scholarly journals Occurrence of the Black lace-weaver spider, Amaurobius ferox, in caves

2020 ◽  
Vol 49 (1) ◽  
Author(s):  
Enrico Lunghi
Keyword(s):  
Early Spring ◽  
Late Winter ◽  
Ecological Conditions ◽  
Cave Entrance ◽  
Wide Range ◽  
Amaurobius Ferox

Subterranean habitats house a wide range of species which show a number of adaptations to prevailing ecological conditions. Spiders are among the most abundant predators in caves; however, most studies on cave spiders focus on species adapted to these habitats. This is the first study related to the occurrence of the Black lace-weaver spider, Amaurobius ferox, in caves. The species lacks adaptations to the subterranean habitats and has been observed within meters from the cave entrance all year round, except in late winter until early spring. Furthermore, its occupancy is positively related to the presence of other three cave-dwelling spiders: Metellina merianae, Meta menardi and Tegenaria sp.

Seasonal activity and estivation of lumbricid earthworms in the midlands of Tasmania

Soil Research ◽  
1994 ◽  
Vol 32 (6) ◽  
pp. 1355 ◽  
Author(s):  
RB Garnsey
Keyword(s):  
Soil Moisture ◽  
Adult Development ◽  
Survival Rates ◽  
Soil Surface ◽  
Early Spring ◽  
Lumbricus Rubellus ◽  
Late Winter ◽  
Cocoon Production ◽  
Density And Biomass ◽  
Earthworm Activity

Earthworms have the ability to alleviate many soil degradational problems in Australia. An attempt to optimize this resource requires fundamental understanding of earthworm ecology. This study reports the seasonal changes in earthworm populations in the Midlands of Tasmania (<600 mm rainfall p.a.), and examines, for the first time in Australia, the behaviour and survival rates of aestivating earthworms. Earthworms were sampled from 14 permanent pastures in the Midlands from May 1992 to February 1994. Earthworm activity was significantly correlated with soil moisture; maximum earthworm activity in the surface soil was evident during the wetter months of winter and early spring, followed by aestivation in the surface and subsoils during the drier summer months. The two most abundant earthworm species found in the Midlands were Aporrectodea caliginosa (maximum of 174.8 m-2 or 55.06 g m-2) and A. trapezoides (86 m-2 or 52.03 g m-2), with low numbers of Octolasion cyaneum, Lumbricus rubellus and A. rosea. The phenology of A. caliginosa relating to rainfall contrasted with that of A. trapezoides in this study. A caliginosa was particularly dependent upon rainfall in the Midlands: population density, cocoon production and adult development of A. caliginosa were reduced as rainfall reduced from 600 to 425 mm p.a. In contrast, the density and biomass of A. trapezoides were unaffected by rainfall over the same range: cocoon production and adult development continued regardless of rainfall. The depth of earthworm aestivation during the summers of 1992-94 was similar in each year. Most individuals were in aestivation at a depth of 150-200 mm, regardless of species, soil moisture or texture. Smaller aestivating individuals were located nearer the soil surface, as was shown by an increase in mean mass of aestivating individuals with depth. There was a high mortality associated with summer aestivation of up to 60% for juvenile, and 63% for adult earthworms in 1993 in the Midlands. Cocoons did not survive during the summers of 1992 or 1994, but were recovered in 1993, possibly due to the influence of rainfall during late winter and early spring.

