scholarly journals The pigment complex and photosynthetic activity in the annual cycle of Polytrichum commune in the forest belt of the Khibiny Mountains on the Kola Peninsula of Russia

2020 ◽  
Vol 10 (1) ◽  
pp. 37-49
Author(s):  
Natalya Shmakova ◽  
Olga Ermolaeva
Keyword(s):  
Annual Cycle ◽  
Vegetation Period ◽  
Early Spring ◽  
Forest Belt ◽  
The Past ◽  
Assimilation Number ◽  
Polytrichum Commune ◽  
Pigment Complex ◽  
Summer Maximum ◽  
Plastid Pigments

This paper presents data on the content and ratio of pigments, photosynthesis rate, and assimilation number throughout the annual cycle of Polytrichum commune in the forest belt of the Khibiny Mountains. It is shown that the activity of the pigment complex in the photosynthetic organs of P. commune is preserved and maintained over 2 years. The highest content of plastid pigments in this year’s shoots was recorded in fall, in the past year’s shoots in the summer. In winter, the content of chlorophylls in the photosynthetic organs of this year’s shoots decreased in 1.5 times relative to the summer maximum, and carotenoids - in 1.4 times. In the past year’s shoots, no significant changes in the content of the pigments were noted. During the active vegetation period, the photosynthetic intensity in this year’s shoots is in 1.5 times as high as that in the past year’s shoots. At the end of the growing season in the past year’s shoots the value of LHC (76%) due to their immersion deep into the moss clumps and shading them with this year’s shoots. Chlorophyll’s efficiency (assimilation number) in P. commune shoots of different ages in early spring (April) is in 2 times as high as that in fall (October).

scholarly journals Artificial light at night amplifies seasonal relapse of haemosporidian parasites in a widespread songbird

2020 ◽  
Vol 287 (1935) ◽  
pp. 20201831 ◽  
Author(s):  
Daniel J. Becker ◽  
Devraj Singh ◽  
Qiuyun Pan ◽  
Jesse D. Montoure ◽  
Katherine M. Talbott ◽  
...  
Keyword(s):  
Annual Cycle ◽  
Early Spring ◽  
Urban Environments ◽  
Control Group ◽  
Artificial Light ◽  
Chronic Infections ◽  
Light At Night ◽  
Haemosporidian Parasite ◽  
Infection Dynamics ◽  
Additive Mixed Models

Urban habitats can shape interactions between hosts and parasites by altering not only exposure rates but also within-host processes. Artificial light at night (ALAN) is common in urban environments, and chronic exposure can impair host immunity in ways that may increase infection. However, studies of causal links between this stressor, immunity, and infection dynamics are rare, particularly in migratory animals. Here, we experimentally tested how ALAN affects cellular immunity and haemosporidian parasite intensity across the annual cycle of migrant and resident subspecies of the dark-eyed junco ( Junco hyemalis ). We monitored an experimental group exposed to light at night and a control group under natural light/dark cycles as they passed through short days simulating early spring to longer days simulating the breeding season, followed by autumn migration. Using generalized additive mixed models, we show that ALAN increased inflammation, and leucocyte counts were greatest in early spring and autumn. At the start of the experiment, few birds had active infections based on microscopy, but PCR revealed many birds had chronic infections. ALAN increased parasitaemia across the annual cycle, with strong peaks in spring and autumn that were largely absent in control birds. As birds were kept in indoor aviaries to prevent vector exposure, this increased parasitaemia indicates relapse of chronic infection during costly life-history stages (i.e. reproduction). Although the immunological and parasitological time series were in phase for control birds, cross-correlation analyses also revealed ALAN desynchronized leucocyte profiles and parasitaemia, which could suggest a general exaggerated inflammatory response. Our study shows how a common anthropogenic influence can shape within-host processes to affect infection dynamics.

