Article

Application of palaeoecology for peatland conservation at Mossdale Moor, UK

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  • Pate's Grammar School
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Abstract

In a recent discussion of research priorities for palaeoecology, it was suggested that palaeoecological data can be applied and used to inform nature conservation practice. The present study exemplifies this approach and was conducted on a degraded blanket mire in Yorkshire, UK, in collaboration with a field-based moorland restoration agency. High-resolution, multiproxy palaeoecological analyses on a peat core from Mossdale Moor reconstructed mid to late-Holocene vegetation changes. Humification, pollen, plant macrofossil and charcoal analyses carried out throughout the peat profile show marked changes in species composition and indicate their potential causes. Results suggest that human clearance in the Mesolithic–Neolithic transition may have initiated peat growth at Mossdale Moor, making this landscape ‘semi-natural’ in its origin. Further human-induced changes are identified at 1300 cal years BP, most likely clearance by fire, and between 20 and 0 cm depth where a substantial charcoal increase is interpreted as recent (<400 years) management practices using burning to encourage browse on the moor. The long-term ecological history of the moor, derived using palaeoecological techniques, will be used to inform conservation practice and to help set feasible targets for restoration and conservation at Mossdale Moor.

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... Since 2016, the number of studies investigating prescribed burning impacts on UK peatlands has increased. And, as with the evidence presented by Davies et al. (2016b), these new studies suggest that prescribed burning has a variety of impacts (positive, negative or neutral) across a range of peatland ecosystem services (McCarroll et al. 2016a;McCarroll et al. 2016b;Buchanan et al. 2017;Chambers et al. 2017;Douglas et al. 2017;Grau-Andrés et al. 2017;Ludwig et al. 2017;McCarroll et al. 2017;Noble et al. 2017;Robertson et al. 2017;Grau-Andrés et al. 2018;Ludwig et al. 2018;Milligan et al. 2018;Noble et al. 2018a;Noble et al. 2018b;Whitehead and Baines 2018;Grau-Andrés et al. 2019a;Grau-Andrés et al. 2019b;Heinemeyer et al. 2019c;Littlewood et al. 2019;Marrs et al. 2019a;Noble et al. 2019a;Noble et al. 2019b). A conclusion that was also drawn by a more recent review of burning impacts by Harper et al. (2018). ...
... very wet and acidic)? Contemporary evidence suggests that the relationship between Sphagnum abundance and peat (carbon) accumulation is unclear (Garnett et al. 2000;Marrs et al. 2019a;Piilo et al. 2019), and there are multiple UK based paleoecology studies in which core sections encompassing periods of rapid peat growth are dominated by non-Sphagnum plant fragments (Fyfe et al. 2003;Fyfe and Woodbridge 2012;Shepherd et al. 2013;Gillingham et al. 2016;McCarroll et al. 2017;Fyfe et al. 2018). Outside the UK, peatlands within Indonesia, the Amazon Basin and the Everglades (about a third of the world's peat stores) do not contain Sphagnum species (Bacon et al. 2017;Hodgkins et al. 2018). ...
... Historically, fire or controlled burning seems to have played a role in peatland development within the UK uplands (Simmons 2003). Several studies have found charcoal throughout peat profiles taken from wet heath and blanket bog sites across the UK (Fyfe et al. 2003;Ellis 2008;Fyfe and Woodbridge 2012;McCarroll et al. 2017;Fyfe et al. 2018). This suggests that fire occurred throughout the Holocene (~8000 years before present) and that the burning of vegetation is a long-term feature of wet heath and blanket bog development. ...
Article
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Despite substantial contrary evidence, there has been a growing tendency to present prescribed vegetation burning as a management practice that is always damaging to peatland ecosystems in the UK. This is exemplified by the “Burning and Peatlands” position statement published by the International Union for Conservation of Nature UK Peatland Programme. Indeed, while we strongly agree with several of the statements made within this position statement, it also contains a series of unverified assertions and misleading arguments that seemingly serve to simplify the narrative and paint prescribed burning as a wholly damaging peatland management tool. Given that this position statement is published by one of the UK’s most prominent peatland conservation organisations, it is likely to be consulted when debating upland land use policy. Therefore, for the benefit of policymakers, we provide a point-by-point critical review of the “Burning and Peatlands” position statement. We also discuss several further points for researchers and policymakers to consider that are consistently ignored by those attempting to simplify the narrative about prescribed burning. Our aim in producing this discussion paper is to encourage the research and policy community to move towards an evidence-based position about prescribed burning impacts on UK peatlands.
... The study of pollen grains by palynologists is, therefore, widely used to reconstruct past landscapes and quantify environmental change (e.g. [2,3]. In addition to fossilised pollen being used to understand historical temporal change of specific sites, pollen profiling can also be used to answer contemporary spatial questions. ...
... Analysis of fabricincluding clothing, shoes, and materials such as blankets and carpetis particularly common in forensic settings. The insights that can be provided by studying fabric include: (1) matching clothing from a suspect to a crime scene; (2) locating proceeds of crime or human remains; (3) analysing clothes of a murder victim to establish peri-mortem fate and to differentiate the scene of a crime from the scene of deposition; and (4) providing evidence to support or refute alibis [9]. ...
Article
Forensic palynology has been important in criminal investigation since the 1950s and often provides evidence that is vital in identifying suspects and securing convictions. However, for such evidence to be used appropriately, it is necessary to understand the factors affecting taphonomic variability (i.e. the variability in the fate of pollen grains before they are found during forensic examination). Here, we test the relative amount of pollen retained on clothing after a period of simulated light or heavy wear based on pollen and fabric characteristics. We also test the efficiency of forensic laboratory protocols for retrieving pollen from fabrics for analysis. There was no statistically significant difference in retention of fresh or dried pollen on any fabric type. There was a substantial difference in pollen retention according to wear intensity, with considerably more pollen being retained after light wear than after heavy wear. Pollen from insect-pollinated species was retained at higher concentrations than pollen from wind-pollinated species. This pattern was consistent regardless of wear intensity but pollination type explained more of the variability in pollen retention after light wear. Fabric type was significantly related to pollen retention, but interacted strongly with plant species such that patterns were both complex and highly species-specific. The efficiency of removing pollen with the standard washing protocol differed substantially according to plant species, fabric type, and the interaction between these factors. The average efficiency was 67.7% but this ranged from 21% to 93%, demonstrating that previous assumptions on the reliability of the technique providing a representative sample for forensic use should be reviewed. This paper highlights the importance of understanding pollen and fabric characteristics when creating a pollen profile in criminal investigations and to ensure that evidence used in testimony is accurate and robust.
