Predator release from invertebrate generalists does not explain geometrid moth (Lepidoptera: Geometridae) outbreaks at high altitudes

2013 ◽  
Vol 145 (2) ◽  
pp. 184-192 ◽  
Author(s):  
Tino Schott ◽  
Lauri Kapari ◽  
Snorre B. Hagen ◽  
Ole Petter L. Vindstad ◽  
Jane U. Jepsen ◽  
...  
Keyword(s):  
Carabid Beetles ◽  
Birch Forest ◽  
Generalist Predators ◽  
Tree Line ◽  
High Altitudes ◽  
Lower Altitude ◽  
Rove Beetles ◽  
Northern Norway ◽  
Winter Moth ◽  
Underlying Mechanisms

AbstractOutbreaks of geometrid defoliators in subarctic birch forest in Fennoscandia often occur at high altitude in a distinct zone along the tree line. At the same time, moth larvae may not have an impact on the forest at lower altitude. Directly adjacent outbreak and nonoutbreak areas offer unique opportunities for studying the underlying mechanisms of outbreaks. Within two altitudinal gradients in coastal northern Norway, we investigated whether altitudinal outbreaks might be caused by release from pupal predation by ground-dwelling invertebrates such as harvestmen (Opiliones), spiders (Araneae), rove beetles (Coleoptera: Staphylinidae), carabid beetles (Coleoptera: Carabidae), and other beetles (Coleoptera). We predicted a consistently higher abundance of such generalist predators at low versus high altitudes. Our results did not support this prediction. There was no consistent altitudinal variation in the abundance of predators that could be related to zonal moth outbreaks in the birch forest slopes. In addition, none of the predator groups investigated showed any numerical response to a distinct outbreak of winter moth that took place during the course of the study. Consequently, localised moth outbreaks at the altitudinal tree line in northern Norway cannot be explained by the release from pupal predation by the predator groups examined here.

Altitude tolerance of chickens and pigeons

1961 ◽  
Vol 16 (1) ◽  
pp. 141-143 ◽  
Author(s):  
Paul D. Altland
Keyword(s):  
Sex Difference ◽  
High Altitudes ◽  
Lower Altitude ◽  
Altitude Tolerance

Chickens and pigeons were exposed for 6 hours to various simulated high altitudes to determine the highest altitude tolerated without deaths and the lowest altitude at which there are no survivors. Six- to seven-week-old chicks were less tolerant than twenty-to twenty-five-week-old chickens. All chicks survived exposure to 12,000 feet, 90% survived 14- and 16,000 feet and, at higher altitudes, the survival was progressively lower until none survived at 26,000 feet. All older chickens survived exposure to 16,000 feet; approximately 88% survived altitudes up to 20,000 feet and, above this, survival was greatly decreased until none survived at 26,000 feet. Roosters showed a greater altitude tolerance than hens, a sex difference contrary to that found in mammals. Six- to ten-week-old pigeons survived 6-hour exposures to all altitudes including 28,000 feet and 97% survived exposure to 30,000 feet. Only 27% survived 32,000 feet and all died within 10 minutes at 34,000 feet. The results indicate that chickens have a much lower altitude tolerance than all other small warm-blooded animals previously studied. Submitted on July 11, 1960

Applying Hollow Blades for Small Wind Turbines Operating at High Altitudes

2015 ◽  
Author(s):  
Abolfazl Pourrajabian ◽  
Reza Ebrahimi ◽  
Masoud Mirzaei ◽  
Mehdi Ahmadizadeh ◽  
David Wood
Keyword(s):  
Objective Function ◽  
Output Power ◽  
Wind Turbines ◽  
Speed Ratio ◽  
High Altitudes ◽  
Horizontal Axis Wind Turbine ◽  
Lower Altitude ◽  
Starting Time ◽  
Design Variables ◽  
Small Wind Turbines

