Patterned fens in Scotland: evidence from vegetation and water chemistry

Mires with attributes similar to the patterned fens of boreal continental regions have recently been reported from northern Scotland. This paper reports on the vegetation and water chemistry of 18 of these sites. Most of the 18 mires displayed remarkable uniformity in their vegetation, with Carex lasiocarpa being a main character species. Major variation of plant communities is associated with microtopographical niches, similar to those found on ombrotrophic mire systems and secondarily with pH and conductivity of surface waters. Nine vegetation noda are described and compared with existing phytosociological associations and National Vegetation Classification (NVC) communities. The dominant Sphagnum - Carex communities are intermediate between the Oxycocco-Sphagnetea and the Caricion lasiocarpae and are thus difficult to assign to existing associations or to NVC communities. Although there is a large variation in pH of surface waters (3.9–6.6), mean measurements for terrestrial and aquatic communities are 5.12 and 5.51 respectively. pH levels are comparable with poor fen systems elsewhere in Britain and slightly higher than patterned fens in continental regions of Europe and North America. The vegeta-tional and chemical attributes of these sites therefore confirm the existence of true patterned fen systems in the British Isles.     

A phytoecological study of the mire Northern Kisselbergmosen, SE Norway. III. Diversity and habitat niche relationships

Alpha and beta diversity and habitat niche relationships of a poor, boreal mire was studied, based upon an ordination by detrended correspondence analysis and a subjective classification. The three first DCA axes were interpreted as variation along the following ecoclines: (1) mire expanse carpet–mire expanse hummock–mire margin hummock, (2) nutrient status: ombrotrophic–poor minerotrophic, and as a coenocline (3) associated with peat-producing ability of the vegetation with an unclear ecological basis. The autecology of the 39 most frequent species was decribed with respect to these gradients. Alpha diversity patterns varied considerably between coenoclines. Beta diversity was always higher in the bottom layer than in the field layer. Habitat niche breadth was strongly correlated with species abundance, and separable into a frequency-independent and a frequency-dependent component. The former decreased from vascular plants to hepatics, and further to Sphagnum spp. It was argued that the importance of interactions was high in the bottom layer, particularly among Sphagnum spp., but also among hepatics. Interactions among vascular plants was considered unimportant, except in hummocks. Plant strategies were discussed. The niche breadth approach was evaluated, and found fruitful, while niche overlap was considered to provide redundant information. The importance of each of (1) interspecific interactions, (2) destabilizing factors, (3) stress, and (4) chance, as structuring factors in boreal mires, is discussed. Boreal mires are considered to conform to the patch-dynamics theory of non-equilibrium coexistence.     

The impact on the Senjogahara ecosystem of extreme run-off events from the river Sakasagawa,Nikko National Park

Vegetational data from Senjogahara moor, Nikko National Park, Japan have been analysed using two contrasting but parallel multivariate approaches as a basis for future studies. The plant communities objectively defined using a divisive polythetic classificatory approach (TWINSPAN) have been successfully overlayed on an ordination of the same data using detrended correspondence analysis (DCA). The results reveal a vegetational mosaic reflecting differential levels of flood damage to the vegetation and its subsequent rates of recovery, in a space-time continuum. The results from the TWINSPAN classification show that 13 plant communities are present in the sample area and these correlate closely with complete absence, slight, or extremely heavy disturbance. The form of the disturbance as either channel erosion or alluvial depositional features is shown to also correspond quite closely with the vegetational types and is reflected in the ordination axes derived from DCA.     

