Recent vegetation history of Drygarn Fawr (Elenydd SSSI), Cambrian Mountains,Wales: implications for conservation management of degraded blanket mires

Many areas of blanket mire in Britain display apparently degraded vegetation, having a limited range of ericaceous and Sphagnum species. Data are presented here from Wales from the upland locality of Drygarn Fawr (Elenydd SSSI), which is dominated overwhelmingly by Molinia caerulea. Palaeoecological techniques were used to chronicle vegetation history and to determine the nature and timing of vegetation changes, as an aid to devising conservation management and restoration strategies. Although for the past 2000 years the pollen and plant macrofossil data indicate some evidence for cyclic vegetation change, they demonstrate that here the major vegetation change post-dated the start of the industrial revolution. The palaeoecological data show a greater proportion of Sphagnum than currently. Local extinction of some species (e.g., Myrica gale) apparently took place in Medieval times, but most of the degradation and floral impoverishment apparently occurred during the 20th Century. The implications for conservation management are far-reaching. The overwhelming dominance of Molinia is clearly unprecedented. While it was locally present for hundreds of years, some factor(s)—possibly a change in grazer and grazing regime—encouraged its recent ascendancy in the 20th Century. Consequently, any management attempts to reduce the pre-eminence of Molinia would not be countering an ingrained, long-established dominance. It is suggested that investigation of degraded blanket mires elsewhere by historical and multi-proxy palaeoecological techniques—through multiple, dated cores to track species extinctions and directional vegetation changes—would help ascertain previous mire floras and so indicate a range of restoration targets for mire vegetation.     

A chronosequence approach for detecting revegetation patterns after Sphagnum-peat mining, northern Japan

The aim of this study is to detect how vegetation development proceeds after Sphagnum-peat mining and how physical and chemical factors in groundwater are related to the revegetation patterns in Sarobetsu mire, Hokkaido, Japan. A total of 189 plots on peat-mining sites were set in a chronosequence and 18 plots were set on unmined control sites. A vegetation survey was conducted, and seasonal changes in groundwater levels and chemistry (pH, electrical conductance, total nitrogen, total phosphorus, anions, and cations) were monitored. Species richness and plot cover tended to increase with increasing age, but were significantly lower in mined sites than in unmined sites dominated by Sphagnum spp. The trends in vegetation change were (1) bare ground, (2) grasslands dominated by grasses and sedges, e.g., Rhyncohospora alba, Phragmites communis, and Moliniopsis japonica and (3) Sphagnum-dominated vegetation. The characteristics of groundwater level during the plant-growth period mostly determined vegetation recovery, i.e., Sphagnum establishment was promoted when groundwater declined greatly in early summer. The patterns of temporal vegetation changes affected by groundwater characteristics were detected by chronological sequence, and hydrological factors in groundwater were more important for revegetation than chemical factors. The original vegetation has not returned after three decades.     

Reconstruction of local vegetation in ad 915 at an oligotrophic mire in northern Japan from pollen, present-day vegetation and tephra data

The use of data for present-day vegetation, modern and pretephra pollen have, together, allowed reconstruction of the spatial pattern of the vegetation of an oligotrophic mire, Shimo-kenashi Mire, in ad 915. The modern pollen data were compared with the surrounding vegetation, showing that pollen of Ericaceae, Rosaceae (excluding Sanguisorba), Sphagnum and Liliaceae, together with trees and shrubs, which form scrub or thicket, indicate the limits of the mires. Shimo-kenashi Mire was narrower in ad 915 and had more islands and peninsulas of scrub. Subsequently, the mire margin has advanced and the scrub islands and peninsulas have disappeared at some sites. The fact that the mire is spreading implies that conditions are wetter since ad 915, caused by changes in local hydrology. This history of vegetation at the site will contribute to the conservation and management of the mire as trends in vegetational change provide the basic information for conservation strategy.     

