The periodic motion of lodgepole pine trees as affected by collisions with neighbors

The periodic sways of a group of ten Pinus contorta var. latifolia (lodgepole pine) trees with slender stems from the Two Creeks site (TW) and ten stout trees from the Chickadee site (CH) both in Alberta, Canada were quantified. Tree displacement at TW was measured during periods of consistent wind direction with three mean wind speeds (1.9, 4.6, and 5.4 m/s) and for two mean wind speeds at CH (5.0 and 7.9 m/s). Spectral analysis of sway displacement data showed a decrease in the frequency with wind speed for trees at TW, but remained unchanged for trees at CH. Significant correlations between tree sway frequency and amplitude during high winds at TW indicate a loss of sway energy concomitant with the occurrence of high collision intensity. These observations support the hypothesis that inter-crown collisions have an important influence on the sway frequency of trees and should be incorporated into efforts to model their sway dynamics. We also present a theoretical collision-damped sway model which supports our empirical findings.     

科尔沁沙地人工杨树林生态服务效能评价

采用定位观测法,系统评价了杨树(Populus simonii)林的防风、抗蚀和滞尘等生态服务效能及其间接价值,同时定量探讨了风速减弱系数与实测林地叶面积指数的关系。结果表明,在研究区主害风(西北风)天气下,林地迎风区6H(H为平均树高)、3H、林地中央、林地背风区林缘、6和8H处2m高度的日平均风速与对照点(流动沙丘)相比均有不同程度减弱,风速减弱系数在18．3％～66．2％之间。林地背风区6H处0．25、0．5、1和2 m 4个高度的月平均风速减弱系数与林地叶面积指数呈显著非线性相关,其间存在良好的三次曲线关系(P<0．0001,R²=0．43～0．94,n=80)。在主害风天气下,林地各观测点的地表日风蚀量与对照点相比大幅度降低,平均降幅85．2％～99．9％。在观测期内,林地中央的日平均降尘量为13.2 kg·hm^-2,而林地迎风区6H处的日平均降尘量为9．9 kg·hm^-2,林地的日滞尘能力约为3．3kg·hm^-2。       

Intracanopy plasticity under strong wind conditions in the wild olive tree (Olea europaea L.): a conserved response between closely related taxa?

Trees have the ability to respond to local environmental cues by expressing particular phenotypes across their canopy through a mechanism known as intracanopy plasticity. In this study, intracanopy plasticity of Olea europaea subsp. europaea was analyzed by sampling leeward and windward canopy exposures of individuals occurring in an area with sustained strong wind conditions. A suite of morphofunctional and reproductive traits was measured at these contrasting canopy positions and, for comparison, also in wind-protected trees. Furthermore, the pattern of intracanopy plasticity of these plants was compared to that previously documented in a closely related species, Olea europaea subsp. guanchica. Plants exposed to strong winds displayed substantial differences between leeward and windward exposures in most of the study traits. Leeward exposures experienced a mean reduction of 73% in wind speed as compared to windward ones, and displayed a modular phenotype matching that observed in wind-protected plants. Wind-exposed plants, however, were comparatively smaller and had fewer and smaller inflorescences, since inflorescence size was positively associated with crown size. The two closely related species showed similar crown and leaf sizes between populations exposed to strong winds, and intracanopy responses were comparable for most traits. These observations suggest that intracanopy plasticity resulted in the expression of contrasting phenotypes within individuals, which allowed trees to persist under sustained wind stress, although at the cost of a reduced reproductive fitness. In addition, this study gives support to the idea that intracanopy responses are conserved among closely related taxa evolving in different habitats, but experiencing a comparable limiting factor.     

Oviposition site selection and effect of meteorological conditions on flight of Eudonia sabulosella (Lepidoptera: Scopariinae) with implications for pasture damage

Abstract

Eudonia sabulosella (Walker) is economically the most important hill country sod webworm in New Zealand. Female moths selected long, sparse pasture cover for oviposition. Adult flight patterns were assessed in relation to meteorological factors (temperature, humidity, rainfall, barometric pressure, wind speed and direction, and cloud cover) as well as lunar cycle phase. Moths were responsive to wind speed and direction, aggregating on slopes from east through south to west (i.e., 180° arc) particularly those of SW orientation, at wind speeds of ≤ 10 km/h. At higher wind speeds adults were confined to leeward slopes only within the 180° arc. Light rain was correlated with increased flight and oviposition. In sites where rainfall coincided with strong winds which confined adults, especially over favourable (long, sparse) pasture types, much oviposition occurred. Grasses in these sites were susceptible to larval sod webworm feeding damage several months later. Pasture management to remove the favoured sward type may therefore constitute an effective means of pest control for E. sabulosella on hill country.     

