher permeability in the descending duodenum was observed in severe than mild AP. Further large-scale studies are needed to confirm the relationship between altered duodenal permeability and the severity of AP.

scholarly journals Spatial variation and mechanisms of leaf water content in grassland plants at the biome scale: evidence from three comparative transects

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ruomeng Wang ◽  
Nianpeng He ◽  
Shenggong Li ◽  
Li Xu ◽  
Mingxu Li
Keyword(s):  
Spatial Variation ◽  
Water Content ◽  
Large Scale ◽  
Life Forms ◽  
Important Variable ◽  
Leaf Water ◽  
Leaf Water Content ◽  
Desert Grassland ◽  
Large Spatial Scale ◽  
Grassland Plants

AbstractLeaf water content (LWC) has important physiological and ecological significance for plant growth. However, it is still unclear how LWC varies over large spatial scale and with plant adaptation strategies. Here, we measured the LWC of 1365 grassland plants, along three comparative precipitation transects from meadow to desert on the Mongolia Plateau (MP), Loess Plateau, and Tibetan Plateau, respectively, to explore its spatial variation and the underlying mechanisms that determine this variation. The LWC data were normally distributed with an average value of 0.66 g g−1. LWC was not significantly different among the three plateaus, but it differed significantly among different plant life forms. Spatially, LWC in the three plateaus all decreased and then increased from meadow to desert grassland along a precipitation gradient. Unexpectedly, climate and genetic evolution only explained a small proportion of the spatial variation of LWC in all plateaus, and LWC was only weakly correlated with precipitation in the water-limited MP. Overall, the lasso variation in LWC with precipitation in all plateaus represented an underlying trade-off between structural investment and water income in plants, for better survival in various environments. In brief, plants should invest less to thrive in a humid environment (meadow), increase more investment to keep a relatively stable LWC in a drying environment, and have high investment to hold higher LWC in a dry environment (desert). Combined, these results indicate that LWC should be an important variable in future studies of large-scale trait variations.

scholarly journals Effects of a workplace prevention programme for problem gambling: study protocol for a cluster randomised controlled trial

BMJ Open ◽  
2017 ◽  
Vol 7 (9) ◽  
pp. e015963 ◽  
Author(s):  
Jonas Rafi ◽  
Ekaterina Ivanova ◽  
Alexander Rozental ◽  
Per Carlbring
Keyword(s):  
Problem Gambling ◽  
Large Scale ◽  
Controlled Trial ◽  
Public Health Problem ◽  
Cluster Randomised Controlled Trial ◽  
Severity Index ◽  
The Body ◽  
Prevention Programme ◽  
Open Access Journals ◽  
Randomised Controlled

IntroductionDespite being considered a public health problem, no prevention programme for problem gambling in workplace settings has been scientifically evaluated. This study aims to fill a critical gap in the field of problem gambling by implementing and evaluating a large-scale prevention programme in organisations.Methods and analysisTen organisations, with a total of n=549 managers and n=8572 employees, will be randomised to either receiving a prevention programme or to a waitlist control condition. Measurements will be collected at the baseline and 3, 12 and 24 months after intervention. The primary outcome of interest is the managers’ inclination to act when worried or suspicious about an employee’s problem gambling or other harmful use. Additional outcomes of interest include the Problem Gambling Severity Index and gambling habits in both managers and employees. Furthermore, qualitative analyses of the responses from semistructured interviews with managers will be performed.Ethics and disseminationThis study has been approved by the regional ethics board of Stockholm, Sweden, and it will contribute to the body of knowledge concerning prevention of problem gambling. The findings will be published in peer-reviewed, open-access journals.Trial registration numberNCT02925286; Pre-results.

scholarly journals Vegetation dynamics and soil water balance in a water-limited Mediterranean ecosystem on Sardinia, Italy

2008 ◽  
Vol 12 (6) ◽  
pp. 1257-1271 ◽  
Author(s):  
N. Montaldo ◽  
J. D. Albertson ◽  
M. Mancini
Keyword(s):  
Soil Water ◽  
Land Surface ◽  
Vegetation Dynamics ◽  
Mediterranean Ecosystems ◽  
Surface Fluxes ◽  
Annual Rainfall ◽  
Woody Vegetation ◽  
Wide Range ◽  
Hydrometeorological Conditions

