29 results
6 - Hamar and Underhoull, Unst: Settlement in Northernmost Scotland
- Edited by Tom Horne, University of Glasgow, Elizabeth Pierce, University of Glasgow, Rachel Barrowman, University of Glasgow
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- Book:
- The Viking Age in Scotland
- Published by:
- Edinburgh University Press
- Published online:
- 20 October 2023
- Print publication:
- 31 January 2023, pp 85-97
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Summary
The island of Unst has a large number of recorded longhouses of apparently Viking or Norse date (Dyer et al. 2013). Unst is unique in that sites like this are found in a density and state of preservation unseen elsewhere in Britain, and it was this that led Shetland Amenity Trust to propose the ‘Viking Unst Project’ to investigate some of these sites and display them as a means of encouraging archaeological tourism to the island (Turner et al. 2013). In research terms, the unusual nature of the Unst settlement pattern demanded investigation. Previous survey and excavation (for example, Stumman-Hansen 1995, 2000) had suggested the sites were largely single-period with no evidence of earlier occupation. Many are on or above the 30m contour, which at this northern extremity of the British Isles today makes for environmentally precarious conditions. Just 20m above the site of Hamar House 2, for example, is the Keen of Hamar, where solifluction stripes caused by freeze-thaw action, and subarctic plant species, can be seen.
A settlement pattern of Viking-period farms with no pre-Viking activity, such as the Unst data suggested, is largely absent elsewhere in the Northern Isles, where Norse settlement is usually identified as a phase within multi-period sites located on good agricultural land (Dockrill and Bond, this volume). These deeply stratified sites, such as Jarlshof and Old Scatness in southern Shetland, often represent several millennia of occupation, of which the Viking-Age/Late Norse periods are late in the sequence (Hamilton 1956; Dockrill et al. 2010).
The main aim of the excavations at Hamar and Underhoull was to investigate this unusual settlement pattern, to test the presumed date of the houses and the theory that they were single-period settlements. Hamar was chosen as one of the sites because previous investigation had suggested it was early in date (Stummann-Hansen 2000) and it appeared remarkably well preserved with defined wall lines. Upper House, Underhoull, with its proximity to both Underhoull broch and Small’s excavations at the Norse site nearby, seemed likely to increase our understanding of the settlement pattern there (Small 1966).
Hamar
The site of Hamar consists of two single longhouses on the south-facing slope below the Keen of Hamar above Baltasound, Unst (Figure 6.1).
2 - What Does Landnám Look Like? Excavations at Swandro and Old Scatness
- Edited by Tom Horne, University of Glasgow, Elizabeth Pierce, University of Glasgow, Rachel Barrowman, University of Glasgow
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- Book:
- The Viking Age in Scotland
- Published by:
- Edinburgh University Press
- Published online:
- 20 October 2023
- Print publication:
- 31 January 2023, pp 29-42
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Summary
Research at two multi-period settlement mounds, Old Scatness (Shetland; Dockrill et al. 2010) and Swandro (Rousay, Orkney; ongoing, Bond and Dockrill 2016), suggests that many first-generation Scandinavian settlements occur at pre-existing Pictish settlements and associated landscapes. Both sites have settlement biographies that provide evidence for long sequences spanning the Early Iron Age to the Norse period, including evidence for landnam, or first settlement. Settlement on existing Pictish ‘estates’ (highstatus settlements with associated agricultural land, often originating in the Iron Age or earlier) would provide access to both maritime and agricultural resources, and it is suggested that ‘estate taking’ may have been a means of procuring key locations.
The term landnam is used in several ways in archaeology; Cleasby in his Icelandic–English dictionary defined it as ‘taking possession of land as settler, settlement’ (Cleasby and Vigfusson 1874), while Danish palynologist Iversen used it in the 1940s to describe features in pollen diagrams which he thought indicated clearance of the landscape by incoming Neolithic farmers, and it is still used in this sense (Iversen 1941). In North Atlantic archaeology it is often used in the context of settlement of a presumed empty landscape by the Norse in Iceland or the Faroe Islands. Here we use it in preference to the more loaded term ‘colonisation’ to indicate initial Norse settlement.