TEMPERATURE RESISTANCE OF GOLDFISH MAINTAINED UNDER CONTROLLED PHOTOPERIODS

1959 ◽  
Vol 37 (4) ◽  
pp. 419-428 ◽  
Author(s):  
William S. Hoar ◽  
G. Beth Robertson
Keyword(s):  
Temperature Change ◽  
Seasonal Variations ◽  
Rapid Growth ◽  
Endocrine System ◽  
Early Spring ◽  
Late Winter ◽  
Thyroid Activity ◽  
Temperature Resistance ◽  
Sudden Temperature Change

Goldfish maintained under controlled photoperiods for 6 weeks or longer were relatively more resistant to a sudden elevation in temperature when the daily photoperiods had been long (16 hours) and relatively more resistant to sudden chilling when they had been short (8 hours). The magnitude of the effect varied with the season. Thyroid activity was slightly greater in fish maintained under the shorter photoperiods. The longer photoperiods stimulated more rapid growth of ovaries during late winter and early spring. The endocrine system is considered a link in the chain of events regulating seasonal variations in resistance to sudden temperature change.

Leaf spot and dry rot of lettuce caused by Xanthomonas vitians (Brown) Dowson

1963 ◽  
Vol 14 (6) ◽  
pp. 778 ◽  
Author(s):  
DE Harrison
Keyword(s):  
Leaf Spot ◽  
Early Spring ◽  
Late Winter ◽  
Laboratory Studies ◽  
Dry Rot ◽  
Complete Destruction ◽  
Western Victoria ◽  
Valley Area ◽  
North Western

During the late winter and early spring of 1960, and again to a lesser extent in 1961 and 1962, many lettuce crops in the Murray Valley area of north-western Victoria were seriously affected by a disease characterized by blackening, dry rotting, and collapse of the affected leaves. The incidence of disease varied from about 10% up to practically complete destruction of some plantings. A yellow bacterium was consistently isolated from affected plants and proved to be pathogenic to lettuce. Laboratory studies have shown that the organism agrees closely with the recorded description of Xanthomonas vitians (Brown) Dowson, which has not, apparently, been previously studied in Australia.

scholarly journals A Brief Overview of Social Network Analysis and its Current State within Romanian Sociology

2013 ◽  
Vol 3 (3) ◽  
pp. 5-11
Author(s):  
Marian-Gabriel Hâncean
Keyword(s):  
Social Network ◽  
Social Network Analysis ◽  
Network Analysis ◽  
International Relations ◽  
Early Spring ◽  
Research Topics ◽  
Political Sciences ◽  
Current State ◽  
Wide Range ◽  
Network Studies

Abstract The field of social network studies has been growing within the last 40 years, gathering scholars from a wide range of disciplines (biology, chemistry, geography, international relations, mathematics, political sciences, sociology etc.) and covering diverse substantive research topics. Using Google metrics, the scientific production within the field it is shown to follow an ascending trend since the late 60s. Within the Romanian sociology, social network analysis is still in his early spring, network studies being low in number and rather peripheral. This note gives a brief overview of social network analysis and makes some short references to the current state of the network studies within Romanian sociology

Insecticide sprays, natural enemy assemblages and predation on Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae)

2014 ◽  
Vol 104 (5) ◽  
pp. 576-585 ◽  
Author(s):  
C. Monzo ◽  
J.A. Qureshi ◽  
P.A. Stansly
Keyword(s):  
Natural Enemy ◽  
Early Spring ◽  
Citrus Greening ◽  
Asian Citrus Psyllid ◽  
Late Winter ◽  
Diaphorina Citri ◽  
Citrus Groves ◽  
Arthropod Fauna ◽  
Predator Exclusion ◽  
Insecticide Sprays

AbstractThe Asian citrus psyllid (ACP), Diaphorina citri Kuwayama is considered a key citrus pest due to its role as vector of ‘huanglongbing’ (HLB) or citrus greening, probably the most economically damaging disease of citrus. Insecticidal control of the vector is still considered a cornerstone of HLB management to prevent infection and to reduce reinoculation of infected trees. The severity of HLB has driven implementation of intensive insecticide programs against ACP with unknown side effects on beneficial arthropod fauna in citrus agroecosystems. We evaluated effects of calendar sprays directed against this pest on natural enemy assemblages and used exclusion to estimate mortality they imposed on ACP populations in citrus groves. Predator exclusion techniques were used on nascent colonies of D. citri in replicated large untreated and sprayed plots of citrus during the four major flushing periods over 2 years. Population of spiders, arboreal ants and ladybeetles were independently assessed. Monthly sprays of recommended insecticides for control of ACP, adversely affected natural enemy populations resulting in reduced predation on ACP immature stages, especially during the critical late winter/early spring flush. Consequently, projected growth rates of the ACP population were greatest where natural enemies had been adversely affected by insecticides. Whereas, this result does not obviate the need for insecticidal control of ACP, it does indicate that even a selective regimen of sprays can impose as yet undetermined costs in terms of reduced biological control of this and probably other citrus pests.

