Bog Surface Research Articles

Effects of temperature, rainfall and conifer felling practices on the surface water chemistry of northern peatlands

Afforested peatlands account for about 25 % of human-affected peatlands worldwide. In some regions, particularly the British Isles, forest-to-bog conversions are now underway in the hope of increasing carbon storage and restoring original ecosystem functions. In this study, the effects on surface water quality of forest-to-bog restoration in the Flow Country peatlands of northern Scotland were monitored during 15 months. The hydrochemistry of rainwater, resurgence ground water, forestry drainage ditch water, open bog surface water, forestry-influenced loch water and stream water was examined before, during and after felling. The seasonal cycles of biologically active (C, Si, P) and organically complexed (Fe, Al) elements were characterised by major changes in concentration. The felling operations amplified these effects due to (i) the decomposition of felling residues (leaching K and C) and (ii) the disturbance and partial mineralisation of shallow peat soils (releasing P, Fe and Al). Shorter term changes (1–10 days) produced by rainfall events and associated changes in hydrological flow paths controlled the concentrations of Na, Ca, Mg, Mn, and to a lesser extent K and Al. There were significant negative correlations with flow of [K], [Ca] and [Mg] but a positive correlation between stream flow and [Al]. Concentration-flow relationships were not significantly altered by the felling operations because of the relatively low volume of water released from the felled area. Fluctuations in the water table represented another important control of surface water composition. Resurgence waters produced high [Fe] and [Si] values when water table levels were low. These contributions were diluted with runoff and surface soil waters enriched in dissolved organic carbon (DOC) when levels rose. Sequential ultrafiltration revealed that Fe, C and P co-occurred in the >30 kDa molecular weight fraction in constant relative concentrations. Since forest-to-bog restoration raises the water table, it can be anticipated to result initially in more intense flushing of DOC, including the >30 kDa molecular weight fraction where Fe and P co-occur.

Pine stumps in Irish peats: is their occurrence a valid proxy climate indicator?

ABSTRACTWe investigate the temporal and spatial distribution of pine (Pinus sylvestris) stumps preserved in peat deposits to test whether their occurrence can be used as an indicator of climatic shifts to drier conditions. Radiocarbon dates of sub‐fossil stumps were collected from the literature, along with environmental data throughout the island of Ireland. Data were analysed using non‐parametric statistical techniques. There was no distinct geographical pattern observed in the distribution of pine stumps on bog surfaces. Tree ages ranged from 66 to 500 years with 85.7 % of these <300 years. Pines occurred on bogs from ca. 8500 to 500 cal a BP. The temporal distribution during the Holocene was characterized as a mid‐Holocene peak in sites supporting pine, with two gaps either side of this peak. Our current understanding of past climate dynamics failed to explain this temporal distribution. The onset, mid‐Holocene peak and cessation of bog sites supporting the presence of bog pines appears to be driven by changes in pine seed and bog surface area availability during the Holocene rather than changes in climate. We conclude that variability in the occurrence of Irish bog pines is not a valid climate proxy as factors other than climate influence their presence and thereby disrupt the climate signals.

Climate change records between the mid- and late Holocene in a peat bog from Serra do Xistral (SW Europe) using plant macrofossils and peat humification analyses

To implement models of global change, information from peripheral regions and concerning the distinction between global and local events is needed. In this context, we studied the occurrence of hydrological changes over the last 5300years in the southern most European area of active blanket bogs. The reconstruction of the bog surface wetness was performed on the basis of the analysis of plant macrofossils and peat humification. To interpret these proxies, the current botanical composition of the bog and the ecological behavior of the different plant species were used.From its present ecological behavior, we have established the main indicator species for different bog surface wetness. The seeds of Juncus bulbosus and Drosera rotundifolia, which were significantly correlated with the humification index, as well as the seeds and rhizomes of Eriophorum angustifolium, were the primary indicators for wetness. The Sphagnum species are not abundant, and most are restricted to wet and damp periods.The concordance between both proxies, in spite of certain discrepancies, allowed us to estimate the chronological sequence of hydrological changes along the bog profile. We have differentiated 10 wet periods during which the bog surface could be flooded or wet (5300–4850; 4350–3900; 3550–3350; 3150–3050; 2700–2450; 2250–2150; 1950–1300; 1150–1050; 900–800 and 700–20cal. yr. BP). These identified wet periods are in agreement with previous paleoclimate studies with different spatial scales and proxies.