Old Scatness, Shetland
The site of Old Scatness formed a focus of archaeological research in Shetland, with excavations taking place between 1995 and 2006 (Dockrill 2002; Dockrill et al. 2006, 2010). Old Scatness lies on the western coastline of Dunrossness, on the southern tip of Mainland Shetland. To the west is the Atlantic Ocean, and to the north-east, the natural harbour of the Pool of Virkie and the North Sea. The Old Red Sandstone sedimentary sequence is a continuation of the same geological sequence as Orkney and provides a fertile agricultural zone together with good building stone. A substantial Iron-Age village was built around an early broch, which formed the focal point of the settlement. The broch demonstrates a complex sequence of at least three main phases of use, the last of which extends into the Pictish period (Figure 2.1).
Refining the Chronology of the Neolithic Settlement at Pool, Sanday, Orkney: Implications for the Emergence and Development of Grooved Ware
- Ann Macsween, John Hunter, Alison Sheridan, Julie Bond, Christopher Bronk Ramsey, Paula Reimer, Alex Bayliss, Seren Griffiths, Alasdair Whittle
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- Journal:
- Proceedings of the Prehistoric Society / Volume 81 / December 2015
- Published online by Cambridge University Press:
- 03 September 2015, pp. 283-310
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- December 2015
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New radiocarbon dates for the Neolithic settlement at Pool on Sanday, Orkney, are interpreted in a formal chronological framework. Phases 2.2 and 2.3, during which flat-based Grooved Ware pottery with incised decoration developed, have been modelled as probably dating to between the 31st and 28th centuries cal bc. There followed a hiatus of a century or so, before the resumption of occupation in Phase 3, which has a different Grooved Ware style featuring the use of applied decoration. This has been modelled as probably dating from the 26th to the 24th centuries cal bc. The implications of these results are discussed for the emergence and development of Grooved Ware, and for the trajectory of settlement and monumentality on Sanday.
Contributors
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- By Tod C. Aeby, Melanie D. Altizer, Ronan A. Bakker, Meghann E. Batten, Anita K. Blanchard, Brian Bond, Megan A. Brady, Saweda A. Bright, Ellen L. Brock, Amy Brown, Ashley Carroll, Jori S. Carter, Frances Casey, Weldon Chafe, David Chelmow, Jessica M. Ciaburri, Stephen A. Cohen, Adrianne M. Colton, PonJola Coney, Jennifer A. Cross, Julie Zemaitis DeCesare, Layson L. Denney, Megan L. Evans, Nicole S. Fanning, Tanaz R. Ferzandi, Katie P. Friday, Nancy D. Gaba, Rajiv B. Gala, Andrew Galffy, Adrienne L. Gentry, Edward J. Gill, Philippe Girerd, Meredith Gray, Amy Hempel, Audra Jolyn Hill, Chris J. Hong, Kathryn A. Houston, Patricia S. Huguelet, Warner K. Huh, Jordan Hylton, Christine R. Isaacs, Alison F. Jacoby, Isaiah M. Johnson, Nicole W. Karjane, Emily E. Landers, Susan M. Lanni, Eduardo Lara-Torre, Lee A. Learman, Nikola Alexander Letham, Rachel K. Love, Richard Scott Lucidi, Elisabeth McGaw, Kimberly Woods McMorrow, Christopher A. Manipula, Kirk J. Matthews, Michelle Meglin, Megan Metcalf, Sarah H. Milton, Gaby Moawad, Christopher Morosky, Lindsay H. Morrell, Elizabeth L. Munter, Erin L. Murata, Amanda B. Murchison, Nguyet A. Nguyen, Nan G. O’Connell, Tony Ogburn, K. Nathan Parthasarathy, Thomas C. Peng, Ashley Peterson, Sarah Peterson, John G. Pierce, Amber Price, Heidi J. Purcell, Ronald M. Ramus, Nicole Calloway Rankins, Fidelma B. Rigby, Amanda H. Ritter, Barbara L. Robinson, Danielle Roncari, Lisa Rubinsak, Jennifer Salcedo, Mary T. Sale, Peter F. Schnatz, John W. Seeds, Kathryn Shaia, Karen Shelton, Megan M. Shine, Haller J. Smith, Roger P. Smith, Nancy A. Sokkary, Reni A. Soon, Aparna Sridhar, Lilja Stefansson, Laurie S. Swaim, Chemen M. Tate, Hong-Thao Thieu, Meredith S. Thomas, L. Chesney Thompson, Tiffany Tonismae, Angela M. Tran, Breanna Walker, Alan G. Waxman, C. Nathan Webb, Valerie L. Williams, Sarah B. Wilson, Elizabeth M. Yoselevsky, Amy E. Young
- Edited by David Chelmow, Virginia Commonwealth University, Christine R. Isaacs, Virginia Commonwealth University, Ashley Carroll, Virginia Commonwealth University
