The Effect of Artificial Wind on the Growth-rate of Plants in Water Culture: With Plate and three Figures in the Text

Young plants of Brassica napus (rape), Hordeum vulgare, andPisum sativum growing in water culture have been exposed tofour continuous wind speeds for from 4 to 5 days. The plantswere exposed to natural daylight, humidity, and temperaturein a wind tunnel in which only air movement was controlled.The wind speeds found among the plants in the four sectionsof this tunnel were approximately 0·3, 0·7, 1·7,and 4·0 m./sec. The results showed no significant changein relative growth-rate or net assinilation rate with wind speed. Previously published results, obtained with plants in soil orsand culture, have differed from those in the present experimentsin showing a fall in the amount of growth as wind speed increased.It is suggested that the reduction in growth found in theseprevious experiments was caused by partial drying out of theplants, whilst in the present experiments water-supply to theroots was abundant and this effect was considerably reduced.     

粘虫成虫在气流场中飞行行为的观察研究

通过改进悬吊测飞技术、室内风洞和野外雷达相结合的观测方法,研究了粘虫在气流场中的飞行行为特征及其与气流的关系。直筒风洞自由飞行观测的结果表明,粘虫蛾对气流有明显行为反应,表现为头部迎风起飞和迎风飞行的特性;在3.0～5.5 m/s风速下,有92%～94% 的个体可一次逆风飞行通过2 m长的风洞;当风速≥6.0 m/s时,有71.9%的蛾子沿螺旋状的飞行轨迹逆风通过风洞。环形风洞悬吊飞行测试的结果表明,粘虫可逆风飞行的最大风速为7.2 m/s;在风速≤4 m/s条件下,90%以上个体头部迎风飞行或头部朝向与风向成一定的夹角,侧逆风飞行。 雷达观测发现粘虫在空中迁飞过程中具有成层现象,并有较强的秋季回迁定向行为,其头部总是朝向西南;迁飞的最终位移与风向及风速大小有关,迁飞位移速度是飞行速度与风速的矢量和。     

The Influence of Wind on the Behaviour of Stomata of Photosynthetic Stems of Cytisus scoparius (L.) Link

Potted transplants of Cytisus scoparius (L.) Link sub-speciesmaritimus (Rouy) Heywood (prostrate) and sub-species scoparius(erect) were subjected to an abrupt increase in wind speed.Following this change, stomata of the prostrate plants closedquite markedly to an equilibrium conductance within 60 min andremained substantially closed for at least the next 8 h. Stomatalconductance of erect plants increased slightly in the hour followingthe increase in windspeed but decreased gradually in the next8 h. These changes resulted in changes in transpiration andplant water status but stomatal responses to wind were not directresponses to changes in the bulk water status of the plants.It is suggested that the occurrence of sub-species maritimuson exposed sea cliffs and the limitation of the erect sub-speciesscoparius to relatively more sheltered habitats may be relatedto the stomatal responses to wind and the plant-water relationshipsof the two sub-species. Cytisus scoparius, broom, stomata, wind     

Transient response of sap flow to wind speed

Transient responses of sap flow to step changes in wind speedwere experimentally investigated in a wind tunnel. A Granier-typesap flow sensor was calibrated and tested in a cylindrical tubefor analysis of its transient time response. Then the sensorwas used to measure the transient response of a well-wateredPachira macrocarpa plant to wind speed variations. The transientresponse of sap flow was described using the resistance–capacitancemodel. The steady sap flow rate increased as the wind speedincreased at low wind speeds. Once the wind speed exceeded 8.0m s^–1, the steady sap flow rate did not increase further.The transpiration rate, measured gravimetrically, showed a similartrend. The response of nocturnal sap flow to wind speed variationwas also measured and compared with the results in the daytime.Under the same wind speed, the steady sap flow rate was smallerthan that in the daytime, indicating differences between diurnaland nocturnal hydraulic function, and incomplete stomatal closureat night. In addition, it was found that the temporal responseof the Granier sensor is fast enough to resolve the transientbehaviour of water flux in plant tissue. Key words: Nocturnal transpiration, sap flow, transient response, wind speed Received 31 July 2008; Revised 6 October 2008 Accepted 20 October 2008     

