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Ecological Range (ecological + range)
Selected AbstractsAquatic Coleoptera Distribution and Environmental Relationships in a Large Patagonian RiverINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 5 2006María Laura Miserendino Abstract The benthic coleopteran assemblages of the Chubut River basin were studied in order to assess the main factors affecting species composition and distribution along the upper, middle and lower catchments. A total of 13 sampling sites were selected and sampled seasonally. Eight taxa and 1,601 individuals were collected during the study. Richness was higher in the main channel of Chubut River at the upper basin than at the middle basin. Beetles were completely absent at the lower basin. Mean monthly density per sites varied from 0 to 85 ind m,2. Stethelmis kaszabi had a more restricted distribution whereas Hemiosus dejeanii, Austrelmis sp. and Austrolimnius spp. were more frequent and abundant. Austrelmis sp. appears as the most tolerant species, especially to higher TSS, ammonia, and conductivity values. Luchoelmis cekalovici was absent in stations associated with urban areas. A Canonical Correspondence Analysis shows that conductivity, total suspended solids, wet width, water temperature and pH were the most important variables structuring beetle assemblages. Land use related variables such as NH4, TP, and NO3 were less important but still significant. An increase in TSS affected negatively the coleopteran community; this could be related to both hydrogeological characteristics and agricultural activities (including overgrazing). This is the first approach to the knowledge of the ecological range of distribution of the coleopteran species in Patagonian rivers. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Eucalyptus infestation by Leptocybe invasa in UgandaAFRICAN JOURNAL OF ECOLOGY, Issue 3 2009Philip Nyeko Abstract Very little is known about Leptocybe invasa Fisher & LaSalle, a new fast-spreading alien pest infesting Eucalyptus in several countries. This study examined L. invasa infestation on Eucalyptus germplasms in different agroecological zones of Uganda. The incidence and severity of the pest infestation were higher in hotter and drier agroecological zones than in cooler and wetter zones. There were direct negative relationships between altitude and L. invasa infestation on Eucalyptus species. No infestation was observed on any Eucalyptus species in stands at altitudes ranging from 1938 to 2452 (the maximum encountered) m above sea level. Leptocybe invasa infestation occurred on all Eucalyptus species encountered (Eucalyptus grandis, Eucalyptus camaldulensis, Eucalyptus saligna, Eucalyptus robusta), except Eucalyptus maidenii that escaped attack because it was located outside the ecological range of the insect. The incidence and severity of L. invasa infestation was generally higher on clonal hybrids E. grandis × E. camaldulensis than on E. grandis × Eucalyptus urophylla. Research on host germplasms, L. invasa biology and ecology, impact of the pest infestation and possible control strategies are suggested to facilitate the development of sustainable management strategies. Résumé On sait très peu de choses sur Leptocybe invasa Fisher & LaSalle, une nouvelle espèce nuisible très invasive qui infeste les Eucalyptus dans plusieurs pays. Cette étude a examiné l'infestation par L. invasa des germoplasmes d'Eucalyptus dans différentes zones agroécologiques d'Ouganda. L'occurrence et la gravité de l'infestation par cette espèce nuisible étaient plus élevées dans les zones agroécologiques plus chaudes et plus sèches que dans les zones plus fraîches et plus humides. Il y avait des relations négatives directes entre l'altitude et l'infestation des espèces d'eucalyptus par L. invasa. On n'a observé aucune infestation de quelque espèce d'eucalyptus que ce soit dans les plantations allant de 1938 à 2452 mètres d'altitude (la plus haute altitude à cet endroit). L'infestation par Leptocybe invasa touchait toutes les espèces d'eucalyptus rencontrées (Eucalyptus grandis, E. camaldulensis, E. saligna et E. robusta) à l'exception d'E. maidenii qui a échappéà cette attaque parce qu'il était situé en dehors de l'aire de dispersion écologique de cet insecte. L'occurrence et la gravité de l'infestation par cette espèce nuisible étaient plus élevées chez les hybrides clonés d'Eucalyptus grandis ×E. camaldulensis que chez les hybrides E. grandis × E. urophylla. Des recherches sur les germoplasmes hôtes, sur la biologie et l'écologie de L. invasa, sur l'impact de l'infestation par cette espèce nuisible et sur d'éventuelles stratégies de contrôle sont suggérées ici pour faciliter le développement de stratégies de gestion durables. [source] Devonian monospecific assemblages: new insights into the ecology of reduced-oxygen depositional settingsLETHAIA, Issue 4 2007DIANA L. BOYER Low-diversity fossil assemblages interpreted as representing dysaerobic communities are common in the Phanerozoic rock record, and those composed of a single species have particular utility for recognizing the lowest bottom-water oxygen levels. An unusually high-diversity of clades including three rhynchonelliform, two linguliform, and one bivalve species occur in monospecific assemblages within Middle and Upper Devonian black shales of New York State. These six taxa are interpreted to be adapted to extremely reduced bottom-water oxygen levels as inferred from detailed sedimentological data and their repeated monospecific occurrence; however these groups represent two distinct ecologies. Three of these taxa are restricted to sediments deposited under the lowest dysaerobic conditions, while the other three taxa, unlike other fossils characteristic of reduced-oxygen levels, also occur in and are even dominant in high-diversity assemblages. The