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- Book:
- Acute Care and Emergency Gynecology
- Published online:
- 05 November 2014
- Print publication:
- 30 October 2014, pp ix-xiv
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Contributors
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- By Michael Harris Bond, Xinyin Chen, Dov Cohen, Ella Daniel, Nancy Eisenberg, Doran C. French, Sigal Gabay, Pehr Granqvist, Aisha Griffith, Jessica Halliday Hardie, Lene Arnett Jensen, Hyeyoung Kang, Ariel Knafo, Hans-Joachim Kornadt, Reed W. Larson, Liman Man Wai Li, Junsheng Liu, Vivian Miu-Chi Lun, Sami Mahajna, Tina Malti, Boris Mayer, Kristina McDonald, Ramesh Chandra Mishra, Bernhard Nauck, Vinai Norasakkunkit, Lisa D. Pearce, Urip Purwono, Vikki Rompala, Fred Rothbaum, Kenneth H. Rubin, Julie A. Sallquist, Vassilis Saroglou, Shalom H. Schwartz, Rachel Seginer, Rivka Shir, Anja Steinbach, Gisela Trommsdorff, Yukiko Uchida, Li Wang, Yan Z. Wang, Ran Zilber
- Edited by Gisela Trommsdorff, Universität Konstanz, Germany, Xinyin Chen, University of Pennsylvania
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- Book:
- Values, Religion, and Culture in Adolescent Development
- Published online:
- 05 September 2012
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- 27 August 2012, pp xiii-xxiv
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Maternal Dietary Intake in Twin Pregnancies: Does it Diminish Towards Term?
- Ruth Morley, Mark P. Umstad, Jodie Bond, Vivienne M. Moore, Julie A. Owens, Terence Dwyer, John B. Carlin
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- Journal:
- Twin Research and Human Genetics / Volume 9 / Issue 5 / 01 October 2006
- Published online by Cambridge University Press:
- 21 February 2012, pp. 656-658
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We tested the hypothesis that energy intake among women with twin pregnancies decreases in late gestation, as the uterus enlarges and they become increasingly uncomfortable. We asked women to recall dietary intake for the previous 24 hours, every 2 weeks from around 29 weeks of gestation, using a photographic atlas and other strategies to estimate portion size. Eighty women provided data at around 29, 31, 33 and 35 weeks of gestation. We calculated total energy intake, and energy intake from carbohydrate, fat and protein. Data were log transformed to reduce skewness. Using mixed effects linear regression models, we found minimal evidence that total energy intake changed over this time period, either before or after adjustment for potential confounding factors (95% confidence interval for relative change per week: −1.4%, 0.6%). There was weak evidence of a small decline in carbohydrate intake over time, both before and after controlling for energy intake. We cannot exclude change in energy intake or diet composition before 29 weeks or after 35 weeks of twin gestation.
9 - Fire-adaptive Trait Evolution
- from Section III - Comparative Ecology, Evolution and Management
- Jon E. Keeley, United States Geological Survey, California, William J. Bond, University of Cape Town, Ross A. Bradstock, University of Wollongong, New South Wales, Juli G. Pausas, Consejo Superior de Investigaciones Cientificas, Madrid, Philip W. Rundel, University of California, Los Angeles
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- Fire in Mediterranean Ecosystems
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- 05 January 2012
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- 30 December 2011, pp 233-274
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Summary
Until relatively recently the importance of fire and the origin of fire-adaptive traits have received minimal attention from paleoecologists, and appreciation of this importance has varied across the different mediterranean-type climate (MTC) ecosystems. For example, Axelrod (1973) and Raven & Axelrod (1978) wrote extensive treatises on the origins of the California flora, and yet gave little or no mention to the issue of fire in the evolution of these taxa. Hopper (2009) suggests that fire has only been an incidental factor in the evolution of the Western Australian flora. These investigators have weighed climate and soils far above fire as an important evolutionary driver in these plant assemblages and have downplayed this component of community assembly (see Fig. 1.4).