The Effect of Wind Speed on Assimilation Rate--a Re-assessment

Deneke concluded from wind-tunnel experiments that CO₂ uptakeis increased by wind, but that this stimulation is proportionatelyless at higher wind speeds, and that above Ioo m./min. (I₆₇cm./sec.) no further increase results. His data in fact indicatea linear relationship between wind and assimilation rate overthe whole range investigated. The wind speeds he used were ofthe same order as those occurring in vegetation in the field. Published experiments on the effect of wind on dry-weight increase,on the other hand, show that wind reduces growth; but theseexperiments have used winds equivalent to 'gale' or 'hurricane',and at such speeds other, harmful effects of wind become important. Wind-tunnel investigations on stands of Brassica napus reconcilethese observations by showing growth-rates to increase withwind speed up to an optimum near 30 cm./sec., and to fall offat higher speeds. It is considered that the stimulating effectof wind on assimilation shown by Deneke's and these experimentsis likely to be significant in the field.     

螟黄赤眼蜂在棉田的扩散方向及其与风速风向的关系

1994—1995年,在山东禹城进行了螟黄赤眼蜂Trichogramma chilonis在棉田的扩散方向及其影响因素的研究,结果表明：①螟黄赤眼蜂在棉田的扩散方向主要是受当时的风向和风速影响,其次是光照;②当平均风速为1.6 m/s时,螟黄赤眼蜂非常明显地顺风扩 散;当平均风速为1.1 m/s时,顺风扩散稍高于逆风扩散;当平均风速为0.9—1.0 m/s 时,逆风扩散高于顺风扩散;当平均风速为0.6 m/s时,各方向上扩散差异不大。③第二代棉铃虫发生期(7月上旬以前),螟黄赤眼蜂主要向西南和西北方向扩散;第三代棉铃虫发生期(7月),螟黄赤眼蜂各方向均等扩散;第四代棉铃虫发生期(8月中旬以后),螟黄赤眼蜂主要朝东和东北及北扩散。④总结6次放蜂情况,西和南两个方向上扩散均较少。     

Does turbulence play a role in feeding and reproduction of Calanus finmarchicus?

Data collected on cruises in the Norwegian Sea and the NortEast Atlantic have been re-analysed, introducing wind speedas a factor to explain gut fluorescence and egg production ofCalanus finmarchicus. Wind speed showed a negative relationwith gut fluorescence but not with egg production.     

Size, composition and distribution of particles related to wind induced resuspension in a shallow tropical lagoon

The size, composition and distribution of particles in the watercolumn were surveyed in a shallow area (1 m depth) of a tropicallagoon (Cte d'Ivoire) during a sequence of wind-induced resuspension.Water samples were collected hourly near the surface duringone tidal cycle. Three characteristic periods were distinguished:a calm period with low wind speed (average 1.2 m s^–1 awindy period with wind speed >3 m^–1 s (range between4 and 6 m s^–1) inducing sediment resuspension and a relaxationperiod during the decrease of wind velocity. From the analysisof several parameters (particle size and volume, bacteria. pico-and nanophytoplankton, ciliates and detritus), sediment resuspensioncaused a regular injection of particles from the bed. The finestparticles (1.5–6 µm: chlorophytes such as Chiorellaspp., picocyanobacteria such as Synechococcus) were the firstto be affected by wind-induced turbulence, whereas large particles(6–12 µm: diatoms. cyanobacteria such as Lyngbiaspp.) were dispersed into the water column at the highest windspeed. The fate of the different seston components differedaccording to their size. Therefore, wind-induced resuspensioncould greatly influence the food web organization through thequantity, quality and size of edible particles available ata given time.     

Influence of Wind Speed on the Sensitivity of Ryegrass to SO2

The sensitivity of S23 Lolium perenne L. to 11 parts 10^–8SO₂ was investigated at two different wind speeds. At the higherwind speed of 25 m min^–8, SO₂ caused significant reductionsin leaf area, root/shoot ratio, and all dry weight fractionsmeasured. At the lower wind speed of 10 m min^–1 growthreductions were not found. The differences in sensitivity ofplants to SO₂ at different wind speeds is discussed in relationto boundary layer resistances of leaves. It is concluded thatthe sensitivity of a plant to a particular pollutant shouldno longer be measured in terms of only the concentration andlength of exposure.     

