Height Zones Research Articles

DISTRIBUTION REGULATIONS AND LIFE FORMS OF THE SPECIES OF THE BERBERIDACEAE JUSS. FAMILY WHICH ARE DISTRIBUTED IN THE NAKCHIVAN AUTONOMOUS REPUBLIC OVER ALTITUDE ZONES

Nakhchivan Autonomous Republic, which is part of Azerbaijan, has unique physical and geographical conditions. The total length of the border lines of the autonomous republic, located in the south west of the Lesser Caucasus, is 398 km. The main plain of the Autonomous Republic, 2/3 of which is mountainous and 1/3 is plain, is Araz-Long Plain, which in turn is divided into Ordubad, Nakhchivan, Sharur, Sadarak and other small Plains. Due to the fact that the territory of Nakhichevan Autonomous Republic consists of mountainous and lowland areas, the vegetation cover was formed in accordance with these conditions. The north-eastern territories of the autonomous republic, being part of the high mountain belt, cover heights of more than 2500 meters, and the Alpine and subalpine meadows of the Zangazur and Daralayaz ranges included here cover large areas. Plants belonging to the family Berberidaceae Juss. are distributed mainly in the middle and lower mountain belts, sometimes in the upper mountain belt, Alpine and subalpine belts on dry slopes, clayey, salty soils, Stony-gravel areas, as well as in arable land, field and grounds. In the article berberidaceae juss. The distribution of plants belonging to the family in the height zones, life forms have been studied and it has been determined that the species belonging to this family are most common in the middle and low mountain zones. Keywords: low mountain belt, barberry, height belts, shrub, Berberis vulgaris L., biological spectrum, distribution pattern.

The influence of slope exposure and altitude on the height of trees in the stands of the Carpathian beech forest Dentario glandulosae-Fagetum in the lower montane zone in the Bieszczady National Park

The influence of slope exposure and altitude on the height of trees in the stands of the Carpathian beech forest Dentario glandulosae-Fagetum in the lower montane zone in the Bieszczady National Park. The aim of the study was to investigate the influence of slope exposure and elevation above sea level on the average height of trees in the stands of the Carpathian beech forest Dentario Glandulosae-Fagetum in the lower montane zone of the Bieszczady National Park. The research material consisted of measurements made as part of a grid of permanent research plots of the Bieszczady National Park with a size of 4 ares, arranged in a grid of squares with a spacing of 500 x 500 m. Using a two-factor analysis of variance, the average height of beech trees in two height zones (600-800 and 800-1000 m above sea level) and at two slope exposures (north and south) were compared. The influence of the interaction between the two factors was also studied. The height of beech stands was mainly determined by the altitude and the interaction between the exposure of the slope and the altitude. It was not found that the exposure of the slope significantly differentiated the average heights of beech trees in the lower montane zone in the Bieszczady National Park.

Achieving fully equiaxed grain microstructure and isotropic mechanical properties in wire arc additive-manufactured Mg-Y-Nd-Zr alloys

The thin-wall Mg-3.82Y-2.46Nd-0.56Zr (WE43) alloy component was fabricated using cold metal transfer-based wire arc additive manufacturing technology (WAAM-CMT) and the way in which microstructure evolution influences the corresponding mechanical properties in different height zones was studied. The thin-wall WE43 alloy component was mostly composed of fully equiaxed grains that had low texture strength. As a result of the layer-by-layer deposition, its microstructure exhibited obvious layer characteristics, mainly including melt pools (MP) with coarse equiaxed grains and melt pool boundaries (MPBs) with fine equiaxed grains. The grain size of the thin wall in the building direction decreased from 25.3 ± 1.2 µm in the bottom zones to 22.3 ± 0.7 µm in the top zones, whereas the content of the second phase increased. No obvious anisotropy was observed in the mechanical properties of the thin wall. The top zone specimens were found to have the best mechanical properties with ultimate tensile strength (UTS) of 233 MPa, yield strength (YS) of 153 MPa and elongation (EL) of 10.4%. In comparison to the bottom zone specimens, improvement in the mechanical properties of the top zone specimens resulted from secondary phase strengthening and grain boundary strengthening.