Testing the cause of the Sphagnum austinii (Sull. ex Aust.) decline: Multiproxy evidence from a raised bog in Northern Ireland

We use a multiproxy palaeoecological dataset from Dead Island bog in Northern Ireland to examine the cause of the Sphagnum austinii (Sphagnum imbricatum) decline. The disappearance of this species from the peat record occurred just after the ‘AD 860’ tephra layer and is coeval with a rapid increase in bog surface wetness and increased mineral dust and charcoal abundance. Although it is difficult to identify one specific cause of the decline, the evidence for increased soil-derived dust is apparent and is supported by regional tephra-dated pollen diagrams that reveal extensive landscape changes due to agricultural intensification in early Medieval Ireland. As the decline of S. austinii occurred much later (~AD 1860) in Fallahogy bog (~1.2km away), we suggest that the decline of S. austinii at Dead Island was caused by a combination of fire and the deposition of soil-derived dust. We suggest that future studies should consider the use of multiple cores from each site to examine the within-site variability of the decline of S. austinii.

Increased tree establishment in Lithuanian peat bogs — Insights from field and remotely sensed approaches

Over the past century an ongoing establishment of Scots pine (Pinus sylvestris L.), sometimes at accelerating rates, is noted at three studied Lithuanian peat bogs, namely Kerėplis, Rėkyva and Aukštumala, all representing different degrees of tree coverage and geographic settings. Present establishment rates seem to depend on tree density on the bog surface and are most significant at sparsely covered sites where about three-fourth of the trees have established since the mid-1990s, whereas the initial establishment in general was during the early to mid-19th century. Three methods were used to detect, compare and describe tree establishment: (1) tree counts in small plots, (2) dendrochronological dating of bog pine trees, and (3) interpretation of aerial photographs and historical maps of the study areas. In combination, the different approaches provide complimentary information but also weigh up each other's drawbacks. Tree counts in plots provided a reasonable overview of age class distributions and enabled capturing of the most recently established trees with ages less than 50years. The dendrochronological analysis yielded accurate tree ages and a good temporal resolution of long-term changes. Tree establishment and spread interpreted from aerial photographs and historical maps provided a good overview of tree spread and total affected area. It also helped to verify the results obtained with the other methods and an upscaling of findings to the entire peat bogs. The ongoing spread of trees in predominantly undisturbed peat bogs is related to warmer and/or drier climatic conditions, and to a minor degree to land-use changes. Our results therefore provide valuable insights into vegetation changes in peat bogs, also with respect to bog response to ongoing and future climatic changes.

The changing landscape of Clara Bog: the history of an Irish raised bog

Clara Bog is one of the few raised bogs that has not been fully exploited in the Irish midlands and is a reminder of how the landscape of this region once appeared. This paper describes how the Clara Bog landscape has been changing since the commencement of the Holocene 11,500 years ago. Initially change was relatively slow as the bog naturally developed from its origins in an early Holocene lake, which became in-filled to form a fen circa 8000 years ago, before it continued to develop into an acid raised bog reaching its maximum extent by the beginning of the nineteenth century. Clara Bog has changed dramatically in the last 200 years due to human activity. Today less than 50% of its original bog surface remains. The changes in the bog during the historic past have been driven by population change, poverty, economic growth, construction of the Grand Canal, the building of roads, the need for fuel and farmland, nature conservation and tourism. The prehistoric development of the bog and land use in its hinterland was reconstructed from a detailed analysis of published archaeological records, palaeoecological studies and stratigraphical studies. Published maps and historical records have been vital in establishing a chronology for the changes that have occurred on Clara Bog since the beginning of the nineteenth century.

