This thesis researches forest history and human impact on it in prehistory and early Middle Ages by means of soil charcoal analysis, i.e. pedoanthracology. It focuses on a site called "Roztocký háj" with long-term human settlement near Roztoky u Prahy in central Bohemia. Pedoanthracology brings information about past woody vegetation that is very local and without much anthropogenic influence. On the other hand, archeoanthracology focuses on charcoal originating from archeological excavations directly from human settlements. These charcoals are therefore formed by human behaviour and provide general view on woody vegetation in wider surroundings of the site. Comparing results of these two approaches in Roztoky is allowed by long-term archeological excavations. They provided previously analyzed and partially published charcoal dataset. Newly obtained pedoanthracological dataset brings finer spatial scale, allows to find out the effect of local conditions on the charcoal spectra and also allows identification of possible purposefully selected taxa in the archeoanthracological assemblage. Another part of this work describes present-day vegetation around the soil profiles and examines it's possible continuity with the past vegetation. 4 soil profiles provided quite species-rich (17 taxa) charcoal...

xiv, 227 p. : ill. (some col.) A print copy of this title is available through the UO Libraries under the call numbers: KNIGHT QE720.2.K53 B75 2008 / The Holocene vegetation and fire history of the Klamath Mountains (KM), northern California, was reconstructed at three sites based on an analysis of pollen and high-resolution macroscopic charcoal in lake-sediment cores. These data were compared with five existing records to examine regional patterns. The objective was to determine the relative importance of climate history, substrate, and disturbance regime on the development of the Klamath vegetation. In the first study, two middle-elevation sites were compared along a moisture gradient in the northern KM. The pollen data indicated a similar vegetation history, beginning with subalpine parkland in the late-glacial period, and changing to open forest in the early Holocene and closed forest in the late Holocene. However, the timing of these changes differed between sites and is attributed to the relative importance of coastal influences and topography. The second study examined the effect of substrate and nutrient limitations on the vegetation history. The pollen data suggest that ultramafic substrates (UMS), containing heavy metals and low nutrients that limit plant growth, supported drier plant communities than those on non-ultramafic substrates (NUMS) for any given period. For example, between 14,000 and 11,000 cal yr BP, cooler and wetter conditions than present led to the establishment of a subalpine parkland of Pinus monticola and/or Pinus lambertina, Tsuga, Picea on non-ultramafic substrates (NUMS). On UMS, an open Pinus jeffreyi and/or Pinus contorta woodland developed. In the early Holocene, when conditions were warmer and drier than present, open forests of Pinus monticola/lambertina , Cupressaceae, Quercus and/or Amelanchier grew on NUMS, whereas open forest consisting of Pinus Jeffreyi/contorta , Cupressaceac and Quercus developed on UMS. In the late Holocene, cool wet conditions favored closed forests of Abies, Pseudotsuga , and Tsuga on NUMS, whereas Pinus jeffreyi/contorta , Cupressaceae and Quercus forest persisted with little change on UMS. The charcoal data indicate that past fire activity was similar at all sites, implying a strong climatic control. The results of both studies suggest that the influence of Holocene climate variations, disturbance regime, and substrate type have helped create the current mosaic of vegetation in the KM. / Adviser: Cathy Whitlock, Patrick Bartlein