Improvement of the multi-source weighted-ensemble precipitation dataset and application in the arid area of Tianshan Mountains, central Asia

With high resolution and wide coverage, satellite precipitation products like the Multi-Source Weighted Ensemble Precipitation (MSWEP) could support hydrological research in arid regions, where the spatial heterogeneity of precipitation is high, but rain gauges are sparse, but these products are inevitably subject to errors. In this study, we integrated measured precipitation and topographic data, and improved MSWEP by interpolation and an optimal regression model. The Tianshan Mountain area was taken as a typical arid area, and spatial stratified heterogeneity of precipitation was analyzed. The results show that: (1) The optimal regression model combined the advantages of site interpolation and MSWEP and improved the underestimation of precipitation in mountainous areas; (2) The precipitation decreased from West to East, and from North to South, and the precipitation in West and East subregions increased linearly with the elevation. The maximum precipitation height zone in the North is located at 4300 m. There are two maximum precipitation height zones in the South; (3) The accuracy of spatial interpolation of station data was limited by the uneven distribution of the stations in the East subregion, and the inaccuracy of MSWEP was due to the land cover and topography of the North and South subregions. The improved MSWEP (IMMSWEP) not only resolved the problem of lack of rainfall stations in arid area, but also resulted in an inversion of regional spatial precipitation differentiation with high resolution and high precision, providing a reference for meteorological researchers.

Genetic population structure of Cheilolejeunea rigidula (Lejeuneaceae) in the Amazon region

We studied the community structure and diversity of epiphytic bryophytes in a vertical gradient from tree base to canopy in four lowland rain forest sites of the Colombian Amazon (Amazonas, Caquetá, Putumayo, and Vaupés). Each of the 64 sampled phorophytes was divided into six height zones from the base (Z1) to the outer canopy (Z6). As a subproject, we carried out a genetic population study using the liverwort Cheilolejeunea rigidula (Lejeuneaceae) as our model species, which occurred in all six height zones. In addition to 65 successfully sequenced samples from the study sites, we included individuals of C. rigidula from Guiana and Brazil (Manaus and Tapajos) to investigate the connectivity and genetic structure of this species across the Amazon region and to evaluate the genetic structure based on phorophyte height zones. Each site in Colombia, Brazil and Guiana was considered a subpopulation. The sequenced chloroplast markers (partial atpB gene, partial psbA gene/psbA-trnH spacer) showed little variation across the Amazon and the height zones on the trees. The nuclear marker (ITS) showed a spatial structure indicating genetic differentiation of subpopulations across the Amazon, but little genetic differentiation of C. rigidula along the height of the trees. The gradient across the Amazon shows a relationship between genetic distance and geographic distance, indicating dispersal limitations (P<0.001). At local and regional scales, our results suggest that dispersal can have a dominant effect on populations and communities, increasing connectivity.

Vegetation spectral characteristics based on altitude zone in galunggung volcano

Galunggung is an active volcano with an altitude of 2168 meter above sea level. Galunggung Volcano has a diversity of vegetation and habitat for various fauna. Previous research explained that Galunggung Volcano has at least 43 species of typical plants, which are divided into categories of mature trees, poles, saplings, and seedlings / undergrowth. However, the spectral characteristics of these plant types are still unknown. On the other hand, remote sensing with infrared channels is the right technology to analyze the spectral characteristics of vegetation in Galunggung Volcano. Therefore, this study aims to analyze the specific characteristics of vegetation on Galunggung Volcano based on height zones. This research uses Landsat 8 imagery, Aster GDEM imagery, and Hyperion imagery. It is expected that the results of image processing can show how the altitude affects the different spectral characteristics and types of vegetation in the study area.

Path Planning of Electric VTOL UAV Considering Minimum Energy Consumption in Urban Areas

