Vegetation Associations Research Articles

Vegetation associations of the endangered Opuntia cespitosa (Prickly Pear, Cactaceae) and microsite variation in Point Pelee National Park, Ontario, Canada

ABSTRACT Many Opuntia engage in nurse associations. Opuntia cespitosa is an endangered cactus species in Canada that is infrequent to rare in many parts of its US range. This study quantifies Opuntia cespitosa associations with other native and non-native plant species in its only substantial extant population in Canada, at Point Pelee National Park. Species cover was estimated along 100 transects across 50 Opuntia plants and in matched non-Opuntia transects. To determine Opuntia influence on its microsite, paired soil samples from under the cacti and near the cacti compared soil nutrients. Kruskal-Wallis tests, Wilcoxon Rank Signed tests and ANOVA tests compared microsites with and without cactus cover and compared groupings such as native/non-native status, growth form and life cycle. Soil moisture is low in the open, but higher yet variable under Opuntia. Opuntia soils have higher magnesium levels. Opuntia do not strongly favor any one species, but may be more beneficial to non-native species than to native ones. Poa compressa and other non-native graminoids were associated with Opuntia. Opuntia cespitosa, despite being at their northern range limit, do not appear to engage in facilitative associations with native species either as nurse or as protégé, but may be nursing non-native species.

Drivers of the Distribution of Ecological Species Groups in Temperate Deciduous Managed Forests in the Western Carpathian Mountains

Managed broadleaf deciduous forests are an important type of forest vegetation in Central Europe, also in the Western Carpathians. These forests are both economically and environmentally valuable. However, little is known about ecological species groups and the inter-specific associations of dominant species in temperate deciduous managed forests in Central Europe. Since the forest stands are in a managed landscape, they are not consistent with the traditionally recognized and used vegetation associations in the Western Carpathians. For these reasons our research contributes to understanding the consequences of broadleaf deciduous forest management. The aim of this research was the determination of ecological species groups and an investigation into the main environmental drivers, in order to explain the distribution of ecological species groups. The numerical TWINSPAN classification was selected to distribute 146 relevés to the five ecological species groups. Of these, 77 relevés were divided into two groups with Fagus sylvatica dominant, while 63 relevés were Quercus petraea dominant. Carpinus betulus, Tilia cordata and Fraxinus excelsior were dominant in 19 relevés. Constrained Analysis of Principal Components was used to explain the vegetation–environment relationship on three transects in the Male Karpaty Mountains. Altitude, pH, Ca, C, K and Mg were selected as the significant environmental drivers responsible for a large part of the species group variability (31.8%). The main requirement for sustainable forest management is knowledge of the vegetation–environment relationship and this research was focused on gaining such understanding. This knowledge can be used as a decision support tool for sustainable management in managed deciduous forests.

The habitat and management of hairy jointgrass (Arthraxon hispidus, Poaceae) on the north coast of New South Wales, Australia

Ecological information about threatened species is required to guide strategic management approaches for effective biodiversity conservation in Australia. Arthraxon hispidus (hairy jointgrass) is a listed threatened species in New South Wales (NSW), but there is limited information on its habitat preferences and native vegetation associations, as well as the impact of historical and ongoing anthropogenic disturbance on its distribution and abundance. In the present study, populations of A. hispidus on the north coast of NSW were surveyed to investigate the habitat characteristics associated with various occurrences of the species. Its preferred habitat was found to be dense ground-cover formations in high-moisture, low-canopy conditions. Cover was highest in moisture-associated assemblages in and around wetlands, drainage lines and groundwater seepages, often in association with native grasses, sedges and herbs. These findings suggest that naturally open freshwater wetland communities comprise the most plausible native habitat niches for A. hispidus populations on the north coast of NSW. A. hispidus also occurs widely among introduced pastures and weeds in previously forested areas, demonstrating the species’ potential to exploit derived habitat. Results indicate that, although ongoing disturbance continues to promote A. hispidus in these exotic-dominated landscapes where historical clearing has created potential habitat opportunities, anthropogenic disturbance (slashing or cattle grazing) is not necessary to sustain A. hispidus within native-dominated wetland communities. Findings suggest more scope for integrated management of A. hispidus within broader native vegetation conservation strategies rather than a single species approach.

