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Ecological Amplitude (ecological + amplitude)

Distribution by Scientific Domains

Life Sciences	66%

Selected Abstracts

Heimische Orchideen in urbanen Biotopen,

FEDDES REPERTORIUM, Issue 5-6 2008
W. Heinrich Dr.
In den letzten Jahren häufen sich Angaben über das Auftreten von Orchideen an sekundären und vor allem auch urbanen Standorten. Durch diese auffällige Biotoperweiterung muss die Aussage, dass Orchideen als Anzeiger intakter Lebensräume gelten, relativiert werden. Gerade als konkurrenzschwache Arten haben dabei vermutlich euryöke Orchideen mit einer relativ breiten ökologischen Amplitude auf jungen, anthropogen entstandenen Böden, zumindest über eine begrenzte Zeit, Chancen einer Erstansiedlung, teilweise mit Massenvorkommen. Zahlreiche konkrete Beispiele werden dafür aus Deutschland mit Schwerpunkt Jena und Thüringen aufgeführt. Es wird belegt, dass vor allem klonal wachsende Orchideen (Epipactis helleborine, Listera ovata, Cephalanthera damasonium) sowie die autogame Ophrys apifera ihre ökologische Amplitude und ihre Biotopbindung erweitert haben. Man sollte aber auch in diesem Zusammenhang Aspekte eines Klimawandels berücksichtigen. Lohnenswert erscheint es, diese Prozesse weiter zu verfolgen, auf neue Fundorte an urbanen Standorten in Städten und Dörfern zu achten. Wichtig aber ist es, künftig die Zusammenhänge zwischen Keimungsbedingungen, Individualansiedlung und Populationsbildung im Wechselspiel mit Klima und Bodeneigenschaften (und ihren darin siedelnden Organismen) gezielt in solchen Biotopen zu erforschen. Weitere populationsökologische Studien sind daher dringend erforderlich, um diese neuen Prozesse folgerichtig interpretieren zu können. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Indigenous orchids in urban biotopes During the last years informations about the appearance of orchids multiplied in secondary and urban locations. The statement that orchids count as an indicator of intact habitats must be qualified by this remarkable biotope extension. Even as competition-weak species have, besides, presumably euryoecious orchids with relatively spread ecological amplitude on young, anthropogen resulted soils, at least on a restricted time, chances of a first settlement, partially with mass occurrence. Numerous precise examples from Germany with main focus Jena and Thuringia are mentioned for it. It is proved that, above all, klonal growing orchids (Epipactis helleborine, Listera ovata, Cephalanthera damasonium) as well as autogame Ophrys apifera her ecological amplitude and her biotope links have extended. Worthwhile appears to investigate these relations between germination terms, individual colonization, and development of population in the interaction with climate and soil qualities (and her organisms settling in it) concerted in urban biotopes. Further population-ecological studies are urgently necessary to interpret these new processes consistently. [source]

