Donnerstag, 14 Juni 2018 08:10

STUART, C. & T. (1995)

Africa - A Natural History.

170 Seiten, 300 Farbfotos, Landkarten.
Southern Book Publishers (Pty.) Ltd. ISBN 1-86812-520-3.

Anbietertext:

Documenting the wild variance and natural extravagance of the African continent, this book takes the reader on a journey through the seven major habitats of Africa: savanna, dryland, forest, highland, Cape heathland, the fresh waters, and the coastal zones. Detailed descriptions of the mammals, birds, reptiles and amphibians, fish and vegetation that make each habitat their home, accompany each chapter.

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Donnerstag, 14 Juni 2018 06:54

SCHIESS, H. (1989)

Schilfbestände als Habitatinseln von Vögeln.

Eidg. Anstalt für das forstliche Versuchswesen, Birmensdorf. Berichte Nt. 321, ISSN 0259-3092. 48 Seiten. / Vierteljahrsschrift der Naturforschenden Gesellschaft in Zürich (1990) 135/4: 259-265

Einleitung (Auszug):

Seit einigen Jahren lenken Ökologen ihre Aufmerksamkeit vermehrt auf die biogeographischen Fragestellungen nach Zeit und Raum und nach deren Einfluss auf Flora und Fauna. Massgebliche Impulse gingen dabei von amerikanischen Autoren aus, welche die Grösse von Inseln und den Grad ihrer Isoliertheit als bestimmende Faktoren für die Anzahl vorkommender Arten erkannten. Nach R. H. MacArthur und E.O. Wilson (1963, 1967) gibt es für jede Insel, entsprechend ihrer Fläche und ihrer geographischen Lage, einen Gleichgewichtszustand, in dem sich Aussterbe- und Einwanderungsrate von Tierpopulationen die Waage halten. In diesem Gleichgewichtszustand pendelt die Artenzahl um ein konstantes Niveau. Je kleiner eine Insel ist, und je weiter entfernt sie von elner Quelle potentieller Kolonisation liegt, desto geringer ist einerseits die Wahrscheinlichkeit, dass sie gefunden und besiedelt wird; andererseits erreichen etablierte Populationen auf kleinen Inseln nur bescheidene Individuenstärken, so dass sie in vermehrtem Masse gefährdet sind, bei zufälligen Bestandesschwankungen auszusterben. Die Anzahl vorkommender Arten sinkt deshalb mit zunehmender Isolation und abnehmender Fläche.

Die Inseltheorie ist seitdem Gegenstand und Ausgangspunkt zahlreicher Untersuchungen ge-
worden. Ihre Voraussagen wurden an Pflanzen und vielen Tiergruppen geprüft und weiterentwik-
kelt. In einigen Arbeiten wurden gleichartige, aber voneinander isolierte Habitate auf dem Festland als Insel-Analoga aufgefasst. Die neuen Erkenntnisse wurden auch für die Planung von Reservaten eingesetzt.

Mit der hier auszugsweise vorgestellten Arbeit verfolgte ich das Ziel, die Faktoren zu beschreiben und zu erfassen, die für das Vorkommen der Brutvögel in den Schilfbeständen von Zürlch- und Obersee eine Rolle spielen.

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Donnerstag, 14 Juni 2018 16:48

RÖSSLER, M. (2000)

Der Lebensraum der Europäischen Sumpfschildkröte Emys orbicularis (L) in den niederösterreichischen Donau-Auen (Reptilia: Testudines: Emydidae).

12 Seiten © Biologiezentrum Linz/Austria

Abstract:

Over a period of three years (1997-1999) I studied habitat requirements of the European pond turtle in the  National Park "Donau-Auen" in the Austrian state of Lower Austria. Two side arms of the Danube inhabited by Emys orbicularis are characterized. Juvenile European pond turtles preferred shallower, more vegetated areas than adults.Sixty-eight percent of all sighted basking turtles (n = 303 sightings) were observed on tree trunks,23 % on the embankment, and 10 % on floating  leaves  of aquatic  macrophytes. Nesting sites are xerothermic, sandy meadows up to  800  m away from water bodies. Temperature  regimes, predation rates and vegetation cover of nest sites are described and  related to the vertical distribution of the nests at a sun-exposed embankment.