Wind-induced stresses in cherry trees: evidence against the hypothesis of constant stress levels

We calculated the wind-induced bending moments and stresses generated in the stems of five Prunus serotina conspecifics differing in height and canopy shape and size (based on detailed measurements of stem projected area and location with respect to ground level) to test the hypothesis that wind-loads generate uniform and constant stress levels along the lengths of tree twigs, branches, and trunks. These calculations were performed using five different wind speed profiles to evaluate the relative importance of the shape of wind speed profiles versus the ’geometry’ of tree shape on stem stress distributions and magnitudes. Additionally, we evaluated the effect of absolute tree size and stem taper on wind- induced stresses by scaling the size of smaller conspecifics to the absolute height of the largest of the five trees yet retaining the original stem proportions (i.e., diameter relative to stem length) for each plant. Finally, we also determined how the factor of safety for wind-loading (i.e., the quotient of stem yield stress and wind-load stress) changed as a function of tree size (and, presumably, age). Our results indicate that wind-load stress levels (1) vary along stem length even for the same wind speed profile and the same maximum wind speed; (2) would increase to dangerous levels with increasing tree height if it were not for ontogenetic changes in stem taper and canopy shape that reduce stress intensities to manageable levels; (3) tend to be more dependent on stem taper and canopy shape and size than on the shape of the wind speed profile; and (4) the factor of safety against wind-induced mechanical failure decreases as trees get larger, but varies along the length of large trees such that preferential stem failure is likely and functionally adaptive. We thus (1) reject the hypothesis of constant wind-induced stress levels; (2) support the view that size-dependent changes in stem taper are required to maintain wind-load mechanical reliability; and (3) suggest that certain portions of mature trees are ’designed’ to fail under high winds speeds, thereby reducing drag and the bending moments and stresses experienced by trunks. Received: 24 May 1999 / Accepted: 8 October 1999     

Interactive effects of body mass changes and species‐specific morphology on flight behavior of chick‐rearing Antarctic fulmarine petrels under diurnal wind patterns

For procellariiform seabirds, wind and morphology are crucial determinants of flight costs and flight speeds. During chick‐rearing, parental seabirds commute frequently to provision their chicks, and their body mass typically changes between outbound and return legs. In Antarctica, the characteristic diurnal katabatic winds, which blow stronger in the mornings, form a natural experimental setup to investigate flight behaviors of commuting seabirds in response to wind conditions. We GPS‐tracked three closely related species of sympatrically breeding Antarctic fulmarine petrels, which differ in wing loading and aspect ratio, and investigated their flight behavior in response to wind and changes in body mass. Such information is critical for understanding how species may respond to climate change. All three species reached higher ground speeds (i.e., the speed over ground) under stronger tailwinds, especially on return legs from foraging. Ground speeds decreased under stronger headwinds. Antarctic petrels (Thalassoica antarctica; intermediate body mass, highest wing loading, and aspect ratio) responded stronger to changes in wind speed and direction than cape petrels (Daption capense; lowest body mass, wing loading, and aspect ratio) or southern fulmars (Fulmarus glacialoides; highest body mass, intermediate wing loading, and aspect ratio). Birds did not adjust their flight direction in relation to wind direction nor the maximum distance from their nests when encountering headwinds on outbound commutes. However, birds appeared to adjust the timing of commutes to benefit from strong katabatic winds as tailwinds on outbound legs and avoid strong katabatic winds as headwinds on return legs. Despite these adaptations to the predictable diurnal wind conditions, birds frequently encountered unfavorably strong headwinds, possibly as a result of weather systems disrupting the katabatics. How the predicted decrease in Antarctic near‐coastal wind speeds over the remainder of the century will affect flight costs and breeding success and ultimately population trajectories remains to be seen.     

