In contrast to the wealth of palaeoenvironmental research stemming from the eastern Afromontane archipelago, the southern Afromontane component, which comprises largely of the Drakensberg, remains understudied. The Drakensberg constitute an area of significant biodiversity, cultural and economic importance. Suitable sites for palaeoenvironmental research are rare in South Africa due to general arid climatic conditions over much of the country. The KwaZulu-Natal Drakensberg offers a unique opportunity for palaeoenvironmental research through its increased rainfall and higher altitudes, which enable the development of wetlands that have the potential for polliniferous accumulation to occur. Catchment Six in Cathedral Peak is one such wetland that has provided an opportunity to research palaeoenvironmental conditions of the southern Afromontane archipelago component. A 371 cm sediment core was extracted from a subalpine wetland in Catchment Six and analysed using multiple proxies including; pollen, charcoal and geochemistry (carbon and nitrogen stable isotopes). A chronological framework for the core was established based on accelerated mass spectrometry radiocarbon dating of eight bulk sediment samples. A basal date of 15,100 ± 445 cal yr BP was determined at a depth of 298 cm. Poor pollen preservation of the basal portion of the core limited palaeoenvironmental inference for the late Pleistocene section of the record. The multiproxy record provides high chronological resolution for the early to late Holocene. Multi-proxy data indicate that the Holocene period in the Drakensberg was characterised by variable climatic conditions. Charcoal data indicate periods of increased regional fires in the last ca. 400 cal yr BP. Palaeoenvironmental inferences from the Catchment Six record are broadly in agreement with regional climatic indications based on existing literature. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Thesis (M. Sc.)--Carleton University, 1992. / Also available in electronic format on the Internet.

Thesis (M.S.)--University of Delaware, 2005. / Principal faculty advisor: Ronald E. Martin, Dept. of Geology. Includes bibliographical references.

The pollen, plant macrofossil and aquatic fossil stratigraphies from a transect of sites in the Sierra Nevada, California, were examined to deduce paleoenvironmental change since the late-Wisconsinan. Fossil pollen samples were compared to modern pollen samples from both sides of the Sierra Nevada crest. Modern samples corresponded largely to modern vegetation units, validating the use of pollen for this purpose in mountainous environments. Vegetation change during the Holocene was largely contemporaneous on both sides of the crest at elevations where lake cores and meadow sections were analysed. Deglaciation occurred by ca. 12,500 yr BP at a site on the east side, and by ca. 11,000 yr BP at a west side site. Prior to ca. 10,000 yr BP, few trees were found around the higher elevation sites. An open forest with trees characteristic of the modern Sierra Montane and Upper Montane forest grew around the mid- to high elevation sites by the early Holocene. Montane chaparral species, such as bush chinquapin, mountain mahogany and probably huckleberry oak, with sagebrush, were most abundant then. Along with lowered lake levels or absence of perennially standing water, and greater affinities to modern pollen samples from the more arid east side, these observations suggest drier conditions than today. However, by ca. 6500-5500 yr BP, effective precipitation increased, as shown by increases in subalpine conifers (mountain hemlock and red fir) and higher lake levels, and less affinities to modern samples from the east side. Modern vegetation developed at most sites within the last 2-3 millenia. Specific changes in the vegetation at this time included a reduction in upper elevational limits of mountain hemlock and red fir, with possible downslope retreat of whitebark pine, indicating greater cooling and/or wetter conditions. This is consistent with the record of wet meadow genesis as well as tree-ring and Neoglacial chronologies.

Identification of pollen in fecal pellets is a potential technique for describing an animals diet and in turn the vegetation of an area. Mule deer and Bighorn Sheep pellets representing both summer and winter browsing and a variety of habitats were examined using relative percentages and the absolute pollen frequencies. In addition, fossil pellets from Stanton's Cave, Grand Canyon, Arizona, were examined and compared with modern pellets. Absolute pollen frequencies of individual pellets showed higher values and greater variation for summer pellets than for winter pellets. Relative pollen percentages for a specific vegetation type showed more variation in fecal pellets than in soil surface samples. Unless specifically being eaten, arboreal pollen types such as Pinus are less abundant in fecal pellets than in soil samples. Unlike soil surface samples, arboreal pollen types in fecal pellets are frequently limited to the immediate source area.