Vegetation, climatic changes and net carbon sequestration in a North-Scandinavian subarctic mire over 30 years

This study deals with changes in the plant cover and its net carbon sequestration over 30 years on a subarctic Sphagnum-mire with permafrost near Abisko, northernmost Sweden, in relation to climatic variations during the same period. Aerial colour infrared images from 1970 and 2000 were compared to reveal changes in surface structure and vegetation over the whole mire, while the plant populations were studied within a smaller, mainly ombrotrophic part. The results demonstrated two processes, namely (1) that wet sites dominated by graminoids expanded while hummock sites dominated by dwarf shrubs receded, and (2) that on the hummocks lichens expanded while evergreen dwarf shrubs and mosses decreased, both processes creating an instability in the surface structure. A successive degradation of the permafrost is the likely reason for the increase in wet areas, while the changes in the hummock vegetation might have resulted from higher spring temperatures giving rise to an intensified snow melt, exposing the vegetation to frost drought. Because of the vegetation changes, the annual litter input of carbon to the mire has increased slightly, by 4 g m⁻² a⁻¹ (7.3%), over these years while an increased erosion has resulted in a loss of 40–80 Mg carbon or 7–17 g m⁻² a⁻¹ for the entire mire over the same period. As the recalcitrant proportion of the litter has decreased, the decay rate in the acrotelm might be expected to increase in the future.     

Late-glacial and Holocene vegetation history of the Magellanic rain forest in southwestern Patagonia,Chile

A ¹⁴C-dated high-resolution palaeoenvironmental record from a mire in southern Chile is used to reconstruct the Late-glacial and Holocene vegetation history of the Magellanic rain forest. The Late-glacial environment after around 15400–13500 cal b.p. was dominated by Gunnera magellanica, Nothofagus species (dombeyi type) and Gramineae (Poaceae) indicating an open parkland with cool and damp climatic conditions. At the end of the Late-glacial there was an increase in G. magellanica and a decline in Nothofagus dombeyi type. This ecological signal is interpreted as a result of a re-advance of the Gran Campo Nevado icefield, caused by either Younger Dryas cooling or a latitudinal shift of the southern Westerlies. After around 11250–10750 cal b.p. Nothofagus species, Drimys winteri and Embothrium coccineum expanded, indicating development of the Magellanic rain forest. At 4254±120 cal b.p. a tephra layer was deposited by the eruption of the Mt. Burney volcano leading to a long-term decline of the Nothofagus forest. A primary succession was then initiated, lasting for over 800 years before pre-eruption vegetation patterns redeveloped. In summary, our results indicate the extreme sensitivity of the Magellanic rain forest to climatic or volcanic impacts and the slow recovery of a mature forest after environmental changes.     

Vegetation regeneration on blanket mire after mechanized peat-cutting

• 1 Blanket mire in Northern Ireland is an ecologically threatened habitat in which land use for hand peat‐cutting, forestry and agriculture has had a major influence. A recent land use change is the introduction of tractor‐powered peat‐harvesting. In this paper, the effect of machine peat‐cutting on ombrotrophic blanket mire vegetation is assessed from a regional sample of cut and uncut plots.
• 2 Principal components analysis identified water‐table depth and grazing intensity as major factors influencing the species composition of uncut mire. A key variable affecting the composition of machine‐cut mire across the drainage gradient was the number of times cut, with multiple annual cutting causing progressive decreases in acrotelm depth, catotelm bulk density and plant cover. Ericaceous species and Sphagnum spp. were particularly sensitive to cutting, with Eriophorum angustifolium and Campylopus introflexus characteristic of multiple‐cut sites.
• 3 Redundancy analysis, with number of times cut partialled out, showed that recovery time accounted for a significant amount of variance in vegetation composition. Species that significantly increased in abundance with recovery time were Sphagnum spp., Odontoschisma sphagni , Erica tetralix and Drosera rotundifolia.
• 4 Sites cut frequently, or which were grazed, recovered more slowly. Recovery from cutting was partly dependent on the post‐cutting structure of the mire surface and the species that survive cutting. The rate of recovery on sites cut once, then abandoned, is relatively rapid compared with multiple‐cut sites where species colonization is constrained by bare compacted peat.