As a new mode of transportation in the future, electric vertical take-off and landing unmanned aerial vehicles (eVTOL UAV) can undertake the task of logistics distribution and carry people in urban areas. It is challenging to carry out research designed to plan the path of eVTOL UAVs which can have a safe and sustainable operation mode in urban areas. Therefore, this work proposes a method for planning an obstacle-free path for eVTOL UAVs in urban areas with the goal of minimizing energy consumption. It aims to improve the safety and sustainability of eVTOL UAV operations. Based on variations of air density with height, a more accurate formula for calculating battery energy consumption of eVTOL UAV is derived. It is used in the vertical takeoff and landing phase and horizontal flight phase, respectively. Considering the influence of buildings on eVTOL UAV operation, a path planning method applicable to complex urban environments is proposed. The safe nodes of eVTOL UAV flight are obtained by using Voronoi diagrams based on building locations. Then, the complete shortest and obstacle-free path is obtained by using a Dubins geometric path and Floyd algorithm. After obtaining the obstacle-free paths for all flight height zones, the battery energy consumption of the eVTOL UAV in each flight height zone is calculated. Then, the flight height with the minimum energy consumption is obtained. The simulation results show that the path length obtained by the proposed path planning method is shorter than that obtained by particle swarm optimization; the total battery energy consumption changes in the same pattern in the low-altitude areas and high-altitude areas; the difference between the maximum and minimum energy consumption in the small area enables the eVTOL UAV to cover about 350 m more, and about 420 m more in the large area. Therefore, in future high-frequency UAV mission flights, choosing the altitude with the lowest energy consumption can reduce UAV operator costs. It can also significantly increase UAV transport range and make UAVs operate more sustainably.

Importance of the vertical gradient in the variation of epiphyte community structure in the Brazilian Atlantic Forest

Epiphytes are strongly affected by the microclimate of the forest canopy. Therefore, understanding how microclimatic changes are related to the functional characteristics of taxa and the patterns of communities is essential. Our objective was to examine the stratification of the epiphyte community along the vertical gradient of the forests and to investigate whether the pattern of species distribution in the canopy height zones is similar among forests with different characteristics and between the families of epiphytic plants. The study was carried out in the Atlantic Forest of Ilha Grande, in southeastern Brazil, where we recorded 76 species. The highest richness and abundance were found on tree trunks. The high crown had less diversity and a characteristic set of species. The vertical stratification pattern was similar across forests with different phytophysiognomies. The main epiphytic families exhibited different patterns of diversity along the canopy. The highest richness of Araceae occurred in the trunk zones, while Polypodiaceae, Bromeliaceae, and Orchidaceae were more diverse in the trunk and inner crown, and Cactaceae were more diverse in the inner crown. Tree height zones select epiphytic taxa with distinct characteristics according to the fundamental conditions for their survival and, therefore, we suggest that the ecological niche theory is adequate to explain the assembly of epiphytic communities at a local scale.

Topography and wind moulding directions of autumn migration between Europe and the West African savannas

This review on autumn migratory directions is thought as a complement to an earlier overview on the vertical distribution of bird migration between the Baltic Sea and the Sahara (Bruderer et al. in J Ornithol 159:315–336, 2018): (1) A broad synopsis shows that nocturnal migration is generally SW-oriented above the western half of the European mainland, bending gradually southward above the western Sahara and shifting SE at the Sahara-Sahel transition. Important deviations of the SW stream occur along mountain ranges and coastlines. (2) Taking the Alps as a case example of such a leading-line reveals that the effect of the Alpine arc on migratory directions increases from E to W, becoming most prominent in Switzerland where the northern border and the main ridges of the Alps bend from WSW towards SSW. Thus, the migratory stream gets increasingly aligned with the course of the mountain range and reaches highest concentrations in the Swiss Lowlands. (3) Simultaneously recorded tracking radar data on nocturnal migration above Southern Germany and above the Swiss Lowlands show similar distributions of headings, but different tracks (flight directions over ground). (4) Generally, a large proportion of the tracks above the rather flat country N of the Rhine is shifted towards S or SE by frequent westerly winds. This contrasts with barely drifting birds facing south-westerly headwinds canalized along the Jura Mountains in the Swiss Lowlands. (5) Tracks and headings under varying wind conditions above Southern Germany visualise different reactions to following vs opposing winds as well as to side-winds from the right and left. (6) Radar-tracked night migrants above three different sites in south-western Switzerland show their reactions to different topographical conditions which vary from moderate leading effects of the Jura Mountains at a lowland site, to extreme funnelling at an Alpine pass, and wide scatter when a large Alpine valley perpendicular to the principal SW-direction of migration is crossed. (7) Distinguishing between three height zones reveals that (a) the proportion of SSW migration increases with height; this besides a few birds drifting across the Jura Mountains; (b) at the Alpine pass, forward migration is canalised as a narrow stream and complemented by notable reverse movements, while the highest level (above the crests) is characterised by wide directional scatter including moderate southward drift; (c) the proportion of movements along the SE–NW leading Rhone Valley decreases with altitude, while the proportion of SW migration increases, and the distribution approximates that at the pass in the highest zone. (8) This information leads to ideas for continuative studies, particularly on reverse movements, drift and compensation in the Alps and their northern approach areas.