Evaluating long‐term regional climate variability in the maritime region of the St. Lawrence North Shore (eastern Canada) using a multi‐site comparison of peat‐based paleohydrological records

ABSTRACTThis study presents paleohydrological reconstructions from ombrotrophic peatlands (bogs) along the north shore of the Estuary and the Gulf of St. Lawrence in eastern Canada. Past water table depths were reconstructed based on testate amoebae analyses within four peatlands from two maritime ecoclimatic regions (boreal and subarctic) using a new transfer function. The comparison of multiple peat‐based paleohydrological records was used to distinguish climate‐driven changes from variations related to site‐specific factors. Coherence between the water table reconstructions at the regional scale suggests a common climatic influence on bog paleohydrology but there are inconsistencies which also suggest an influence of non‐climatic factors (e.g. internal peatland processes and feedbacks). The surface drying and increased hydrological variability after 3000 cal a BP in the studied bogs coincide with the transition from the Holocene Climatic Optimum to the Neoglacial cooling documented by proxy climate records in eastern Canada. The bogs of Havre St‐Pierre have experienced major drying during the late Holocene, indicating important annual‐to‐centennial water deficits at the peatland surface. Regional differences in the magnitude of the hydrological fluctuations may result from distinctive climatic conditions or could indicate that bog surface wetness in the Gulf of St. Lawrence was more sensitive to past climate changes.

Aquatic invertebrate communities of ombrotrophic bogs in Ireland with special reference to microcrustaceans

The contribution of ombrotrophic bogs to regional biodiversity is sometimes underestimated. Due to their acidic and nutrient-poor nature they present a unique and challenging environment for the fauna. Bog surfaces consist of a mosaic of terrestrial and aquatic habitats providing a range of environmental conditions. The open-water bodies and the associated invertebrate fauna have received limited attention in Ireland. This paper aims to gather together what is known about the macroinverterbate and microcrustacean communities present in these water bodies. The resulting list of taxa recorded by various studies indicates a community that includes both characteristic and generalist taxa. The diversity of groups such as Coleoptera and Heteroptera was relatively high; however, other groups including rotifers and Diptera, specifically the chironomids, need further attention if the biodiversity of ombrotrophic peatlands is to be fully characterised. The importance of habitat heterogeneity is also highlighted by a number of studies.

Late Holocene ecohydrological and carbon dynamics of a UK raised bog: impact of human activity and climate change

Understanding the ecohydrological responses of peatlands to climate change is particularly challenging over the late Holocene owing to the confounding influence of anthropogenic activity. To address this, a core spanning the last ∼2400 years from a raised bog in northern England was analysed using a comprehensive suite of proxy methods in an attempt to elucidate the drivers of change. A testate amoebae-based transfer function was used to quantitatively reconstruct changes in water table depth, supported by humification analysis and a plant macrofossil-derived hydroclimatic index. Pollen and plant macrofossil data were used to examine regional and local vegetation change, and human impacts were inferred from charcoal and geochemistry. Chronological control was achieved through a Bayesian age-depth model based on AMS radiocarbon dates and spheroidal carbonaceous particles, from which peat and carbon accumulation rates were calculated. Phases of both increased and decreased bog surface wetness (inferred effective precipitation) are present, with dry phases at c. AD 320–830, AD 920–1190 and AD 1850–present, and a marked period of increased effective precipitation at c. AD 1460–1850. Coherence with other records from across Northern Europe suggests that these episodes are primarily driven by allogenic climatic change. Periods of high bog surface wetness correspond to the Wolf, Spörer and Maunder sunspot activity minima, suggesting solar forcing was a significant driver of climate change over the last ∼1000 years. Following the intensification of agriculture and industry over the last two centuries, the combined climatic and anthropogenic forcing effects become increasingly difficult to separate due to increases in atmospheric deposition of anthropogenically derived pollutants, fertilising compounds, and additions of wind-blown soil dust. We illustrate the need for multiproxy approaches based on high-resolution palaeoecology and geochemistry to examine the recent trajectories of peatlands.