Recent and Predicted Changes in Habitat of the Eurasian Skylark Alauda arvensis Based on the Link between the Land Cover and the Field Survey Based Abundance Data

The European avifauna on agricultural land has been permanently diminished over the past few decades. This phenomenon is clearly connected with agricultural intensification and the recent land cover changes. The main aims of this study were to identify the land cover preferences of a farmland bird species, the Eurasian Skylark Alauda arvensis in Hungary and investigate the link between the recent trend of the abundance of this species and the land-cover change. We employed GIS and statistical methods to assess the link between the abundance of this species based on the Hungarian common bird monitoring database (MMM) and the spatial proportion of the Corine Land Cover (CLC) categories in different buffer zones with 300, 600 and 1200 m from the observation points. Based on the significant statistical connections, we could identify and select land cover categories that serve as habitats and land cover categories that this bird species does not inhabit. The land cover preference of the Eurasian Skylark, in case of some land cover category, is depending on the grain scale (circle radius distance from the observation points). In analyses arable lands has been omitted because this land cover type is the well-known habitat of the species. According to our results, the Eurasian Skylark prefers permanent crops (vineyards, fruit trees and berry plantations) inside 600m and 1200m buffer zones, and pastures inside 1200m buffer zones, while it does not prefer urban fabric areas and heterogeneous agricultural, forests, and wetlands or water bodies inside 300m and 600m, scrub and/or herbaceous vegetation associations (transitional woodland-shrub and natural grassland areas) inside the 600m and 1200m radius buffer areas. The identification of these regional (European level) land-cover categories allowed us to analyse the recent (1990–2012) and the predicted (2006–2050) characteristics of habitat changes of this bird species, associated with land cover change. Based on our results, we could estimate that the Skylark habitat will decrease by 188 560 ha between 2006–2050 in Hungary.

Vegetation associations and relative abundance of rodents on St. Eustatius, Caribbean Netherlands

Since the introduction of non-native rodents to the Caribbean region, these invaders have successfully occupied many, if not most, islands where they pose tremendous threats to native biodiversity and ecosystems. The objective of our study was to conduct a preliminary assessment of the relative abundance of invasive alien rodents in different vegetation types on the small Caribbean island of St. Eustatius, which has no native rodent species. We used tracking tunnels (baited ink cards placed in tunnels to identify the prints of animals lured to the card) to determine the presence of rodent species. We collected data in 25 × 25 m (n = 13) and 5 × 5 m (n = 130) plots to determine whether elevation, number of tree species, canopy cover or other microhabitat components were correlated with rodent relative abundance. Invasive rodents are present in varying relative abundances in rural areas on St. Eustatius. House mice (Mus musculus) were not recorded inside the terrestrial protected areas, whereas black rats (Rattus rattus) were detected in all elevations and all but one vegetation type sampled. We determined significant correlations between some of the habitat characteristics, especially elevation, canopy height, leaf litter cover and number of tree species, which showed significant collinearity with 27 of 45 pairwise comparisons. There was a significant correlation between rodent relative abundance and the number of tree species, but not between elevation, number of living trees, number of shrubs, rainfall, canopy cover, canopy height, leaf litter cover, leaf litter depth, or slope. There was a significant difference within vegetation types for the frequency of traps containing rat versus mouse tracks. Our study was impacted by two major hurricanes in September 2017.