A CONTEMPORARY SITUATION OF THE VEGETABLE GROWING AND ITS LOCATION ON ALTITUDE ZONES IN THE GANJA-GAZAKH ECONOMIC-GEOGRAPHICAL REGION

Purpose. One of the main issues disturbing all the countries in recent years is to ensure food security. İn this regard the development of the country's agriculture is very important. Depending on natural and economic factors agriculture has different development properties in the regions. Different programs have been realised to support the development of this sector nationwide. The main purpose of the research is territorial organisation, to determine the level of the development in vegetable growing and development properties according to height zones, to investigate the root of the problems, to find solutions to them. Research method. The analysis is based on the data of the Institute of Geography of the National Academy of Sciences of Azerbaijan and the State Statistics Committee and the works of the scientists having held research on economic and social fields. The situation of the vegetable growing in the last 10 years and its location according to the height zones, the effect of the economic reforms to the development of this sector in the region, existing problems and their solutions have been analysed in this research. Results. The development of the vegetable growing plays an important role in meeting daily demands for food and in providing the population with fresh vegetables all the year round. It is also of highly importance in population employment and in the increase of their income in the height zones. Though natural conditions in the height zones are available for cultivation of different vegetables, the development of plant cultivation also depends on the application of the innovative methods. Alongside with the increase in vegetable production, it will also lead to the absolute elimination of the imported goods and will ensure the increase in exporting potential. The application of intensive methods,the appropriate usage of highly productive vegetable sorts and local conditions will lead to the development of the vegetable growing and to the meeting of demands of the population in the country at the expense of local production. Scientific innovations. The organisation of the vegetable growing according to the height zones in the Ganja-Gazakh economic region have been investigated in the article for the first time. The situation of vegetable cultivation in this region in recent years has been investigated according to the statistical analysis and the survey in the region. The level of development in the vegetable growing and its location according to the height zones in the region has been analysed according to the statistical data. The analysis shows that there is a great potential for the development of the vegetable growing in this economic region and it affects positively the meeting of the demands in vegetable growing and the increase in exporting potential. However, there are factors negatively affecting the development of the vegetable cultivation and the high quality production. The inappropriate choice of vegetable types,seed choice, not paying attention to the sorts and sowing quality, agrochemical service, not struggling with illnesses and pests in time and other reasons have led to serious problems. In this regard purposeful measures must be taken to eliminate the problems mentioned and to achieve the highest development of vegetable cultivation in the Ganja-Gazakh economic region. Practical importance. The results of the resarch can be used in territorial organisation and the support of the development of the vegetable cultivation in the Ganja-Gazakh economic region.

Measuring Streetscape Features with High-Density Aerial Light Detection and Ranging

This study investigates the feasibility of extracting streetscape features from high-density United States Geological Survey (USGS) quality level 1 (QL1) light detection and ranging (LiDAR) and quantifying the features into three-dimensional (3D) volumetric pixel (voxel) zones. As the USGS embarks on a national LiDAR database with the goal of collecting LiDAR across the continuous U.S.A., the USGS primarily requires QL2 or QL1 as a collection standard. The authors’ previous study thoroughly investigated the limits of extracting streetscape features with QL2 data, which was primarily limited to buildings and street trees. Recent studies published by other researchers that utilize advanced digital mapping techniques for streetscape measuring acknowledge that most features outside of buildings and street trees are too small to detect. QL1 data, however, is four times denser than QL2 data. This study divides streetscapes into Thiessen proximal polygons, sets voxel parameters, classifies QL1 LiDAR point cloud data, and computes quantitative statistics where classified point cloud data intersects voxels within the streetscape polygons. It demonstrates how most other common streetscape features are detectable in a standard urban QL1 dataset. In addition to street trees and buildings, one can also legitimately extract and statistically quantify walls, fences, landscape vegetation, light posts, traffic lights, power poles, power lines, street signs, and miscellaneous street furniture. Furthermore, as these features are processed into their appropriate voxel height zones, this study introduces a new methodology for obtaining comprehensive tabular descriptive statistics describing how streetscape features are truly represented in 3D.