Noctuid migration in Texas within the nocturnal aeroecological boundary layer

Long-distance migration of adult corn earworm moths (Helicoverpazea), and several other noctuid moth species, facilitates seasonalexpansion of pest populations and consequent increased infestationsof agricultural crops on a continental scale in North America.Long-term field studies of population dynamics and migratoryflights of H. zea and fall armyworm (Spodoptera frugiperda)in the United States were evaluated using X-band radar observationsand profiles of atmospheric conditions. These studies identifiedcharacteristic patterns of migratory flight that are largelyassociated with vertical profiles of temperature and wind speed.Collective patterns of moth migrations were generally highlycorrelated with wind headings, but often at a significant angulardeviation. Preliminary analyses are presented between moth distributionsin the aerosphere estimated from discrete moth counts usingX-band radar and bulk reflectivity data from NEXRAD Dopplerradar. Identification of associations between atmospheric factorsand noctuid population dynamics and migratory flights will improvethe ability to predict infestations by pest species throughouttheir broad seasonal range expansion.     

Optimal strategies for insects migrating in the flight boundary layer: mechanisms and consequences

Directed aerial displacement requires that a volant organism'sairspeed exceeds ambient wind speed. For biologically relevantaltitudes, wind speed increases exponentially with increasedheight above the ground. Thus, dispersal of most insects isinfluenced by atmospheric conditions. However, insects thatfly close to the Earth's surface displace within the flightboundary layer where insect airspeeds are relatively high. Overthe past 17 years, we have studied boundary-layer insects byfollowing individuals as they migrate across the Caribbean Seaand the Panama Canal. Although most migrants evade either droughtor cold, nymphalid and pierid butterflies migrate across Panamanear the onset of the rainy season. Dragonflies of the genusPantala migrate in October concurrently with frontal weathersystems. Migrating the furthest and thereby being the most difficultto study, the diurnal moth Urania fulgens migrates between Centraland South America. Migratory butterflies and dragonflies arecapable of directed movement towards a preferred compass directionin variable winds, whereas the moths drift with winds over water.Butterflies orient using both global and local cues. Consistentwith optimal migration theory, butterflies and dragonflies adjusttheir flight speeds in ways that maximize migratory distancetraveled per unit fuel, whereas the moths do not. Moreover,only butterflies adjust their flight speed in relation to endogenousfat reserves. It is likely that these insects use optic flowto gauge their speed and drift, and thus must migrate wheresufficient detail in the Earth's surface is visible to them.The abilities of butterflies and dragonflies to adjust theirairspeed over water indicate sophisticated control and guidancesystems pertaining to migration.     

The Boundary Layer over a Populus Leaf

Air flow over a Populus leaf was investigated using a hot-wireanemometer. When the air flow in the wind tunnel was laminar,the boundary layer was often turbulent at a wind speed of only1.5 m s^–1, particularly when encouraged by uneven topographyand roughness of the surface, as on the lower side of the leaf.The smoother upper surface behaved in a similar way to a flatplate when at low wind speeds, and the profiles of wind speedcould be shown to be equivalent to those expected from laminarboundary layer theory. Nevertheless, the boundary layer becameturbulent at Reynolds numbers much lower than those requiredto cause the transition to turbulence in a flat plate. Turbulentair flow in the wind tunnel greatly increased boundary layerturbulence but had only a small effect on evaporation from amodel of the leaf. The evaporation rates observed were 2.5 timeshigher than expected from theory, irrespective of the turbulenceregime.     

The Effect of Wind and a Reduced Supply of Water on the Growth and Water Relations of Festuca arundinacea Schreb

Festuca arundinacea was grown at high and low wind-speeds attwo levels of soil water. Transpiration was increased at highwind-speed and accompanied by leaf water stress. Growth of leafarea was progressively reduced according to the severity ofthe experimental treatments in the sequence: wet soil and lowwind; dry soil and low wind; wet soil and high wind; dry soiland high wind. The leaf water potential was also reduced inthis sequence. Festuca arundinacea Schreb., transpiration, water stress, wind, water potential     

Environmental Factors Affecting Airborne Pollen Concentration in Anemophilous Species of Plantago