Control of wind strength and frequency in the Aral Sea basin during the late Holocene

2007 ◽  
Vol 67 (3) ◽  
pp. 371-382 ◽  
Author(s):  
Philippe Sorrel ◽  
Hedi Oberhänsli ◽  
Nikolaus Boroffka ◽  
Danis Nourgaliev ◽  
Peter Dulski ◽  
...  
Keyword(s):  
Central Asia ◽  
Atmospheric Circulation ◽  
Ice Core ◽  
Titanium Content ◽  
Early Spring ◽  
Laminated Sediments ◽  
Aral Sea ◽  
Pressure System ◽  
Siberian High ◽  
The Past

AbstractChanging content of detrital input in laminated sediments traced by XRF scanning and microfacies analyses reflect prominent variations in sedimentation processes in the Aral Sea. A high-resolution record of titanium from a core retrieved in the northwestern Large Aral Sea allows a continuous reconstruction of wind strength and frequency in western Central Asia for the past 1500 yr. During AD 450–700, AD 1210–1265, AD 1350–1750 and AD 1800–1975, detrital inputs (bearing titanium) are high, documenting an enhanced early spring atmospheric circulation associated with an increase in intensity of the Siberian High pressure system over Central Asia. In contrast, lower titanium content during AD 1750–1800 and AD 1980–1985 reflects a diminished influence of the Siberian High during early spring with a reduced atmospheric circulation. A moderate circulation characterizes the time period AD 700–1150. Unprecedented weakened atmospheric circulation over western Central Asia are inferred during ca. AD 1180–1210 and AD 1265–1310 with a considerable decrease in dust storm frequency, sedimentation rates, lamination thickness and detrital inputs (screened at 40-μm resolution). Our results are concurrent with changes in the intensity of the Siberian High during the past 1400 yr as reported in the GISP2 Ice Core from Greenland.

scholarly journals Spinal Motocross Injuries in the United Kingdom

2018 ◽  
Vol 6 (1) ◽  
pp. 232596711774864
Author(s):  
Rohit Singh ◽  
Amit Bhalla ◽  
Matthew Ockendon ◽  
Stuart Hay
Keyword(s):  
United Kingdom ◽  
Spinal Injury ◽  
Burst Fracture ◽  
Current Trend ◽  
Early Spring ◽  
Spinal Injuries ◽  
Data Series ◽  
The Past ◽  
The United Kingdom ◽  
Age Range

Background: Motocross is a form of motorcycle racing held on established off-road circuits and has been a recreational and competitive sport across the world for >100 years. In the United Kingdom alone, motocross has grown into a phenomenally ambitious and popular franchise. There are >200 motocross clubs across the country, permitting >900 events annually. Purpose: To assess the current trend of spine-related motocross injuries over the past 5 years. Study Design: Descriptive epidemiology study. Methods: Data were prospectively collected over 5 years (August 2010–August 2015) at our regional trauma and spine unit, regardless of whether the rider was performing the sport competitively or recreationally. Results: During the study period, spine-related injuries were identified for 174 patients (age range, 6-75 years) who were directly referred to our department following recreational or competitive motocross, with most injuries being sustained within the early spring and summer months, representing the start of the motocross season. A significant number of injuries were in males (n = 203, 94%), with the majority of injuries occurring within the 21- to 30-year-old age group. A total of 116 (54%) injuries required operative treatment. The most common spinal injury was thoracolumbar burst fracture (n = 95), followed by chance fractures (n = 26). Conclusion: This data series emphasizes the prevalence and devastation of motocross-related spinal injuries in the United Kingdom and may serve in administering sanctions and guidelines to governing bodies of motocross. The spinal injuries that occur during motocross have significant capital connotations for regional spinal centers. The recent surge in motocross popularity is correlated with the number of injuries, which have increased over the past 5 years by almost 500%.

scholarly journals Evaluation of near-surface ozone over Europe from the MACC reanalysis