Emission of CO2 from the surface of oligotrophic bogs with due account for their microrelief in the southern taiga of European Russia

The results of studying the carbon dioxide fluxes from the soil’s surface during three years taking into account the microrelief are summarized. More precise estimates were obtained for the annual CO2 emission from the oligotrophic peat bogs differing in vegetation and waterlogging in the southern taiga of European Russia. The maximum differences in the rates of the CO2 emission related to the microrelief elements are characteristic of the treeless ridge-pool complex, where the hollows (without vegetation) emitted CO2 twice less than the flat areas and thrice less than the hummocks. In the forest bogs, the differences related to the microrelief were significantly lower. In the areas with the ridge-pool microrelief, the weighted average (for 3 years) CO2 emission was 436 g C/m2 per year; in the better drained natural dwarf shrub-cotton grass-sphagnum pine forest, 930; and in the drained pine forest, 1292 g C/m2 per year. The share of the CO2 amount emitted in the cold period (November–April) amounted to 10% of its annual flux from the peat soils of the ridge-pool complex and 17 and 24%, respectively, in the natural and drained pine forests.

Size fractionation and optical properties of dissolved organic matter in the continuum soil solution-bog-river and terminal lake of a boreal watershed

The size distribution and speciation of organic matter (OM) in soil solution, bog, stream, and humic and clearwater lake in the north boreal zone (Karelia region, north west Russia) during the summer base-flow period for several years were investigated. The samples were filtered in the field using cascade filtration through progressively decreasing pore size (100, 20, 10, 5, 0.8, 0.4, 0.22, 0.1, 0.046μm, 100kDa, 10kDa and 1kDa) followed by dissolved organic carbon (DOC) analysis, UV–vis and size exclusion chromatography measurements. Surrogate parameters, such as specific UV absorbance (SUVA; absorbance at 254nm normalized for DOC concentration in lmg−1m−1) and the absorbance ratios E254/E436, E280/E350, E254/E365, E365/E470 and E470/E655 (ratio of spectrophotometric absorbance of the sample at two wavelengths) were applied for the characterization of OM in filtered and ultrafiltered water from soil solution, bog, river and lake.In the<0.22μm filtrates, there was a systematic decrease in DOC concentration, C/N ratio, SUVA (hydrophobicity and aromaticity) and proportion of colloidal (1kDa–0.22μm) OC along the watershed profile from peat bog soil solution, feeding humic lake, to the middle course of the stream towards the terminal oligotrophic lake. Within the filtrates and ultrafiltrates of soil solution and terminal lake, C/N increased from 100 to 140 and from 7 to 25 for 0.22–10μm and<1kDa fractions, respectively. SUVA, degree of humification, hydrophobicity and aromaticity generally increased from high molecular weight (HMW) to low molecular weight (LMW) fractions, being highest in the<1kDa fraction. The results allowed a comprehensive view of DOM transport and transformation among various size fractions within a small boreal watershed that can serve as an analogue of small rivers discharge to the Arctic Ocean. It follows that, during the summer baseflow season, the signature of organic-rich interstitial soil solutions originating in a typical peat bog zone can be completely masked by processes occurring in adjacent bog surface waters feeding lakes, as well as in the stream itself. As such, depending on local landscape, one may expect extremely high variability in both chemical nature and MW of DOM delivered by small coastal watersheds to the Arctic Ocean during the summer baseflow period.

Neolithic agriculture on the European western frontier: the boom and bust of early farming in Ireland

A multi-disciplinary study assessing the evidence for agriculture in Neolithic Ireland is presented, examining the timing, extent and nature of settlement and farming. Bayesian analyses of palaeoenvironmental and archaeological 14C data have allowed us to re-examine evidential strands within a strong chronological framework. While the nature and timing of the very beginning of the Neolithic in Ireland is still debated, our results – based on new Bayesian chronologies of plant macro-remains – are consistent with a rapid and abrupt transition to agriculture from c. 3750 cal BC, though there are hints of earlier Neolithic presence at a number of sites. We have emphatically confirmed the start of extensive Neolithic settlement in Ireland with the existence of a distinct ‘house horizon’, dating to 3720–3620 cal BC, lasting for up to a century. Cereals were being consumed at many sites during this period, with emmer wheat dominant, but also barley (naked and hulled), as well as occasional evidence for einkorn wheat, naked wheat and flax. The earliest farmers in Ireland, like farmers elsewhere across NW Europe, were not engaged in shifting cultivation, but practised longer-term fixed-plot agriculture. The association between early agriculture and the Elm Decline seen in many pollen diagrams shows that this latter event was not synchronous across all sites investigated, starting earlier in the north compared with the west, but that there is a strong coincidence with early agriculture at many sites. After this early boom, there are changes in the nature of settlement records; aside from passage tombs, the evidence for activity between 3400 and 3100 cal BC is limited. From 3400 cal BC, we see a decrease in the frequency of cereal evidence and an increase in some wild resources (e.g. fruits, but not nuts, in the records), alongside evidence for re-afforestation in pollen diagrams (3500–3000 cal BC). Changes occur at a time of worsening climatic conditions, as shown in Irish bog oak and reconstructed bog surface wetness records, although the links between the various records, and assessment of causes and effects, will require further investigation and may prove complex. This period seems to have been one of environmental, landscape, settlement and economic change. The later 4th millennium BC emerges as a period that would benefit from focused research attention, particularly as the observed changes in Ireland seem to have parallels in Britain and further afield.