Classificação do relevo com base nos elementos de Geomorphons e sua relação com a vegetação florestal nativa na Serra do Caverá - Sudoeste do RS, Brasil

As formas e a composição do relevo são fatores que contribuem na determinação da ocorrência e dos tipos de vegetação de determinado local. A associação da vegetação com determinados ambientes, em função da insolação recebida, da disponibilidade hídrica, entre outros fatores, está diretamente relacionada à configuração do relevo de uma área. Este trabalho busca demonstrar a relação existente entre a configuração do relevo e a distribuição da vegetação florestal nativa na Serra do Caverá, na região sudoeste do Rio Grande do Sul. A classificação do relevo da área de estudo foi realizada com base nos Geomorphons, a partir do MDE oriundo dos dados SRTM, obtendo-se dez elementos de relevo. Após o mapeamento da vegetação, realizado com base na interpretação de imagens do satélite LANDSAT 8 OLI, foi realizado o cruzamento das informações em ambiente SIG, com o software ArcGis 10.3, ferramenta ArcMap, e também através do cálculo da razão de frequência (Fr). A maior correlação observada foi com os elementos vales e áreas planas (42,52%), seguida da vegetação ocorrente em encostas, bases de encostas e relevos escavados, que juntos somaram 40,85% do total da vegetação florestal da área de estudo.
 
 Abstract
 
 RELIEF CLASSIFICATION BASED ON THE ELEMENTS OF GEOMORPHONS AND THEIR RELATIONS WITH NATIVE FOREST VEGETATION IN THE SERRA DO CAVERÁ - SOUTHWEST OF RS, BRAZIL
 
 The composition and the forms of the relief are factors that contribute in the determination of the occurrence and the types of vegetation of a certain place. The association of vegetation with certain environments due to the sunshine received, water availability, among others, are directly related to the configuration of the relief of an area. The objective of this work is to demonstrate the relations between the configuration of the relief and the distribution of the native forest vegetation in the Serra do Caverá, in the southwest region of Rio Grande do Sul. The relief classification of the study area was based on the Geomorphons, from the DEM generated through the SRTM data, obtaining ten elements. After the vegetation mapping was carried out based on the interpretation of images of the satellite LANDSAT 8 OLI, the information was cross-referenced in a GIS environment, with ArcGis 10.3 software, ArcMap tool, also by calculating the frequency ratio (Fr). The highest correlation observed was with the valleys and flat areas (42.52%), followed by vegetation on hillsides, slope bases and excavated reliefs, which together added up to 40.85% of the total forest vegetation in the study area.

The conservation of ecosystem and biological diversity in Alakol Biosphere Reserve (East Kazakhstan)

Alakol Biosphere Reserve includes Alakol-Sasykkol lake system and is situated in Alakol depression. Its total area is 193 089.9 ha including water areas (529 300 ha): the core zone is 19 712,9 ha, buffer zone – 26 667 ha and transition zone – about 511 300 ha. There are 58 ecosystems in the Reserve’s territory, grouped in 3 orders: terrestrial natural (35 types), aquatic (10 types) and terrestrial anthropogenically transformed (13 types) ecosystems. The largest area is occupied by terrestrial natural ecosystems (49.45%), followed by aquatic ecosystems (44.37%) and anthropogenically transformed ecosystems, which are registered for comparatively large area (13.43%). Terrestrial natural ecosystems are merely touched by human activity and occupy large spaces mainly on the territory of the core and buffer zone of Alakol Reserve, as well as Eastern and South-Eastern parts of the transition zone. Biosphere Reserve as a whole is situated in transition zone between Dzhungar and Northern-Turan desert types, and this is the cause of unique vegetation associations with peculiar floristic composition and different geographic orientation. Zonal spectrum of foothill plains is characterized by the change of ephemeroid-Artemisia deserts on sierozem soils, steppified cereal-Artemisia deserts on brown soils and genuine deserts on gray-brown soils. Central lowest part of Alakol depression is occupied by lakes surrounded by hydromorphous vegetation (meadow and marsh vegetation). The territory of biosphere reserve is located on the Central Asian – Indian bird migration route and is a wetland of world significance as waterbirds’ habitat and aggregation site. The biosphere reserve reflects regional ecosystem and biological diversity and represents rich composition of flora and fauna.