Grassland communities on a Sahelian peneplain in Burkina Faso

FEDDES REPERTORIUM, Issue 1-2 2008
J. V. Müller Dr.
A detailed phytosociological analysis of grassland communities of a Sahelian peneplain in Burkina Faso (West Africa) is presented. The floristic structure of the vegetation was documented with 113 relevés, which were classified manually and in addition ordinated to characterize main floristic gradients. The topographical situation from high-lying areas of the peneplain with erosion of material to low-lying areas with accumulation of material turned out to be the most important differentiating factor in the data set. All grassland communities are dominated by annual grasses and have large distribution ranges. They colonize sandy-silty, loamy to clayey soils and can be water-saturated or repeatedly inundated during the rainy season, while dry, non-inundated habitats are also colonized. Many grasses are valuable fodder plants and are appreciated by livestock , the peneplain is economically highly important as a grazing ground. Whereas exozoochorous annual species are constantly present companions, perennial herbaceous species are almost completely missing. Stands were grouped into one alliance Panico laeti-Echinochloion colonae and only two phytocoenoses: a rankless Schoenefeldia gracilis -community (with two subcommunities: a typical subcommunity with a large ecological amplitude from sandy-silty to loamy soils, and an Aristida funiculata -subcommunity on sandy, dry, non-inundated soils) and Eragrostietum pilosae. The Eragrostietum pilosae grows in the low-lying areas of the peneplain and connects between communities of seasonally inundated lakes and the grasslands on the upper parts of the pene- plain. Following the topography, the two plant communities form a large transition (zonation complex). It is widespread across the study area and contains the diagnostic species of both plant communities. The plant communities are compared with other Sahelian grass-dominated plant communities, and with plant communities from the Sahara and the (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Grasfluren einer sahelischen Rumpffläche in Burkina Faso In diesem Beitrag wird eine detaillierte pflanzensoziologische Analyse der Grasfluren einer sahelischen Rumpffläche in Burkina Faso (Westafrika) präsentiert. Die floristische Struktur der Vegetation wurde mit 113 pflanzensoziologischen Aufnahmen dokumentiert. Diese wurden zunächst manuell klassifiziert und anschließend einem Ordinationsverfahren unterzogen, um die wichtigsten Gradienten im floristischen Datensatz aufzuzeigen. Die topographische Geländesituation der Rumpffläche, beginnend mit hochgelegenen Bereichen mit Materialaustrag bis in die Niederungen mit Materialeintrag, wurde als wichtigster differenzierender Faktor des floristischen Datensatzes identifiziert. Alle untersuchten Pflanzengesellschaften der Grasfluren haben große Verbreitungsgebiete und werden von annuellen Gräsern dominiert. Sie sind auf sandig-schluffigen, lehmigen bis tonigen Böden zu finden. Sie können in der Regenzeit entweder wassergesättigt oder wiederholt überflutet sein. Die Grasfluren sind auch auf trockenen, nicht überfluteten Standorten nachgewiesen. Viele der Grasarten sind vom Weidevieh geschätzte Futterpflanzen , die Rumpffläche dient als wirtschaftlich bedeutendes Weideland. Exozoochore, einjährige Arten sind hochstet als Begleiter vorhanden. Hingegen fehlen mehrjährige, krautige Arten fast vollständig. Die Bestände konnten einem pflanzensoziologischen Verband Panico laeti-Echinochloion colonae und zwei Pflanzengesellschaften zugeordnet werden. Die ranglose Schoenefeldia gracilis -Gesellschaft kommt in zwei Untereinheiten vor: eine typische Untereinheit mit breiter ökologischer Amplitude von sandig-schluffigen bis lehmigen Böden, und eine Aristida funiculata Untereinheit auf trockenen, sandigen, nicht überfluteten Böden. Das Eragrostietum pilosae kommt in den tiefliegenden Bereichen Sudanian zone. A close floristic relationship of Sahelian grassland communities with Saharan vegetation could be shown. der Rumpffläche vor und vermittelt zwischen den Pflanzengesellschaften temporärer Seen und den Grasfluren der hochgelegenen Bereiche der Rumpffläche. Der Geländesituation folgend bilden beide Pflanzengesellschaften einen breiten Übergangsbereich (Zonationskomplex). Dieser Übergangsbereich ist im Untersuchungsgebiet weit verbreitet und enthält diagnostische Arten beider Pflanzengesellschaften. Die beschriebenen Einheiten werden mit anderen grasdominierten Pflanzengesellschaften des Sahels sowie der Sahara und der Sudanzone verglichen. Eine enge floristische Beziehung der sahelischen Grasfluren mit Vegetationseinheiten der Sahara wird aufgezeigt. [source]

Contrasting phylogeographies inferred for the two alpine sister species Cardamine resedifolia and C. alpina (Brassicaceae)