A novel geochemical approach to paleorecords of dust deposition and effective humidity: 8500 years of peat accumulation at Store Mosse (the “Great Bog”), Sweden

Both bog surface wetness and atmospheric dust deposition are intricately linked to changes in the hydrological cycle and pairing these types of records at the same site provides complementary information. Here a peat core from Store Mosse in southern Sweden covering the last 8500 years was used to make a high-resolution paleoclimate reconstruction based on a combination of bog development, colourimetric humification and inorganic geochemistry data. The coupling of Principal Component Analysis with changepoint modelling allowed for precise linking of changes in bog surface wetness and dust deposition records.A long-term trend towards warm (and possibly wet) conditions starts ca 8150 cal yr BP and culminates with the most pronounced conditions from 6900 to 6600 cal yr BP. The most significant arid period at Store Mosse occurred between 6500 and 5600 cal yr BP during which dust deposition was significantly higher. Wetter conditions dominate from 5500 to 4980 cal yr BP as the transition from the Hypsithermal and into the Neoglacial is made. After a shift to drier conditions, humification enters a more stable period that lasts from 4525 until 3200 cal yr BP. It is during this time that the first possible anthropogenic dust signals occur at ca 4200 cal yr BP. From 3200 cal yr BP to present humification generally shows a long-term decline moving towards wetter conditions. The main exceptions are during the transition from the Neoglacial to Roman Warm Period which is registered as a significantly wetter period and two dry periods recorded 2365 to 2155 cal yr BP and 1275–1105 cal yr BP. In general, the observed changes agree well with regional records of effective humidity and temperature. The high temporal resolution of the Store Mosse record reveals that palaeoclimatic change over the last 8500 years in southern Sweden has had a complex and variable structure.

Stable (Cu, Mg) and radiogenic (Sr, Nd) isotope fractionation in colloids of boreal organic-rich waters

Stable (Cu and Mg) and radiogenic (Sr and Nd) isotopic compositions in filtrates and ultrafiltrates of various size fractions have been measured in waters of subarctic watersheds (NW Russia) and in temperate rivers and lakes of the south boreal zone. A large volume of samples were filtered in the field using cascade filtration and ultrafiltration employing progressively decreasing pore sizes (100, 20, 10, 5, 0.8, 0.4, 0.22, and 0.1μm; 100, 10 and 1kDa) followed by element isotopic analysis using thermal ionization mass spectrometers and a Neptune multicollector ICP-MS. In the boreal watershed underlain by Archean and Proterozoic rocks, the 87Sr/86Sr ratio decreased in the 1–100kDa ultrafiltrates and dialysates by 0.0001–0.0004 units compared to the 0.45μm filtrates. Despite the dominance of colloids in the Nd speciation in surface waters, the isotopic value of Nd in the filtrates and ultrafiltrates remained constant within the uncertainty of the measurements. We hypothesize the absence of an atmospheric input of silicate dust for Nd but the presence of marine aerosols for Sr. It follows that the Sr in the investigated surface waters has a short residence time compared to the time required for achieving isotopic equilibrium between the colloidal (1kDa–0.22μm) and truly dissolved (<1kDa) pools. For Nd, the residence time is long enough to achieve this equilibrium. The stable isotope composition of Cu in the streams remained constant within ±0.1‰ during filtration through 100μm to 1kDa membranes, despite the fact that 40–60% of Cu was colloidal. This result suggests that the homogeneity of the Cu isotopic composition within the colloidal and truly dissolved pools is likely associated with the similarity of the structure and stability of Cu(II) complexes with fulvic acids of different molecular weights. The stable isotope composition of dissolved Mg in soil solution and bog surface water demonstrates similar, within the analytical uncertainty, isotopic signatures between truly dissolved and colloidal fractions.Despite the dramatically different structures of the metal–dissolved organic matter (DOM) complexes for Cu2+ and Mg2+, the results of the present work reveal a high homogeneity of stable isotope compositions between colloidal (1kDa–0.22μm) and ultrafiltered (<1kDa) fractions, which is presumably due to the high rate of isotopic exchange between the colloidal and ionic forms of the metals. Variation of radiogenic isotopic composition of Sr among ultrafiltered, colloidal and particulate fractions suggests that there is a contribution of atmospheric input to the chemical composition of surface waters and provides certain constraints on the isotopic composition of Sr carried by small organic-rich boreal rivers to the Arctic Ocean.