2015 ◽  
Vol 8 (7) ◽  
pp. 2299-2314 ◽  
Author(s):  
E. Katragkou ◽  
P. Zanis ◽  
A. Tsikerdekis ◽  
J. Kapsomenakis ◽  
D. Melas ◽  
...  
Keyword(s):  
Surface Ozone ◽  
Monitoring And Evaluation ◽  
Early Spring ◽  
Atmospheric Composition ◽  
Near Surface ◽  
Gross Error ◽  
Diurnal Range ◽  
North Eastern ◽  
Funded Project ◽  
Summer Maximum

Abstract. This work is an extended evaluation of near-surface ozone as part of the global reanalysis of atmospheric composition, produced within the European-funded project MACC (Monitoring Atmospheric Composition and Climate). It includes an evaluation over the period 2003–2012 and provides an overall assessment of the modeling system performance with respect to near-surface ozone for specific European subregions. Measurements at rural locations from the European Monitoring and Evaluation Program (EMEP) and the European Air Quality Database (AirBase) were used for the evaluation assessment. The fractional gross error of near-surface ozone reanalysis is on average 24 % over Europe, the highest found over Scandinavia (27 %) and the lowest over the Mediterranean marine stations (21 %). Near-surface ozone shows mostly a negative bias in winter and a positive bias during warm months. Assimilation reduces the bias in near-surface ozone in most of the European subregions – with the exception of Britain and Ireland and the Iberian Peninsula and its impact is mostly notable in winter. With respect to the seasonal cycle, the MACC reanalysis reproduces the photochemically driven broad spring-summer maximum of surface ozone of central and south Europe. However, it does not capture adequately the early spring peak and the shape of the seasonality at northern and north-eastern Europe. The diurnal range of surface ozone, which is as an indication of the local photochemical production processes, is reproduced fairly well, with a tendency for a small overestimation during the warm months for most subregions (especially in central and southern Europe). Possible reasons leading to discrepancies between the MACC reanalysis and observations are discussed.

scholarly journals Trends and annual cycles in soundings of Arctic tropospheric ozone

2017 ◽  
Author(s):  
Bo Christiansen ◽  
Nis Jepsen ◽  
Rigel Kivi ◽  
Georg Hansen ◽  
Niels Larsen ◽  
...  
Keyword(s):  
Annual Cycle ◽  
Low Frequency ◽  
Autoregressive Process ◽  
Early Summer ◽  
Model Parameters ◽  
Free Troposphere ◽  
Mean Values ◽  
Annual Cycles ◽  
Low Frequency Variability ◽  
Summer Maximum

Abstract. Ozone soundings from 9 Nordic stations have been homogenized and interpolated to standard pressure levels. The different stations have very different data coverage; the longest period with data is from the end of the 1980ies to 2014. At each pressure level the homogenized ozone time-series have been analyzed with a model which includes both low-frequency variability in form of a polynomial, an annual cycle with harmonics, the possibility for low-frequency variability in the annual amplitude and phasing, and either white noise or noise given by a first order autoregressive process. The fitting of the parameters is performed with a Bayesian approach not only giving the mean values but also confidence intervals. The results show that all stations agree on a well-defined annual cycle in the free troposphere with a relatively confined maximum in the early summer. Regarding the low-frequency variability it is found that Scoresbysund, Ny Aalesund, Sodankylae, Eureka, and Orland show similar, significant signals with a maximum near 2005 followed by a decrease. This change is characteristic for all pressure levels in the free troposphere. A significant change in the annual cycle was found for Ny Aalesund, Scoresbysund and Sodankylae. The changes at these stations are in agreement with the interpretation that the early summer maximum is appearing earlier in the year. The results are shown to be robust to the different settings of the model parameters such as the order of the polynomial, number of harmonics in the annual cycle, and the type of noise.

scholarly journals Prolonged Dry Episodes over the Conterminous United States: New Tendencies Emerging during the Last 40 Years

2008 ◽  
Vol 21 (9) ◽  
pp. 1850-1862 ◽  
Author(s):  
Pavel Ya Groisman ◽  
Richard W. Knight
Keyword(s):  
United States ◽  
Average Duration ◽  
Warm Season ◽  
Vegetation Period ◽  
Total Precipitation ◽  
Eastern United States ◽  
The Past ◽  
The Mean ◽  
Rain Events ◽  
Precipitation Events