... Early examples of palaeoecological studies to aid conservationists in the UK include research in the 1970s in Cumbria ( Oldfield, 1970) and Upper Teesdale ( Turner, Hewetson, Hibbert, Lowry, & Chambers, 1973) with a pause in such research during the 1980s before it resumes in the 1990s with a paper by Huntley (1991), followed by work on Exmoor ( Chambers et al., 1999), in Wales (Chambers, Mauquoy, Cloutman, Daniell, & Jones, 2007;Chambers, Mauquoy, Gent et al., 2007), Scotland ( Davies and Watson, 2007), Northern England ( Chambers and Daniell, 2011) and the Pennines ( Davies, 2015), with encouraging results. More recently, three further studies have been conducted in Yorkshire at Keighley Moor, by Blundell and Holden (2015); at Mossdale Moor, by McCarroll, Chambers, Webb, and Thom (2015); and at Oxenhope Moor by McCarroll (2015). The present vegetation at Keighley Moor has only been characteristic for the last c. 100 years ( Blundell and Holden, 2015), whereas at Oxenhope Moor, human influence began 2100 cal. ...
... The present vegetation at Keighley Moor has only been characteristic for the last c. 100 years ( Blundell and Holden, 2015), whereas at Oxenhope Moor, human influence began 2100 cal. BP with the current vegetation being characteristic for 300 years ( McCarroll, 2015) and at Mossdale Moor, a long history of human influence was observed with an intensification in human activity where a substantial charcoal increase is interpreted as recent (<450 years) management practices ( McCarroll et al., 2015). ...
... Because these sites are peat-forming, their continuously accumulating organic sediment, preserving several biotic and abiotic proxies, enables to perform palaeoecological reconstruction. Palaeoecological investigations may provide valuable insights to the habitat origin and history as was demonstrated for different regions across Europe (Willis and Birks, 2006;Froyd and Willis, 2008;Davies and Bunting, 2010;Gillson and Marchant, 2014;McCarroll et al., 2017). For some habitats, e.g. ...
Article
Western-Carpathian travertine fens developed on deep-circulation groundwater are highly localised and harbour unique communities that combine rare species of calcareous fens and salt marshes, with many species considered glacial or Early-Holocene relicts. Using a multi-proxy palaeoecological approach, we tested the assumption of naturalness and Holocene continuity of the current plant and mollusc communities occupying one of the best-preserved travertine fens in Europe. Our novel results, based on two complete cores throughout the fen deposits, document an anthropogenic origin of the current communities, despite their richness in rare and relict species. The habitat originated in the very beginning of the Holocene, later it was encroached by a semi-open woodland with spruce and alder and then by a dense reed bed that suppressed fen species even more than woodland encroachment. When compared with a fen site on shallow-circulation groundwater, the Holocene succession to woodlands has been blocked by travertine formation, allowing survival of light-demanding relicts in small patches. The current communities were established once the woody plants, and especially reed, were reduced by medieval land use. The community itself is therefore not relict, but it harbours probable descendants of relict populations that survived in neighbouring small refugia throughout the Holocene. Our results strongly support the need for active conservation actions as mowing and extensive grazing, mimicking the traditional type of land use, which has conditioned the recent travertine assemblages in the past.
... The legacy of the Quaternary is an integral part of Scotland's natural heritage but is at risk from inappropriate land use, development and other human impacts, as well as climate change. The need for Quaternary geoconservation in general reflects the value and vulnerability of particular features and sites (Burek 2012;Brown et al. 2014;Gordon 2015), as well as the relevance of understanding the past for nature conservation, habitat restoration and environmental management (Vegas-Vilarrú bia et al. 2011;Gray et al. 2013;Dietl et al. 2015;McCarroll et al. 2017). At the same time, there are pressing challenges to promote better understanding of the value and benefits of geoconservation for society, to mainstream geoconservation in the wider nature conservation agenda and to contribute toward natural solutions to global problems (Gordon et al. 2018a). ...
Article
Quaternary deposits and landforms are an integral component of Scotland's geodiversity and natural heritage with intrinsic, scientific, educational, cultural, aesthetic and ecological values. Their conservation is founded on the assessment and safeguard of key protected areas principally for their scientific values. The evaluation of site networks for Quaternary deposits and landforms (including glacial, fluvial, coastal, mass movement, karst and cave features) has evolved since the late 1940s, culminating in the Great Britain Geological Conservation Review (GCR) site assessments undertaken principally between 1977 and the early 1990s. Significant scientific progress since then has arisen, for example, from re-investigation of existing sites and discoveries of new sites, developments in geochronology and the formulation and application of new concepts and models. Both the GCR site lists and the supporting site documentation now require updating in the light of this progress. Today there is greater emphasis on the wider, non-scientific values of geoconservation including, for example, on ecosystem services, links with biodiversity and cultural heritage, geotourism and the benefits for human health and wellbeing through improved understanding of dynamic landscapes, climate change and natural hazards. Involvement of wider public support beyond the geoscience community and fostering better integration of geoheritage within the developing nature conservation agenda, including a land systems approach, protected area planning and management, natural capital and connecting people and nature, will help further to protect our Quaternary geoheritage.
... In particular, the pyrophyte Melampyrum (Fig. 1e) is considered to be a good indicator of burning within woodland. It should however be noted that charcoal is recorded in basal blanket peat horizons of late Mesolithic and Meso-Neolithic transition age at many sites in the British uplands (Simmons & Innes 1987;McCarroll et al. 2017) and fire disturbance, especially if repeated at a site, may have initiated peat formation by altering the hydrology and encouraging local surface water surpluses. North Gill (Simmons 1969) and May Moss (Atherden 1979) on the North York Moors, Mire Holes in the North Pennines (Squires 1978) and the Aukhorn peat mounds in northern Scotland (Robinson 1987) are good examples. ...
... Paleofire and paleoecological research offer a unique time perspective allowing to assess long term ecosystem trajectories, which represents an underestimated potential of information for ecosystem management and conservation. Even though the integration of paleoecological data into management faces some difficulties (Barnosky et al., 2017;Birks, 2012;Vegas-Vilarrúbia et al., 2011), there already exist examples of successful application of paleoecology into sitebased conservation decisions, mainly for defining reference conditions and management strategies in wetland restoration (Blundell and Holden, 2015;Chambers et al., 2013;McCarroll et al., 2017;Riedinger-Whitmore, 2016) or in shrubland and grassland ecosystems (Forbes et al., 2018) or in forest ecosystems (Hennebelle et al., 2018). However, this potential is not explored enough, for example, a respondent from Sweden underlined that "[long term knowledge of fire regime could be useful] in some areas at least, especially since it is getting warmer and the fire-weather is likely to get worse and fire regime is likely to change". ...