Damaged digital surfaces also deserve realistic healing

Modern image processing software include inpainting tools for various applications: removing an undesirable feature from an image, restoring damaged parts of old photographs, erasing watermarks, etc. But as concern digital surfaces, the only way of erasing remaining dirt or filling in unread height zones is to apply Laplace’s operator. Laplace’s operator has many advantages: it is easy to implement, it minimizes the surface curvature i.e. no particular relief is created, it is only defined by the damaged zone frontier and the result is the same whatever the software. The major drawback is its excessive smoothness: when the hole to be fill in is large compared to the correlation length, a Laplacian patch contrasts too much with the neighboring relief. When dealing with digital surface study, the problem is not as much the visual aspect of the healing as its potential consequences on the surface parameters. Three alternative healing methods are applied on rough surfaces: a totally new approach, and point- and exemplar-based methods. The accuracy of the repairs are compared by means of parametric and statistical analyses. The results show that, unlike any expectation, Laplacian healing is efficient for small repairs but that point- and exemplar-based methods are statistically better solutions.

Pecan Kernel Phenolics Content and Antioxidant Capacity Are Enhanced by Mechanical Pruning and Higher Fruit Position in the Tree Canopy

Pecan (Carya illinoinensis) is a tree nut native to North America. Although inhibited light exposure (most specifically as a result of overlapping tree canopies) has been shown to impair yield, the effect of this factor on nut antioxidant properties remains unknown. This study investigated effects of mechanical pruning and canopy height position of fruit on pecan kernel antioxidant contents and capacity. Beginning in 2006, trees in a ‘Western’ pecan orchard in New Mexico were subjected to three mechanical pruning frequency treatments (annual, biennial, and triennial) paralleling conventional practices, while other trees were maintained as unpruned controls. During the 2012 to 2014 seasons, pecans were sampled at fruit maturity from three canopy height zones (“low,” “middle,” and “high,” corresponding to 1.5 to 3.0 m, 3.0 to 4.5 m, and 4.5 to 6.0 m above the orchard floor). In vitro phenolics contents and antioxidant capacities of the nutmeats were evaluated by total phenolics content (TPC) and oxygen radical absorbance capacity (H-ORACFL), respectively. Soluble ester- and glycoside-bound phenolics were quantified by reversed-phase high-performance liquid chromatography (HPLC). For both TPC and H-ORACFL, results determined pruned samples had significantly higher values than unpruned samples (P < 0.001 for both comparisons), and that samples of “high” canopy height were significantly greater than those of “middle” height, which were in turn greater than those of “low” height (P < 0.001 for all comparisons). HPLC findings showed that in all three phenolic fractions (free, esterified, and glycoside-bound phenolics), nuts acquired from pruned trees had substantially greater concentrations of ellagic acid and its derivatives. Our findings indicate mechanical pruning of pecan trees and higher tree canopy position of fruit increase nut antioxidant properties.

Vertical Gradient of Epiphytic Bryophytes in the Amazon: the Rule and its Exception

In Amazonian Terra Firme vegetation, epiphytic bryophytes present a deterministic distribution along height zones in host trees, at both local and regional scale. Recent findings about the influence of vegetation structure variation on epiphytic bryophyte assemblages suggest that the vertical gradient may also change among adjacent vegetation types. In order to analyze this influence, bryophytes were sampled in five zones from the base to the top of 24 host trees in Várzea and Igapó (flooded) and Terra Firme (non-flooded) vegetation. The species richness and diversity, distribution of guilds of tolerance to light incidence, floristic similarity, and turnover of species composition were evaluated within and between vegetation types. The vertical gradient was observed only in Igapó and Terra Firme. Species richness and diversity were higher at the base in flooded forests, and at the outer canopy in non-flooded forests. These zones also showed higher floristic similarities among vegetation types. The distribution of guilds explained the main patterns observed in assemblages. The spatial distribution of epiphytes in the studied forests is regulated by the interaction between the height zone and vegetation type, and light tolerance is one of the most important attributes explaining the distribution patterns of epiphytes in the Amazon.