Unmanned aerial vehicles as innovative remote sensing platforms for high‐resolution infrared imagery to support restoration monitoring in cut‐over bogs

AbstractQuestionCan UAV‐based NIR remote sensing support restoration monitoring of cut‐over bogs by providing valid information on species distribution and surface structure?LocationRestored polders of the Uchter Moor, a bog complex in NW Germany.MethodsWe used autonomously flying quadrocopters, supplied with either a panchromatic or colour infrared calibrated small frame digital camera to generate high resolution images of the restored bog surface. We performed a two‐step classification process of automatic image segmentation and object‐based classification to distinguish between four pre‐defined classes (waterlogged bare peat, Sphagnum spp., Eriophorum vaginatum and Betula pubescens. An independent validation procedure was performed to evaluate the accuracy of the classification.ResultsA set‐up composed of decision rules for reflectance, geometry and textural features was applied for identification of the four classes. The presented classification revealed an overall accuracy level of 91%. Most reliable attribution was obtained for waterlogged bare peat and Sphagnum‐covered surfaces, revealing producer accuracies of 95% and 91%, respectively. Lower but still feasible accuracy levels were obtained for Eriophorum vaginatum and Betula pubescens individuals (89% and 84%, respectively).ConclusionsUAV‐based NIR remote sensing is a promising tool for monitoring the restoration of cut‐over bogs and has the potential to significantly reduce laborious field surveys. UAVs may increasingly play a significant role in future ecological monitoring studies, since they are small in size, highly flexible, easy to handle, non‐emissive and available at a comparatively low cost.

Future Climate Impacts in Woodland and Forest Steppe Based on Holocene Paleoclimatic Trends, Paleobotanical Change in Central Part of the Carpathian Basin (Hungary)

The Sirok Nyírjes-tó peat bog provides an almost full Holocene climatic record reconstructed by bog surface wetness investigations based on plant macrofossil analysis. We compared our macrofossil data to anthracological material derived from archaeological sites and to the newest bioclimatological models of the Carpathian basin. On the basis of environmental historical and climatic data we aimed to reconstruct the expected changes of forested areas in the Carpathian Basin. The results indicate that the surface wetness decreases in long term. Parallel to the Sphagnum-peat decline an open forest and forest steppe developed surrounding the bog. The complete disappearance of Sphagna from the area must be linked to a steady drop in rainfall, resulting in at least 50 mm deficit in the local water balance. This could have been achieved by an increased evapotranspiration as a result of elevated temperatures of the summer growth season. This deficit value must have exceeded even 100 mm during the Middle Holocene Transition.