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This report summarizes the outcome of the PAGES Global Paleofire Working Group workshop 2017 that took place in Montreal, Canada-Paleofire knowledge for current and future ecosystem management. The workshop aimed to (1) discuss the importance of past fire or paleofire research, focused on long-term influence of fire on the environments worldwide, in nature conservation, (2) find ways to integrate scientific achievements of paleofire research into ecosystem management practices, and (3) start the dialogue with ecosystem managers, practitioners and policymakers (EMPPs). With this report, the members of the Global Paleofire Working Group would like to open a discussion about how igniting new collaborations with EMPPs and make paleofire data useful for fire risk management. We recognized four main challenges in communication and cooperation between scientists and EMPPs: little awareness of EMPPs about paleofire research, differences in professional language used in an operational context by scientists and EMPPs, scientific data availability, and costs of paleoecological expertise. Moreover, we indicate the way to improve the communication between scientists and EMPPs by proposing a scheme of cooperation between both groups. We want to encourage researchers working in various fields of paleoecology to open up for the cooperation with EMPPs in the future, especially helping to create ecosystem management plans, because paleoecological data carry important information about the evolution of ecosystems that is vital in the context of global change.
... In Europe, changes in mountain peatland plant communities are often so distinctive that only paleoecological studies can determine both the native state and the drivers responsible for these changes. Thus palaeoecological records utilizing plant macrofossils and pollen are beneficial for quantifying ecological changes and providing baseline information necessary for identifying conservation targets that can be used in peatland restoration projects (Chambers et al. 2007;Gałka et al. 2017b;McCarroll et al. 2017). From a biogeographical point of view, a central focus of paleoecological studies is to locate past refugia for many rare and endangered mosses and vascular plants presently named as glacial relicts, e.g., Messia triquetra, Paludella squarrosa, Helodium blandowii, Sphagnum wulfianum, Betula nana or Saxifraga hirculus, as well as to determine their migration routes and rates (Dítě et al. 2018;Feurdean et al. 2013a;Overbeck 1975;Rybníček 1966). ...
Article
In this paper, we present high-resolution, contiguous plant macrofossil records taken from two glacial cirque mountain wetland ecosystems located in the subalpine zone of the Eastern Carpathians. We provide 1) a detailed reconstruction of plant succession from mountain peatland ecosystems; 2) a possible scenario of Holocene paleohydrological changes; 3) the presence of rare plants presently considered glacial relicts, e.g. Meesia triquetra; and 4) the peat forming potential of certain plants at altitudes above 1800 m a.s.l. At Ga˘rga˘la˘u, a gradual decrease of water level and isolation from ground water influence approximately 7000 cal yr BP trigged the colonization of minerotrophic Sphagnum species (S. teres, S. centrale and S. subsecundum). The decline of Sphagnum subsecundum ca. 3000 cal yr BP was most likely caused by an increase of water level and competiton with Sarmentypnum sarmentosum populations. In the Late Holocene, ca. 2000 cal yr BP, Selaginella selaginoides expansion was recorded, followed by the reappearance of Sphagnum populations, most likely due to a lowering of the water table. The Gropile ecosystem transformed from a shallow lake into peatland at ca. 4200 cal yr BP. The temporary presence of Warnstorfia exannulata in peat sediments ca. 2300, 1600, 1300–1200, and 700–600 cal yr BP may indicate an increase of water level and very wet habitat, or the presence of small ponds. Paleohydrological changes only partly agree at both studied wetlands, suggesting the importance of local climatic and morphological conditions on past vegetation development. According to our paleoecological data, Straminergon stramineum indicates wet stages in peatlands and cannot be considered a high peat-forming species in subalpine zones in European mountain ranges. Projected warm and dry conditions may trigger mountain peatland water tables in Eastern Carpathians to decline, potentially resulting in the expansion of moss species that demand more acidic and drier habitats, e.g. Sphagnum russowii.
... The plant macrofossil and ash-content analysis showed changes in the species composition. McCaroll et al. [11] suggested that it could be difficult to differentiate between natural and anthropogenic patterns vegetation changes during the late Holocene. According to the results of our study, a high content of mineral elements in the peat cores from the last 300 years may be explained by a wide spread of agriculture in the study area.In addition, pollen analysis will be obtained in the next period of our research project. ...
Article
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Plant macrofossils data were used to identify the successive peatland communities during the last 3500 years in the floodplain of the Mana River (foothills of the Eastern Sayan Mountains). The reconstruction of the peatland development indicated that the peatland in the Mana River basin formed about 3500 years ago. The peatland formed as a result of overgrowing floodplain and water logging of terrace lows. The authors observed three successive changes: birch forest with sedge and hypnum mosses in the second half of the Subboreal period, wood-marsh plant association at the start of the Middle Subatlantic period (1600 years BP), the herb-wort phytocoenosis with inclusions of mezoeutrophycal plant species have been growing since the Late Subboreal period (950 years BP).
... As there exists a level of uncertainty with each dating method, a combination of dating methods is always recommended, when possible [30][31][32]. Table 7 provides a summary of the utility of the palaeoecological techniques applied in this study; it includes some others that could be used, with their evaluation based also on prior [8][9][10] and subsequent [27,33,34] work. This may be of assistance to conservation agencies contemplating commissioning similar research, in considering use of particular techniques, their costs, level of expertise required, whether samples can be used for more than one technique (destructive of samples or not), appraisal of any inherent bias in their application, whether the results are easily interpretable by non-specialists and whether there are more suitable techniques. ...
Article
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Large areas of upland mire and moorland in Northwest Europe are regarded as degraded, not actively peat-forming, and releasing carbon. Conservation agencies have short-term targets to restore such areas, but often have no clear knowledge of the timing and nature of degradation. It has been suggested that palaeoecology can be used to inform conservation management about past vegetation states, so as to help identify feasible restoration targets. Our research study in northern England, commissioned by the national statutory conservation agency, applied multiple palaeoecological techniques to establish the vegetation history of several mire and moorland sites, specifically to ascertain the nature and timing of degradation. Techniques applied included pollen analysis, plant macrofossil and charcoal analyses, determination of peat humification and mineral magnetic susceptibility, with ages ascertained using spheroidal carbonaceous particle analysis, 210 Pb and 14 C dating. Data are presented from case-study sites in the North York Moors, North-and South Pennines to illustrate how palaeoecology can extend long-term monitoring and guide conservation management. Palaeoecological data from a site within a National Nature Reserve, subject to exceptionally long-term (half-centennial) ecological monitoring, showed that this period does not include its pre-degradation state and that its current valued vegetation is novel and may have 55 AIMS Environmental Science Volume 4, Issue 1, 54-82. established after major fire. Overall, the studies suggest that the principal vegetation change at the sites took place after the start of the Industrial Revolution, and that the current landscape appearance not only has no long history, but that valued aspects, such as extensive heather moorland, feature only recently in the cultural landscape. These findings pose challenging questions for conservation management. We offer a non-specialist guide to the palaeoecological techniques that considers level of skill, cost, and comparability with ecological aspects of conservation and monitoring interest. We suggest palaeoecological data can provide valuable information and insights to aid practical conservation. While mires are particularly suitable, palaeoecological techniques could be applied in many other degraded landscapes internationally.