Since the air density reduces as the altitude increases, operation of Small Wind Turbines (SWTs) which usually have no pitch mechanism, remains as a challengeable task at high altitudes due largely to the reduction of starting aerodynamic torque. By reducing the blades moment of inertia through the use of hollow blades, the study aims to mitigate that issue and speed up the starting. A three-bladed, 2 m diameter small horizontal axis wind turbine with hollow cross-section was designed for operating at two sites with altitude of 500 and 3,000 m. The design variables consist of distribution of the chord, twist and shell thickness along the blade. The blade-element momentum theory was employed to calculate the output power and starting time and, the beam theory was used for the structural analysis to investigate whether the hollow blades could withstand the aerodynamic and centrifugal forces. A combination of the starting time and the output power was included in an objective function and then, the genetic algorithm was used to find a blade for which the output power and the starting performance, the goals of the objective function, are high while the stress limitation, the objective function constraint, is also met. While the resultant stresses remain below the allowable stress, results show that the performance of the hollow blades is far better than the solid ones such that their starting time is shorter than the solid blades by approximately 70%. However, in the presence of the generator resistive torque, the algorithm could not find the blade for the altitude near to 3000 m. To solve that problem, the tip speed ratio of the turbine was added to other design variables and another optimization process was done which led to the optimal blades not only for the lower altitude but also for the higher one.

scholarly journals Observations of lower hybrid cavities in the inner magnetosphere by the Cluster and Viking satellites

2004 ◽  
Vol 22 (8) ◽  
pp. 2961-2972 ◽  
Author(s):  
A. Tjulin ◽  
M. André ◽  
A. I. Eriksson ◽  
M. Maksimovic
Keyword(s):  
Time Scales ◽  
Sounding Rocket ◽  
Lower Hybrid ◽  
High Altitudes ◽  
Frequency Range ◽  
General Shape ◽  
Lower Altitude ◽  
Inner Magnetosphere ◽  
Hybrid Frequency ◽  
The Individual

Abstract. Observations by the Viking and Cluster satellites at altitudes up to 35000km show that Lower Hybrid Cavities (LHCs) are common in the inner magnetosphere. LHCs are density depletions filled with waves in the lower hybrid frequency range. The LHCs have, until recently, only been found at altitudes up to 2000km. Statistics of the locations and general shape of the LHCs is performed to obtain an overview of some of their properties. In total, we have observed 166 LHCs on Viking during 27h of data, and 535 LHCs on Cluster during 87h of data. These LHCs are found at invariant latitudes from the auroral region to the plasmapause. A comparison with lower altitude observations shows that the LHC occurrence frequency does not scale with the flux tube radius, so that the LHCs are moderately rarer at high altitudes. This indicates that the individual LHCs do not reach from the ionosphere to 35000km altitude, which gives an upper bound for their length. The width of the LHCs perpendicular to the geomagnetic field at high altitudes is a few times the ion gyroradius, consistent with observations at low altitudes. The estimated depth of the density depletions vary with altitude, being larger at altitudes of 20000-35000km (Cluster, 10-20%), smaller around 1500-13000km (Viking and previous Freja results, a few percent) and again larger around 1000km (previous sounding rocket observations, 10-20%). The LHCs in the inner magnetosphere are situated in regions with background electrostatic hiss in the lower hybrid frequency range, consistent with investigations at low altitudes. Individual LHCs observed at high altitudes are stable at least on time scales of 0.2s (about the ion gyro period), which is consistent with previous results at lower altitudes, and observations by the four Cluster satellites show that the occurrence of LHCs in a region in space is a stable phenomenon, at least on time scales of an hour.