Central boreal mire plant communities along soil nutrient potential and water content gradients

Peatlands have traditionally been exploited in forestry and agriculture over the boreal region, yet they also provide substantial source of fuel production. The large-scale exploitation of peatlands has raised a concern about the diversity of mire plant communities. We studied composition of mire plant communities along soil nutrient potential and water content gradients, to recognize the areas with the high plant diversity. Soil electrical conductivity (EC_b) was measured to characterise soil nutrient regimes and soil dielectric permittivity (DP) the soil (volumetric) water regimes. A total of 115 mire sites were studied in the central boreal region of south-western Finnish Lapland. We found that Ward’s hierarchical cluster analysis produced eight stable EC_b and DP clusters with discrete vegetation compositions. On the basis of a locally weighted regression analysis (Loess), Carex dioica L., Comarum palustre L., Equisetum fluviatile L., Menyanthes trifoliata L., and Scorpidium scorpioides (Hedw.) Limpr. were found as indicator species for nutrient-rich regimes as designated by high soil EC_b. The soil EC_b is a diagnostic measure of plant diversity as EC_b?>?7 mSm^?1 resulted in a considerable increase in species richness. Our classification method, based on electrical measurements, provides a simple way to classify mires and focus detailed research to areas with potentially high conservation value.     

A

A valley mire was sampled on the flanks of Swampy Hill, east Otago, New Zealand. It formed in a narrow valley, apparently originally comprising two basins. The end of the mire nearest the outlet contained species typical of fens (i.e., rheotrophic mires). At the head of the valley there was a section of the mire with mixed vegetation cover comprising the tussock grass Chionochloa rubra, Sphagnum species, and cushion/herb/shrub cover. Ombrotrophic status of this section was indicated by a slightly raised profile, greater acidity, lower exchangeable Na and K, and lower substrate cation exchange capacity, identifying it as a bog. Total Ca:Mg molar ratios were generally above 1.0, but this rule-of-thumb for ombrotrophic status may be inapplicable here. It is not known whether New Zealand Sphagnum species are as efficient at lowering the pH as those investigated elsewhere. Macrofosssil evidence indicates that some components of the bog, such as Sphagnum and epacridaceous subshrubs, have remained constant, almost since the inception of the bog. However, Empodisma minus, currently absent from the bog and rare in the region, was present at one stage. The change from cover with Empodisma and Dracophyllum as significant components, to the present Chionochloa/Sphagnum/cushion composition, occurred a few hundred years ago, probably initiated by fire. Comparison with preliminary information for other bogs suggests that those in the eastern part of the South Island vary considerably in species composition, with individualistic assemblages of species. The site is seen as having high conservation values. To protect these values the bog needs protection from invasive exotic weeds, and from damage by wild pigs.     

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.     

Sphagnum subfulvum Sjörs in Ireland compared with the occurrences in Norway

Abstract

The discovery of Sphagnum subfulvum in Western Ireland is reported and the Irish specimens are described. The habitat of the species at Errisbeg, Co. Galway, is described and compared with the occurrences in Norway. It is concluded that the ecology of S. subfulvum at Errisbeg closely resembles its ecology in Norway where it is an intermediate/rich fen species, and in the ‘mud-bottomto hummock’ vegetational gradient it belongs to lawn and low hummock vegetation. The occurrence of Sphagnum subfulvum on flushed mountain slopesin West Mayo is apparently related to localised basic conditions as indicated by its association with Schoenus nigricans, Anagallis tenella, Selaginella selaginoides and Breutelia chrysocoma. Sphagnum subfulvum is reported from raised bog in Co. Roscommon. Its occurrence in ombrotrophic vegetation is somewhat unexpected but the ombrotrophic vegetation in Western Ireland includes some species which are restricted to minerotrophic vegetation elsewhere.     