... Being very sensitive ecosystems, they are very vulnerable to any disturbances and extremely difficult to restore especially in the present climatic scenario. The better the knowledge about their past dynamics, the better the restoration strategy will be (McCarroll et al., 2015). However, the common notion exists that the neo-ecological approach is enough to appropriately manage with the future of peatlands. ...
Article
This study explores the history of the development of Sphagnum communities in an ombrotrophic peatland – Bagno Kusowo – over the past 650 years, based on high-resolution plant macrofossil and testate amoebae analysis. Our research provided information related to the length of peatland existence and the characteristics of its natural/pristine state before the most recent human impacts. Changes in the Sphagnum communities before human impact could have resulted from climate cooling during the ‘Little Ice Age’ (LIA). In this cold and unstable hydrological period, among vascular plants, Eriophorum vaginatum and Baeothryon caespitosum dominated in the peatland vegetation. Peat-forming Sphagnum communities survived the drainage conducted during the 20th century at the Bagno Kusowo bog. We provide three important messages through this study: (1) testate amoebae reflect similar hydrological trends in two peat cores despite considerable microhabitat variability, (2) average long-term water level 10 cm below the surface should be a target for active bog conservation and (3) sites like Bagno Kusowo are extremely important to preserve the remains of pristine biodiversity (including genetic diversity of plants and protists) that was completely removed from most of the raised bogs in Europe due to human activities, for example, drainage.
... Palaeoecological studies to aid conservationists in the British Isles were first carried out on Exmoor (Chambers et al. 1999) followed soon after by studies in Wales (Chambers et al. 2007a, Chambers et al. 2007b), Scotland (Davies & Watson 2007), northern England (Chambers & Daniell 2011), the Pennine Hills (Davies 2015), Ireland (Stevenson & Thompson 1993) and other locations (Stevenson & Rhodes 2000). Studies have also been conducted in the county of Yorkshire, at Keighley Moor by Blundell & Holden (2015) and at Mossdale Moor by McCarroll et al. (2015). At Keighley Moor it was found that the present vegetation at the site has only been characteristic for the last ca. ...
Article
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Actively growing mires have high conservation value and the potential to sequester carbon. However, drainage, burning, overgrazing and atmospheric pollution have led to depauperation of native flora and loss of peat at many peatland sites. In order to counteract such degradation, palaeoecological techniques can be applied and the data then used to inform nature conservation practice. The present study exemplifies this approach and was conducted on degraded blanket mire in Yorkshire, UK, in collaboration with a field-based moorland restoration agency. High-resolution, multiproxy palaeoecological analyses on a peat core from Oxenhope Moor were used to reconstruct Holocene vegetation changes spanning approximately the last 7000 years. Humification, pollen, plant macrofossil and charcoal analyses show distinct changes in species composition and indicate their potential causes. Human-induced changes identified at 2100 cal. BP are most likely to reflect deliberate clearance by fire. Sphagnum imbricatum disappears and is subsequently replaced by S. papillosum at ca. 1000 cal. BP, possibly due to drier conditions and competition between the two species. Increased human activity is identified since the Industrial Revolution where monocots and Eriophorum vaginatum increase, interpreted as a result of managed burning. It is intended that the long-term ecological history of the site, derived using palaeoecological techniques, will be used to inform conservation practice and can help set feasible targets for restoration and conservation. Specifically, encouraging a species mix that has pre-19th century longevity is suggested, including the specific recommendation that translocation of S. imbricatum be explored experimentally at this site, with a view to ascertaining likely success elsewhere. © 2016 International Mire Conservation Group and International Peatland Society.
... plant macrofossils, pollen, testate amoebae), might be used as a guide to inform restoration of damaged peatlands (cf. Chambers et al., 2007;McCarroll et al., 2017). ...
Article
High-resolution plant macrofossil records were examined alongside geochemical analysis (non-destructive X-Ray fluorescence and carbon stable isotopes), pollen, and micro-charcoal data of an ombrotrophic mountain peatland located in the Harz Mountains, central Germany, Europe. We hypothesize that increased deposition of dust and pollutants across the bog surface causes changes in habitat conditions, which in turn lead to shifts in mossdominated communities. We observe that increases in the abundance of Sphagnum magellanicum macrofossils – a species with a wider ecological range that occurs even in weakly minerotrophic habitats - coincide with increases of pollutant concentrations in the peat; conversely, increases of Sphagnum rubellum and Sphagnum capillifolium populations – indicators of oligotrophic conditions – coincide with decreases of pollutant concentrations. Pristine Sphagnum populations in the studied ombrotrophic bog have thus repeatedly returned to their original oligotrophic state (an autogenic process) following declines in pollutant input. Modern levels of pollutants should be taken into account in peatland restoration efforts, as they exert a strong control on the composition of present day Sphagnum communities. Moreover, Sphagnum angustifolium in paleoecological studies might be considered as an indicator of water level rise. In this study, the presence of S. angustifolium apparently correlates with wetter moisture conditions.
Article
Quaternary (last 2.6 million years) botany involves studying plant megafossils (e.g. tree stumps), macrofossils (e.g. seeds, leaves), and microfossils (e.g. pollen, spores) preserved in peat bogs and lake sediments. Although megafossils and macrofossils have been studied since the late eighteenth century, Quaternary botany today is largely dominated by pollen analysis. Quaternary pollen analysis is just over 100 years old. It started primarily as a geological tool for correlation, relative dating, and climate reconstruction. In 1950 a major advance occurred with the publication by Knut Fægri and Johs Iversen of their Text-book of Modern Pollen Analysis which provided the foundations for pollen analysis as a botanical and ecological tool for studying past dynamics of biota and biotic systems. The development of radiocarbon dating in the 1950s freed pollen analysis from being a tool for relative dating. As a result of these developments, pollen analysis became a valuable implement in long-term ecology and biogeography. Selected contributions that Quaternary botany has made to ecology and biogeography since 1950 are reviewed. They fall into four general parts: (1) ecological aspects of interglacial and glacial stages such as location and nature of glacial-stage tree refugia and long-term soil development in glaciated and unglaciated areas; (2) biotic responses to Quaternary environmental change (spreading, extinction, persistence, adaptation); (3) ecological topics such as potential niches, the nature of vegetation, and tree and forest dynamics; and (4) its application to ecological topics such as human impact in tropical systems, conservation in a changing world, island palaeoecology, plant–animal interactions, and biodiversity patterns in time. The future of Quaternary botany is briefly discussed and 10 suggestions are presented to help strengthen it and its links with ecology and biogeography. Quaternary botany has much to contribute to ecology and biogeography when used in conjunction with new approaches such as ancient-DNA, molecular biomarkers, and multi-proxy palaeoecology.