Aircraft Cabin Pressurization and Concern for Non-Arteritic Anterior Ischemic Optic Neuropathy

2020 ◽  
Vol 91 (9) ◽  
pp. 715-719
Author(s):  
Samir Nazarali ◽  
Henry Liu ◽  
Maleeha Syed ◽  
Terry Wood ◽  
Samuel Asanad ◽  
...  
Keyword(s):  
High Risk ◽  
Optic Neuropathy ◽  
Anterior Ischemic Optic Neuropathy ◽  
Ischemic Optic Neuropathy ◽  
High Altitudes ◽  
Commercial Aircraft ◽  
Lower Altitude ◽  
Aircraft Cabin ◽  
The Mean ◽  
Aircraft Type

BACKGROUND: Cabin pressurization is the process by which aircraft maintain a comfortable and safe environment for passengers flying at high altitudes. At high altitudes, most patients can tolerate changes in pressurization; however, passengers at high risk of hypoxia may experience ischemic events. The purpose of this study was to evaluate variations in pressurization of commercial aircraft at cruising altitude and describe its relevance in relation to patients with non-arteritic anterior ischemic optic neuropathy (NAION).METHODS: Altimeters were used to measure altitude and cabin altitude at cruising altitude aboard 113 commercial flights, including 53 narrow-body and 60 wide-body aircraft.RESULTS: Cabin altitude ranged from 4232 ft to 7956 ft at cruising altitudes ranging from 30,000 ft to 41,000 ft. The mean cabin altitude for all flights was 6309 876 ft. Narrow-body aircraft had a significantly higher mean cabin altitude (6739 829 ft) compared to wide-body aircraft (5929 733 ft). For all flights, the mean cruising altitude was 35,369 2881 ft with narrow-body aircraft cruising at a lower altitude of 34,238 2389 ft compared to wide-body aircraft at 36,369 2925 ft. Newer generation aircraft had a mean cabin altitude of 6066 837 ft, which was lower than the mean cabin altitude of older aircraft (6616 835 ft).DISCUSSION: Innovation in flight design has offered the ability for aircraft to fly at greater altitudes while maintaining lower cabin altitude. Those at high risk of hypoxia-induced complications may consider aircraft type when air travel is required.Nazarali S, Liu H, Syed M, Wood T, Asanad S, Sadun AA, Karanjia R. Aircraft cabin pressurization and concern for non-arteritic anterior ischemic optic neuropathy. Aerosp Med Hum Perform. 2020; 91(9):715719.

scholarly journals Increase in 6-Hydroxymelatonin Excretion in Humans during Ascent to High Altitudes

2004 ◽  
Vol 89 (9) ◽  
pp. 4388-4390 ◽  
Author(s):  
Herwig Frisch ◽  
Franz Waldhauser ◽  
Thomas Waldhör ◽  
Andrea Müllner-Eidenböck ◽  
Pritam Neupane ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Circadian Rhythms ◽  
Pineal Gland ◽  
Diurnal Variation ◽  
Healthy Volunteers ◽  
High Altitude ◽  
Physiological Role ◽  
Physiological Significance ◽  
High Altitudes ◽  
Lower Altitude

Melatonin (MLT), the pineal gland hormone involved in the regulation of circadian rhythms, shows characteristic diurnal variation. Its physiological role in humans is not clear. Exposure to high altitudes may disrupt the circadian rhythm and lead to various endocrine changes. MLT in humans has not been studied under these conditions. Urinary 6-hydroxy-MLT sulfate (aMT6s) excretion was analyzed during the day (0700–2200 h) and night (2200–0700 h) phases. A cohort of 33 healthy volunteers, aged 19–65 yr, was studied during an ascent to a high altitude in the Himalayas on three occasions (at a lower altitude, at 3400 m, and after reaching maximal altitudes of 5600–6100 m). aMT6s excretion during the daytime remained unchanged during exposure to high altitudes. As expected, nocturnal values were higher than diurnal values at each point in time. However, there was a significant increase in nocturnal MLT excretion after the ascent to high altitudes. Ascent to high altitudes is associated with increased nocturnal excretion of aMT6s. The mechanism and physiological significance of this MLT increase are unclear.