Abstract. Mediterranean ecosystems are commonly heterogeneous savanna-like ecosystems, with contrasting plant functional types (PFTs, e.g. grass and woody vegetation) competing for water. Mediterranean ecosystems are also commonly characterized by strong inter-annual rainfall variability, which influences the distributions of PFTs that vary spatially and temporally. An extensive field campaign in a Mediterranean setting was performed with the objective to investigate interactions between vegetation dynamics, soil water budget and land-surface fluxes in a water-limited ecosystem. Also a vegetation dynamic model (VDM) is coupled to a 3-component (bare soil, grass and woody vegetation) Land surface model (LSM). The case study is in Orroli, situated in the mid-west of Sardegna within the Flumendosa river basin. The landscape is a mixture of Mediterranean patchy vegetation types: trees, including wild olives and cork oaks, different shrubs and herbaceous species. Land surface fluxes, soil moisture and vegetation growth were monitored during the May 2003–June 2006 period. Interestingly, hydrometeorological conditions of the monitored years strongly differ, with dry and wet years in turn, such that a wide range of hydrometeorological conditions can be analyzed. The coupled VDM-LSM model is successfully tested for the case study, demonstrating high model performance for the wide range of eco-hydrologic conditions. Results demonstrate also that vegetation dynamics are strongly influenced by the inter-annual variability of atmospheric forcing, with grass leaf area index changing significantly each spring season according to seasonal rainfall amount.

On the Early Cambrian age of two late orogenic granites from. west-central Ahaggar (Algerian Sahara)

1969 ◽  
Vol 6 (1) ◽  
pp. 25-37 ◽  
Author(s):  
J. Boissonnas ◽  
S. Borsi ◽  
G. Ferrara ◽  
J. Fabre ◽  
J. Fabries ◽  
...  
Keyword(s):  
Random Sampling ◽  
Field Data ◽  
Large Scale ◽  
Early Cambrian ◽  
Basement Complex ◽  
West Central ◽  
Algerian Sahara ◽  
Igneous Activity ◽  
Made In

The Pharusian belt of west-central Ahaggar belongs to the 'basement complex' underlying the Paleozoic and later sediments of the Sahara. This paper reports and discusses the Rb–Sr ages obtained on total rocks and minerals from two granitic stocks of the belt: the Tioueiine and Iskel intrusions.Both plutons gave good whole-rock isochrons, which show that the systems were closed 560 ± 40 m.y. ago with respect to Rb and Sr. This is, most probably, the age of crystallization. Three of the four values obtained on biotites are somewhat lower and scattered in the range 502–526 m.y. The discrepancies are probably due to deuteric reactions or incipient weathering. They can be ascribed neither to the loss of 87Sr during the cooling down of the granites, nor to rejuvenation by some later thermal or tectonic event.These studies confirm previous results of random sampling in Ahaggar and prove that large-scale igneous activity took place during the Early Cambrian Epoch. Knowing from field data that the Tioueiine and Iskel are late orogenic granites, it must be concluded that the Pharusian orogeny came to an end at that time.Such a result contradicts early assumptions, made in the field, of a middle Precambrian age for the Pharusian orogeny. It gives further weight to modern ideas concerning the 700–500 m.y. events in Africa, and it leaves time for erosion to create the Saharian platform before the deposition of the first Paleozoic sandstones.

Satellite-based large-scale vegetation dynamics in ecological restoration programmes of Northern China

2018 ◽  
Vol 40 (5-6) ◽  
pp. 2296-2312 ◽  
Author(s):  
Zhitao Wu ◽  
Lu Yu ◽  
Xiaoyu Zhang ◽  
Ziqiang Du ◽  
Hong Zhang
Keyword(s):  
Ecological Restoration ◽  
Vegetation Dynamics ◽  
Large Scale ◽  
Northern China

scholarly journals An Atlantic streamer in stratospheric ozone observations and SD-WACCM simulation data

2016 ◽  
Author(s):  
Klemens Hocke ◽  
Franziska Schranz ◽  
Eliane Maillard Barras ◽  
Lorena Moreira ◽  
Niklaus Kämpfer
Keyword(s):  
Water Vapour ◽  
Central Europe ◽  
Large Scale ◽  
Surf Zone ◽  
Middle Atmosphere ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
Transport Processes ◽  
Sudden Increase ◽  
Nonlinear Transport