     

Vegetation, landscape and human activity in Midland Ireland: mire and lake records from the Lough Kinale-Derragh Lough area, Central Ireland

A high-resolution pollen record for the Holocene has been obtained from Derragh Bog, a small raised mire located on a peninsula in Lough Kinale-Derragh Lough, in Central Ireland as part of the Discovery Programme (Ireland) Lake Settlements Project. The data are compared with two lower resolution diagrams, one obtained from Derragh Lough and one from adjacent to a crannog in Lough Kinale. The general trends of vegetation change are similar and indicate that landscape-scale clearance did not occur until the Medieval period (ca. a.d. 800–900). There are, however, significant differences between the diagrams due primarily to core location and taphonomy, including pollen source area. Only the pollen profile from Derragh Bog reveals an unusually well represented multi-phase primary decline in Ulmus ca. 3500–3100 b.c. (4800–4750¹⁴C b.p.) which is associated with the first arable farming in the area. The pollen diagram indicates a rapid, and almost complete, clearance of a stand of Ulmus with some Quercus on the Derragh peninsula, arable cultivation in the clearing and then abandonment by mobile/shifting late Neolithic farmers. Subsequently there are a number of clearance phases which allow the colonisation of the area by Fraxinus and are probably associated with pastoral activity. The pollen sequence from adjacent to a crannog in Lough Kinale shows clear evidence of the construction and use of the crannog for the storage of crops (Hordeum and Avena) whereas the Derragh Bog diagram and the diagram from Derragh Lough reflect the growth of the mire. This study reveals that in this landscape the record from a small mire shows changes in prehistoric vegetation caused by human agriculture that are not detectable in the lake sequences. Although in part this is due to the higher temporal resolution and more consistent and complete chronology for the mire, the most important factor is the closer proximity of the raised mire sequence to the dry land. However, the pollen sequence from adjacent to a crannog does provide detailed evidence of the construction and function of the site. It is concluded that in order to ascertain a complete picture of vegetation changes in a lowland shallow lake-dominated landscape, cores from both the lake and surrounding small mires should be analysed.     

X-ray microdensitometry applied to subfossil tree-rings: growth characteristics of ancient pines from the southern boreal forest zone in Finland at intra-annual to centennial time-scales

A collection of subfossil wood of Pinus sylvestris (Scots pine) was exposed to X-ray densitometry. The collection of 64 samples from the southern boreal forest zone was dendrochronologically cross-dated to a.d. 673-1788. Growth characteristics were determined by performing density profiles including the following parameters: minimum density, earlywood and latewood boundary density, maximum density, earlywood width, earlywood density, latewood width, latewood density, annual ring width and annual ring density. Seven out of the nine parameters were found to contain non-climatic growth trends and six were found to be heteroscedastic in their variance. Tree-specific records were indexed, to remove the non-climatic growth trends and stabilize the variance, and combined into nine parameter-specific tree-ring chronologies. Growth characteristics of the pines changed in parallel with the generally agreed climatic cooling from the Medieval Warm Period to the Little Ice Age: pine tree-rings showed decreasing maximum densities from the period a.d. 975-1150 to a.d. 1450–1625. A concomitant change in the intra-annual growth characteristics was detected between these periods. The findings indicate that not only the trees growing near the species’ distributional limits are sensitive to large-scale climatic variations but also the trees growing in habitats remote from the timberline have noticeably responded to past climate changes.     