Axelrod (1989) even went so far as to suggest fire was irrelevant to the evolution of California chaparral. Although he acknowledged that fire could have played a role in the spread of chaparral-like vegetation during the late Tertiary (2–10 Ma), he insisted that fire had played no significant role in the origin of “adaptive types.” In his view, “Several lines of evidence suggest that the modern fire-adapted taxa may not reflect an evolutionary response to fire. The diverse adaptations to fire probably represent features that originated without the stimulus of fire. . .” Contrary to this belief, we suggest there is sufficient reason to accept a fire origin for many fire-adaptive traits in mediterranean-type vegetation (MTV), and that fire has been a potential ecosystem process on landscapes far longer than the late Tertiary (Bowman et al. 2009; Pausas & Keeley 2009).
12 - Alien Species and Fire
- from Section III - Comparative Ecology, Evolution and Management
- Jon E. Keeley, United States Geological Survey, California, William J. Bond, University of Cape Town, Ross A. Bradstock, University of Wollongong, New South Wales, Juli G. Pausas, Consejo Superior de Investigaciones Cientificas, Madrid, Philip W. Rundel, University of California, Los Angeles
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- Fire in Mediterranean Ecosystems
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- 05 January 2012
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- 30 December 2011, pp 330-348
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A large diversity of alien plants is found in most mediterranean-type climate (MTC) regions and fire is sometimes closely linked to their ability to invade natural ecosystems. This is a concern because aliens often upset natural ecosystem processes, and thus are a major management concern. These five regions not only differ in their contributions of non-native plant species to other regions, but also vary in their susceptibility to invasion by alien species, something often referred to as a community's invasibility.
Fire is a key factor behind plant invasions into natural plant communities and particularly critical is the timing of propagule availability and characteristics of the fire regime. Fire also interacts with geology in dictating functional types that become pernicious invasive problems. For example, on coarse-textured low-fertility soils in two of the southern hemisphere MTC regions, shrubs and trees are among the most aggressive invasives, and are capable of invading seemingly undisturbed intact shrublands. However, on more fertile soils such as in California and Chile, grasses and other herbaceous species are bigger threats, but invasion typically requires disturbance and under some circumstances fire can effect type conversion from woody vegetation to alien-dominated grasslands.
11 - Plant Diversity and Fire
- from Section III - Comparative Ecology, Evolution and Management
- Jon E. Keeley, United States Geological Survey, California, William J. Bond, University of Cape Town, Ross A. Bradstock, University of Wollongong, New South Wales, Juli G. Pausas, Consejo Superior de Investigaciones Cientificas, Madrid, Philip W. Rundel, University of California, Los Angeles
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- Fire in Mediterranean Ecosystems
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- 05 January 2012
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- 30 December 2011, pp 310-329
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Mediterranean-type climate (MTC) regions are some of the most botanically diverse landscapes in the world (Table 11.1). They are among the 25 global hotspots of diversity in both richness of species and endemics (Myers et al. 2000). Occupying a bit more than 2% of the Earth's surface these landscapes hold 15–20% of the world's total vascular plants (Cowling et al. 1996; Rundel 2004). Between the five regions there is extraordinary variation in temporal and spatial patterns of vascular plant diversity and the relationship between fire and diversity is quite different across the five MTC ecosystems.
Differences between MTC regions are evident at many scales but one of the frequently noted differences is the regional species density or number of species per unit area. To put this in perspective we need to recognize that one of the commonly held generalizations about species diversity is that it increases with area (Fig. 11.1a,b). This species–area relationship is understandable since there are constraints on the number of individuals that can sustainably occupy a given area. Thus, as area increases, the probability of encountering more species increases. However, despite the observation that the number of species increases with increasing area is one of the few “laws” in ecology (Lomolino 2001), there are exceptions. Dissimilar environments often have very different species richness. Thus, this species–area relationship only approaches the status of a “law” when describing patterns in nested samples (Dunn & Loehl 1988); that is, samples of different size taken from within the boundaries of larger samples so that species from the smallest sample unit share environmental features with larger sample units (Box 11.1). There is no clearer demonstration of this than the species–area relationship observed for total regional diversity between the five MTC regions (Fig. 11.1c). The glaring lack of fit to an idealized species–area relationship (Fig. 11.1a) points up some of the important differences in diversity between these MTC regions. These patterns are the result of complex responses to subtle variations in climate, not so subtle variations in geology, and to their interaction with fire, as well as to phylogenetic and biogeographic histories.