rhynchonellid brachiopod Eumetabolotoechia multicostata is the most abundant taxon within these units and has a remarkable ecological range as dominant from the lowest dysaerobic zone to near-normal marine oxygen levels. These Devonian groups, when present in monospecific assemblages, have utility for characterizing the lowest dysaerobic zone where trace fossil assemblages, most commonly used to describe these low-oxygen depositional settings, are absent or poorly developed. [source] Ecological distribution of terrestrial orchids in a south Brazilian Atlantic regionNORDIC JOURNAL OF BOTANY, Issue 1 2010Fernando Souza Rocha Terrestrial orchids comprise a taxonomically and ecologically varied group, ranging from tropical to subpolar regions and from wet marshy to dry sand-dune environments. An ecological survey of these plants was performed in a natural region of Rio Grande do Sul, south Brazil, namely the northern coastal plain, between the abrupt slopes of the Serra Geral and the coastal line of the Atlantic Ocean (29°01,S to 30°00,S, 49°43,W to 50°16,W). The study area presents a humid subtropical climate of the Cfa type. Mean annual temperature and precipitation range from 17.5 to 20.0°C and from 1200 to 1700,mm, respectively. The occurrence of indigenous terrestrial orchid species was recorded for six major habitats or vegetation types: bogs and marshes, peat forests, rain forests, dune forests, Butia -palm stands and coastal sand-dunes. The ecological range was defined for 39 species belonging to 23 genera, based on literature, herbarium revisions and extensive collecting along the studied area. Species richness ranged from nine species, in both coastal dunes and palm-groves, to 17 species in peat forests. A negative correlation was observed between species richness and ecological range, showing a general tendency for terrestrial orchids to be confined to one or a few habitats. Multivariate analyses indicated light (herbaceous vs woody vegetation) as a primary ecological factor, and soil drainage (sandy vs peaty substrates) as a secondary factor controlling terrestrial orchid distribution. [source] INTRAMARGINAL VEINED LAURACEAE LEAVES FROM THE ALBIAN,CENOMANIAN OF CHARENTE-MARITIME (WESTERN FRANCE)PALAEONTOLOGY, Issue 2 2009CLÉMENT COIFFARD Abstract:,Eucalyptolaurus depreii gen. et sp. nov. is proposed for angiosperm leaves newly collected from uppermost Albian , lowermost Cenomanian of Charente-Maritime (western France). They consist of simple, narrow, elongate laminas with entire margins and intramarginal veins. The epidermal cells of adaxial cuticle shows small, rounded, blunt papillae outward that protrude inward and fuse together as rolls along and parallel to the margins, while the adaxial cuticle bears brachyparacytic stomatal apparatus that exhibit sunken guard cells and hair bases consisting of a thick-walled pore surrounded by radially arranged differentiated cells. Resin bodies occur inside the mesophyll. These characters closely resemble the lauroid taxa ,Myrtophyllum' and Pandemophyllum from the Cenomanian of the Czech Republic and Dakota (USA) respectively. The narrow angle of basilaminar secondaries and the whole suite of features in the guard cells (sunken guard cells embedded into subsidiary cells and stomatal ledges) strongly support close affinity with the Lauraceae. From the Cenomanian lauraceous reproductive organs and their related leaves already showed high disparity and diversity. In addition they displayed a broad ecological range from freshwater floodplains to brackish swamps. This combined to high diversity of reproductive organs suggest ecological radiation of Lauraceae by the Cenomanian. [source] White pines, Ribes, and blister rust: integration and actionFOREST PATHOLOGY, Issue 3-4 2010R. S. Hunt Summary The preceding articles in this series review the history, biology and management of white pine blister rust in North America, Europe and eastern Asia. In this integration, we connect and discuss seven recurring themes important for understanding and managing epidemics of Cronartium ribicola in the white pines (five-needle pines in subgenus Strobus). Information and action priorities for research and management of the pathogen, telial and aecial hosts, and their interactions are listed in a detailed Appendix. Syntheses focused on genetics, plant disease, invasive species or forest management have provided alternative but knowledgeable lessons on the white pine blister rust pathosystem. Two critical issues for the conservation of white pines are to sustain ecosystems affected by blister rust and to maintain genetic diversity for adaptive traits such as disease resistance. Forest genetics includes tree improvement and molecular techniques for research; their application can increase rust resistance by artificial and natural selection. Silviculture augments genetics with methods to deploy and enhance resistance as well as to regenerate and tend white pine stands. Although cultivated or wild Ribes might serve as inoculum sources, silviculture and horticulture can reduce the risk of serious impacts from blister rust using genetics for breeding and epidemiology for hazard assessment and disease control. Climate change threatens to cause major alterations in temperature and precipitation regimes, resulting in maladapted conifers succumbing to various diseases and insect outbreaks. In contrast, many white pine species have broad ecological ranges and are tolerant of harsh environments,traits that permit successful establishment and growth over wide geographic and altitudinal zones. Given appropriate management, white pines could thrive as valuable commercial and ecologically important keystone species. In an uncertain environment, adaptive management provides a learning and participatory approach for sustaining resilient ecosystems. [source] | |||||||||||||