Do sub‐Arctic winter moth populations in coastal birch forest exhibit spatially synchronous dynamics?

2004 ◽  
Vol 73 (6) ◽  
pp. 1129-1136 ◽  
Author(s):  
ROLF A. IMS ◽  
NIGEL G. YOCCOZ ◽  
SNORRE B. HAGEN
Keyword(s):  
Birch Forest ◽  
Winter Moth

scholarly journals Differences in Mobility and Dispersal Capacity Determine Body Size Clines in Two Common Alpine-Tundra Arthropods

Insects ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 74 ◽  
Author(s):  
Beckers ◽  
Hein ◽  
Anneser ◽  
Vanselow ◽  
Löffler
Keyword(s):  
Body Size ◽  
High Mobility ◽  
Carabid Beetles ◽  
Alpine Tundra ◽  
The Arctic ◽  
Dispersal Capacity ◽  
Spatial Gradients ◽  
Temperature And Precipitation ◽  
Underlying Mechanisms ◽  
Possible Cause

The Arctic is projected to be severely impacted by changes in temperature and precipitation. Species react to these changes by shifts in ranges, phenology, and body size. In ectotherms, the patterns of body size clines and their underlying mechanisms are often hard to untangle. Mountains provide a space-for-time substitute to study these shifts along multiple spatial gradients. As such, mobility and dispersal capacity might conceal reactions with elevation. We test this influence on body size clines by comparing two common arthropods of the alpine tundra. We find that high mobility in the lycosid spider Pardosa palustris blurs elevational effects. Partially low mobility at least during development makes the carabid beetle Amara alpina more susceptible to elevational effects. Specific life-history mechanisms, such as brood care in lycosid spiders and holometabolic development in carabid beetles, are the possible cause.

scholarly journals Influence of Cover Crop Termination on Ground Dwelling Arthropods in Organic Vegetable Systems

Insects ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 445
Author(s):  
Laura Depalo ◽  
Giovanni Burgio ◽  
Serena Magagnoli ◽  
Daniele Sommaggio ◽  
Francesco Montemurro ◽  
...  
Keyword(s):  
Cover Crops ◽  
Cover Crop ◽  
Growing Season ◽  
Ground Beetles ◽  
Generalist Predators ◽  
Rove Beetles ◽  
Green Manuring ◽  
Growing Seasons ◽  
Cash Crops ◽  
Second Year

A key aspect in cover crop management is termination before the cash crop is planted. The aim of this study was to assess the effects of termination methods on ground-dwelling arthropods. The conventional mechanical termination method—i.e., green manuring by means of a disc harrow—was compared to flattening using a roller crimper. Two different crop systems were investigated for two growing seasons; cauliflower was grown in autumn after the termination of a mixture of cowpea, pearl millet, and radish, and tomato was cropped in spring and summer after the termination of a mixture of barley and vetch. Ground beetles (Coleoptera: Carabidae), rove beetles (Coleoptera: Staphylinidae), and spiders (Araneae) were sampled by means of standard pitfall traps throughout the growing season of both cash crops. The roller crimper increased the overall abundance of ground beetles in the first growing season of both cash crops, whereas in the second year, no significant effect could be detected. Rove beetles were more abundant in plots where the cover crops were terminated by the roller crimper. Finally, green manuring increased the abundance of spiders, especially on the first sampling date after cover crop termination. Albeit different taxa showed different responses, the termination of cover crops by a roller crimper generally increased the abundance of ground dwelling arthropods. Given that most of the sampled species were generalist predators, their increased abundance could possibly improve biological control.

Holocene tree‐line fluctuations and climate in central troms, Northern Norway

1996 ◽  
Vol 12 (1) ◽  
pp. 25-38 ◽  
Author(s):  
Torbjørn Alm ◽  
Karl‐Dag Vorren ◽  
Brynhild Mørkved
Keyword(s):  
Tree Line ◽  
Northern Norway
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