Ecology of a paramo cushion mire

Abstract. The vegetation ecology of a paramo cushion mire was studied along four transects. Six local vegetation types were distinguished. Two types are called cushion bogs; one is dominated by Oreobolus cleefii and the other by Plantago rigida. Types 3 and 4 are mire vegetation dominated by bryophytes; one is characterised by Sphagnum sparsum, Breutelia sp. and Campylopus cucullatifolius, the other one is dominated by Lophozia subinflata with Cortaderia sericantha. Vegetation type 5 is dominated by submerged Sphagnum cyclophyllum; type 6 refers to aquatic vegetation with only Equisetum bogotense and algae. The relation between the first four vegetation types and edaphical and hydrological gradients is analysed by means of Canonical Correspondence Analysis (CCA). From the results of CCA it can be concluded that the occurrence of the Oreobolus cleefii type is restricted to areas with a thinner peat layer, a wider distance surface-anaerobic zone and water table-anaerobic zone, a higher NO₂ concentration and a lower pH. The occurrence of the Plantago rigida type is restricted to a situation with a lower electrical conductivity of the ground water, a lower NO₃ and PO₄ concentration, and a higher Fe concentration. The occurrence of the Sphagnum type is restricted to places with a higher conductivity of the ground water, a higher NO₃ and PO₄ concentration, and a lower Fe concentration. The occurrence of the Lophozia subinflata with Cortaderia sericantha type is restricted to a situation with a lower K and Al concentration.     

Vegetation history,climate and human impact over the last 15,000 years at Lago dell’Accesa (Tuscany,Central Italy)

Interdisciplinary studies of the sediments of Lago dell’Accesa started in 2001. We present here results from the palynological study. The pollen diagram provides a record of vegetation and climatic change spanning over 15,000 years. The oldest pollen spectra show a late-glacial steppe vegetation typical of central and southern Italy during this period. The Late-glacial Interstadial, interrupted by two cooling events, is dominated by open deciduous oak forests. The Younger Dryas is represented by 150 cm of sediment and shows the presence of steppic vegetation. The Holocene vegetation is characterised by alternating dominance of deciduous oaks and Quercus ilex. The three zones characterised by Q. ilex are accompanied by peat layers marking lake-level lowering at ca. 8600–7900, 4600–4300 and 3700–2800 cal b.p. Between approximately 9000 and 6000 cal b.p. extensive Abies-forests existed on the Colline Metallifere located 15–20 km to the north and northeast of the lake. Local fir populations may also have existed by the lake. Human impact starts at approximately 8000 cal b.p. during the Neolithic period, and increases at ca. 4300 cal b.p. Castanea and Juglans pollen is recorded from ca. 2800 cal b.p. The impact of the Etruscan settlement near the lakeshore is shown in the increasing values of arable crops, species of secondary forest canopy (Ericaceae, Pinus, Pistacia, Myrtus) and anthropogenic indicators (Chenopodiaceae, Plantago lanceolata, Rumex etc).     

Compositional differentiation,vegetation‐environment relationships and classification of willow‐characterised vegetation in the western Eurasian Arctic

Question: How does willow‐characterised tundra vegetation of western Eurasia vary, and what are the main vegetation types? What are the ecological gradients and climatic regimes underlying vegetation differentiation? Location: The dataset was collected across a wide spectrum of tundra habitats at 12 sites in subarctic and arctic areas spanning from NW Fennoscandia to West Siberia. Methods: The dataset, including 758 vegetation sample plots (relevés), was analysed using a TWINSPAN classification and NMDS ordination that also included analyses of vegetation‐environment correlations. Results: Based on the TWINSPAN classification, eight vegetation types characterised by willow (cover of upright willows >10%) were discerned: (1) Salix glauca‐Carex aquatilis type, (2) Aulacomnium‐Tomentypnum type, (3) Salix‐Betula‐Hylocomium type, (4) Salix lanata‐Brachythecium mildeanum type, (5) Salix‐Pachypleurum type, (6) S. lanata‐Myosotis nemorosa type, (7) Salix‐Trollius‐Geranium type and (8) Salix‐Comarum palustre‐Filipendula ulmaria type. Willow‐characterised vegetation types were compositionally differentiated from other tundra vegetation and were confined to relatively moist valley and sloping tundra sites, from mire to mineral soils. These vegetation types were encountered across a broad latitudinal zone in which July mean temperature ranged from 6 to 10°C. Conclusions: Willow‐characterised tundra vegetation forms a broad category of ecologically and geographically differentiated vegetation types that are linked to dwarf shrub tundra, shrub tundra or mire. Because of complex ecological gradients underlying compositional differentiation, predicting the responses of willow‐characterised tundra vegetation to a warming climate may be complicated.     