13 - Fire Management of Mediterranean Landscapes
- from Section III - Comparative Ecology, Evolution and Management
- Jon E. Keeley, United States Geological Survey, California, William J. Bond, University of Cape Town, Ross A. Bradstock, University of Wollongong, New South Wales, Juli G. Pausas, Consejo Superior de Investigaciones Cientificas, Madrid, Philip W. Rundel, University of California, Los Angeles
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- Fire in Mediterranean Ecosystems
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- 05 January 2012
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- 30 December 2011, pp 349-387
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Summary
The hazardous mediterranean climate, highly flammable vegetation, and rugged terrain, all important elements of fire behavior, become problems only in the presence of people. People recreate and build homes in the mediterranean wildlands because of the delightful climate and will continue to do so as long as space is available. People start most fires, and their mere presence tends to warp fire suppression strategies because fire agencies must protect lives and property threatened by fires rather than “back off” and build fire lines around fire perimeters.
Carl C. Wilson (1979a), Chief of Division of Forest and Fire Research, USFS/Pacific Southwest Forest and Range Experiment StationHuman presence in mediterranean-type climate (MTC) regions has differed markedly in the length of human occupation; however, there are remarkable similarities in how early inhabitants altered fire regimes and how modern societies deal with the fire hazard. Here we draw on the history of human impacts outlined in the regional reviews (see Chapters 4–8), the problems created by nineteenth and twentieth century management practices, and conclude with twenty-first century problems and future options. As discussed throughout this book, MTC ecosystems are highly fire adapted but, as illustrated here, contemporary societies have not fully adapted to balancing fire hazard risk and resource needs on these landscapes.
Early Human Fire Use and Impacts
Fire has been a widely utilized management tool throughout the history of humankind (Pyne 1995). Early hunter–gatherers utilized fire to manage for plant and animal resources. Fire also played an important role in early domestication of crops as clearing off woody or other perennial vegetation would have required fire on many landscapes. With domestication of livestock it was an important tool for increasing forage.
2 - Fire and the Fire Regime Framework
- from Section I - Introduction
- Jon E. Keeley, United States Geological Survey, California, William J. Bond, University of Cape Town, Ross A. Bradstock, University of Wollongong, New South Wales, Juli G. Pausas, Consejo Superior de Investigaciones Cientificas, Madrid, Philip W. Rundel, University of California, Los Angeles
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- Fire in Mediterranean Ecosystems
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- 05 January 2012
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- 30 December 2011, pp 30-57
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Summary
A global view of potential vs. actual vegetation distributions points to fire as a major driver of biome distribution and determinant of community structure (Bond et al. 2005). In ecological terms, fire acts much like an herbivore, consuming biomass and competing with biotic consumers for resources, and in this sense is an important part of trophic ecology (Bond & Keeley 2005). As in other competitive interactions, not only can fire competitively exclude herbivores by temporarily eliminating resources, but intensive grazing is known to exclude fire by consuming herbaceous ground fuels (Savage & Swetnam 1990). Coexistence is often enhanced by temporal separation of trophic niches, with herbivores grazing early in the spring on green herbaceous material that is unavailable for burning, whereas later in the season the remaining dry thatch is readily consumed by fire. In many respects fire is a more potent competitor because it is not limited by either toxins or protein deficiency and readily consumes dead woody biomass, but by contrast it is often limited by ignition sources and continuity of fuels.
Fire scientists have long symbolized the critical elements of fire in a triangle of fuel, oxygen and heat (Pyne et al. 1996). These are indeed necessary for fire ignition and propagation but are insufficient for predicting the global distribution of fire-prone ecosystems. The conditions both necessary and sufficient to explain the ecological distribution of fire activity can be summarized by four parameters: biomass, seasonality, ignitions and fuel structure (Fig. 2.1). In addition to biomass fuels to spread a fire there must be a dry season that converts potential fuels to available fuels. In mediterranean-type climate (MTC) ecosystems summer drought results in high fire hazard on an annual basis, in contrast to many temperate forests that are only periodically vulnerable to fire in response to decadal or longer oscillations in climate. Vegetation only burns when ignitions are present to initiate the combustion process and landscapes vary markedly in the potential for natural ignitions from lightning, and in the extent of anthropogenic ignition sources. However, understanding the ecosystem distribution of fire requires consideration of a fourth parameter, fuel structure, which is fundamental to recognizing how different fire regimes develop.