Abstract A disproportionate increase in precipitation coming from intense rain events, in the situation of general warming (thus, an extension of the vegetation period with intensive transpiration), and an insignificant change in total precipitation could lead to an increase in the frequency of a potentially serious type of extreme events: prolonged periods without precipitation (even when the mean seasonal rainfall totals increase). This paper investigates whether this development is already occurring during the past several decades over the conterminous United States, for the same period when changes in frequency of intense precipitation events are being observed. Lengthy strings of “dry” days without sizeable (>1.0 mm) precipitation were assessed only during the warm season (defined as a period when mean daily temperature is above the 5°C threshold) when water is intensively used for transpiration and prolonged periods without sizable rainfall represent a hazard for terrestrial ecosystem’s health and agriculture. During the past four decades, the mean duration of prolonged dry episodes (1 month or longer in the eastern United States and 2 months or longer in the southwestern United States) has significantly increased. As a consequence the return period of 1-month-long dry episodes over the eastern United States has reduced more than twofold from 15 to 6–7 yr. The longer average duration of dry episodes has occurred during a relatively wet period across the country but is not observed over the northwestern United States.

scholarly journals WHITE MUSTARD — MEANING, APPLICATION

2020 ◽  
Vol 2020 (2) ◽  
pp. 41-67
Author(s):  
Valentina Volovik
Keyword(s):  
Dry Matter ◽  
Insect Pests ◽  
Vegetation Period ◽  
Early Spring ◽  
Perennial Grasses ◽  
Biofuel Production ◽  
White Mustard ◽  
Distant Hybridization ◽  
Green Mass ◽  
Green Fodder

A review of the literature on the significance, biological features, and use of white mustard is presented. White mustard is one of the most precocious crops of the cabbage family. It is used as a forage and sideral crop. It has a large yield of green mass, is unpretentious in cultivation, it can be used from early spring to late autumn. When sown as an intermediate crop, white mustard plants in the early flowering phase contain 21–25% protein, 24–27% fiber in the dry matter; the nutritional value of 1 kg of dry matter is 0.7–0.8 feed units. Great preceding crop, phytomeliorant and phytoremediate soil, improves the physical properties of soils. It is used in multicomponent mixtures for green fodder and as a supporting crop in mixed agrocenoses with legumes, and is increasingly used as a cover crop for perennial grasses. The oil is used in the food industry and for biofuel production. Seeds, cake and meal are used in the medical, cosmetic, food, chemical industries, have herbicidal and insecticidal properties when used in biological agriculture. White mustard is characterized by such positive economic signs, as the resistance to cracking of pods, the early blight, heat stress, insect pests and nematodes; used in distant hybridization with rapeseed spring with the aim of improving rapeseed on a number of sings. For 2020, 19 varieties of white mustard are allowed to be used, 4 of them are foreign, and 5 varieties are declared as non-erucic. The variety of white mustard Lugovskaya, created in the Federal Research Center "VIK named after V.R. Williams", is used for forage and sideration purposes both in the main and in intermediate crops. The vegetation period in the Center Non-Chernozem zone is from 78 to 92 days. Seed yield from 1.94 to 2.35 t/ha, yield of green mass when sown in spring from 19.9 to 23.4 t/ha, dry matter – from 2.5 to 3.9 t/ha.

scholarly journals Relationship between the activity of guaiacol peroxidase and the content of photosynthetic pigments in tea leaves

10.5219/1401 ◽  
2020 ◽  
Vol 14 ◽  
pp. 1020-1026
Author(s):  
Nataliia Platonova ◽  
Oksana Belous
Keyword(s):  
Photosynthetic Pigments ◽  
Redox Reactions ◽  
Vegetation Period ◽  
Tea Plant ◽  
Guaiacol Peroxidase ◽  
Tea Leaves ◽  
Low Intensity ◽  
Pigment Complex ◽  
Tea Plants ◽  
Green Pigments