Entwicklung des Moores Mokré Louky bei Třeboň im Postglazial (Paläoökologische Studie)

The origin, age and development of a mire deposit in the locality of the Mokré Louky meadows near T?eboň were ascertained by means of palaeoecological methods. The first minerogenic sediments originated in a depression at the turn of the Late-Glacial and the Holocene Periods. In the course of minerogenic sedimentation, the vegetational cover was formed by stands ofFilipendula. In the middle of the Pre-Boreal Period, the first organic sediments formed by reed plant communities were deposited in the area. In the course of the following periods, plant communities of mire and marshy meadows belonging to the associations of the classScheuchzerio-Caricetea fuscae predominated on the site. Stands of willow and alder trees were formed in some parts of the deposit most probably towards the end of the Atlantic Period, with their maximum development in the Sub-Boreal to Upper Sub-Atlantic Periods. Pollen analysis produced a more precise foundation for reconstructing the forest vegetation in the centre of the T?eboňská pánev Basin. A higher presence ofQuercus and a lower one ofFagus, as compared with the results of previous pollen analyses from the borders of the Basin, were ascertained. The palaeoecological analyses are supported by radiocarbon datings.     

Field studies of nitrogen fixation of Australian alpine plants and soils

Alpine grassland areas in Victoria and New South Wales have been subjected to summer grazing by cattle and sheep for well over a hundred years. Legumes other than a few species of shrubs, which provide a very small percentage of the vegetation cover in the grasslands, are absent. Other alpine communities include Sphagnum ‘mossbeds’ in the valleys and areas of snowgum woodland and shrubland. Virtually nothing is known of the mineral status of these communities and nothing of their nitrogen economy. On the Bogong High Plains, enclosure of grassland and of Sphagnum mossbeds from grazing and trampling has resulted, in the last few decades, in considerable changes in both cover and composition of the vegetation. A portable gas chromatogram was used to carry out determinations of the capacity of samples of the grassland and Sphagnum to support acetylene reduction to ethylene, by convention equated to a capacity to fix nitrogen. There appears to be a substantial capacity for acetylene reduction associated with the rhizosphere of the grasses (Poa australis agg.). The capacity of the Sphagnum for acetylene reduction is even greater and appears to be due to facultative anaerobes, abundant only in the upper, living part of the Sphagnum. These organisms may depend in part on leakage of photosynthate from the living Sphagnum. Associations of Sphagnum with blue-green algae appear to be unusual in contrast with work on Swedish subarctic mosses, which is discussed. The only non-leguminous Australian alpine plant so far examined for nitrogen fixation is Podocarpus lawrencei. A capacity for acetylene reduction was found for neither the nodules of the roots of this plant nor the associated soils.     

A simulated map of the potential natural forest vegetation of Switzerland

Using empirical data (ca. 7500 phytosociological releves), a simple, probabilistic ‘vegetation-site’ model was developed, to simulate geographical distribution of 71 forest community types, representing the potential natural vegetation (PNV) of Switzerland. The model was interfaced to a geographic information system (GIS) and used to generate a numerical vegetation map, on the basis of digital maps of 12 environmental variables including climatic conditions (temperature and precipitation), topography (elevation, slope, aspect), and soil parameters (soil pH and physical soil parameters). The predicted distribution of forest communities was compared with several vegetation maps, prepared for some subregions of Switzerland by means of traditional field methods. Similarity ranged from 50 to 80 %, depending on the community type, level of vegetational hierarchy and the geographical region. The current resolution and accuracy of the simulated vegetation map allows us to study the vegetational patterns on the level of the entire country or its major geographical and climatic regions. The simulated vegetation map is potentially an important tool in ecological risk assessment studies concerning the possible impacts of climate change on the ecological potential of forest sites and biological diversity of forest communities.     

太白山表土花粉和气孔器与植物类型的关系研究

通过陕西太白山13个样点表土花粉组合特征和气孔器及其与植物类型之间关系的分析,结果发现:针阔混交林花粉组合能很好地反映植物类型特征,落叶阔叶林和针叶林花粉组合能较好地与植物类型相对应,高山灌丛草甸花粉组合未能反映植物类型数量特征;主要花粉类型松属、铁杉属和桦属花粉具超代表性,胡桃属和榆属花粉具适宜代表性,落叶松属、冷杉属、杜鹃花科和槭属花粉具低代表性;DCA(Detrended Correspondence Analysis)分析表明,通过花粉数据能够较好区分不同植被类型,结合气孔器特征能够准确反映植被特征。     