Contents
- Jon E. Keeley, United States Geological Survey, California, William J. Bond, University of Cape Town, Ross A. Bradstock, University of Wollongong, New South Wales, Juli G. Pausas, Consejo Superior de Investigaciones Cientificas, Madrid, Philip W. Rundel, University of California, Los Angeles
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- Fire in Mediterranean Ecosystems
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- 05 January 2012
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- 30 December 2011, pp v-vi
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Section II - Regional patterns
- Jon E. Keeley, United States Geological Survey, California, William J. Bond, University of Cape Town, Ross A. Bradstock, University of Wollongong, New South Wales, Juli G. Pausas, Consejo Superior de Investigaciones Cientificas, Madrid, Philip W. Rundel, University of California, Los Angeles
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- Fire in Mediterranean Ecosystems
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- 05 January 2012
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- 30 December 2011, pp 81-82
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Summary
Regional patterns
Mediterranean-type climates (MTC) comprise a diverse array of woody, herbaceous, and even succulent vegetation types in each of the five regions. Shrublands are universal across all MTC regions and have been the main focus of past comparative studies; however, woodlands and forests are of great interest in understanding drivers in these ecosystems. InSection IIwe examine in detail the intraregional patterns of variation in vegetation types and the ecological role fire plays in each of the five regions. We are concerned with the degree to which similar environments have converged on similar fire regimes and those factors responsible for divergence. A boiler-plate approach of topics covered in each region is not the appropriate metaphor here as each region presents very different problems associated with different landscape histories and fire responses. The nominate region, the Mediterranean Basin, has such an extraordinarily long and intensive human history that landscapes exist as a palimpsest with ecological patterns overriding signatures from earlier uses. Crown fires dominate all MTC regions but California is unique among these in having substantial forests of tall conifers prone to surface fire regimes, with different trajectories of trait evolution and fire management impacts. Central Chile exhibits patterns best interpreted as a fading fire regime, once quite evident but, like a dying star, it has been extinguished by the Late Miocene completion of the Andean uplift that now blocks ignition sources due to lightning. The Western Cape of South Africa is considered to have the climate and geology sufficient to support forests, but these are extremely limited and restricted to narrow refugia from fire. Southern Australia is phenomenal in that sclerophyllous-leaved mediterranean-type vegetation (MTV) covers much of the southern third of the continent, despite the lack of a MTC from middle Victoria to New South Wales in the southeastern corner of the continent.
6 - Fire in Chile
- from Section II - Regional patterns
- Jon E. Keeley, United States Geological Survey, California, William J. Bond, University of Cape Town, Ross A. Bradstock, University of Wollongong, New South Wales, Juli G. Pausas, Consejo Superior de Investigaciones Cientificas, Madrid, Philip W. Rundel, University of California, Los Angeles
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- Fire in Mediterranean Ecosystems
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- 05 January 2012
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- 30 December 2011, pp 150-167
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Summary
The Mediterranean-type Climate Region of Chile
The mediterranean-type climate (MTC) in Chile (Fig. 6.1) is distributed from La Serena (30° S; Región IV, see Appendix 6.1) in the north to Concepción (37° S; Región X) in the south. It is constrained to the west side of the Andean mountain range, although as the height of this range decreases in the south, a MTC is observed at least as far eastward as Bariloche, Argentina. Although a pattern of winter rains and summer droughts extends northward into the Atacama Desert, this area falls outside our definition of MTC because winter evaporation exceeds rainfall in these areas of extremely low precipitation. The northern border of the MTC region is the transition from desert communities to shrubby matorral, while the southern border corresponds to the point of transition from sclerophyll woodlands to Valdivian evergreen forests (Gajardo 1994; Amigo & Ramirez 1998; Rundel et al. 2007).
The landforms of central Chile can be divided into three north–south trending geomorphic zones (Fig. 6.1): the Coastal Cordillera, the Central Valley, and the high Andean Cordillera (Armesto et al. 2007). The Coastal Cordillera rises relatively sharply from the coast, with little extent of coastal terraces, and reaches elevations as high as 2222 m at Cerro Roble and 1880 m at Cerro Campana, which lie between Valparaíso (Región V) on the coast and Santiago (Región Metropolitana) at the base of the Andes. The Central Valley is a structural basin filled to great depth by sediments from the surrounding mountains. North of Santiago, spurs from the Andes extend west across the valley and connect with the Coastal Cordillera, separating individual river basins such as that of the Río Aconcagua (Región V). From Santiago to the south, however, the valley extends uninterrupted for a distance of 900 km to Puerto Montt (Región X), with typical elevations of 400–700 m. The Andean Cordillera marks the eastern boundary of the MTC zone of central Chile. It is the product of complex tectonic activity beginning in the Cretaceous (see Fig. 9.1), but with major uplift in the late Tertiary. Paleobotanical evidence suggests that the central Andes had not attained more than half their current elevation by 10 Ma (Gregory-Wodzicki 2000), but was close to the present height by the end of the Miocene (Reynolds et al. 1990). Elevations reach from 4000 m to nearly 7000 m. To the north of Santiago the Andes are largely composed of metamorphosed sedimentary rock, but a major volcanic zone extends from south of Santiago through the Lake District (Los Lagos Región X).