Abstract. Observation and simulation of individual ozone streamers are important for the description and understanding of nonlinear transport processes in the middle atmosphere. A sudden increase in mid-stratospheric ozone occurred above Central Europe on December 4, 2015. The GROunbased Millimeter-wave Ozone Spectrometer (GROMOS) and the Stratospheric Ozone MOnitoring RAdiometer (SOMORA) in Switzerland measured an ozone enhancement of about 30 % at 34 km altitude from December 1 to December 4. A similar ozone increase is simulated by the Specified Dynamics-Whole Atmosphere Community Climate (SD-WACCM) model. Further, the global ozone fields at 34 km altitude from SD-WACCM and the satellite experiment Aura/MLS show a remarkable agreement for the location and the timing of an ozone streamer (large-scale tongue like structure) extending from the subtropics in Northern America over the Atlantic to Central Europe. This agreement indicates that SD-WACCM can inform us about the wind inside the Atlantic ozone streamer. SD-WACCM shows an eastward wind of about 100 m/s inside the Atlantic streamer in the mid-stratosphere. SD-WACCM shows that the Atlantic streamer flows along the edge region of the polar vortex. The Atlantic streamer turns southward at an erosion region of the polar vortex located above the Caspian Sea. The spatial distribution of stratospheric water vapour indicates a filament outgoing from this erosion region. The Atlantic streamer, the polar vortex erosion region and the water vapour filament belong to the process of planetary wave breaking in the so-called surf zone of the Northern mid-latitude winter stratosphere.

The Geosynchronous Substorm

1996 ◽  
Author(s):  
Charles F. Kennel
Keyword(s):  
Magnetic Field ◽  
Growth Phase ◽  
Large Scale ◽  
Current System ◽  
Dynamic Pressure ◽  
Geosynchronous Orbit ◽  
Sudden Increase ◽  
Tail Current ◽  
Tightly Coupled ◽  
The Cross

The reconnection model of substorms deals with the large-scale changes in the structure of the magnetosphere and tail as convection intensifies following a sudden increase in the dayside reconnection rate. The model has difficulty making statements relevant to the small scales that characterize auroral onset. However, there has been considerable progress in assembling high-resolution observations of the events in space that now appear to be tightly coupled to the dramatic auroral events that first defined the term substorm. We will call this clear and consistent ensemble the geosynchronous model of substorms, since most of it was first conceived from observations made on geostationary spacecraft. We will also include in this ensemble the recent observations made using the quasigeostationary spacecraft, AMPTE/CCE, and so, by the geosynchronous substorm, we really mean the substorm as it appears on the earth's nightside typically between 6 and, say, 10 RE downtail. The earth’s magnetic field at geosynchronous orbit is about 100 nT, some three times larger than in the tail lobes. Study of quiet field intervals singles out the dependence of the geosynchronous field on solar wind dynamic pressure, since the modulation due to changes in the direction of the interplanetary field is presumably negligible during quiet conditions. The periodic variations in the quiet field depend on local time, season, and orientation of the earth’s dipole axis relative to spacecraft location (McPherron and Barfield, 1980; Rufenach et al., 1992). Superposed on the quiet field are perturbations up to about 50 nT due to several magnetospheric current systems, including the magnetopause current, the ring current, and the cross-tail current; the most striking are due to changes in the cross-tail current system. Observations from geosynchronous orbit were the first to indicate that the nightside magnetic field becomes more “tail-like” during substorm growth phase, and more dipolar during the expansion phase. This simple observation is the foundation on which today’s elaborate geosynchronous substorm model rests. The geosynchronous field becomes progressively more “tail-like” as the cross-tail current system intensifies and/or moves earthward during the substorm growth phase (McPherron et al., 1975; Coleman and McPherron, 1976; McPherron, 1979; Kauffmann, 1987).

The use of feed supplements to reduce livestock greenhouse gas emissions: direct-fed microbials

2021 ◽  
pp. 261-286
Author(s):  
Natasha Doyle ◽  
◽  
Philiswa Mbandlwa ◽  
Sinead Leahy ◽  
Graeme Attwood ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Nitrous Oxide ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Large Scale ◽  
Important Variable ◽  
Gas Emissions ◽  
Feed Supplements ◽  
Beneficial Response ◽  
On Farm

This chapter aims to outline the strategy of using feed supplements for the reduction of greenhouse gas emissions (GHG) in ruminants, including methane (CH4), carbon dioxide and nitrous oxide, given that feed intake is an important variable in predicting these emissions. Focus will be given to direct-fed microbials, a term reserved for live microbes which can be supplemented to feed to elicit a beneficial response. The viability of such methods will also be analysed for their use in large scale on-farm operations.

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