Vertical distribution and diversity of epiphytic bryophytes in the Colombian Amazon

ABSTRACTIntroduction. The purpose of this study was to analyse the variation in the vertical and spatial distribution of epiphytic bryophytes across four forests in the north-western Amazon. We sampled along the entire vertical gradient from tree base to upper canopy in order to answer these questions: Is there vertical zonation? Is there a relationship between composition species and geographical distance?Methods. The vertical gradient was studied in 64 phorophytes, and each phorophyte was divided into six height zones. We used Detrended Corresponded Analysis for plot ordination and Permutation Multivariate Analysis of Variance to analyse variation in species composition. The relationship between species composition and geographic distance was evaluated using a Mantel Test. We used Indicator species analysis to determine the preference of the species for each of the six height zones, and an ANOVA analysis to evaluate the significance of species richness per zone.Key results. There was a gradual differentiation of the bryophyte communities across the tree height zones. We identified 63 indicator species; the tree base had the highest number of indicator species, followed by the outer canopy.Conclusions. The strong influence of height zones on species assemblages revealed the importance of the environmental differences across the vertical gradient within a single tree. Epiphytic bryophyte communities are mainly structured according to the height zone of trees. The presence of a high percentage of indicator species across the Colombian Amazon is evidence to further support a high specificity of species for a particular microhabitat within the forest.

The double role of pigmentation and convolute leaves in community assemblage of Amazonian epiphytic Lejeuneaceae

BackgroundEpiphytic bryophyte communities in the Amazon forest show a vertical gradient in species composition along the trunk of the host trees. The investigation of species traits related to this pattern has focused on the physiology of selected taxa with a clear preference for one of the extremes of the gradient. Although some species are indeed only found on the tree base or in the outer canopy, the vertical gradient is composed mainly by the variation in the abundances of species with a broader occurrence along the height zones. Therefore, this study approaches the differences among community assemblages, rather than among species, to test the role of morphological and dispersal traits on the establishment of the vertical gradient in species composition.MethodsA character state matrix was built for 104 species of the family Lejeuneaceae recorded as epiphytes in the Amazonian terra firme forests, and six binary traits supposed to influence species occurrence: dark pigmentation on leaves; ability to convolute leaves when drying; possession of thickened cell walls; reproduction mode (monoicous or dioicous); occurrence of asexual reproduction; and facultative epiphyllous habit. Based on a previous dataset on community composition along the vertical gradient, trait occurrences in random draws of the metacommunity was compared to trait occurrences in field data, in order to detect significant deviations in the different height zones.ResultsFour out of the six traits tested showed significantly higher or lower occurrence in the species composition of canopy and/or understory communities. Traits related to high dispersal ability did not vary much along the vertical gradient; although facultative epiphylls were overrepresented on tree base. Dark pigmentation and convolute leaves were significantly more frequent in the canopy communities, but also significantly less frequent in communities at the base of the tree.DiscussionDark pigmentation and convolute leaves seem to be advantageous for the establishment in the canopy zones. They may, respectively, prevent light damage and allow longer periods of photosynthesis. Interestingly, these traits occur randomly along the trunk, but are wiped out of communities on the tree base. In the relatively deep shade of the first meters of the understory, they possibly hamper net carbon gain, the first by darkening the leaf surface and the second by delaying desiccation—which can be damaging under high temperatures and low light. The fact that production of asexual propagules is not overrepresented in the most dynamic microenvironment along the gradient, the canopy, challenges current views of bryophyte life strategy theory.

Vertical distribution of epiphytic bryophytes in Atlantic Forest fragments in northeastern Brazil

The microclimatic gradient established from the forest understory to the canopy provides a range of different conditions for the establishment of bryophytes along the height of a tree. We investigated epiphytic bryophyte communities of four fragments of Atlantic Forest with the aim of describing their vertical zonation and assessing differentiation among the communities of the different fragments. In each fragment, five host trees were selected from which bryophyte samples were collected in four height zones from the base to the canopy. Furthermore, 10 plots were demarcated in each fragment where bryophytes were collected from the understory. In total, 114 bryophyte species were found on the 20 sampled phorophytes, plus an additional 51 species in the understory, for a total of 165 species. Species composition of height zones differed significantly between communities of the trunk base and the canopy. The samples from the understory included 77% of all species. Among all species found, 10 showed a significant preference for a specific height. Around 70% of the bryophyte species grew as mats; this life form occurred in all trees and height zones. The results showed a weak, yet significant, vertical gradient, which differs from what is usually found in the Atlantic Forest.