JOURNAL OF BIOGEOGRAPHY, Issue 1 2009
Judita Lihová
Abstract Aim, We use Cardamine alpina and C. resedifolia as models to address the detailed history of disjunctions in the European alpine system. These species grow on siliceous bedrock: C. alpina in the Alps and Pyrenees, and C. resedifolia in several mountain ranges from the Sierra Nevada to the Balkans. We explore differentiation among their disjunct populations as well as within the contiguous Alpine and Pyrenean ranges, and compare the phylogeographical histories of these diploid sister species. We also include samples of the closely related, arctic diploid C. bellidifolia in order to explore its origin and post-glacial establishment. Location, European alpine system, Norway and Iceland. Methods, We employed amplified fragment length polymorphisms (AFLPs). AFLP data were analysed using principal coordinates analysis, neighbour joining and Bayesian clustering, and measures of diversity and differentiation were computed. Results, For the snow-bed species C. alpina (27 populations, 203 plants) we resolved two strongly divergent lineages, corresponding to the Alps and the Pyrenees. Although multiple glacial refugia were invoked in the Pyrenees, we inferred only a single one in the Maritime Alps , from which rapid post-glacial colonization of the entire Alps occurred, accompanied by a strong founder effect. For C. resedifolia (33 populations, 247 plants), which has a broader ecological amplitude and a wider distribution, the genetic structuring was rather weak and did not correspond to the main geographical disjunctions. This species consists of two widespread and largely sympatric main genetic groups (one of them subdivided into four geographically more restricted groups), and frequent secondary contacts exist between them. Main conclusions, The conspicuously different histories of these two sister species are likely to be associated with their different ecologies. The more abundant habitats available for C. resedifolia may have increased the probability of its gradual migration during colder periods and also of successful establishment after long-distance dispersal, whereas C. alpina has been restricted by its dependence on snow-beds. Surprisingly, the arctic C. bellidifolia formed a very divergent lineage with little variation, contradicting a scenario of recent, post-glacial migration from the Alps or Pyrenees. [source]

Shifts in the ecological behaviour of plant species between two distant regions: evidence from the base richness gradient in mires

JOURNAL OF BIOGEOGRAPHY, Issue 2 2008
Petra Hájková
Abstract Aim, Water pH and conductivity are known to be major environmental factors controlling the species composition of nutrient-poor wetlands. Based on the analysis of two large data sets of species co-occurrence, sampled along the entire pH/calcium gradient, we explored whether species exhibit similar or different ecological behaviour in the two regions. Location, West Carpathians (central Europe) and Bulgaria (south-eastern Europe), situated 800 km apart. Bulgaria represents a range margin for many mire species. Methods, The probability of occurrence of the 41 most common species along the pH and conductivity gradients was assessed using logistic regression fitted by means of generalized additive models. The species optimum and amplitude were determined. To check the possible effect of competitive release, we estimated where the potential maximum number of species (maximum overlap in realized niches) occurs along the base richness gradient. Results, Most of the 41 frequently occurring species showed a significant response to water pH and ln-transformed conductivity (approximating total mineral richness) in both regions. Eight species showed a shift in pH optimum greater than one unit, while 12 species showed the same or a larger shift along the conductivity gradient. Nearly all these striking shifts were connected to an extension of species tolerance towards mineral-poor acid habitats in Bulgaria, which causes links between species and measured factors to be conspicuously weaker in Bulgaria than in the West Carpathians. Regarding ecological amplitude, 24 species exhibited a wider tolerance to water conductivity in the West Carpathians, whereas 17 species exhibited a wider tolerance in Bulgaria. Main conclusions, A distinctive variation in the realized niche was observed in a large portion of the species examined. Niche shifts between local populations of the same species were similar to those of closely related vicariant species. Ecotypic adaptation within species is a possible explanation for this pattern. Other possible explanations (competitive release, specific habitat conditions, compensation for climate) seem to be less justified. The local populations of rich-fen species may have adapted to mineral-poor acid conditions in the high crystalline mountains of Bulgaria during dry periods of pleniglacials. Nomenclature,Marhold & Hindák (1998); for Balkan elements not included in this source, Andreev et al. (1992). [source]

Inbreeding and inbreeding depression in a threatened endemic plant, the African violet (Saintpaulia ionantha ssp. grotei), of the East Usambara Mountains, Tanzania