BELT DISTRIBUTION OF VEGETATION IN THE BASIN OF THE AT-BASHI RIVER OF THE INNER TIEN-SHAN OF KYRGYZSTAN

Geobotanical characteristics of the main types, subtypes, formations and groups of vegetation associations in the section of the altitude profile are given. Kyrgyzstan is a high-mountainous country of Central Asia, which is located in the center of the mountain systems of Tien-Shan and Pamir-Alay. Up to 90% of its territory is raised to absolute heights of more than 1500 m. Vegetation cover of Kyrgyzstan is located in a system of vertical belts. Steppes and meadow-steppes are the most widespread in the At-Bashi river basin. Among them there are bunchgrass steppes and meadow-steppes, dry steppes and meadow-steppes with a significant share of wormwood and drought-resistant motley grasses, as well as mountain meadows. Among mountain meadows there are tall, medium and low grass meadows. High grass meadows, developed in low mountains and middle mountains, in the north and south differ in the species composition of plants. In the northern regions, the following species are of major importance: Dactylis glomerata, Bromus inermis, Elytrigia repens, Brachypodium pinnatum ; representatives of the genera: Poa, Vicia, Thalictrum . The largest share of the steppe vegetation is occupied by plants, which according to the requirements to heat and moisture occupy an intermediate position between desert plants and meadows. The basis of vegetation of steppes is formed by species of genera of turf cereals: Stipa, Festuca , Ptilagrostis with very characteristic hairy and blue-gray leaves. Steppes, unlike deserts and semi-deserts, are characterized by a greater richness of plant species and density of vegetation. Steppes serve as good pastures.

A composite measure of habitat loss for entire assemblages of species.

Habitat destruction is among the greatest threats facing biodiversity, and it affects common and threatened species alike. However, metrics for communicating its impacts typically overlook the nonthreatened component of assemblages. This risks the loss of habitat going unreported for species that comprise the majority of assemblages. We adapted a widely used measure for summarizing researcher output (the h index) to provide a metric that describes natural habitat loss for entire assemblages, inclusive of threatened and nonthreatened species. For each of 447 Australian native terrestrial bird species, we combined information on their association with broad vegetation groups with distributional range maps to identify the difference between the estimated pre-European and current extents of potential habitat, defined as vegetation groups most closely associated with each species. From this, we calculated the loss index (LI), which revealed that 30% of native birds have each lost at least 30% of their potential natural habitat (LI = 30). At the subcontinental scale, LIs ranged from 15 in arid Australia to 61 in the highly transformed southeastern part of the country. Different subcomponents of the assemblage had different LI values. For example, Australia's parrots (n = 52 species) had an LI of 38, whereas raptors (n = 32 species) had an LI of 25. The LI is simple to calculate and can be determined using readily available spatial information on species distributions, native vegetation associations, and human impacts on natural land cover. This metric, including the curves used to deduce it, could complement other biodiversity indices if it is used for regional and global biodiversity assessments that compare the status of natural habitat extent for assemblages within and among nations, monitor changes through time, and forecast future changes to guide strategic land-use planning. The LI is an intuitive tool that can be used to summarize and communicate how human actions affect whole assemblages, not just threatened species.

Plant Community Composition and Biodiversity Patterns in Urban Parks of Portland, Oregon

Urban parks are biodiversity hotspots and are integral components of green infrastructure in urban areas. A variety of land use practices and environmental factors affect urban park biodiversity and vegetation structure, composition, and ecological function, but few studies have compared plant taxonomic composition, structural complexity, and species traits across different types of urban green spaces. The purpose of this study was to better understand the relationships between plant community composition, structural patterns, and environmental and species traits by using a standardized data collection method across different types of urban parks in Portland, Oregon. We examined the potential ways that different types of urban parks preserve native species and/or harbor non-native and invasive species. We used a stratified random sampling design to select 15 parks of different types based on use: 1) recreational-active use parks, 2) natural-passive use parks, and 3) multi-use parks. We found a total of 178 plant species belonging to 141 genera and 65 families. Multivariate analyses, including ordination with non-metric multidimensional scaling and cluster analysis were used to explore vegetation composition data and associations of different species assemblages with environmental variables. One-way analysis of variance was used to test hypotheses about variables associated with diversity. Statistically-significant differences in species richness and biodiversity indices were found between different park types. More native species were found in natural-passive use parks than other park types, more non-native species are found in multi-use parks than the other park types, and more invasive species were found in natural passive-use parks than in recreational-active use parks. Attributes such as natural-passive use park type, wetland habitat, steep slopes, native species origin, non-native species origin, and vine and tree plant forms were those most strongly correlated with the non-metric multidimensional scaling ordination, indicating that these attributes exert the strongest influence on species abundance and distribution with Portland’s urban parks. The findings of this study can assist park managers in their aims to promote native species cover, reduce invasive species presence, or achieve additional management goals for urban parks.