10 - Fire and the Origins of Mediterranean-type Vegetation
- from Section III - Comparative Ecology, Evolution and Management
- Jon E. Keeley, United States Geological Survey, California, William J. Bond, University of Cape Town, Ross A. Bradstock, University of Wollongong, New South Wales, Juli G. Pausas, Consejo Superior de Investigaciones Cientificas, Madrid, Philip W. Rundel, University of California, Los Angeles
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- Fire in Mediterranean Ecosystems
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- 05 January 2012
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- 30 December 2011, pp 275-309
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Summary
The mediterranean-type climate (MTC) is widely agreed to have been in place in all five MTC regions since at least the late Pliocene (see Fig. 9.1), ~2 Ma, with much of the contemporary mediterranean-type vegetation (MTV) present and contributing to a highly fire-prone environment. There is far less agreement on: (1) the timing of the origin of the MTC, (2) the timing of and factors responsible for the origins of MTV, and (3) the paleohistory of fire and extent to which it has played a role in the origins of MTV. Ample evidence exists to suggest a much earlier origin of MTC and MTV.
A widely held paradigm is that many of the woody sclerophylls that comprise MTV are much older than the Pliocene and thus have not adapted to contemporary fire-prone MTC conditions (Axelrod 1989; Herrera 1992; Verdú et al. 2003; Ackerly 2004a). Most of these have origins in the Tertiary Period of the early Cenozoic and are viewed as relictual taxa that represent evolutionary inertia and are present today merely by chance avoidance of random extinctions.
Fire in Mediterranean Ecosystems
- Ecology, Evolution and Management
- Jon E. Keeley, William J. Bond, Ross A. Bradstock, Juli G. Pausas, Philip W. Rundel
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- Published online:
- 05 January 2012
- Print publication:
- 30 December 2011
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Exploring the role of fire in each of the five Mediterranean-type climate ecosystems, this book offers a unique view of the evolution of fire-adapted traits and the role of fire in shaping Earth's ecosystems. Analyzing these geographically separate but ecologically convergent ecosystems provides key tools for understanding fire regime diversity and its role in the assembly and evolutionary convergence of ecosystems. Topics covered include regional patterns, the ecological role of wildfires, the evolution of species within those systems, and the ways in which societies have adapted to living in fire-prone environments. Outlining complex processes clearly and methodically, the discussion challenges the belief that climate and soils alone can explain the global distribution and assembly of plant communities. An ideal research tool for graduates and researchers, this study provides valuable insights into fire management and the requirements for regionally tailored approaches to fire management across the globe.
3 - Fire-related Plant Traits
- from Section I - Introduction
- Jon E. Keeley, United States Geological Survey, California, William J. Bond, University of Cape Town, Ross A. Bradstock, University of Wollongong, New South Wales, Juli G. Pausas, Consejo Superior de Investigaciones Cientificas, Madrid, Philip W. Rundel, University of California, Los Angeles
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- Fire in Mediterranean Ecosystems
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- 05 January 2012
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- 30 December 2011, pp 58-80
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Summary
As illustrated in Fig. 2.1 there are four environmental parameters that are necessary to determine the distribution of fire-prone ecosystems. However, they are insufficient to predict ecosystem responses to fire without a detailed understanding of the fire regime (see Fig. 2.7). Different fire regimes have very different potentials for recovery and place very different premiums on specific plant traits. For example, those traits contributing to the persistence of species in crown fire regimes will often be very different from those in surface fire regimes. In short, organisms are not adapted to fire per se, but rather to a particular fire regime. Plant traits that are adaptive in fire-prone environments are discussed here. The evolution of such traits and the extent to which they represent adaptations to fire are considered in Chapter 9.
Plant populations exhibit four modes of recovery following fire:
endogenous regeneration from resprouts or fire-triggered seedling recruitment,
delayed seedling recruitment from postfire resprout seed production,
delayed seedling recruitment from in situ surviving parent plants, or
colonization from unburned metapopulations.