Phenological phases of pollination related to climate change

2021 ◽  
Author(s):  
Samuel Monnier ◽  
Michel Thibaudon ◽  
Jean-Pierre Besancenot ◽  
Charlotte Sindt ◽  
Gilles Oliver
Keyword(s):  
Climate Change ◽  
Pollen Season ◽  
Microscopic Analysis ◽  
Allergic Diseases ◽  
Early Spring ◽  
Late Winter ◽  
General Tendency ◽  
New Production ◽  
Start Date ◽  
Generic Term

&lt;p&gt;Knowledge:&lt;/p&gt;&lt;p&gt;Rising CO2 levels and climate change may be resulting in some shift in the geographical range of certain plant species, as well as in increased rate of photosynthesis. Many plants respond accordingly with increased growth and reproduction and possibly greater pollen yields, that could affect allergic diseases among other things.&lt;/p&gt;&lt;p&gt;The aim of this study is the evolution of aerobiological measurements in France for 25-30 years. This allows to follow the main phenological parameters in connection with the pollination and the ensuing allergy risk.&lt;/p&gt;&lt;p&gt;Material and method:&lt;/p&gt;&lt;p&gt;The RNSA (French Aerobiology Network) has pollen background-traps located in more than 60 towns throughout France. These traps are volumetric Hirst models making it possible to obtain impacted strips for microscopic analysis by trained operators. The main taxa studied here are birch, grasses and ragweed for a long period of more than 25 years over some cities of France.&lt;/p&gt;&lt;p&gt;Results:&lt;/p&gt;&lt;p&gt;Concerning birch but also other catkins or buds&amp;#8217; trees pollinating in late winter or spring, it can be seen an overall advance of the pollen season start date until 2004 and then a progressive delay, the current date being nearly the same as it was 20 years ago, and an increasing trend in the quantities of pollen emitted.&lt;/p&gt;&lt;p&gt;For grasses and ragweed, we only found a few minor changes in the start date but a longer duration of the pollen season.&lt;/p&gt;&lt;p&gt;Discussion:&lt;/p&gt;&lt;p&gt;As regards the trees, the start date of the new production of catkins or buds is never the 1&lt;sup&gt;st&lt;/sup&gt; of January but depends on the species. For example, it is early July for birch. For breaking dormancy, flowering, and pollinating, the trees and other perennial species need a period of accumulation of cold degrees (Chilling) and later an accumulation of warm degrees (Forcing). With climate change these periods may be shorter or longer depending of the autumn and winter temperature. Therefore, a change in the annual temperature may have a direct effect on the vegetal physiology and hence on pollen release. It may also explain why the quantities of pollen produced are increasing.&lt;/p&gt;&lt;p&gt;The Poaceae reserve, from one place to another and without any spatial structuring, very contrasted patterns which make it impossible to identify a general tendency. This is probably due to the great diversity of taxa grouped under the generic term Poaceae, which are clearly not equally sensitive to climate change.&lt;/p&gt;&lt;p&gt;Conclusion:&lt;/p&gt;&lt;p&gt;Trees with allergenic pollen blowing late winter or early spring pollinate since 2004 later and produce amounts of pollen constantly increasing. Grasses and ragweed have longer periods of pollination with either slightly higher or most often lower pollen production.&lt;/p&gt;