Volatile Variability and Antioxidant Activity of Rosmarinus officinalis Essential Oil as Affected by Elevation Gradient and Vegetal Associations

The essential oil yield, volatile profile and antioxidant activity, of 37 samples collected from the Rosmarinus officinalis shrubs growing wild in the different ecosystems of the provinces of Taourirt and Jerada (Oriental region in the east of Morocco), were studied in order to determine the effect of the habitat and how the vegetal associations are influencing the volatile variability of their essential oil. The essential oil compositions were determined by gas chromatography-mass spectrometry (GC-MS). The yield of the essential oil extraction ranged from 1.09 to 2.81 %. The major components found were 1.8-cineol (37.71-65.02 %), camphor (6.09-27.49 %), α-pinene (3.08-9.98 %) and β-pinene (2.83-11.7 %). The interpretation of these results revealed that the variability is attributed to varieties and genetic background rather than the ecosystems. The antioxidant activity was determined by 1,1-diphenyl-1-picrylhydrazyl (DPPH) assay which revealed a strong radical scavenging capacity for all the samples with some variability which can be explained by the variability of the content of monoterpenes oxygenated.

Detecting inundation thresholds for dryland wetland vulnerability

Dryland wetlands receiving periodical floods are of key importance for ecological resilience. The inundation regime (i.e., frequency, duration, depth, and timing of inundation), is one of the major factors that determine the suitability of local conditions for specific wetland species. During droughts, inundation conditions can reach a threshold after which wetland vegetation could transition to dryland vegetation. This study analyses the response of vegetation to hydrologic variability in an arid wetland in Australia over a period of 22 years (including the Millennium drought) in order to identify inundation thresholds for transitions. We use numerical modelling, field observations and remote sensing data to relate continuous detailed simulations of the inundation regime with the response of patches of Common reed, Water couch and River red gum, three key vegetation associations in the study site. We focus in patches that were affected by the drought and presented dryland vegetation invasion as well as reference patches that remained healthy throughout the drought. On each patch, we compare annual and inter-annual simulated inundation regimes to the minimum inundation conditions that can support the specific vegetation, and we compute the percentage area of the patch that verifies minimum inundation for each year. We define this area percentage as minimum inundation index. This index is analysed in conjunction with Landsat derived information on green vegetation coverage (green Seasonal Fractional Cover) for the selected patches. We found that the minimum inundation index and inter annual frequency are able to describe the vegetation dynamics of the patches, which can be characterised by two distinct response modes that depend on a threshold value of the minimum inundation index. Inundation below the threshold noticeably leads to degraded vegetation, but the vegetation can recover quickly if this threshold is later maintained for one or two years. Values below the threshold for more extended periods (drought) result in a gradual decrease of wetland vegetation to almost complete disappearance after four years and subsequent dryland vegetation invasion.