Volltext (PDF)

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Donnerstag, 14 Juni 2018 16:44

ROOTH, J. (1975)

Caribbean Flamingos in a man-made habitat.

In KEAR, J. & DUPLAIX-HALL, N. (eds.) Flamingos. 248 Seiten.
T. & AD Poyser Publishers. Berkhamsted. ISBN-13: 978-1408137505

Verlagstext:

An international gathering of scientists from a variety of disciplines met at The Wildfowl Trust, Slimbridge, from 10-12 July 1973, to report on the world situation, in the wild and in captivity, of the six types of flamingos. The occasion was the International Flamingo Symposium, called to discuss problems encountered in flamingo conservation and research, and participants came from North and South America, Africa, the Middle East and Europe. Flamingos' thirty-nine chapters derive from papers delivered at the Symposium. They form four sections: Populations, Ecology and Conservation; Flamingos in captivity; Ethology and Taxonomy; Flamingo Physiology - in addition there are appendices of biological and other information, a comprehensive bibliography,and an Introduction by Sir Peter Scott.Flamingos, one of the oldest bird groups alive today, are also among the most popular and common of zoo animals, and part of the book is concerned with the problems of .breeding and rearing the birds in captivity, and the stress and disease to which they can be prone. One of the aims of the Symposium and of the book is to disseminate the knowledge that will help improve captive conditions.Hopefully, greater success in breeding from captive birds may ensure that fewer of those born to the wild will be deprived of their freedom. Sir Peter Scott in his Introduction believes that within ten years zoos should be breeding all the flamingos they need.Approximately half of the book is concerned with populations in the wild, with field studies and conservation, and there are reports from all but one of the major population areas.Jacket illustration by lan Willis.

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Donnerstag, 14 Juni 2018 17:24

REINER, E. & LÖFFLER, E. (Hrsg. 1977)

Australien.

224 Seiten mit einigen Karten und 138 teils ganzseitigen farbigen Fotos auf Kunstdrucktafeln, farbige Karte auf den Vorsätzen.
Kümmerly & Frey, Geographischer Verlag, Bern. ISBN 3-259-08471-1.

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Donnerstag, 14 Juni 2018 17:16

REIMOSER, S. & REIMOSER, F. (2006)

Lebensraum und Abschuss, Abschussdichten verschiedener Wildarten in den österreichischen Bezirken seit 1955.
14.Teil: Murmeltier, Alpenschneehuhn, Steinhuhn.

Weidwerk 2006 Nr. 7: 8-9.

Einleitung:

Das Jubiläum „50 Jahre Staatsvertrag“ im vergangenen Jahr war Anlass für einen jagdlichen Rückblick auf die Veränderung der Abschüsse in Österreich in Abhängigkeit von Lebensraumtyp und Wildart. Diese mehrteilige WEIDWERK-Serie bietet einen Überblick über die oft interessanten Veränderungen während der letzten 50 Jahre, der Leser kann seinen Bezirk mit anderen vergleichen.

 

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Donnerstag, 14 Juni 2018 17:15

REIMOSER, S. & REIMOSER, F. (2006)

Lebensraum und Abschuss, Abschussdichten verschiedener Wildarten in den österreichischen Bezirken seit 1955.
11.Teil: Auerwild, Birkwild und Haselwild.

Weidwerk 2006 Nr. 4: 8-11.

Einleitung:

Das Jubiläum „50 Jahre Staatsvertrag“ im vergangenen Jahr war Anlass für einen jagdlichen Rückblick auf die Veränderung der Abschüsse in Österreich in Abhängigkeit von Lebensraumtyp und Wildart. Diese mehrteilige WEIDWERK-Serie bietet einen Überblick über die oft interessanten Veränderungen während der letzten 50 Jahre, der Leser kann seinen Bezirk mit anderen vergleichen.