The dynamics of guaiacol peroxidase and photosynthetic pigments in 3-leaf sprouts (flushes) of tea plants were studied. The presence of declines and peaks in the activity of the enzyme associated with the meteorological conditions of each month was noted. It is shown that there is a direct relationship between the increase in enzyme activity and hydrothermal factors. The most significant correlation was found between the activity of GPO in a 3-leaf tea flush and the amount of precipitation (r = 0.86). The highest activity of guaiacol peroxidase during the entire vegetation period is distinguished by the Sochi variety and form 582. The lowest activity was observed in forms 3823 and 2264, which indicates a low intensity of redox reactions in these plants in stressful situations. Determining the dynamics of the pigment complex revealed its dependence on hydrothermal factors. Studies have shown that precipitation is a significant factor affecting the pigment complex of tea plants. It was found that the largest amount of green pigments is synthesized by leaves at the beginning of active vegetation (May). The participation of the pigment apparatus in the adaptation of the tea plant is directly related to carotenoids, the increase in the number of carotenoids coincides with the period of drought. In the content of photosynthetic pigments and the activity of guaiacol peroxidase manifest genotypic features. The revealed patterns are common to all tea plants.

scholarly journals The content of chlorophyll a and chlorophyll b in leaves of undergrowth species in hornbeam-oak forest stands of the forest-steppe zone in Western Ukraine

2018 ◽  
Vol 79 (1) ◽  
pp. 23-28
Author(s):  
Volodymyr Zaïka ◽  
Taras Bondarenko
Keyword(s):  
Chlorophyll A ◽  
Canopy Cover ◽  
Vegetation Period ◽  
Steppe Zone ◽  
Growth Conditions ◽  
Forest Steppe ◽  
Oak Forest ◽  
Forest Stands ◽  
Pigment Complex ◽  
Western Ukraine

Abstract In this study, the biosynthesis of the plastid pigments chlorophyll a and b was examined for the most common shrubs in hornbeam-oak forest stands of the Western forest-steppe zone of Ukraine. The characteristics of the pigments’ biosynthesis were determined in terms of plant species, vegetation period and growth conditions (under canopy cover and out in the open). The gathered data on the changes of the pigment complex with respect to the examined variables confirms the sensitivity of plastid pigment biosynthesis to environmental factors.

scholarly journals Annual cycle of ozone at and above the tropical tropopause: observations versus simulations with the Chemical Model of the Stratosphere (CLaMS)

2009 ◽  
Vol 9 (5) ◽  
pp. 17937-17962
Author(s):  
P. Konopka ◽  
J.-U. Grooß ◽  
G. Günther ◽  
F. Plöger ◽  
R. Pommrich ◽  
...  
Keyword(s):  
Annual Cycle ◽  
Potential Temperature ◽  
Early Spring ◽  
Chemical Model ◽  
Boreal Summer ◽  
Meridional Transport ◽  
Tropical Tropopause Layer ◽  
Tropical Tropopause ◽  
The Mean

Abstract. Multi-annual simulations with the Chemical Model of the Stratosphere (CLaMS) are used to study the seasonality of O3 and of the mean age within the stratospheric part of the tropical tropopause layer (TTL) In agreement with satellite (HALOE) and in-situ observations (SHADOZ), CLaMS simulations show above ≈360 K potential temperature, a pronounced annual cycle in O3 and in the mean age of air with highest values in the late boreal summer. Within the model, this seasonality is driven by the seasonality of both upwelling and in-mixing. The latter process describes enhanced meridional transport from the extratropics into the TTL. The strongest in-mixing occurs from the Northern Hemisphere during the boreal summer in the potential temperature range between 380 and 420 K. Contrary, an increase of upwelling with highest values in winter reduces O3 up to the lowest values in early spring. Both, CLaMS simulations and Aura MLS O3 observations show that this enhanced equatorward transport in summer is mainly driven by the Asian monsoon anticyclone.

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