海岸不同坡向滨麦光合特性与风速异质环境的关系

在自然条件下,测定分析了夏季和秋季静风天及秋季大风天,海岸沙丘不同坡向环境因子及滨麦株高、叶片叶绿素含量、土壤含水量和光合日变化特性,以期明晰滨麦响应不同风速环境的生理调控机理。结果表明,不同坡向环境异质性明显,滨麦形态可塑性强。海岸迎风坡风大、温度低、湿度大,滨麦植株低矮、叶绿素含量较高;背风坡温度高、土壤干旱、空气流动差,滨麦植株高大,叶绿素含量低。在夏秋季静风天,迎风坡和背风坡滨麦叶片Pn出现光合"午休"现象,但迎风坡滨麦日均Gs、Tr、Pn均显著高于背风坡;而在秋季大风天,迎风坡和背风坡滨麦叶片Pn"午休"现象消失,并且背风坡滨麦日均Pn、Tr、Gs均显著高于迎风坡滨麦。同坡向相比,秋季大风天迎风坡滨麦日均Pn、Tr、Gs明显较秋季静风天低,而背风坡滨麦日均叶片Pn、Tr、Gs却较静风天分别增高126%、66.3%、134%。强海风吹袭引发迎风坡温度降低、滨麦叶片摇摆、气孔导度降低导致Pn下降,而强海风使背风坡空气流动加快、温度降低、气孔导度增大、"午休"消失使Pn增高。不同坡向滨麦对不同海风风速的适应表现出明显的光合生理可塑性,它在滨麦适应不同风力、提高其光合速率和增加物质积累上具有重要作用。而滨麦的形态和光合生理可塑性可能是其在不同海风强度下生存、生长、实现种群扩张的重要生理调控机理,这一特性在未来作物、牧草和树木抗风、抗盐育种中具有重要应用价值。     

Dispersal of the winged fruits of Nuytsia floribunda (Loranthaceae)

Fruits of the tree Nuytsia floribunda are dispersed by wind during autumn to mid-winter when conditions are suitable for germination. While the greatest density of fallen fruits occurs beneath the canopy, most are dispersed well beyond the tree in the direction of the prevailing west-southwesterly winds, with a minor peak corresponding to the easterlies. A multiple regression equation, which accounted for 77.5% of variance, was derived to account for the greatest dispersal distance per tree. This comprises, in decreasing order of importance, tree height, log (fruit load), and leeward and windward plant cover in the vertical plane. Extrapolation indicated a maximum distance of about 50 m can be expected, which is insufficient to account for the location of at least 6.5% of adult trees at the study site. This supports other evidence that suckering may play a major role in the spread of this species. Additional experiments confirmed the importance of wind velocity in the distance reached by fruits and the absence of biotic dispersal agents.     

Confronting the winds: orientation and flight behaviour of roosting swifts, Apus apus

Swifts, Apus apus, spend the night aloft and this offers an opportunity to test the degree of adaptability of bird orientation and flight to different ecological situations. We predicted the swifts' behaviour by assuming that they are adapted to minimize energy expenditure during the nocturnal flight and during a compensatory homing flight if they become displaced by wind. We tested the predictions by recording the swifts' altitudes, speeds and directions under different wind conditions with tracking radar; we found an agreement between predictions and observations for orientation behaviour, but not for altitude and speed regulation. The swifts orientated consistently into the head wind, with angular concentration increasing with increasing wind speed. However, contrary to our predictions, they did not select altitudes with slow or moderate winds, nor did they increase their airspeed distinctly when flying into strong head winds. A possible explanation is that their head-wind orientation is sufficient to keep nocturnal displacement from their home area within tolerable limits, leaving flight altitude to be determined by other factors (correlated with temperature), and airspeed to show only a marginal increase in strong winds. The swifts were often moving "backwards", heading straight into the wind but being overpowered by wind speeds exceeding their airspeed. The regular occurrence of such flights is probably uniquely associated with the swifts' remarkable habit of roosting on the wing.     

Historical frequency of wind dispersal events and role of topography in the dispersal of anostracan cysts in a semi-arid environment

Propagules of several freshwater invertebrates are passively dispersed by wind, but the importance of wind as a dispersal vector remains poorly understood. We examined the historical frequency of wind dispersal events in cysts of Artemia franciscana. A threshold wind speed of ~5 km/h was required to begin dispersing surface-resting cysts, beyond which cyst dispersal increased rapidly with increasing wind speed. The analysis of wind speed and cyst dispersal data from our field experiment and wind data for the last 45 years from a nearby airport revealed that wind events strong enough to disperse most cysts at a wind-exposed site are common, occurring on ~16 snow-free days per year and occurring consistently over long time periods. In a topographically uneven landscape, however, wind speeds vary substantially from one location to another; wind speeds at our exposed site were 69% higher than in a nearby wind-sheltered depression. Accordingly, winds strong enough to disperse most cysts from this sheltered site occurred on only 5 days of the 45 year period. Cysts are thus less likely to disperse from, and more likely to settle in, sheltered depressions than wind-exposed areas. Sheltered areas could thus function as traps for wind-dispersing propagules.     