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This thesis investigates past structure and dynamics of native Caledonian pine woodland, representing part of the western fringes of the northern European boreal woodlands. The biogeographical extent and Holocene history of the Scottish pine woods are well studied, yet questions remain at finer scales. This thesis is concerned with two factors over the recent Holocene oceanic period; (i) the long-term ecology within the woods; the spatio-temporal dynamics, the canopy structure, and community composition and continuity; and (ii) the former extent of the woods, especially the temporal pattern of the inferred easterly contraction in woodland over recent history. The importance of these factors - to ecologists, challenged with understanding the theories of equilibrium and non-equilibrium processes in long-lived woodland communities - and to conservation managers - challenged, by policy directives, with implementing the restoration and expansion of native woodlands - is discussed. Equally the identification and quantification of ecological detail over ecologically relevant temporal and spatial scales is an important challenge for palaeoecology. The thesis therefore applies fine spatial resolution pollen analyses over a network of sites, within, and at the western edge of, the extant woodland zone in east Glen Affric. Correlation between these individual site histories develops a detailed view of the grain and extent of woodland within the landscape, previously missing from western pine woods. Careful attention is paid to the interpretive potential and limitations of fine resolution palaeoecology; especially with regard (i) to techniques that can identify and spatially quantify stand-scale structure and community composition via reference to modern analogues; and (ii) to defining chronologies and elucidating rates and patterns of temporal change. The opportunities and limitations of the technique are explored and discussed, to ensure an understanding of the rigour and potential of the palaeoecological contribution to ecological research and to provide an evidence base for conservation. The application of 210Pb dating using the CRS and CIC models is explored. The CRS model is confirmed as suitable for peat deposits, but its use may mask fluctuations in peat sedimentation rate, which may be illustrated by the CIC model. The value of multiple 14C assays for each core and a need for a new approach to chronologies for application to fine-scale palaeecological studies is discussed. The relevant source area around the small basins in this semi-open pinewood is tentatively confirmed at 20 m from the pollen source. Tentative pollen productivity estimates for five key taxa in this ecosystem are presented. The temporal stability of native woodland in Glen Affric is confirmed to the eastern part of the extant woodland zone; but challenged to the west, where the open and semi-open landscape has a long history. Woodland diversity decreased over the last c. 200 years, and past woodland also shows a greater ground flora diversity. The western extent of the Caledonian woodland in this landscape may have changed little in the last c. 4000 years. Fluctuations, some clearly cyclical, in heath, and in woodland, communities are identified in the pollen record. The former may be aligned to changes in grazing regime or climatic shifts; and the latter to autochthonous shifts important in the maintenance of suitable edaphic conditions for the continuity of woodland. Former woodland is confirmed as likely to have been open in structure and mixed in tree species composition. The results presented here suggest that some caution should be applied to use of the term Caledonian, or native ‘pine’ forest: ‘Caledonian forest’ may better reflect the heterogeneity of past forests, particularly the importance, and persistence, of birch. The implications for conservation management and restoration are discussed. It may be difficult to establish a sustainable woodland to the west of the extant stands, and any pine woodland here may need to be mixed with stands of broadleaved trees to maintain or restore soil structure and ecological function. The landscape to the west may have been open for several thousands of years, and consideration of this is required when managing for the future to prevent loss of biodiversity.

Three continuous terrestrial high-resolution palaeoenvironmental records for the Late-glacial and the Holocene have been reconstructed for different ecosystems in Fuego-Patagonia on a longitudinal transect at latitude 53°S. The records describe the nature and extent of environmental and climatic changes inferred from palynological evidence supported by lithostratigraphy, tephrochronology and radiocarbon dating. The environmental changes recorded at the three sites displays a significant degree of synchrony in response to similar large-scale climatic changes. Clear stratigraphical evidence alongside the pollen record indicates a shift to warmer interstadial conditions between c. 14,800 Cal yr BP and 14,400 Cal yrs BP. During the period coeval with ACR the vegetation was dominated by cold resistant dry land herbs such as Poaceae, Asteraceae (Suf. Asteroideae) and Acaena, by c. 13,200 Cal yr BP the vegetation changed from the dominance of cold resistant dry land herbs towards more mesic conditions and the expansion of steppe dominated by Poaceae with patches of Nothofagus forest. The establishment of the forest and an eastward shift of the forest-steppe ecotone by c. 12,500 Cal yr BP from which a gradual shift from colder to warmer conditions and the relatively stronger influences of the SSWs is inferred. The sequence of Late-glacial environmental changes places Fuego-Patagonia within the new palaeoecological data provided by this study includes “the earliest” evidence for the establishment of subantarctic Nothofagus forest during the LGIT in Fuego-Patagonia. During the Early-Holocene two major phases of Nothofagus forest expansion were registered between c. 11,700 - 10,500 Cal yr BP and c. 9,500 - 8,200 Cal yr BP. These intervals of expansion of Nothofagus forest are separated by an interval of forest contraction in response to lower effective moisture between c. 10,500 - 9,500 Cal yr BP. An intense arid phase is inferred between c. 8,250 Cal yr BP and 6,800 Cal yr BP and probably leading to an increase in the amount of dry fuel available during the mid-Holocene in Fuego-Patagonia leading to the highest fire activity promoted by very weak SSWs at this time. The later Holocene was characterised by an increase in humidity and an inferred intensification of the SSWs.