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The paper presents the results of comprehensive studies of the general technical properties and electronic spectra of the humus substances of the Boltnoe high-moor peat section with a thickness of 720 cm (southern taiga in Western Siberia). It was found that high-moor peats mainly exhibited low degrees of decomposition (on average, 10%) and humification (0.6). Considerable variations in the degree of humification (0.14–1.30) within the deposit were established; the extinction coefficients of the alkaline extracts of peat varied over wide ranges: E465 0.25–2.41 and E665 0.08–0.43. A crucial effect of the botanical composition of peat on the spectral coefficients was established. A decrease in the indicator significance of the extinction coefficients of the alkaline extracts of weakly decomposed peats for the reconstruction of the hydrothermal conditions of Western Siberian bogs was found.
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t is with great interest that we read the recent paper by Young et al. entitled “Misinterpreting carbon accumulation rates in records from near-surface peat”. However, we have some concerns about: (i) the use of an unvalidated deep drainage model to criticise studies investigating the impact of heather burning; (ii) the model scenarios and underlying model assumptions used; and (iii) misleading claims made about net C budgets and deep C losses. We feel that these issues require clarification and, in some cases, correction, especially as Young et al. has been used by a leading peatland policy and conservation body (IUCN UK Peatland Programme) to incorrectly characterise two recent studies by Heinemeyer et al. and Marrs et al. as having “presented misleading conclusions”. We strongly believe that one of the main ways to increase our scientific understanding is through vigorous and factual debate. Whilst we are open to and welcome criticism, such criticism needs to be accurate, balanced and evidence-based. Criticism must avoid unfounded or speculative accusations, especially when based on unrelated and unvalidated model scenarios. Indeed, study aims, hypotheses and discussion sections all need to be considered to ensure any criticism is applicable. We accept that deep C losses can be caused by peatland drainage and that this can lead to the misinterpretation of peat surface C accumulation rates or peatland C budgets. But these issues do not apply to the Heinemeyer et al. study, which investigated two specific and clearly stated burn-related hypotheses (charcoal impacts on peat properties and thus peat C accumulation), which only required comparisons of C accumulation rates within recent peat layers. Moreover, using peat core data collected by Heinemeyer et al., we provide strong evidence that the accusations of deep C losses by Young et al. are unfounded. However, the peat core data from Heinemeyer et al. does highlight the value of the Young et al. model scenarios for predicting short-term C loss caused by recent drainage. Finally, we also highlight the value of a detailed peat layer organic C content (%Corg) assessments to detect potential management (i.e. drainage) induced deep peat C loss.
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This NCC publication is one of two which describes the nature conservation interest and importance of the Flow Country, in Caithness and Sutherland, northern Scotland. This area is now recognised as the largest expanse of blanket bog in Europe and the report provided the first global review of the extent of this peatland type. The Flow Country is of outstanding importance, both nationally and internationally. These peatlands are three times larger than any other in either Britain or Ireland. The scale and diversity of the habitat is unique, and the total size and range of bird species present, and other aspects of the fauna, is of international importance. At the time of publication, in the mid-1980s, this area was suffering from widespread afforestation. This 1988 review summarised NCC’s detailed surveys of peatland vegetation in the Flow Country, and is complementary to a 1987 publication Birds, bogs and forestry: the peatlands of Caithness and Sutherland which outlined the ornithological importance of this area, and documented and called for a halt to the destructive afforestation which was then occurring. Published (publisher's copy) Peer Reviewed
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The Geomorphology of Upland Peat offers a detailed synthesis of existing literature on peat erosion, incorporating new research ideas and data from two leading experts in the field. Presents the most detailed and current work to date. Written in a style that is both intelligent and accessible. Fully illustrated with original drawings and photographs. Relevant and information for a broad audience working on organic sediments in various environments.
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The stratigraphy of southern Pennine peats is outlined and the occurrence of periodic horizontal bands of unhumified Sphagnum in the peat described. It is possible that these Sphagnum bands are true recurrence surfaces, dateable to 1200 B.C., 600 B.C., A.D. 400 and A.D. 1300. Striking peaks in Sphagnum spore counts in the peat are shown to correspond closely with the Sphagnum bands, and these peaks can be subdivided into separate peaks for the different Sphagnum species; typically a peak of spores of S. acutifolium s.l. occurs at the lower edge of a Sphagnum band and one of S. cuspidatum at the upper edge. The status of S. imbricatum as a peat-former in the southern Pennines in the past is discussed. Recent vegetation changes are examined in the light of documentary and palynological evidence, and it is concluded that Eriophorum vaginatum assumed dominance some time after the fourteenth century as a result of human interference with the vegetation. The modifications produced resulted in a decline in the frequency of Sphagnum in the vegetation, but the almost total absence of Sphagnum at the present day can probably be ascribed to the atmospheric pollution of the last 150 years.
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Until recently, ecological palaeoecology (a part of long-term ecology) and conservation biology were considered two separate subjects with little relevance to each other. With the shift from description and evaluation in conservation biology in the 1960s–1990s to the paradigm of ‘conservation in a rapidly changing world’ in the late 1990s, conservationists began to realise the importance of the temporal dimension in developing conservation strategies to allow for landscape and ecosystem change.Despite this paradigm shift, ecological palaeoecology is still largely ignored by conservation biology. I explore why this may be and outline recent advances in the subject of direct relevance to conservation science. I present nine questions of critical importance to conservation that palaeoecology can answer.Inevitably during this honeymoon phase of conservation biology and palaeoecology, there are controversies, challenges, and compromises. I outline these and suggest how some can be overcome by breakdown of the largely artificial boundaries between landscape history, cultural history, conservation, and palaeoecology, and by the appreciation that all can make important contributions to our understanding of people and nature and conservation in the face of changing land-use, environment, and landscapes.
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We used input and decomposition data from 14C studies of soils to determine rates of vertical accumulation of moss combined with carbon storage inventories on a sequence of burns to model how carbon accumulates in soils and moss after a stand-killing fire. We used soil drainage-moss associations and soil drainage maps of the old black spruce (OBS) site at the BOREAS northern study area (NSA) to areally weight the contributions of each moderately well drained, feathermoss areas; poorly drained sphagnum-feathermoss areas; and very poorly drained brown moss areas to the carbon storage and flux at the OBS NSA site. On this very old (117 years) complex of black spruce, sphagnum bog veneer, and fen systems we conclude that these systems are likely sequestering 0.01-0.03kgCm-2yr-1 at OBS-NSA today. Soil drainage in boreal forests near Thompson, Manitoba, controls carbon storage and flux by controlling moss input and decomposition rates and by controlling through fire the amount and quality of carbon left after burning. On poorly drained soils rich in sphagnum moss, net accumulation and long-term storage of carbon is higher than on better drained soils colonized by feathermosses. The carbon flux of these contrasting ecosystems is best characterized by soil drainage class and stand age, where stands recently burned are net sources of CO2, and maturing stands become increasingly stronger sinks of atmospheric CO2. This approach to measuring carbon storage and flux presents a method of scaling to larger areas using soil drainage, moss cover, and stand age information.