To what extent can the tiny parasitoid wasps,Eretmocerus mundus,fly upwind?

Body miniaturization in insects is predicted to result in decreased flight speed and therefore limited ability of these insects to fly upwind. Therefore, tiny insects are often regarded as relying on passive dispersal by winds. We tested this assumption in a wind tunnel by measuring the burst speed of Eretmocerus mundus (Mercet), a beneficial parasitoid wasp with body length <1 mm. Insects were filmed flying upwind towards a UV light source in a range of wind speed 0–0.5 m/s. The Insects flew towards the UV light in the absence and presence of wind but increased their flight speed in the presence of wind. They also changed flight direction to be directly upwind and maintained this body orientation even while drifted backwards relative to the ground by stronger winds. Field measurements showed that the average flight speed observed in the wind tunnel (0.3 m/s) is sufficient to allow flying between plants even when the wind speed above the vegetation was 3–5 folds higher. A simulation of the ability of the insects to control their flight trajectory towards a visual target (sticky traps) in winds show that the insects can manipulate their progress relative to the ground even when the wind speed exceeds their flight speed. The main factors determining the ability of the insects to reach the trap were trap diameter and the difference between insect flight speed and wind speed. The simulation also predicts the direction of arrival to the sticky target showing that many of the insects reach the target from the leeward side (i.e. by flight upwind). In light of these results, the notion that miniature insects passively disperse by winds is misleading because it disregards the ability of the insects to control their drift relative to the ground in winds that are faster than their flight speed.     

Effects of host-odour plume altitude and changing wind velocity on upwind flight manoeuvres of a specialist braconid parasitoid

Abstract. Females of the specialist parasitoid, Microplitis croceipes (Cresson) (Hymenoptera: Braconidae), were released in a wind tunnel into host-odour plumes dispersed by winds of three velocities and winds whose speed was changed while the wasps were engaged in upwind flight. In steady winds of 61, 122 and 183 cms-^-1, wasps maintained similar 'preferred' ground speeds by adjusting their airspeed, while turning to a lesser degree as wind velocity increased. In winds of changing velocity (either increasing or decreasing within a 60–100 cm s-¹ range), wasps lowered their rate of upwind progress, leading to more tortuous tracks. During changing wind speeds longitudinal image flow decreased. Wasps flying in host-odour plumes 10 cm and 20 cm above the flight tunnel floor in a 122 cm s-¹ wind had similar ground speeds; thus their rate of ventral visual image flow varied two-fold. M.croceipes may 'aim' upwind by comparing how changes in the course angle vary with the direction of visual image flow. During changing wind velocities the relationship between changes in visual and flight muscle generated torque is ambiguous. Under these conditions most wasps cast, a manoeuvre characterized by wide lateral excursions across the wind without upwind progress. Once wind speed stabilizes, flight straightens out and upwind flight resumes.     

Nocturnal passerine migration without tailwind assistance

Nocturnal passerine migrants could substantially reduce the amount of energy spent per distance covered if they fly with tailwind assistance and thus achieve ground speeds that exceed their airspeeds (the birds’ speed in relation to the surrounding air). We analysed tracking radar data from two study sites in southern and northern Scandinavia and show that nocturnally migrating passerines, during both spring and autumn migration, regularly travelled without tailwind assistance. Average ground and airspeeds of the birds were strikingly similar for all seasonal and site‐specific samples, demonstrating that winds had little overall influence on the birds’ resulting travel speeds. Distributions of wind effects, measured as (1) the difference between ground and airspeed and (2) the tail/headwind component along the birds’ direction of travel, showed peaks close to a zero wind effect, indicating that the migratory flights often occurred irrespective of wind direction. An assessment of prevailing wind speeds at the birds’ mean altitude indicated a preference for lower wind speeds, with flights often taking place in moderate winds of 3–10 m/s. The limited frequency of wind‐assisted flights among the nocturnal passerine migrants studied is surprising and in clear contrast to the strong selectivity of tailwinds exhibited by some other bird groups. Relatively high costs of waiting for favourable winds, rather low probabilities of occurrence of tailwind conditions and a need to use a large proportion of nights for flying are probably among the factors that explain the lack of a distinct preference for wind‐assisted flights among nocturnal passerine migrants.     

Can wind help explain seasonal differences in avian migration speed?