Twenty-year changes in riparian bird communities of east-central Oregon

Riparian zones in the semi-arid West are disproportionately important habitats for both breeding birds and agricultural operations. Despite growing interest in studying avian–habitat relationships to inform land management decisions, few studies have described temporal changes in riparian bird communities. We compared indices of avian abundance and diversity from 3 streamside vegetation associations in east-central Oregon during May–June 2014 with indices from 1993–1994. Our objectives were to identify patterns of change in the avian community with a focus on riparian shrub-dependent species, re-examine previously reported relationships between avian abundance and vegetation volume, and identify possible causes of declines in bird abundance and diversity. We combined historical field protocols to survey birds and measure riparian vegetation with modern analytical techniques. We found few differences in species richness between study periods but documented approximately 30% species turnover. Increases in diversity were driven by increased detections of grassland and wetland bird species and increased evenness due to precipitous declines in detections for 2 of 3 riparian shrub–dependent focal species (i.e., Yellow Warbler [Setophaga petechia] and Willow Flycatcher [Empidonax traillii]). Detections of Song Sparrows (Melospiza melodia), our third focal species, declined by a smaller margin. Large changes in detections of riparian shrub–dependent species did not reflect trends in mesic shrub cover or volume, which had been identified as likely drivers of obligate species abundance. Focal species' declines reflected regional Breeding Bird Survey trends, corroborating our finding that their declines were not a result of changes in local site conditions. Our findings suggest that managing lands to increase wetness and extent of riparian zones can be beneficial for grassland and wetland bird species. However, managing for riparian shrub cover or volume, important metrics of grazing intensity and riparian system health, may be insufficient to conserve riparian shrub–dependent birds because other unidentified local and/or regional factors are likely contributing to habitat suitability of riparian shrub–dependent birds.

Influence of the Agricultural Conservation Easement Program wetland practices on winter occupancy of Passerellidae sparrows and avian species richness.

Wetlands enrolled in the Agricultural Conservation Easement Program (ACEP) are established as a means of restoring wetland ecosystems and wildlife habitat on private, agricultural land. In West Virginia, USA, ACEP wetlands have never been evaluated to determine how they function as wildlife habitat in comparison to other available wetland habitat in the state. We measured the wintering occupancy of Passerellidae species and apparent avian species richness on ACEP wetlands and a set of reference wetlands located on public land in West Virginia to evaluate if ACEP wetlands are being used similarly by avian species to other available wetland habitat in the state. Apparent avian species richness and the occupancy probability of four Passerellidae species—song sparrows (Melospiza melodia), dark-eyed juncos (Junco hyemalis), swamp sparrows (Melospiza georgiana), and white-throated sparrows (Zonotrichia albicollis)—did not differ between ACEP and reference sites. In addition to other vegetative and habitat associations for each species, dark-eyed junco occupancy was negatively correlated with wetland size while swamp sparrow occupancy and apparent avian species richness were positively associated with wetland size. These results indicate that ACEP wetlands are providing winter avian habitat as well as another source of wetland habitat in the state. Maintaining and expanding ACEP wetlands in West Virginia would continue to provide wetland systems in areas that are otherwise lacking these habitats.

GIS Analysis of Land-Use Change in Threatened Landscapes by Xylella fastidiosa

Land-use/land-cover analysis using Geographic Information System (GIS) application can describe and quantify the transformation of the landscape, evaluating the effectiveness of municipal planning in driving urban expansion. This approach was applied in the municipality of Spongano (Salento, South Italy) in order to evaluate the spatial heterogeneity and the transformations of the land use/land cover from 1988 to 2016. This approach was also used to examine the spread of Xylella fastidiosa, which is a plant pathogen of global importance that is reshaping the Salento landscape. The land-use maps are based on the CORINE Land Cover project classification, while the topological consistency was verified through field surveys. A change detection analysis was carried out using the land-use maps of 1988 and 2016. The most extensive land-use class is olive groves (34–36%), followed by non-irrigated arable lands and shrub and/or herbaceous vegetation associations. The main transition of land involved non-irrigated arable lands, which lost 76 ha and 23 ha to shrub and olive areas, respectively. Meanwhile, the artificial surfaces class doubled its extension, which involved mainly the transition from shrub and heterogeneous agricultural areas. However, the olive groves class is threatened by the dramatic phytosanitary condition of the area, indicating a compromised agroecosystem, which is causing a de facto transition into unproductive areas. The results highlight the inconsistency between what was planned by the urban plan in the past and how the landscape of Spongano has been changed over time. This evidence suggests that it is necessary to develop a plan based on learning by doing, in order to shape and adapt the processes of territorial transformation to the unpredictability of the ecologic, social, and economic systems, as well as ensure that these processes are always focused on environmental issues.