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Peat cores collected from three sites in the Jura region of Switzerland, La Tourbière des Genevez, Etang de la Gruère and Praz Rodet, were analysed for the fallout radionuclides 210Pb, 137Cs, 134Cs and 241Am, and the minerogenic radionuclide 226Ra. Unsupported 210Pb inventories of the cores were all in the range 3900-4784 Bq m-2 and are consistent with their having largely retained the atmospheric flux (ca. 130 Bq m-2y-1). In contrast, comparisons with earlier (1986) cores from these sites suggest that there have been significant losses of fallout 137Cs. Samples from all three sites had low but significant levels of supported 210Pb (226Ra) activity, the origin of which is presumably wind blown soil dust. 210Pb dates calculated using the CRS model were independently validated by 241Am and pollen stratigraphy. The core from La Tourbière des Genevez had a fairly conventional 210Pb activity versus depth profile indicating more or less constant net accumulation during the past 100 years. At the other two sites however the 210Pb profiles contained significant deviations from simple exponential decline that may record episodes in the bog during which there were major variations in the net dry mass accumulation rate. These episodes are dated 1930-50 (Etang de la Gruère) and 1960-80 (Praz Rodet). Although the depths at which total 210Pb reaches equilibrium with the supporting 226Ra range widely, from ca.37 cm in Etang de la Gruére to ca.60 cm in Praz Rodet, mean net dry mass accumulation rates for the past 100 years are remarkably similar, the values for all three sites are in the range 0.023-0.027 g cm-2y-1.
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The interactions between field layer vascular plants andSphagnum mosses in peat-forming systems are discussed in terms of differences in growth strategies, access to light, acquisition of mineral nutrients and water and the processes involved in the formation of the micro-topographical structures characteristic for these systems. To keep pace with the vertical growth ofSphagnum, the co-occurring vascular plants require a growth strategy involving continuous movement of the growing point and meristematic tissue upwards and a frequent formation of adventitious roots. The growth form and architecture of the vascular plants determine the occurrence and distribution of the structural units on a mire, the hummocks, lawns and hollows. Dwarf shrubs and other vascular plants with an orthotropic growth pattern characterise hummocks, where they form a firm matrix which reinforces and supports the spongy biomass ofSphagnum. In a similar way, clonal herbs stabilise the lawns because of the predominantly plagiotropic, or only weakly orthotropic, growth pattern of the rhizomes and coarse roots in the upper, oxic layers. Extended periods of drought often may have deleterious effects on the mosses but smaller impacts on the vascular plants because of their more efficient water conducting system. Different sources of mineral nutrients are used bySphagnum (atmospheric deposition) and the vascular plants (mineralisation of the organic matter). The presence ofSphagnum, therefore, reduces the supply of nutrient resources to the vascular plants.Sphagnum thereby gains a competitive advantage. A high rate of mineralisation would be beneficial to the vascular plants by increasing their growth rates causing shading of theSphagnum mosses and covering the moss layer by the above-ground litter fall. However, the slow decomposition ofSphagnum litter keeps the system in balance as it will reduce the nutrient supply to the vascular plants.
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. Quaternary palaeoecology has traditionally been associated with the reconstruction of past biota and past environments over long time periods such as the Holocene period. Recent methodological developments and conceptual advances have resulted in an ‘applied palaeoecology’ that can address specific ecological and environmental questions over the last 100-200 yr, the time span of primary interest to nature conservationists. The contributions of palaeoecology to the assessment of naturalness of ecosystems, to the assessment of the fragility of ecosystems, to the assessment of the conservation status of rare species, and to the development of a factual basis for attempts at ecosystem enhancement and restoration are discussed, with reference to palaeoecological studies in Scotland, England, southwest Ireland, and Sweden. Palaeoecological results indicate that few, if any, vegetation types in western Europe are natural. Palaeoecology can provide unique insights into the fragility of ecosystems in response to human activity and other biotic factors such as grazing and to acidification. Palaeoecology can contribute basic information required for understanding the causes of recent decline of taxa such as the natterjack toad, aquatic macrophytes, and arcticalpine plants. Palaeoecology is often the only source of baseline data about past ecosystem composition and function that are essential for any realistic attempts at ecosystem restoration or enhancement.
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Proxy-climatic data in the form of plant macrofossils have been analysed from a 5 m core from Bolton Fell Moss, Cumbria, UK. Detailed analysis of peat from the upper 50 cm of this core is used to demonstrate a strong correlation between changes in the relative proportion of taxa and known climatic changes over the last 1000 years. The record of changes in bog vegetation contained within the peat profile is used to reconstruct changes in bog-surface wetness for the latter half of the Holocene. As bog- surface wetness is directly controlled by the prevailing climatic conditions, this reconstruction can be viewed as a proxy-climate record. Twelve radiocarbon age estimates on the 5m core suggest that between 50 and 500 cm peat accumulated at a relatively constant rate of 12.4 yr cm-1 . The regular sampling intervals thus provide a time series of past bog-surface wetness; spectral analyses of this series indicates that wetness changes are cyclic, with a ca. 800 year periodicity.
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[1] The ongoing warming in high-latitude regions may be causing rapid changes in the structure and functioning of terrestrial ecosystems. Of particular concern is the fate of belowground soil organic carbon stored in peat-accumulating wetlands, as these large carbon pools are sensitive to temperature and moisture conditions. Despite their important role in the global carbon cycle, considerable uncertainty remains over the carbon balance of northern peatlands in a changing climate. Here we examine the response of vegetation and carbon dynamics in a wet boreal peatland to recent climate warming using empirical peat core data and a new modeling approach. We observed a widespread shift from herbaceous Carex fen peat to Sphagnum moss peat around 100 years ago that was accompanied by a sharp increase in carbon accumulation rate. The observed apparent carbon accumulation rates over the past 100 years (96.8 g C m-2 yr-1) were almost 10 times greater than those over the past 4000 years (11.5 g C m-2 yr-1). Once differential decomposition history was considered using three modeling approaches, the expected long-term accumulation rate of recent peat was still 2–6 times greater than that of the past 4000 years. We propose that recent warming has led to Sphagnum establishment, which rapidly altered the peatland surface chemistry and hydrology, further promoting Sphagnum growth and enhancing the carbon sink capacity of this peatland. Longer and warmer growing seasons could also have stimulated plant growth. Our results imply that accelerated carbon accumulation under global warming in some wet peatlands might offset some of the carbon losses experienced from other peatland types.