Pollen analysis of a sediment core from Lake SP02, Melville Peninsula, Nunavut, Canada provides a ~6300 year record of post-glacial vegetation and climate change. Dominant local and regional taxa identified include Cyperaceae, Ericaceae, Artemisia, Salix, and Oxyria. Fossil pollen assemblages, pollen accumulations rates, and variations in sediment organic matter, indicate a period of optimal Holocene warmth between 5300-3900 yr BP, followed by a prolonged period of Neoglacial cooling, as well as a period of relative warmth between 1300-1000 yr BP, interpreted as evidence for the Medieval Warm Period. Variations in pollen abundances and accumulations during the 20th century suggest a response to recent warming that is unprecedented since deglaciation of the Peninsula. Comparisons of the timing and rates of multi-scale climate variations for Melville Peninsula with adjacent sites reveal a potential late Holocene shift in the boundary separating continental and maritime climate regions in the eastern Canadian Arctic.

Pollen analysis of a sediment core from Lake SP02, Melville Peninsula, Nunavut, Canada provides a ~6300 year record of post-glacial vegetation and climate change. Dominant local and regional taxa identified include Cyperaceae, Ericaceae, Artemisia, Salix, and Oxyria. Fossil pollen assemblages, pollen accumulations rates, and variations in sediment organic matter, indicate a period of optimal Holocene warmth between 5300-3900 yr BP, followed by a prolonged period of Neoglacial cooling, as well as a period of relative warmth between 1300-1000 yr BP, interpreted as evidence for the Medieval Warm Period. Variations in pollen abundances and accumulations during the 20th century suggest a response to recent warming that is unprecedented since deglaciation of the Peninsula. Comparisons of the timing and rates of multi-scale climate variations for Melville Peninsula with adjacent sites reveal a potential late Holocene shift in the boundary separating continental and maritime climate regions in the eastern Canadian Arctic.

In semi-arid regions subject to rising temperatures and drought, palaeoecological insights into past vegetation dynamics under a range of boundary conditions are needed to develop our understanding of environmental responses to climatic changes. Here, we present a new high-resolution record of vegetation history and fire activity spanning the last 12,000 years from Lake Sidi Ali in the southern Middle Atlas Mountains, Morocco. The record is underpinned by a robust AMS radiocarbon and 210Pb/137Cs chronology and multi-proxy approach allowing direct comparison of vegetation, hydroclimate, and catchment tracers. The record reveals the persistence of steppic landscapes until 10,340 cal yr BP, prevailing sclerophyll woodland with evergreen Quercus until 6,300 cal yr BP, predominance of montane conifers (Cedrus and Cupressaceae) until 1,300 cal yr BP with matorralization and increased fire activity from 4,320 cal yr BP, and major reduction of forest cover after 1,300 cal yr BP. Detailed comparisons between the pollen record of Lake Sidi Ali (2,080m a.s.l.) and previously published data from nearby Tigalmamine (1,626m a.s.l.) highlight common patterns of vegetation change in response to Holocene climatic and anthropogenic drivers, as well as local differences relating to elevation and bioclimate contrasts between the sites. Variability in evergreen Quercus and Cedrus at both sites supports a Holocene summer temperature maximum between 9,000 and 7,000 cal yr BP in contrast with previous large-scale pollen-based climate reconstructions, and furthermore indicates pervasive millennial temperature variability. Millennial-scale cooling episodes are inferred from Cedrus expansion around 10,200, 8,200, 6,100, 4,500, 3,000, and 1,700 cal yr BP, and during the Little Ice Age (400 cal yr BP). A two-part trajectory of Late Holocene forest decline is evident, with gradual decline from 4,320 cal yr BP linked to synergism between pastoralism, increased fire and low winter rainfall, and a marked reduction from 1,300 cal yr BP, attributed to intensification of human activity around the Early Muslim conquest of Morocco. This trajectory, however, does not mask vegetation responses to millennial climate variability. The findings reveal the sensitive response ofMiddle Atlas forests to rapid climate changes and underscore the exposure of the montane forest ecosystems to future warming.