Section III - Comparative Ecology, Evolution and Management
- Jon E. Keeley, United States Geological Survey, California, William J. Bond, University of Cape Town, Ross A. Bradstock, University of Wollongong, New South Wales, Juli G. Pausas, Consejo Superior de Investigaciones Cientificas, Madrid, Philip W. Rundel, University of California, Los Angeles
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- Fire in Mediterranean Ecosystems
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- 05 January 2012
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- 30 December 2011, pp 231-232
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Summary
Comparative Ecology, Evolution and Management
Here we utilize those points of convergence and divergence between mediterranean-type climate (MTC) ecosystems to develop a synthesis that reveals emergent properties not evident by study of any one region alone. Comparative study of plant traits, functional types and community responses to fire provides insight into selective factors driving the evolution and ecological assembly of fire-prone plant communities. Feedback processes are crucial to understanding evolution on such landscapes. Fire provides a challenge to understanding selective forces because, although inclusive fitness theory can explain fire-adaptive traits, such traits are dependent on community-level assembly that contributes to fire spread. MTC regions exhibit differences in climate and geology that have led to diverse fire environments, and account for many differences in trait evolution and community assembly. Humans have long been attracted to MTC regions but have not always adapted successfully to these fire-prone landscapes. Urban and peri-urban populations have been highly vulnerable to wildfires in some MTC regions, with differences in vulnerability between regions being due largely to innate differences in fuel loads of indigenous vegetation types and profound differences in population density.
8 - Fire in Southern Australia
- from Section II - Regional patterns
- Jon E. Keeley, United States Geological Survey, California, William J. Bond, University of Cape Town, Ross A. Bradstock, University of Wollongong, New South Wales, Juli G. Pausas, Consejo Superior de Investigaciones Cientificas, Madrid, Philip W. Rundel, University of California, Los Angeles
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- Fire in Mediterranean Ecosystems
- Published online:
- 05 January 2012
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- 30 December 2011, pp 201-230
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Summary
The mediterranean-type climate (MTC) in Australia spans from the southwestern part of Western Australia to include much of South Australia and western Victoria (Fig. 8.1), which covers a longitudinal distance second only to the Mediterranean Basin MTC region. As in other MTC regions, the highly fire-prone evergreen sclerophyllous shrub and tree mediterranean-type vegetation (MTV) extends much further east and north into climatic zones that are not MTC. Australia, however, is distinctly unlike other MTC regions in that fire-prone MTV is extensive across the southern part of the continent and transcends climatic boundaries with relatively subtle changes in community structure and composition. Sclerophyllous MTV dominates both the MTC region of the southwestern corner of the continent as well as the southeastern corner under an aseasonal climate. Both regions share a common fire season of summer to early autumn (McArthur 1972); however, the MTC southwest has a potential fire season every summer whereas in the southeast it is tied to weather anomalies that occur once to several times a decade.
Mediterranean-type Vegetation
Within the southern Australian MTC zone (Fig. 8.1) evergreen sclerophyllous vegetation dominates. Such MTV is sometimes defined as shrub dominated (Specht 1979), and indeed large areas of sclerophyllous heaths (see Fig. 1.6f), shrublands (Fig. 8.2a) and mallee (Fig. 8.3) occur. However, woodlands and forests form integral parts of the MTC biome (Dell et al. 1989; Gill 1994), and thus MTV includes shrublands, woodlands and forests, and in southern Australia they dominate both in the MTC region and outside that climatic zone (Fig. 8.1). MTV is found across the southern temperate latitudes of Australia (Table 8.1) in an arc below about 30° latitude, accounting for dominant vegetation types in infertile habitats throughout temperate Australia. We specifically focus on the various heaths, shrublands and dry sclerophyll forests that constitute the most fire prone communities in these temperate landscapes. Although similar fire-prone MTV heathlands occur extensively within the tropics on the northern end of the continent (Keith et al. 2002; Russell-Smith & Stanton 2002), here we focus on the temperate MTV, but do consider broader relationships with other adjoining vegetation types (e.g. wet sclerophyll forests, rainforests, and various arid and semi-arid woodlands and shrublands).
References
- Jon E. Keeley, United States Geological Survey, California, William J. Bond, University of Cape Town, Ross A. Bradstock, University of Wollongong, New South Wales, Juli G. Pausas, Consejo Superior de Investigaciones Cientificas, Madrid, Philip W. Rundel, University of California, Los Angeles
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- Book:
- Fire in Mediterranean Ecosystems
- Published online:
- 05 January 2012
- Print publication:
- 30 December 2011, pp 398-497
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