Cytokinins and abscisic acid in hardening winter wheat

1990 ◽  
Vol 68 (7) ◽  
pp. 1597-1601 ◽  
Author(s):  
John S. Taylor ◽  
Munjeet K. Bhalla ◽  
J. Mason Robertson ◽  
Lu J. Piening
Keyword(s):  
Triticum Aestivum ◽  
Abscisic Acid ◽  
Winter Wheat ◽  
Leaf Tissue ◽  
Triticum Aestivum L ◽  
Early Spring ◽  
Growth Chamber ◽  
Late Winter ◽  
Sequence Of Events ◽  
Freeze Dried

During overwintering in a northern climate, winter wheat goes through a hardening process, followed by dehardening in late winter – early spring. This sequence of events may be partially controlled by changes in endogenous hormone levels. Crowns and leaf tissue from field grown winter wheat (Triticum aestivum L. cv. Norstar) seeded at the beginning of September were collected and freeze-dried at monthly intervals during the winters of 1985–1986 and 1986–1987. Material was also sampled and freeze-dried from seedlings grown in a growth chamber under hardening conditions (21 °C for 2 weeks plus 3 °C for 6 weeks) or nonhardening conditions (3 weeks at 21 °C). The tissues were analysed for cytokinins and abscisic acid. Cytokinin levels, measured with the soybean hypocotyl section assay, declined from October onwards and then rose to a peak in late winter (January and February, winter 1986–1987; February and March, winter 1985–1986), subsequently declining again. Abscisic acid, quantitated as the methyl ester by gas chromatography with an electron capture detector, increased in level from October to December, then decreased to a relatively low level between January and March. Hardened seedlings from the growth chamber contained significantly higher abscisic acid levels and significantly lower cytokinin levels than did the nonhardened seedlings. Key words: abscisic acid, cytokinins, hardening, Triticum aestivum, winter wheat.

scholarly journals Changes of Variability in Response to Increasing Greenhouse Gases. Part II: Hydrology

2009 ◽  
Vol 22 (22) ◽  
pp. 6089-6103 ◽  
Author(s):  
Richard T. Wetherald
Keyword(s):  
Soil Moisture ◽  
Greenhouse Gases ◽  
General Circulation ◽  
Circulation Model ◽  
Early Spring ◽  
Precipitation Rate ◽  
Late Winter ◽  
Annual Data ◽  
Geophysical Fluid Dynamics Laboratory ◽  
The Mean

Abstract This paper examines hydrological variability and its changes in two different versions of a coupled ocean–atmosphere general circulation model developed at the National Oceanic and Atmospheric Administration/Geophysical Fluid Dynamics Laboratory and forced with estimates of future increases of greenhouse gas and aerosol concentrations. This paper is the second part, documenting potential changes in variability as greenhouse gases increase. The variance changes are examined using an ensemble of 8 transient integrations for an older model version and 10 transient integrations for a newer model. Monthly and annual data are used to compute the mean and variance changes. Emphasis is placed on computing and analyzing the variance changes for the middle of the twenty-first century and compared with those found in the respective control integrations. The hydrologic cycle intensifies because of the increase of greenhouse gases. In general, precipitation variance increases in most places. This is the case virtually everywhere the mean precipitation rate increases and many places where the precipitation decreases. The precipitation rate variance decreases in the subtropics, where the mean precipitation rate also decreases. The increased precipitation rate and variance, in middle to higher latitudes during late fall, winter, and early spring leads to increased runoff and its variance during that period. On the other hand, the variance changes of soil moisture are more complicated, because soil moisture has both a lower and upper bound that tends to reduce its fluctuations. This is particularly true in middle to higher latitudes during winter and spring, when the soil moisture is close to its saturation value at many locations. Therefore, changes in its variance are limited. Soil moisture variance change is positive during the summer, when the mean soil moisture decreases and is close to the middle of its allowable range. In middle to high northern latitudes, an increase in runoff and its variance during late winter and spring plus the decrease in soil moisture and its variance during summer lend support to the hypothesis stated in other publications that a warmer climate can cause an increasing frequency of both excessive discharge and drier events, depending on season and latitude.