AFRICAN JOURNAL OF ECOLOGY, Issue 3 2010
Johanna Kolehmainen
Abstract Mating among closely-related individuals in small and isolated plant populations may result in reduced vigour of the inbred offspring, i.e. inbreeding depression, especially in naturally outbreeding plants. Occurrence of inbreeding and inbreeding depression was studied in Saintpaulia ionantha ssp. grotei, a threatened endemic plant species with a narrow ecological amplitude from the East Usambara Mountains. The level of inbreeding (measured as the fixation index, F) was investigated in twelve populations by analyzing variation at one microsatellite marker locus. The effect of one generation of selfing and outcrossing on the progeny fitness was studied by controlled crosses in two small patches that differ in the level isolation. The fixation index (F) across the populations was on the average 0.21 and varied among the populations from substantial inbreeding (F = 0.58) to surplus heterozygosity (F = ,0.29). High inbreeding depression (,) was observed at early and late stages of the life-cycle. The isolated patch exhibited lower inbreeding depression than did the non-isolated patch. The results of this study suggest that inbreeding and subsequent inbreeding depression are potential threats to the survival of Saintpaulia populations. Résumé L'accouplement d'individus étroitement liés, dans des petites populations végétales isolées, peut aboutir à une vigueur moindre de la progéniture de même souche, c'est-à-dire une dépression due à l'endogamie, spécialement chez des plantes qui sont naturellement exogames. L'occurrence de l'endogamie et de la dépression qui y est liée a étéétudiée chez le Saintpaulia ionantha spp. grotei, une plante endémique menacée qui n'a qu'une faible amplitude écologique dans l'est des Usambara Mountains. On a recherché le taux d'endogamie (mesuré par l'indice de fixation F) dans 12 populations en analysant la variation d'un locus microsatellite marqueur. L'effet d'une génération d'auto- et d'allofécondation sur l'aptitude (fitness) de la progéniture a étéétudié par des croisements contrôlés dans deux petites parcelles dont le degré d'isolement différait. L'indice de fixation F dans les populations était en moyenne de 0,21 et il variait d'une autofécondation substantielle (F = 0,58) à une hétérozygosité en surplus (F = ,0,29). Une forte dépression due à l'endogamie (,) a été observée aux stades précoce et tardif du cycle vital. La parcelle isolée a présenté une dépression liée à l'endogamie moins forte que celle de la parcelle non isolée. Les résultats de cette étude suggèrent que l'auto-fécondation et la dépression qui en résulte sont des menaces potentielles pour la survie des populations de Saintpaulia. [source]

Geographical variation in predictive seedling emergence in a perennial desert grass

JOURNAL OF ECOLOGY, Issue 1 2000
Steven E. Smith
Summary 1,Mechanisms that link germination and emergence to environmental cues associated with seedling success (predictive germination) would be expected to evolve when seedlings have a greater mortality risk than seeds, but may be less important in perennial plants than in annual plants. 2,We investigated variation in predictive seedling emergence among divergent populations of a short-lived perennial desert grass, Digitaria californica, from sites that differed in climatic and edaphic factors. This species is native to environments in which the amount and duration of adequate soil moisture may control germination and seedling establishment success. 3,We utilized a special irrigation system that permits application of a range of amounts of water within a single experiment in a glasshouse. Emergence data were subjected to probit and survival analyses to describe differences among the populations in response to applied water. 4,Significant variation in predictive emergence was shown to exist among populations of D. californica when measured as amount of water required for 50% emergence following 3 days of water application, or as time required to achieve this level of emergence. Both climatic and soil characteristics were important with populations that originated from sites with less summer precipitation, and soils with higher water-holding capacity tended to have lower water requirements for emergence. 5,The report demonstrates the existence of subtle variation in predictive emergence among populations of a perennial grass representing a relatively narrow range of ecological amplitude. It also establishes the usefulness of line-source irrigation and probit analysis procedures in studying seedling emergence behaviour. [source]