Mire vegetation of the Muránska Planina Mts — formalised classification,ecology, main environmental gradient and influence of geographical position

Mire vegetation of the Muránska planina Mts and adjacent parts of neighbouring orographical units was studied in 1998–2005 using the standard Zürich-Montpellier (Braun-Blanquet) approach. We applied the defined phytosociological species groups and national formal definitions of mire associations in data processing. Within the classes Scheuchzerio-Caricetea fuscae and Oxycocco-Sphagnetea, seven associations (Caricetum davallianae, Carici flavae-Cratoneuretum filicini, Valeriano simplicifoliae-Caricetum flavae, Caricetum goodenowii, Carici echinatae-Sphagnetum, Carici rostratae-Sphagnetum and Pino mugo-Sphagnetum) were classified using formal classification criteria. Two other communities (Sphagno warnstorfii-Caricetum davallianae and Eriophoro vaginati-Sphagnetum recurvi) were not classified due to the lack of sufficient number of diagnostic species from species groups. The first DCA axis followed the mineral richness gradient. Vegetation plots were arranged from rich fens over moderately rich fens towards poor Sphagnum fens and raised bog. This fact was confirmed by a strong and significant correlation of the DCA site scores on the first axis with the measured pH and water conductivity as a surrogate of mineral richness. The second DCA axis correlated with mean Ellenberg’s indicator values for both temperature and soil nutrients. This pattern corresponds to that found in other regions of diversified Central-European landscape. We can therefore conclude that marginal geographical position and climatic specifity of the region under study did not alter gradient structure of the mire vegetation. When diversity of mire vegetation was compared to other regions in Slovakia by applying the same formal definitions to different regions, the study region was found to be conspicuously less diverse than the distribution centres of mire habitats in Slovakia (Orava and Vysoké Tatry regions), but more diverse than most of other marginal regions of mire distribution. Relatively high beta diversity of mires was probably caused by variable bedrock and local climate.     

Raised peat bog development and possible responses to environmental changes during the mid- to late-Holocene. Can the palaeoecological record be used to predict the nature and response of raised peat bogs to future climate change?

Palaeoecological analyses of raised peat bog deposits in northwest Europe show the naturalness, antiquity and robust response of these ecosystems to environmental changes from c. 7800 years ago to the present. A review of the techniques used to identify these long-term features is presented and the role of climate change, autogenic change processes and human disturbance is discussed. Millennial records of vegetation changes recorded in peat deposits demonstrate the response (often rapid) of raised peat bog vegetation to climatic changes during the mid-Holocene, Bronze Age/Iron Age transition and the Little Ice Age. Greenhouse warming scenarios exceed the reconstructed Holocene record of climatic changes (c. the last 11, 500 years), and bog-water tables may fall considerably. A combination of centennial palaeoecological analyses of bogs affected by human disturbance and experimental manipulations have been used as analogues for the potential response of raised peat bog vegetation to these changes. These show that possible greenhouse gas climate forcing scenarios may exceed the ability of Sphagnum- dominated raised peat bogs to respond to projected increases in summer temperature and decreases in summer precipitation. In combination with increasing N deposition, a loss of their Sphagnum-rich vegetation and increases in the abundance of vascular plants could occur on decadal timescales.     