 

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Species diversity of the Okavango Delta, Botswana.

Aquat. Sci. 68 (2006) 310–337. ISSN 1015-1621/06/030310-28. DOI 10.1007/s00027-006-0857-y © Eawag, Dübendorf, 2006

Abstract:

In the Okavango Delta (about 28,000km2) the number of identified species is 1,300 for plants, 71 for fish, 33 for amphibians, 64 for reptiles, 444 for birds, and 122 for mammals. The local occurrence of different species of these taxonomic groups in the Okavango Delta is mainly due to a hydrological gradient from permanent streams and swamps to seasonal floodplains, riparian woodlands, and dry woodlands. This level of species diversity is normal for the southern African region, and all analyzed aquatic groups are composed of ubiquitous species with an additional significant proportion of species originating from northern, more tropical systems. Cyclical variations in climate over thousands of years have created a huge wetland complex in the upper Zambezi and Okavango Rivers during wet phases. This wetland complex has fragmented into the Okavango Delta and other large wetlands in Zambia during dry phases. There are no endemic species in the Okavango Delta while the South-central African wetland complex is a centre of endemism. Species diversity of the Okavango Delta is a consequence of this unique environment, with dynamic shifts in flooding patterns that in turn force constant changes in patterns of plant succession and dependent animals. Temporal variations in flooding also cause accumulation and sudden mobilization of nutrients which are readily used by well adapted plant species. As a consequence, locally high biological productivity occurs, which in turn results in high numbers of grazing mammals.

Species diversity of the Okavango Delta, Botswana (PDF Download Available). Available from: https://www.researchgate.net/publication/226358917_Species_diversity_of_the_Okavango_Delta_Botswana [accessed Nov 14 2017].

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Donnerstag, 14 Juni 2018 16:59

RAJKARAN, A. (2011)

A status assessment of mangrove forests in South Africa and the utilization of mangroves at Mngazana Estuary.

Phil. II Diss. Nelson Mandela Universität, Port Elizabeth.

Abstract:

In South Africa mangrove forests are located in estuaries from Kosi Bay in KwaZulu-Natal (KZN) to Nahoon Estuary in the Eastern Cape. The aims of this study were to determine the present state of mangroves in KwaZulu-Natal, by assessing the current population structure, the changes in cover over time and associated anthropogenic pressures. A second objective of this study was to determine the effect of harvesting on the population structure and sediment characteristics in the Mngazana mangrove forest. To determine if harvesting was sustainable at Mngazana Estuary; the growth and mortality rates and associated growth conditions were measured. Finally by using population modelling sustainable harvesting limits were determined by predicting the change in population structure over time. The study focussed on the KwaZulu-Natal province as a fairly recent study addressed mangrove distribution and status in the Eastern Cape Province. A historical assessment of all mangroves forests in KwaZulu-Natal (KZN) revealed that the potential threats to mangroves in South Africa include; wood harvesting, altered water flow patterns coupled with salinity changes, prolonged closed-mouth conditions and subsequent changes to the intertidal habitat. As a result mangroves were completely lost from eleven estuaries in KZN between 1982 and 1999 and a further two estuaries by 2006. Mangroves only occurred in those estuaries where the mouth was open for more than 56 percent of the time with the exception of St Lucia, where the mouth has been closed for longer but the mangrove communities have persisted because the roots of the trees were not submerged. All mangrove forests in KZN were regenerating in terms of population structure as they had reverse J-shaped population curves as well as high adult: seedling ratios. Kosi Bay and Mhlathuze Estuary were two of the larger forests that showed signs of harvesting (presence of tree or branch stumps), but the greatest threat to smaller estuaries seems to be altered water flow patterns due to freshwater abstraction in the catchments and the change of land use from natural vegetation to sugar-cane plantations. These threats affect the hydrology of estuaries and the sediment characteristics (particle size, redox, pH, salinity, temperature) of the mangrove forests. The environmental conditions under which the mangrove forests currently exist were determined for five species. Lumnitzera racemosa and Ceriops tagal exhibited a narrow range of conditions as these species are only found at Kosi Bay, while Avicennia marina, Bruguiera gymnorrhiza and Rhizophora mucronata were found to exist under a wider range of conditions. The growth rate and response to environmental conditions of the three dominant species were important to determine as these species are impacted by harvesting. Mangrove growth rates were measured at Mngazana Estuary in the Eastern Cape, the third largest mangrove forest in South Africa. Areas of this estuary where mangroves harvesting has occurred, show significant differences in sediment characteristics as well as changes in population structure in harvested compared to non harvested sites. The growth rate (in terms of height) of Avicennia marina individuals increased from seedlings (0.31 cm month-1) to adults (1.2 cm month-1), while the growth of Bruguiera gymnorrhiza stabilised from a height of 150 cm at 0.65 cm month-1. The growth of Rhizophora mucronata peaked at 0.72 cm month-1 (height 151-250 cm) and then decreased to 0.4 cm month-1 for taller individuals. Increases in diameter at breast height (DBH) ranged between 0.7 and 2.3 mm month-1 for all species. Some environmental variables were found to be important drivers of growth and mortality of individuals less then 150 cm. A decrease in sediment pH significantly increased the mortality of Avicennia marina seedlings (0-50 cm) (r = - 0.71, p<0.05) and significantly decreased the growth of Rhizophora mucronata and Bruguiera gymnorrhiza seedlings (r = -0.8, r = 0.52 – p < 0.05 respectively). At Mngazana Estuary, mortality of this species showed a positive correlation with sediment moisture content indicating that this species prefers drier conditions. The density of Rhizophora mucronata was significantly correlated to porewater temperature in Northern KZN as was the growth of adult (>300 cm) Rhizophora trees at Mngazana Estuary. Mortality of Avicennia marina individuals (51-150 cm) was related to tree density indicating intraspecific competition and self thinning. Selective harvesting of particular size classes of Rhizophora mucronata was recorded when comparing length of harvested poles (~301 cm) and the size class distribution of individuals. Taking into account the differences in growth rate for each size class for this species it will take approximately 13 years to attain a height of 390 cm which is the height at which trees are selected for harvesting at this estuary. This is 2.6 times slower than those individuals growing in Kenya. The feasibility of harvesting is dependent on the growth rate of younger size classes to replace harvested trees as well as the rate of natural recruitment feeding into the population. Different harvesting intensity scenarios tested within a matrix model framework showed that limits should be set at 5 percent trees ha-1 year-1 to maintain seedling density at > 5 000 ha-1 for R. mucronata. However harvesting of Bruguiera gymnorrhiza should be stopped due to the low density of this species at Mngazana Estuary. Harvesting of the tallest trees of Avicennia marina can be maintained at levels less than 10 percent ha-1 year-1. Effective management of mangrove forests in South African is important to maintain the current state, function and diversity of these ecosystems. Management recommendations should begin with determining the freshwater requirements of the estuaries to maintain the mouth dynamics and biotic communities and deter the harvesting of (whole) adult trees particularly those species that do not coppice. Further management is needed to ensure that forests are cleared of pollutants (plastic and industrial), and any further developments near the mangroves should be minimized.

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Donnerstag, 14 Juni 2018 16:33

PRESTON-MAFHAM, K. (1991)

Madagascar - A Natural History.

224 Seiten.
1. Auflage. Facts on file Ltd., Oxford. ISBN-13: 978-0816024032.

Inhalt:

Madagascar is the fourth largest island in the world, with a landmass of 226,739 square miles - over twice the size of the British Isles. Until 65 million years ago, it was part of continental Africa, but broke free and drifted into the Indian Ocean, gradually isolating its flora and fauna. This illustrated study of the extraordinary wildlife of the island covers the lone evolution of many of the species of plant and animal where all of the mammals, 225 of the 257 species of reptile and almost 80% of its plants are unique to Madagascar.

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