Palaeohydrology, fires and vegetation succession in the southern Baltic during the last 7500 years reconstructed from a raised bog based on multi-proxy data

We present the first 7500yr long multi-proxy record from a raised bog located at the southern Baltic coast, Poland. Testate amoebae, plant macrofossils, pollen and microscopic charcoal were used to reconstruct environmental changes in Pomerania (northern Poland, Kaszuby Lakeland) from a 7-m thick peat archive of Stążki bog dated 5500 BC–AD 1250. We obtained a record of proxies representing different spatial scales: regional vegetation changed simultaneously with local vegetation, and testate amoebae showed a pattern of change similar to that of pollen and plant macrofossils. On the basis of the combined proxies, we distinguished three hydroclimatic stages: moist conditions 5500–3450 BC, drier conditions with regionally increased fires up to 600 BC, and again moist conditions from 600 BC onward. During the drier interval, a first climatic shift to wetter conditions at 1700 BC is indicated by regional pollen as the replacement of Corylus by Carpinus, and locally by, e.g., the increase of Hyalosphenia elegans and mire plants such as Sphagnum sec. Cuspidata. Furthermore, we observed a correlation since 600 BC among the re-expansion of Carpinus (after a sudden decline ca. 950 BC), increased peat accumulation, increase of Hyalosphenia species, and fewer fires, suggesting lower evapotranspiration and a stable high water table in the bog. Fagus started to expand after AD 810 gradually replacing Carpinus, which was possibly due to a gradually more oceanic climate, though we cannot exclude human impact on the forests. Peat accumulation, determined by radiocarbon dating, varied with bog surface wetness. The hydroclimatic phases found in Stążki peatland are similar to moisture changes recorded in other sites from Poland and Europe. This is the first detailed record of hydroclimatic change during the Holocene in the southern Baltic region, so it forms a reference site for further studies on other southern Baltic bogs that are in progress.

Multi-proxy fine resolution Holocene palaeoenvironmental record from the Baltic raised bog in northern Poland – bog surface wetness and vegetation change during the last 7000 years

Multi-proxy fine resolution Holocene palaeoenvironmental record from the Baltic raised bog in northern Poland – bog surface wetness and vegetation change during the last 7000 years

Can rapidly accumulating Holocene peat profiles provide sub‐decadal resolution proxy climate data?

AbstractTo test the potential for developing sub‐decadal resolution records of ombrotrophic bog surface wetness (BSW), selected abrupt climate events were identified in cores from four sites in north‐west Europe and time‐slices over each event were investigated at 2–5‐mm resolution using peat humification, testate amoeba and plant macrofossil analyses. Age–depth models based on radiocarbon, spheroidal carbonaceous particle and tephra dates were applied and the error in these models was used to determine the effective temporal sampling resolution, which in most cases was sub‐decadal. Fine‐resolution results revealed some inconsistencies in the co‐variability of individual proxies and there was a lack of correspondence between some results from adjacent cores. However, we found evidence of abrupt shifts in BSW occurring over ca. 5–20 years, indicating a more rapid proxy response than identified in previous research. To maximize potential temporal resolution and produce reliable sub‐decadal BSW data in future research, we recommended that peat‐based studies should obtain the best possible chronological control, focus on sites with high species diversity and rapid accumulation rates and perform replicate coring, or use open peat sections where the stratigraphy can be clearly seen, to assess intra‐site differences in microtopography. Site‐specific factors should be a primary consideration in the selection of sites for future fine‐resolution research. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Reproduction of Arctosa alpigena lamperti (Araneae: Lycosidae) – where, when, how, and how long?

Arctosa alpigena lamperti Dahl, 1908 is a rare wolf spider with a largely unknown biology. This subspecies was studied between 2007 and 2009 both in the field and under controlled conditions. Data on 78 specimens were obtained. The reproductive biology of the subspecies is described here for the first time. Arctosa a. lamperti proved to be a diurnal vagrant, living and hunting on the surface of Sphagnum bogs, being active from May until September. The mating period lasts from mid-May to the beginning of June. Male courtship behaviour includes palpal drumming, leg waving, opisthosomal vibrations, and jerks of the whole body. Copulation consists mostly of four or five palpal insertions and lasts on average for 37 min. Thus, A. a. lamperti possesses the longest copulation time within the genus Arctosa. The influence of temperature on reproductive behaviour is also discussed. The subspecies showed a female monandry and male polygyny mating system. Females spin cocoons within 2 weeks of copulation and carry them for up to 6 weeks. Before opening the cocoon, females construct a silken retreat. Over 40 spiderlings were found to emerge from the cocoon, and females carried them for 2 weeks until the spiderlings dispersed. The maternal care is therefore longer than that of other wolf spiders.