Dynamics or constancy in Sphagnum dominated mire ecosystems? A 40‐year study

Traditionally mire ecosystems (especially bogs) have been viewed as stable systems with slow changes in the vegetation over time. In this study the mire Åkhultmyren, south‐central Sweden was re‐investigated in 1997 after 40 yr of continued natural development. The results show a high degree of dynamics in a Sphagnum dominated bog and fen. Altogether 97 vascular plant and bryophyte species were recorded in the two inventories of the bog and poor fen vegetation. pH and electrical conductivity in the mire water were also surveyed. In 1997 we found 10 new species and that 8 species had disappeared since 1954 but the over‐all mean number of species per plot (size 400 m²) had hardly changed. However, 21% of the species increased and 21% decreased significantly in frequency. Most of the species that decreased in frequency were low‐grown vascular plants, most common in wet microhabitats. Vascular plant species that increased in frequency included trees (defined as >1.3 m in height) and were generally taller than the unchanged or decreasing species. The frequency of dwarf shrubs and hummock bryophytes increased too. Areas with an initial pH of 4.5–5.0 showed the strongest decrease in pH, coinciding with an enlarged distribution of some Sphagnum species. The species diversity increased on the bog, but decreased in the wettest parts of the fen, where the pH also decreased. Species with unchanged or increasing frequency often showed high capacity to colonise new plots. On average the sum of gains and losses of species in the plots in 1997 was ca 50% of the species number in 1954. The vegetation changes indicate a drier mire surface and an increased availability of nitrogen. The increased tree cover may have triggered further changes in the plant cover.     

Stone Age settlements at Sørøya, sub-arctic Norway: impact on the vegetation

Four pollen diagrams, which together cover the period 10400 cal bp to the present, from an area rich in Stone Age house foundations show that vegetation was increasingly influenced by man in a stepwise process. There was a modest, temporary appearance of anthropogenically-induced vegetation about 8600 cal bp. After 7100 cal bp there was a development towards semi-open birch woodland where the open patches were characterised by natural heath and meadow species and more typical apophytic taxa such as Ranunculus acris and Rumex acetosa types, grasses and juniper. The main changes towards this vegetation seem connected with the most important cultural changes, especially at about 7100 cal bp, when there was a transition to honed slate tools in the regional archaeology, at about 4000 cal bp when pottery was introduced, and at about 3000–2800 cal bp since when the use of stone artefacts gradually ceased. It is suggested that the settlements were mainly summer habitations.     

Sphagnum distribution patterns along environmental gradients in Bulgaria

Abstract

The distribution patterns of 18 Sphagnum species along base-richness and altitudinal gradients were studied in Bulgarian treeless wetlands which are noteworthy because of the edge-of-range occurrence of many mire species including Sphagnum. Of 483 spring and mire sites studied, 202 samples contained some Sphagnum species. The most common species were S. subsecundum (n=85), S. platyphyllum (46), S. contortum (41), S. teres (40) and S. capillifolium (26). The significance of Sphagnum responses to environmental gradients was tested by comparing generalized additive models against the null model. Many Sphagnum species displayed a significant response to the altitudinal gradient. Several species were clearly linked to low or to high altitudes, but the realized niche of other species was wide with respect to altitude. Most species significantly responded to water pH, both above and below the timberline. The same result was obtained for water conductivity below the timberline, whereas only a few species had a significant response to conductivity above the timberline. The highest water conductivity under which Sphagnum species occurred was 280 μS cm^?1. Sphagnum contortum was the species occupying the mires with the highest mineral content. On the contrary, Sphagnum warnstorfii, one of the most calcitolerant species in many regions of Europe, often occurred in extremely mineral-poor mires above the timberline. Some other Sphagnum species growing in mineral-rich mires below the timberline, also inhabited extremely mineral-poor mires above the timberline. This could be explained by adaptation to local conditions during long-term isolation on mineral-poor bedrock or by changed competition pressure.     

Restoration of managed pine fens: effect on hydrology and vegetation

Question: How does restoration affect the hydrology and the understorey vegetation of managed pine fens? Location: Oligotrophic pine fens in Natura 2000 areas in Kainuu, eastern Finland. Methods: Eleven managed pine fens and eight pristine reference pine fens were chosen for the study in 2005. The managed fens, which had been drained for forestry during the 1970s and 1980s, were restored in 2007. The water table was monitored in all fens over four growing seasons during 2006 to 2009, and vegetation was surveyed from permanent sample plots in 2006 and 2009. Results: Before restoration in 2006, the water table was at a significantly lower level in the managed fens compared with the pristine fens. Immediately after restoration, the water table rose to the same level as in the pristine fens, and this change was permanent. Forest drainage had had little impact on the understorey vegetation of the managed fens in the three decades before restoration, with species typical of pristine fens still dominating the sites. Forest dwarf shrubs and feather mosses had started to increase in cover, but mire dwarf shrubs and Sphagnum mosses still dominated the managed fens. Only the typical hollow species Sphagnum majus, Sphagnum balticum and Scheuzeria palustris were missing from the managed fens. Two years after restoration, the changes in species composition were also marginal, with increased cover of mire dwarf shrubs and sedges being the only significant change. Conclusions: The success of restoration of oligotrophic pine fens seems likely, given that changes in hydrological functioning occurred rapidly, and since little change has occurred in the vegetation composition after draining. Speeding up the regeneration process in these peatland types by restoration may, therefore, be recommended, especially if the drainage effect extends to nearby pristine mires and influences their biodiversity.     