Pollination of Plantago species in the Extremadura Region (SWof the Iberian Peninsula) was studied using three volumetrictraps located in the cities of Badajoz, Mérida and Cáceresbetween 1994 and 1999. Variations in atmospheric concentrationof Plantago pollen were analysed between locations, and annual,daily, and hourly variations recorded for each location. Thehighest concentrations of pollen were recorded at Cáceres,while the Mérida and Badajoz values were similar. Thisis explained by the nature of the surroundings of each city.Interannual variations in pollination levels were significantlycorrelated with autumn rains, which determine the extent ofdevelopment of the populations. The hourly patterns of pollencapture were well-defined and similar for all three study sites.Maximum levels were reached between 1000 and 1200 h. Nocturnalconcentrations were very low. Furthermore, this pattern wasmaintained throughout the flowering period, impling a very closelink with the patterns of anthesis of the species. The threestations showed similar patterns of daily variation, which weresignificantly correlated with certain meteorological parameters.Pollen concentrations were affected positively by temperature,but negatively by relative humidity. The influence of wind directionalso seemed to be explicable in these terms since the easterlywinds, which are dry and hot in this region, had a positiveinfluence, and the westerly winds which are moist and cool hada negative effect. The most relevant factor influencing levelsofPlantago pollen in the atmosphere was wind speed, which wasnegatively correlated with pollen levels. Copyright 2001 Annalsof Botany Company Plantago, aerobiology, reproduction, anemophily, pollen     

Effect of Wind on the Transpiration of Young Trees

The effects of wind on the transpiration rates of four plantspecies, Pinus sylvestris L., Quercus robur L., Fagus sylvaticaL. and Sorbus aucuparia L., were studied in a controlled environmentwind tunnel. Transpiration declined with increasing wind speedin a manner consistent with predictions of the Penman-Monteithequation. The stomatal resistance declined with increasing windspeed in two species and increased in one, but this effect wassmaller than reported in other studies. In all cases the magnitudeof the stomatal response was over-shadowed by the decliningleaf to air vapour pressure difference. Pinus sylvestris L., Quercus robur L., Fagus sylvatica L., Sorbus aucuparia L., wind, transpiration, cooling curve technique, stomatal resistance, aerodynamic resistance, Penman-Monteith equation     

The Role of the Plumage in Heat Transfer Processes of Birds

The plumage of birds provides a critical thermal buffer betweenthe animal and its environment. Rates of energy expenditureare strongly influenced by the thermal properties of the environmentor the microclimates the animal occupies. Current data suggestthat the addition of solar radiation is equivalent to threeto four-fold changes in wind speed and that solar heat gaincan be extremely sensitive to changes in wind speed. Dry heat transfer through the plumage occurs by three avenues1) conduction and free convection through air 2) conductionalong the solid elements of the plumage and 3) radiation. Overall,about 95% of the total heat flow is evenly divided between thefirst two avenues. Radiative heat transfer accounts for onlyabout 5% of total heat flow. Plumage color, as well as the microstructureand micro-optical properties of plumage elements, when combinedwith environmental properties (e.g., wind speed), determinethe radiative heat loads that birds acquire from solar radiation.Although plumage color or reflectivity determines the fractionof incident solar radiation that is absorbed by the plumageand generates heat, the fraction of this heat that contributesto the thermal load on the animal can vary greatly. In a fibrouscoat such as a plumage, there is some variable penetration intothe coat, with absorption over a range of coat depths. Factorssuch as feather micro-optics and structure are critical determinantsof radiation penetration into avian coats. Significant differencesin solar heat loads can also result from behavioral adjustmentsin plumage thickness.     

Macroscopic Features of Wind Damage to Leaves of Acer pseudoplatanus L. and Its Relationship with Season, Leaf Age, and Windspeed

Exposure to wind produces permanent abrasive damage to Acerpseudoplatanus L. leaves in the form of brown lesions, holes,distortions and tearing of the lamina. The zones of leaf thatare readily damaged change as the leaves expand and their topographyis altered. In the field, most damage was sustained early in the seasondespite the persistence of wind throughout the year. Wind tunnelstudies demonstrated that young expanding leaves were far moresusceptible to wind than mature leaves and that the percentagearea damaged increased linearly with windspeed. Acer pseudoplatanus L., sycamore, wind, leaf damage     