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For ecosystems perceived as degraded, but for which the causal factors or timescales for the degradation are disputed or not known, long-term (palaeo-)ecological records may aid understanding and lead to more meaningful conservation approaches. To help ‘bridge the gap’ between (very) long-term ecology and contemporary ecology for practical application, there have been calls for working relationships to be established between palaeoecologists and conservation ecologists. One environment in which this has been attempted is blanket mire. Many blanket mires in Europe are degraded and contain few sphagna. In South Wales, almost all exhibit symptoms of degradation, with dominance by purple moor grass (Molinia caerulea) widespread. We used palaeoecological techniques on three peat profiles in the Brecon Beacons to investigate vegetation history of highaltitude blanket mire to help assess the relative contribution of various factors in mire degradation and to inform strategies for mire conservation and restoration management. We found that declines in sphagna preceded the rise to dominance of monocotyledons. Macrofossil records showed that although Molinia was already present on the Beacons before the start of the industrial revolution, its major rise to dominance in one profile was within the 20th Century, coincident with evidence for local fire. In another profile, it was out-competed by Eriophorum vaginatum after the start of the industrial revolution; there is circumstantial evidence to suggest that a reduction in burning contributed to the rise in E. vaginatum. Conservation management to reduce the current local dominance of both Eriophorum and Molinia is supported by the palaeoecological data, but severe erosion and hagging of peat will constrain practical methods for achieving this on the Beacons until the peat is stabilised. We suggest that palaeoecological techniques have wider applicability in conservation.
Article
In the Solway Firth - Morecambe Bay region of Great Britain there is evidence for heightened hillslope instability during the late Holocene (after 3000 cal. BP). Little or no hillslope geomorphic activity has been identified occurring during the early Holocene, but there is abundant evidence for late Holocene hillslope erosion (gullying) and associated alluvial fan and valley floor deposition. Interpretation of the regional radiocarbon chronology available from organic matter buried beneath alluvial fan units suggests much of this geomorphic activity can be attributed to four phases of more extensive gullying identified after 2500-2200, 1300-1000, 1000-800 and 500 cal. BP. Both climate and human impact models can be evoked to explain the crossing of geomorphic thresholds: and palaeoecological data on climatic change (bog surface wetness) and human impact (pollen), together with archaeological and documentary evidence of landscape history, provide a context for addressing the causes of late Holocene geomorphic instability. High magnitude storm events are the primary agent responsible for gully incision, but neither such events nor cooler/wetter climatic episodes appear to have produced gully systems in the region before 3000 cal. BP. Increased gullying after 2500-2200 cal. BP coincides with population expansion during Iron Age and Romano-British times. The widespread and extensive gullying after 1300-1000 cal. BP and after 1000-800 cal. BP coincides with periods of population expansion and a growing rural economy identified during Norse times, 91 10th centuries AD, and during the Medieval Period, 12-13th centuries AD. These periods were separated by a downturn associated with the 'harrying of the north' AD 1069 to 1070. The gullying episode after 500 cal. BP also coincides with increased anthropogenic pressure on the uplands, with population growth and agricultural expansion after AD 1500 following 150 years of malaise caused by livestock and human (the Black Death) plagues, poor harvests and conflicts on the Scottish/English border. The increased susceptibility to erosion of gullies is a response to increased anthropogenic pressure on upland hillslopes during the late Holocene, and the role of this pressure appears crucial in priming hillslopes before subsequent major storm events. In particular, the cycles of expansion and contraction in both population and agriculture appear to have affected the susceptibility of the upland landscape to erosion, and the hillslope gullying record in the region, therefore, contributes to understanding of the timing and spatial pattern of human exploitation of the upland landscape. (c) 2006 Elsevier B.V. All rights reserved.
Article
The number and range of Holocene palaeoclimate reconstructions from various regions of the world have increased dramatically over the last decade. The data density for many regions and proxies now offers the potential of robust regional-scale reconstructions that avoid the problems of records from individual sites, and improve communication between palaeoclimate subdisciplines and climate modellers. However, there are problems with chronological uncertainties and quantification of proxies, which make compilation of multiple records difficult. Here we explore a 'stacking' and 'tuning' approach to the derivation of regional records from peatland climate proxies to test its applicability to non-annually resolved terrestrial records. Twelve individual records from northern Britain based on water table reconstructions from testate amoebae analysis were divided into four regions. Records were detrended, normalised and compared within regions to identify clear correlative events. The original chronologies of the records were tuned using both these events and independent age markers. The stacked record for northern Britain indicates pronounced changes to wet conditions at 3600, 2760 and 1600 cal yr BP with more minor changes at 3060, 2050, 1260 860, 550 and 260 cal yr BP. The main wet phases are highly correlated with mid-European take highstands, wider North Atlantic climate change inferred from ocean and ice core records, and solar variability. Tuning and stacking of non-annual terrestrial palaeoclimate records is a new approach to the compilation and reconciliation of individual records within coherent climatic regions and provides a tool for upscaling of palaeoclimate records for climate model-data comparisons. (c) 2005 Elsevier Ltd. All rights reserved.
Article
The study of Quaternary environmental change is directly applicable to on-going issues of global conservation. Palaeoecological research techniques provide the tools to address some of the key questions presently being asked by conservation ecologists and land management organizations. But is this type of analysis currently being utilized to its full potential? Are the results of palaeoenvironmental analyses routinely applied to practical issues of natural resource management, and if not what can be done to expand the application of this research within the conservation community? This paper reviews recent developments in the application of the analysis of late Quaternary environmental change to key environmental issues of biodiversity and conservation management and examines areas which could be strengthened in the future including: (i) determination of baselines and natural ecosystem variability; (ii) understanding ecological thresholds and resilience; (iii) climate change conservation strategies; (iv) biological invasions; and (v) conservation and culture.
Article
1. A characteristic of some heath and moorland areas in maritime north-west Europe is the widespread dominance of Molinia caerulea (purple moor grass). The overwhelming local supremacy of this species concerns farmers, owing to its relatively low palatability for grazing stock, and conservationists, owing to the monotonous, species-poor landscapes that often result under Molinietum. 2. In some environmentally sensitive areas (ESAs) in England and Wales, Molinietum is believed to have ousted Callunetum in recent decades; experiments sponsored to control the species have predicated its infiltration and replacement of heather-dominated stands. 3. Experimental control of Molinia in ESAs on Exmoor, England, was paralleled by palaeoecological studies to verify its recent rise, assess its status in moorland, and test the utility of the techniques for such research. 4. Peat profiles from two localities on Exmoor were sampled and subjected to recently developed techniques of plant macrofossil counting and to conventional pollen analysis. One locality was ‘white moor’, clearly dominated by Molinia; the other was ‘grey moor’ (an admixture of ericaceous shrubs) that had become invaded (allegedly recently) by Molinia. 5. Dating of profiles employed a range of methods, including conventional radiocarbon dating, Accelerator Mass Spectrometry (AMS) dating and the counting of spheroidal carbonaceous particles, to attempt to delimit horizons of recent peat growth. 6. The pollen and macrofossil data confirmed the recent ousting of Calluna and rise to dominance of Molinia in the grey moor, but also provided evidence of an earlier unsuspected (pre-Callunetum) presence of Molinia. The overwhelming dominance of Molinia in the white moor was also a recent phenomenon, but was only partly at the expense of Calluna. The palaeoecological data indicated a greater antiquity and former abundance of Molinia than is often appreciated and suggested that, over the past millennium, vegetation dominance has alternated between Callunetum and grass moor containing at least some Molinia, while the former Calluna-dominated grey moor itself developed originally from grass moor. 7. These findings have implications for conservation management and for restoration targets in ‘degraded’ moorland. Similar palaeoecological studies have since been adopted in Wales, directly to inform conservation and management policy.