A bird's ground speed is influenced by the wind conditions it encounters. Wind conditions, although variable, are not entirely random. Instead, wind exhibits persistent spatial and temporal dynamics described by the general circulation of the atmosphere. As such, in certain geographical areas wind's assistance (or hindrance) on migratory flight is also persistent, being dependent upon the bird's migratory direction in relation to prevailing wind conditions. We propose that, considering the western migration route of nocturnal migrants through Europe, winds should be more supportive in spring than in autumn. Thus, we expect higher ground speeds, contributing to higher overall migration speeds, in spring. To test whether winds were more supportive in spring than autumn, we quantified monthly wind conditions within western Europe relative to the seasonal direction of migration using 30 years (1978–2008) of wind data from the NCEP/NCAR Reanalysis dataset. We found that supporting winds were significantly more frequent for spring migration compared to autumn and up to twice as frequent at higher altitudes. We then analyzed three years (2006–2008) of nocturnal migratory ground speeds measured with radar in the Netherlands which confirmed higher ground speeds in spring than autumn. This seasonal difference in ground speed suggests a 16.9% increase in migration speed from autumn to spring. These results stress the importance of considering the specific wind conditions experienced by birds when interpreting migration speed. We provide a simple methodological approach enabling researchers to quantify regional wind conditions for any geographic area and time period of interest.     

Wind damage and response in New Zealand forests: a review

The literature on wind damage in New Zealand forests is reviewed to investigate how abiotic and biotic factors influence damage severity, damage type, and forest recovery. Winds that damage forests tend to result from extra-tropical depressions or from topographically enhanced westerly air flows. Severe wind damage can occur when wind speeds exceed c. 0 km/hr, although investigating the relationship between damage and wind speeds is difficult, as gusts, for which speed is usually unrecorded, are important. Damage is often quantified by estimates of area affected, with some authors detailing the size and species of damaged trees within a given area. Key abiotic factors that influence damage patterns are topographical position, edaphic conditions, and disturbance history. Important biotic factors are tree height, tree health, position of the tree within the stand, and species. Damage type (uprooting or breakage) is primarily controlled by canopy position and rooting depth. Forest responses to wind damage include sprouting, recruitment, release, and suppression, with the dominant mode of forest recovery being strongly influenced by the severity of damage, and the species composition of the stand. As noted in international literature on wind damage, a lack of consistent methods, combined with poor species and spatial coverage, makes identifying general trends difficult. Investigating the role of wind damage in New Zealand forests has focused to date on Nothofagus forests and plantations of exotic trees and few studies have investigated long term dynamics following wind disturbance events.     

基于CFD模拟的不同地形格局风场规律及其风感规划对策

近地表地形的风场受坡度坡向、地表形态和空间格局等地形要素的控制,从而影响人的"风感"体验,是人居环境的选址与布局需要考虑的重要因素。通过建立地形3D模型、划分网格、设定模拟工况,运用Fluent 14.0软件对不同山体地形坡度、形态和格局的风场进行CFD （Computational Fluid Dynamics）模拟。结果发现：（1）坡度在0.3以下对地形风场影响较小;当坡度大于0.5时,随坡度增大背风坡风影区逐渐增大,挡风效果更加明显;坡度大于0.7以后,随着风影区加大,回流涡旋更加明显。（2）风场受到周边地形形体的影响,尤其是迎风面和背风面截面变化率。迎风面截面变化率越大,风速变化越快;背风面截面变化越大,背风面的出现风影区和回流涡旋的几率越大。迎风面出现凹形迎风口会形成气体滞留区,而背风面凹形口后部会增加风影区和回流涡旋出现的几率。（3）不同地形格局对单个地形的风场具有强化和减弱效果。"三面环山"的相对封闭的地形格局有利于形成稳定的风场,并提高风感舒适度。在人居环境的风感营造和优化中,需要避开风感敏感区域,即风速激增区、回流涡旋区、无固定风向的强烈湍流区、气流不流通的静风区和气流死循环涡旋区等风感敏感区,并利用植被或者人工构筑物来消除敏感区或削弱这一影响。并根据不同的气候类型和城市特点进行选址、地形改造或者进行内部地形格局调整和优化,以提高风感舒适度。选择开放型地形格局和低坡度、平行风向的流线型地形能够加强通风,而塑造封闭性地形格局和垂直风向的陡坡地形能够减小风速。     