Pollen analysis of two surface transects of modern soil samples and four stratigraphic sections from the central Sierra Nevada of California have provided a climatic record covering the time interval since the recession of the last glaciers of the Wisconsin glaciation. Two separate warm intervals are recognized between the recession of the Wisconsin glaciers and the reappearance of glaciers in the Sierra during the Little Ice Age.

Palynology involves the study of past climatic and environmental changes through changes in the relative frequencies of different pollen types through time. Several multivariate statistical methods are suggested which can help in the description of patterns within pollen data. These techniques are based on comparisons between samples. Samples were compared using the product-moment correlation coefficient computed from data which had been subjected to a centering transformation. The methods are described using a geometric model. If there are m samples and n pollen types, then the data can be regarded as a set of m points in an n-dimensional space. Cluster analysis produces a dendrograph or clustering tree in which samples are grouped with other samples on the basis of their similarity to each other. Principal component analysis produces a set of variates which are linear combinations of the pollen samples, are uncorrelated with each other, and do the best job of describing the data using a minimum number of dimensions. This method is useful in reducing the dimensionality of data sets. Varimax rotation acts on a subset of the principal components to make them easier to interpret. Discriminant analysis is used to find the best way to tell groups of samples apart, where the groups are known a priori. Once a means of discrimination among groups has been established using samples whose groups are known, unknown samples may be classified into the original groups. Canonical analysis produces a way to display the maximum separation between groups in a graphic manner. Examples of applications of these methods in palynology are shown using data from Osgood Swamp, California, and from southern Arizona. These methods offer the advantages of reproducibility of results and speed in pattern description. Once the patterns in the data have been described, however, their interpretation must be done by the palynologist.

La conservation des mares temporaires implique la connaissance, à la fois de leur fonctionnement et de leurs dynamiques temporelles, à court et long terme. La thèse, réalisée sur une mare temporaire du plateau gréso-quartzitique de Benslimane, s'organise en trois volets. (1) Le premier concerne la relation entre le pollen de surface et la végétation hydrophytique locale, dans le but d'établir un référentiel actuel pour l'étude paléoécologique de la mare. Les résultats obtenus montrent que la zonation de la végétation de la mare est correctement reconstruite à partir des enregistrements polliniques. Trois taxons clés (Isoetes velata-type, Myriophyllum alterniflorum, Ranunculus-type) peuvent être utilisés pour reconstituer la structure végétale passée. (2) Le second volet concerne l'histoire de la mare, en associant les données de la littérature et les données paléoécologiques obtenues à partir d'un sondage. Les résultats permettent de dater l'origine de la mare entre 1 million et 700 000 ans avant aujourd'hui. Ils témoignent de la conservation de la topographie régionale, par bilan sédimentaire négatif, jusqu'à environ 5000 cal. BP. A cette époque, le changement du fonctionnement morphogénétique de la mare, probablement lié au développement des pratiques agro-pastorales, a entraîné le comblement progressif de la mare. L'intensification des activités humaines constitue à moyen terme la principale menace concernant les mares du plateau de Benslimane, et par voie de conséquence, sur la préservation du plateau lui-même, que les mares protègent de l'érosion. (3) Le dernier volet apporte enfin un éclairage sur les processus mis en jeu dans la régénération de la végétation après micro-perturbations. Les résultats montrent une restauration rapide des microsites perturbés par dispersion proximale et effet de bordure. Toutefois, la dynamique de recolonisation reste liée aux conditions hydrologiques locales / Conservation of temporary pools implies the knowledge, about both their functioning and their temporal dynamics, on the short and the long term. The thesis, dealing with a temporary pool of the limestone-quartzite Benslimane plateau, is organised in three sections. (1) The first one concerns the relationship between the surface pollen and the hydrophytic vegetation, in order to establish a modern reference for the paleoecological study of the pool. The results show that the vegetation zonation is correctly reconstructed from the pollen records. Three key taxa (Isoetes velata-type, Myriophyllum alterniflorum, Ranunculus-type) may be used for reconstructing the past vegetation structure. (2) The second section deals with the pool history, by combining data from literature and palaeoecological data obtained from a sediment profile. Results allow dating the origin of the pool between 1 million and 700,000 years before today. They attest the conserv ation of the regional topography, by negative sedimentary balance, until ca. 5000 cal. BP. Then, the change of morphogenetic functioning of the pool, probably related to the development of agro-pastoral practices, resulted in the progressive filling of the pool. In the medium term, the intensification of human activities constitutes the main threat concerning the Benslimane pools, and consequently, on the conservation of the whole plateau, protected from erosion by pools. (3) The last section finally highlights the processes implied in the regeneration of the vegetation after micro-disturbances. The results show a fast restoration of the disturbed microsites by proximal dispersal and border effect. However, the recolonisation dynamics remains dependent on local hydrological conditions.