Early spring and late autumn response to applied nitrogen in four grasses

1980 ◽  
Vol 94 (2) ◽  
pp. 443-453 ◽  
Author(s):  
D. Wilman ◽  
A. A. Mohamed
Keyword(s):  
Perennial Ryegrass ◽  
Leaf Blade ◽  
Unit Area ◽  
Total Yield ◽  
Early Spring ◽  
Late Winter ◽  
Number Of Leaves ◽  
Four Levels ◽  
Leaf Extension ◽  
Applied Nitrogen

SummaryThe regrowth of Aberystwyth S. 23 perennial ryegrass, S. 24 perennial ryegrass, S. 59 red fescue and S. 170 tall fescue was studied in field swards, comparing four levels of applied nitrogen, for 8 weeks following a clearing cut. The clearing cuts were in mid-October, mid-February and mid-March in each of 3 years, different plots being used on each occasion.The application of N increased the number of leaf primordia, the number of un-emerged leaves, the rate of leaf emergence and death, leaf blade length, width and weight, sheath length, number of leaves per unit area of ground and proportion of green tissue in total yield. The application of N had little effect on the number of leaves per tiller and tended to reduce weight per unit area of leaf blade. The increase in size, weight and number of leaf blades appeared to be major reasons for the positive effect of applied N on yield, previously reported; and the increase in sheath length contributed to the increase in proportion of yield above 4 cm. Rate of leaf extension was not closely related to yield and was more sensitive to temperature than was yield. Changes during regrowth in blade and sheath length helped to explain changes in weight per tiller, previously reported. The effects of improving weather conditions in late winter/early spring were similar to the effects of applied N: larger, heavier leaf blades, longer sheaths, a taller canopy, a lower proportion of dead material, younger leaves. The length of shoot apex per leaf primordium was relatively constant. Leaves continued to emerge, at a slow rate, in the period December–February. S. 170 had the biggest leaves, particularly in May, and the slowest rate of leaf turnover. Rate of leaf extension was increased by applied N more, on average, in the ryegrasses than in the fescues.

scholarly journals One-Dimensional Hydrodynamic Modeling of the Euphrates River and Prediction of Hydraulic Parameters

2020 ◽  
Vol 6 (6) ◽  
pp. 1074-1090
Author(s):  
Nassrin Jassim Hussien Al-Mansori ◽  
Laith Shaker Ashoor Al-Zubaidi
Keyword(s):  
Water Resource ◽  
Gaussian Elimination ◽  
Linear Equations ◽  
Flow Characteristics ◽  
Early Spring ◽  
Future Application ◽  
Hydraulic Parameters ◽  
Euphrates River ◽  
One Dimensional ◽  
Wide Range

Forecasting techniques are essential in the planning, design, and management of water resource systems. The numerical model introduced in this study turns governing differential equations into systems of linear or non-linear equations in the flow field, thereby revealing solutions. This one-dimensional hydrodynamic model represents the varied unsteady flow found in natural channels based on the Saint-Venant Equations. The model consists of the equations for the conservation of mass and momentum, which are recognized as very powerful mathematical tools for studying an important class of water resource problems. These problems are characterized by time dependence of flow and cover a wide range of phenomena. The formulations, held up by the four-point implicit finite difference scheme, solve the nonlinear system of equations using the Newton-Raphson iteration method with a modified Gaussian elimination technique. The model is calibrated using data on the Euphrates River during the early spring flood in 2015. It is verified by its application to an ideal canal and to the reach selected at the Euphrates River; this application is also used to predict the effect of hydraulic parameters on the river’s flow characteristics. A comparison between model results and field data indicates the feasibility of our technique and the accuracy of results (R2 = 0.997), meaning that the model is ready for future application whenever field observations are available. 

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