Wind-induced water movements in the South Basin of Windermere

SUMMARY. The results of direct current measurements in the South Basin of Windermere are presented and related to wind history and horizontal variations in near-surface water temperature. Currents were measured by Lagrangian methods using drift-bottles and depth-specific drogues. Except when sudden calms followed strong winds, internal seiche movements had little effect on horizontal transport in the epilimnion. The most important factor governing mass water movement was direct wind forcing. Variations in wind speed accounted for 93% of the variation in near-surface current speed.
For wind speeds between 100 and 500 cm s⁻¹ the wind factor (current speed/wind speed) decreased linearly with wind speed. At wind speeds above 500 cm s⁻¹ the wind factor remained relatively constant around 1 %.
Coriolis effects deflected near-surface currents 4–38° to the right of the wind. The degree of deflection was strongly correlated with the relative depth D_E / D _* (where D_E was the depth of the epilimnion and D _* the depth of frictional resistance). The influence of the Coriolis force also produced pronounced rotations, with depth, of the wind-driven current. The circulation pattern within the epilimnion was broadly that of a distorted conveyor belt moving at some angle to the wind axis. The strength of the transverse circulation was greatest at low wind speeds with a deep thermocline.
Richardson-number calculations suggest that the thermocline generally acts as a low-friction boundary between a turbulent epilimnion and a relatively quiescent hypolimnion. Horizontal variations in water temperature, although ranging from only 0.2 to 1.0°C per km, served as a good indirect 'tracer' of the circulation pattern.     

Homeostasis in leaf water potentials on leeward and windward sides of desert shrub crowns: water loss control vs. high hydraulic efficiency

Phenotypic plasticity in morphophysiological leaf traits in response to wind was studied in two dominant shrub species of the Patagonian steppe, used as model systems for understanding effects of high wind speed on leaf water relations and hydraulic properties of small woody plants. Morpho-anatomical traits, hydraulic conductance and conductivity and water relations in leaves of wind-exposed and protected crown sides were examined during the summer with nearly continuous high winds. Although exposed sides of the crowns were subjected to higher wind speeds and air saturation deficits than the protected sides, leaves throughout the crown had similar minimum leaf water potential (Ψ_L). The two species were able to maintain homeostasis in minimum Ψ_L using different physiological mechanisms. Berberis microphylla avoided a decrease in the minimum Ψ_L in the exposed side of the crown by reducing water loss by stomatal control, loss of cell turgor and low epidermal conductance. Colliguaja integerrima increased leaf water transport efficiency to maintain transpiration rates without increasing the driving force for water loss in the wind-exposed crown side. Leaf physiological changes within the crown help to prevent the decrease of minimum Ψ_L and thus contribute to the maintenance of homeostasis, assuring the hydraulic integrity of the plant under unfavorable conditions. The responses of leaf traits that contribute to mechanical resistance (leaf mass per area and thickness) differed from those of large physiological traits by exhibiting low phenotypic plasticity. The results of this study help us to understand the unique properties of shrubs which have different hydraulic architecture compared to trees.     

Is microclimate important for Orthoptera in open landscapes?

Orthoptera were monitored on field edge public footpaths on the east (leeward) and west (windward) side of hedgerows in Chelmsford, UK, in 2006. A total of 6 species were recorded from footpaths on the leeward side of hedgerows probably due to the shelter from the prevailing westerly winds provided by the trees and shrubs. On the windward side of hedgerows species richness and abundance of Orthoptera were reduced (only 4 species were recorded). It is suggested that shelter from the wind and the exposure to early morning sunlight for Orthoptera on the east side of hedgerows are important factors governing their occurrence on farmland. Many replicates had Environmental Stewardship (ES) scheme field margins adjacent but they did not affect Orthoptera species richness or abundance.     

Biodiversity buffers pollination from changes in environmental conditions

A hypothesized underlying principle of the diversity‐functioning relationship is that functional groups respond differently to environmental change. Over 3 years, we investigated how pollinator diversity contributes to the magnitude of pollination service through spatial complementarity and differential response to high winds in California almond orchards. We found honey bees preferentially visited the top sections of the tree. Where wild pollinators were present, they showed spatial complementarity to honey bees and visited the bottom tree sections more frequently. As wind speed increased, honey bees' spatial preference shifted toward the bottom tree sections. In high winds (>2.5 m s^?1), orchards with low pollinator diversity (honey bees only) received almost no flower visits. In orchards with high pollinator diversity, visitation decreased to a lesser extent as wild bee visitation was unaffected by high winds. Our results demonstrate how spatial complementarity in diverse communities can help buffer pollination services to environmental changes like wind speed.