Interference of spray volume, fruit growth and rainfall on spray deposits in citrus black spot control periods

ABSTRACT: Citrus black spot (CBS) caused by Guignardia citricarpa is one of the most serious Brazilian citrus diseases. This study aims to assess the interference of three application volumes in spray deposition citrus fruit, as well as fruit growth and rainfall effects on spray deposit reduction during the CBS control period. The experiment was carried out in a commercial citrus orchard, with sixteen-year-old trees of the Valencia variety, in Mogi Guaçu, São Paulo State, Brazil. The spray volumes were: 3.5 (1333L ha-1), 4.5 (1714L ha-1) and 8.5 (3238L ha-1) litres per tree, sprayed by an airblast sprayer using fungicides at recommended periods for disease control. The spray deposition quantification and residue was done by spectrophotometry using a copper oxychloride tracer. Samples were collected in three height zones of the tree (top, middle and bottom) and placed between trees on line plantation. Spray depositions were significantly smaller in the first application as a consequence of reduced fruit size. The spray losses on average for each day of rainfall ranged from 4.0 to 5.7%. There was no significant difference between application volumes regarding spray deposition on citrus fruit,which makes possible the reduction of application volumes, however, it is necessary to improve spraying techniques for the top zone of the citrus tree.

Bryophyte communities in the Amazon forest are regulated by height on the host tree and site elevation

Summary Community composition of epiphytic bryophyte communities, sampled systematically in nine localities across 2800 km from east to west of the Amazon forest, was mostly explained by their height zone along the vertical microenvironmental gradient from the base to the top of the host tree. Despite the lack of correlation between geographical distance and dissimilarity in species composition, communities within the same locality were significantly more similar than communities from different localities in all height zones, with the highest values of similarity found between outer canopy communities. While height zone on the host tree explained most of the variation in species composition at local scale, elevation and temperature were the variables most strongly related to species composition at a geographical scale. Using the concepts of meta/local community of the Neutral Theory of Biodiversity and Biogeography, we showed that establishment limitation was strongest at the extremes of the vertical gradient. We estimated that communities of the tree base and the outer canopy drew individuals from outside the habitat species pool at a rate of 0.28 and 0.22, respectively, in contrast with values between 0.55 and 0.76 of other height zones. Our results offered contrasting evidence for the hypothesis that species inhabiting the canopy have higher chances of engaging in long‐distance dispersal events. If the stronger establishment limitation at the extremes of the gradient is not compensated by facilitated dispersal compared to other zones, as our results suggest, communities on the base and on the outer canopy might be, through time, subjected to stronger selection. Synthesis. This study indicated that the community composition of epiphytic bryophytes in the Amazon is mainly regulated by environmental conditions, both at local and at geographical scales. Dispersal, although predominantly local, did not show geographical structure across the area.

Moss and vascular epiphyte distributions over host tree and elevation gradients in Australian subtropical rainforest

There is a lack of comprehensive studies on the ecology of epiphytic flora in Australia’s rainforests. Globally, rainforest epiphyte distribution is determined by three main factors: micro-climate within the host tree; landscape changes in macro-climate; and the characteristics of the host tree. We tested the influence of these factors on the species richness and composition of vascular and non-vascular epiphytes in the subtropical rainforest of the Border Ranges in New South Wales. Vascular epiphytes and mosses were recorded in situ from four height zones, with 10 trees sampled at five elevations between 300 and 1100 m above sea level (asl). Vascular epiphyte species richness was highest in the inner canopy (6.3 species), whereas mosses tended to have a uniform distribution over the height zones (3.8–5.0 species). We found that both moss and vascular epiphyte species richness peaked at mid-elevations (500–700 m), with moss richness at a slightly higher elevation than the vascular epiphytes. Host tree characteristics (bark roughness, host size) explained very little of the species composition or richness of epiphytes. Strong patterns in species richness and composition over host tree and elevation gradients suggest that moisture, temperature and light may be the major influences on epiphyte distributions in the Border Ranges.