No description available.

South-western Australia is a globally significant hotspot of plant species diversity, with high endemism and many rare plant species. Proteaceae is a major component of the south-western flora, though little is known about how its diversity developed. This prompted the present study to investigate changes in the abundance and diversity of Proteaceae, in south-western Australia, by concurrently studying three sediment sequences of different ages over the Cainozoic and a modern pollen rain study. Modern pollen-vegetation relationships in the two Proteaceae species rich nodes of the northern and southern sandplains were quantified. It was found that Proteaceous genera can contribute up to 50% of the total pollen rain. Banksia/Dryandra pollen was the most abundant with Isopogon, Petrophile and Lambertia also commonly noted. The vegetation and environmental setting during three pivotal periods of the Cainozoic: Holocene, Pliocene and Eocene, were investigated. Eocene sediment from Lake Lefroy confirmed the presence of a Nothofagus dominated rainforest in the Middle to Late Eocene. At this time Proteaceae species were at least as diverse as today, if not more so, contributing up to a maximum of 42% of the total pollen rain. Taxa recorded included: Banksieaeidites arcuatus, Propylipollis biporus, Proteacidites confragosus, Proteacidites crassus, Proteacidites nasus and Proteacidites pachypolus. Several taxa remain undescribed and unnamed. This study also identified that Proteaceae pollen representation varies across small lateral distances. Thus as samples varied spatially and temporally, single core samples are not sufficient to identify spatial patterns in Proteaceae or other low pollen producing taxa. Some 7.91 cm of laminated Pliocene sediment from Yallalie, south-western Australia, was also examined. It covers 84 years of record and confirmed other regional reports that south-western Australia was covered by a rich vegetation mosaic consisting of heathy and wet rainforest elements. Although Proteaceae species were a consistent component of the pollen counts, diversity and abundance (maximum of 5%) was low throughout the studied section. Banksia/Dryandra types were most commonly noted. A 2 m core was retrieved from Two Mile Lake, near the Stirling Ranges and provided an early Holocene vegetation history. Geochemical and palynological evidence recorded little change, suggesting the environment of deposition was relatively uniform. Proteaceae species were noted throughout the core, though in low numbers, at a maximum of 3.5 % of the total pollen rain. Banksia/Dryandra was the most abundant while Isopogon, Lambertia, Petrophile and Franklandia were also noted. A regression model was developed through the modern pollen rain study to predict the number of Proteaceae in the vegetation. This was also applied to the fossil pollen records. The estimated number of Proteaceae species in the Eocene suggests a maximum of 20 and a minimum of 10 taxa. For the Pliocene record, an estimated 7 - 9 species was found and for the Holocene pollen, between 7 - 8 were present. Thus the Eocene was similar in Proteaceae diversity to today. The results from the Pliocene and Holocene suggest that Proteaceae diversity was lower than today. Findings of this research indicate that Proteaceae species are an important and consistent component of vegetation in south-western Australia over the Cainozoic. It is likely that both changing pollination mechanisms and changes in associated vegetation are important in the determining the dispersal of Proteaceaous pollen. By understanding how the vegetation has changed and developed in south-western Australia, present vegetation can be managed to include intra-specific variation and ensure the majority of species are conserved for present and future generations to enjoy.