The dynamics of sponge larvae assemblages from northwestern Mediterranean nearshore bottoms

In this study, we show for the first time the dynamics of spongelarvae assemblages from nearshore meroplankton. Plankton wascollected by SCUBA diving once or twice a week during a 2-yearperiod over a rocky artificial reef in the NW Mediterranean.Data on larval abundance were cross correlated with the valuesof environmental parameters (i.e. seawater temperature, solarradiation, wind speed and atmospheric pressure). In the laboratory,we recorded external features and main behaviors of larvae.We collected larvae belonging to 20 different taxa of sponges,which are among the most common in the sublittoral hard bottomcommunities of the NW Mediterranean and other temperate areas.There was a positive correlation between maximum abundance oflarvae and highest water temperatures. Maximum solar radiationpreceded the maximum of larval abundance. Wind speed showedno clear seasonal patterns and atmospheric pressure was overallthe lowest when larvae were most abundant. Two main patternsin the larval release periods were observed. One was shown byspecies releasing larvae in summer, right before the maximumwater temperatures (orders Dictyoceratida and Dendroceratida)and another by the species whose larvae release from the endof summer till autumn, when temperatures decrease (order Poecilosclerida).The larvae of Phorbas tenacior, Raphidoflus jolicoueri, Mycalerotalis, Tedania anhelans, Pleraplysilla spinifera, Aplysillasulfurea var. rosea and Chelonaplysilla noevus are describedfor the first time. The larvae collected mainly belonged tothe parenchymella type (except for the species Oscarella sp.and probably Cliona viridis) and showed different features andbehaviors: from the elongated parenchymellae of Scopalina lophyropoda(order Halichondrida), which show simple swimming behavior andno response to light, to the parenchymellae of Poeciloscleridaand Dictyoceratida orders with variable morphologies as adaptationsto complex swimming behaviors. Our database will hopefully contributeto the present knowledge of larval types in sponges and definitivelyhighlight the importance of this group in the dynamics of meroplanktonfrom nearshore bottoms.     

Trade Winds Reduce Growth and Influence Gas Exchange Patterns in Papaya Seedlings

Four experiments were conducted to determine the effect of tradewinds in Guam, USA, on growth and gas exchange of three papaya(Carica papaya L.) cultivars. ‘Known You 1’, ‘Sunrise’,and ‘Tainung 2’ papaya seedlings at two differentstages of development were exposed to 0, 36 or 100% ambientwind. Wind exposure reduced stem height and leaf or stem dryweight in most cases, but had little influence on root growth.Net CO₂assimilation (A_CO2) at midday was lower for seedlingsexposed to wind than for those protected from wind. Dark respirationof exposed seedlings increased as much as 120% above that ofthe protected seedlings during the night. Wind exposure decreasedwhole plant evapotranspiration by up to 36% during the photoperiod,but increased evapotranspiration by 58–87% during thenocturnal period. Responses to wind exposure were similar amongcultivars, except that growth of ‘Tainung 2’ seedlingswas less affected by wind than that of the other cultivars.Seedlings that were exposed to the various wind treatments fromgermination onwards were less influenced by wind exposure thanwere seedlings that were grown in a protected nursery beforebeing exposed to the various wind treatments. These data indicatethat: (1) ambient trade winds in Guam are strong enough to decreasethe growth of papaya seedlings; (2) plant age influences theresponse; (3) stem and leaf growth are more influenced thanroot growth; and (4) decreasedA_CO2 and increased dark respirationmay be partly responsible for growth reduction. Copyright 2001Annals of Botany Company Carica papaya, gas exchange, wind     

The Effect of Wind on Provenances of Molinia caerulea L.

The response of seven Welsh provenances of Molinia caeruleato wind was assessed by measuring leaf growth and tillering.Leaf growth was usually depressed whilst tillering tended toincrease. On the basis of the results, an example of a wind-resistantand wind-susceptible provenance was chosen for further study.The wind susceptible provenance displayed the lowest water potentialsin the wind treatment, but this did not arise as a result ofit having a more easily damaged leaf surface than the resistantprovenance. The essential difference between the two provenancesappears to be in the hydraulic pathway from the soil to theleaf surface. Molinia caerulea L., provenance, wind, hydraulic pathway