Multiproxy study of anthropogenic and climatic changes in the last two millennia from a small mire in central Poland

The Żabieniec kettle hole is the first peatland in central Poland analyzed quantitatively with four biotic proxies (plant macrofossils, pollen, testate amoebae and chironomids) to reconstruct the past environmental change. Palaeoecological data were supported by historical and archaeological records. We focused on autogenic vegetation change and human impact in relation to climatic effects. The aims of our study were (a) to describe the development history of the mire during the last 2,000 years, (b) to date and reconstruct the anthropogenic land-use changes and (c) to discuss a possible climatic signal in the peat archive. The combination of proxies revealed dramatic shifts that took place in the peatland since the Roman Period. Żabieniec was a very wet telmatic habitat until ca. AD 600. Then, the water table declined, and the site transformed into a Sphagnum-dominated mire. This dry shift took place mainly during the Early Medieval Period. Human impact was gradually increasing, and it was particularly emphasized by deforestation since AD 1250 (beginning of the Late Medieval Period). Consequently, surface run-off and aeolian transport from the exposed soils caused the eutrophication of the mire. Furthermore, chironomids and testate amoebae reveal the beginning of a wet shift ca. AD 1350. Openness considerably increased in the Late Medieval and the Modern Periods. The highest water table during the last 1,000 years was recorded between AD 1500 and 1800. This wet event is connected with deforestation, but it could be also associated with the Little Ice Age. Our study shows plant succession in the Żabieniec peatland, which can be explained with the recent landscape transformation. However, such changes are also possibly linked with the major climatic episodes during the last two millennia, such as the Medieval Warm Period and the Little Ice Age. Guest editors: K. Buczkó, J. Korponai, J. Padisák & S. W. Starratt Palaeolimnological Proxies as Tools of Environmental Reconstruction in Fresh Water     

Community and species-performance patterns along an alpine poor-rich mire gradient

Abstract. Vegetation, water table depth and water chemistry of 16 peatlands in the southern Alps, Italy, were analysed in 115 sample plots. A poor-rich gradient could be detected along the first axis of a partial Detrended Canonical Correspondence Analysis. Both vegetation and hydrochemistry vary gradually along the gradient. Vascular plants have much broader niches along the gradient than bryophytes. Mosses (except Sphangnum) and hepatics have narrower niches than Sphagnum. The various species of Sphagnum segregate more clearly from each other along the moisture gradient than along the poor-rich one. The positions of species optima along the latter gradient largely reflect the ecological preferences of mire plants in peatlands with respect to nutrient status.     

Effects of nutrient loadings from catchments on Asajino mire, a small coastal ombrotrophic mire in northernmost Japan

The relationship between water chemistry and vegetation was studied in a coastal ombrotrophic mire in northern Hokkaido, Japan. The distributions of Sphagnum and Phragmites communities were separated clearly by the pH and ion concentration of the peat surface-pore water. The drainage ditches along the road across the center of the mire had a high pH and ion concentration, as did the peat water in the western part of the mire. It was found that fields used for livestock farming on a hill to the west of the mire leached materials into the mire through drainage ditches, surface runoff, and probably also through ground water, and thus influenced the water chemistry of the mire. Management of the water, including that in the catchment of the mire, should be introduced before biological buffering capacity against excess nutrient loading caused by human activity is exceeded and the mire loses its ombrotrophic status.