Синтаксономия луговин тундрового пояса гор Мурманской области

Синтаксономия луговин тундрового пояса гор Мурманской области

Status of Mountain Pastures, Including Geobotanical Description of the Main Vegetation Associations in Western Pamir-Alay

The article gives a brief description of the vegetation cover of the Western Pamir-Alai range, as well as a method of describing the phytocenosis of the vegetation of the studied region.

An evaluation of remotely sensed indices for quantifying burn severity in arid ecoregions

It is sometimes assumed the sparse and low statured vegetation in arid systems would limit the effectiveness of two remote-sensing derived indices of burn severity: the difference Normalised Burn Ratio (dNBR) and relativised difference Normalised Burn Ratio (RdNBR). We compared the relationship that dNBR, RdNBR and a ground-based index of burn severity (the Composite Burn Index, CBI) had with woody cover and woody density 1 year after burning in five fires that occurred in the Mojave Desert during 2005. Data were collected within 437 plots spanning geographic and elevation gradients representative of vegetation associations in low- (<1200m), mid- (1200 to 1700m) and high-elevation (>1700m) zones. Statistically, dNBR and RdNBR were both effective measures of severity in all three elevation zones; woody cover and density had steep exponential declines as the values of each remote-sensing index increased. We found though that dNBR was more ecologically interpretable than RdNBR and will likely be of most relevance in the Mojave Desert. It will be necessary though to test these, as well as other remote-sensing burn-severity indices, across more desert regions before inferences can be made of the generality of the patterns we observed.

TURBULENT FLOW INDUCED BY OSCILLATING CIRCULAR CYLINDER ARRAYS

Vegetation association plays important role in the shallower coastal zone for sediment control and the nutrient and carbon absorption. It is necessary to understand the fluid motion including turbulence in the vegetation so that we may evaluate precisely shallow water region including vegetation and wet land. As the first step of research on fluid motion in the vegetation, circular cylinders are sometimes used. Many researches on the fluid force acting on the circular cylinder and fluid motion around the cylinder have been achieved so far. However, the properties of turbulent flow induced around circular cylinders in a wave, especially turbulence transition mechanism and spatial-temporal distribution of turbulence, are not almost investigated. The purpose of this study is to understand the fluid flow including turbulent induced by wave transmitting vegetation association. In this study fluid motion was measured by oscillating circular cylinder arrays in a tank by using the PTV technique.

Evolutionary history of Manihot carthagenensis (Euphorbiaceae) and allied species in eastern South America

Intermittent episodes of climate changes, such as those that occurred during the Pleistocene, likely shaped the diversification of the young genus Manihot Mill. (Euphorbiacheae). One of such recently-derived congeners ─ M. carthagenensis ─ exhibits a widely disjunct distribution across dry environments in Eastern South America. Herein, we used molecular data from four nuclear gene regions (sts, ch_metE, g3pdh, and nia-i3) and seven nuclear microsatellite loci for reconstructing the phylogenetic relationships among M. carthagenensis and allied species and exploring likely phylogeographic scenarios that shaped the diversification and the distribution of gene pools of M. carthagenensis across the Caatinga and Chaco. Our data suggest that M. carthagenensis is not a monophyletic clade, as presently circumscribed. Morphological differences, genealogical relationships, and vegetation associations support three well-differentiated lineages, each of which merits the species rank: M. carthagenensis, M. glaziovii, and M. hahnii. Microsatellite data suggest that the newly circumscribed M. carthagenensis consists of at least three distinct gene pools, which are partly structured according to geography. The three gene pools likely evolved in allopatry, but remained interfertile. Population expansions after climate amelioration contributed to structuring hybrid zones. Moreover, we described two new single-copy gene regions (sts and ch_metE) as sources of molecular variation; they can facilitate the fine-scale probing of other parts of the phylogeny across Manihot.