Article
Many European blanket mires are degraded and contain few Sphagna. In Wales, more than half exhibit symptoms of degradation. We used palaeoecological techniques to chronicle recent vegetation history at two upland localities in South Wales to provide an understanding of the contribution of various factors in mire degradation and to aid wider conservation management strategies. The data suggest a major vegetation change post-dated the start of the industrial revolution. There was evidence for increased burning activity, but as this phenomenon was not present in all profiles it seems unlikely that fire was the principal or sole agent in vegetation change. Rather, increased atmospheric input, plus a change in grazing pressure, may have been responsible. The implications for conservation management are far-reaching. The present overwhelming dominance of Molinia at Hirwaun Common is unprecedented. So also is a local dominance of Calluna, shown in one area at Mynydd Llangatwg. Hence, the approbation often accorded to Callunetum needs to be tempered with the knowledge that its presence in the Mynydd Llangatwg landscape is not long-standing. Indeed, millennial-scale dominance of Sphagnum imbricatum characterizes the earlier record. Its demise and that of Drosera intermedia took place in historical times. Both localities show floristic impoverishment within the 20th Century, with relatively recent single-taxon supremacy. So, conservation management to reduce the current pre-eminence of Molinia would not run counter to long-established dominance; ways to achieve this are suggested. The methods used in this study have wide applicability in mire conservation.
Article
Analyses of plant macrofossils, peat humification and testate amoebae were used to reconstruct a proxy climate record spanning the last 7500 years from an ombrotrophic bog, Temple Hill Moss, in southeast Scotland. The plant macrofossil data were subjected to detrended correspondence analysis (DCA) which modelled effectively the significant wet shifts within the record. A mean water table depth transfer function was applied to the testate amoebae data to provide quantifiable changes. The three proxy records show coherent phase changes which are interpreted as variability in past effective precipitation. Two tephra horizons (Glen Garry and Lairg A) were used in conjunction with radiocarbon dates to construct an age/depth model, producing a robust geochronology from which a time series was calculated. The palaeoclimatic reconstruction identified major wet shifts throughout the Holocene, with specific events occurring around cal. 6650, 5850, 5300, 4500, 3850, 3400, 2800–2450, 1450–1350 and 250–150 BP. Spectral analysis of the plant macrofossil DCA and colorimetric humification data produced a millennial scale periodicity of 1100 years. The same periodicity has also been found in a palaeoclimatic reconstruction from a site in Cumbria (Walton Moss), and may be linked with millennial scale periodicities found in oceanic palaeoclimatic records.
Article
Peatland palaeoclimate sequences produce bog surface wetness (BSW) reconstructions which are commonly interpreted as changes in summer effective precipitation, i.e. the net balance between precipitation and evapotranspiration, the latter being mainly governed by temperature. The relative roles of precipitation and temperature have been investigated previously, although over centennial and millennial timescales no conclusive relationships have as yet been established, but it has been suggested that summer temperature may play the dominant role. We aimed to test this by comparing a late-Holocene peat-based palaeoclimate record from Walton Moss, northern England, with a chironomid-inferred temperature (CI-T) reconstruction from a nearby lake, Talkin Tarn. Both records showed significant changes in inferred climate over the last 3000 years with lower temperatures corresponding to increases in BSW. The CI-T reconstruction, which covered the last 6000 years, was also compared to a longer BSW record, again from Walton Moss, and the same relationships were observed. Our evidence therefore suggests that over centennial timescales summer temperatures are important drivers of the peat-based palaeoclimate record.
Article
Recent research has shown that ombrotrophic mires can yield a proxy climate signal based on changes in the degree of peat humification [1,2], and that oceanic margin sites show the most sensitive record [3]. We compare humification records for the last 1000 yr from two radiocarbon-dated blanket peat profiles from western Ireland, and show several corresponding periods of climatic fluctuations. Periods favouring reduced peat decomposition, suggestive of wetter and/or cooler climatic conditions, seem to coincide with periods of reduced sunspot activity and atmospheric14C anomalies.Whilst climatologists have continued to debate a link between solar variability on a century timescale and climate change, the exact nature of that link remains elusive [4–7]. The results from Ireland demonstrate that data derived from mires could be relevant to the debate as to the extent of solar forcing in natural climatic variability, and the curves shown provide a continuous record to add to previous evidence for the so-called ‘Medieval Optimum’ and ‘Little Ice Age’ [8]. The record may imply that, during the past millennium, climatic change at the oceanic margin of the northeast Atlantic largely corresponded to inferred variations in solar output.
Article
Quantified analyses of plant macrofossil remains have been made from three profiles of peat from raised bogs spanning a distance of 425 km from western Ireland to northern England. The reconstructed vegetation of each profile is related to changing bog surface wetness (BSW), and since the bogs are ombrotrophic these BSW changes are interpreted in terms of changing climate. Using age/depth models based on a total of 49 radiocarbon dates a number of wetter and drier phases are identified, and phase-shifts to wetter and/or cooler climates are defined. Prominent coincident changes to wetter conditions are dated in at least two of the profiles to ca 4400–4000, 1750, 1400, and 1000 cal. BP and in all three profiles at 3200, 2750–2350, 2250, and around 700 cal. BP. These phases are related to proxy climate changes in other terrestrial data sets from northwest Europe and a broad degree of synchroneity is demonstrated.
Article
The affinity of bomb-derived fallout 137Cs and naturally-occurring fallout 210Pb for soil and sediment particles make them valuable sediment tracers, and they have been used in a wide range of environmental investigations. A knowledge of their behaviour and distribution in soils is vital for understanding their movement within the environment and therefore for interpreting the information that they provide as sediment tracers. The study reported in this paper combines both empirical evidence and theoretical reasoning to develop an improved understanding of the distribution of fallout 137Cs and 210Pb in undisturbed and cultivated soils. Results from field experiments suggest that the initial distribution of these radionuclides in topsoils is approximately exponential. The primary factors influencing the post-depositional redistribution of these radionuclides in stable undisturbed soils have been represented as effective diffusion and convection processes, and a one-dimensional transport model has been employed to describe temporal changes in their vertical distribution in the soil profile. Cultivation and soil erosion are the dominant processes controlling their vertical distribution in cultivated soils. The information obtained is essential for exploiting fully the potential for using these fallout radionuclides as tracers in studying soil erosion, sediment delivery and sediment deposition, and associated sediment budgets.