Trends in the recovery of a rosy marsh moth Coenophila subrosea (Lepidoptera, Noctuidae) population in response to fire and conservation management on a lowland raised mire

Following a severe fire in 1986 on the estuarine raised mire of Cors Fochno, Wales, a larval transect was initiated across the burnt and unburnt sections to investigate the recovery of the rosy marsh moth Coenophila subrosea population. This paper reports the results of 16 years of surveillance and relates larval density to the growth of the main food plant, bog myrtle Myrica gale. Earlier suggestions that fire is a necessary management tool to maintain Myrica at a young stage of its growth appear unfounded and hydrological effects are probably sufficient to ensure rapid turnover of the foodplant. Eighteen years in which there has been no significant disturbance to the mire vegetation has not led to the predicted decline in the moth population. However, changes in vegetational composition are occurring as a result of conservation management to the hydrological regime of the mire and further studies will be required to investigate whether restoration of the peatland water table leads to a significant reduction in the abundance in food plants or a decline in the status of the rosy marsh moth.     

Distribution of the plant communities in Tihamah coastal plains of Jazan region,Saudi Arabia

The present study provides quantitative estimates of the vegetation structure and distribution of the plant communities in Tihamah coastal plains of Jazan region. The factors affecting the species distribution and the correlations between the vegetational gradients and the edaphic variables were discussed. Eight major community types constitute the major part of the natural vegetation of the study area and are dominated by nine perennials: Ziziphus spina-christi (L.) Willd, Calotropis procera (Wild) R. Br., Leptadenia pyrotechnica (Forssk.) Decne., Suaeda monoica Forssk., Panicum turgidum Forssk., Salvadora persica L., Acacia tortilis (Forssk) Hayne, Tamarix aphylla (L.) Karst. and Cyperus conglomeratus Rottb.The results of this study confirm that the study area is a subtropical desert and belongs floristically to the Sudanian territory and also that therophytes are the most frequent life-form in this region.Analysis of the correlation between the vegetational gradients and the edaphic factors showed that soil pH, moisture, electrical conductivity, organic carbon, calcium carbonate, bicarbonate, soil cations: sodium, potassium, calcium, and the sodium adsorption ratio are the main operating edaphic factors in the area.     

Community and species responses to water level fluctuations with reference to soil layers in different habitats of mid-boreal mire complexes

The present paper discusses water level fluctuations in different parts of boreal mire complexes (eleven localities), mainly aapa mire complexes, on the basis of measurements performed by means of shallow observation wells and a few deeper observation tubes (piezometers) in the coastal half of the southern aapa mire zone in Finland. The sites represented intact vegetation from 12 different habitat types (communities), which were divided a priori into habitats with a stable surface moisture status (stable habitats) and into habitats with an unstable surface moisture status (unstable habitats). In stable habitats water level fluctuations took place according to the acrotelm–catotelm model, but the unstable habitats clearly deviated from the general pattern: water level fluctuations in them were not at all concentrated to the surficial, porous peat layer. Direct gradient analysis was used for arranging the communities along the water level fluctuation gradient. Variability of the water table, using 80% amplitude of water table residence, was used for the arrangement. The gradient was split into three groups: (1) habitats with a slightly fluctuating water table, (2) habitats with a considerably fluctuating water table and (3) habitats with an extremely fluctuating water table. The last group nearly corresponded to aro wetlands, and represented a very special habitat type. Indirect gradient analysis (NMDS ordination) also revealed the water level fluctuation gradient along with the gradient of traditional water level categories. According to the results of direct and indirect gradient analysis, the water level fluctuation seems to be an independent and important vegetation gradient. In peatlands, it occurs alongside with the traditional gradient of water level categories reflecting the mean water table. The responses of species to the range of water level fluctuations seem to reflect their tolerance to disturbances and evidently to seasonal drought. Most Sphagnum species are absent or in poor condition in habitats with extremely fluctuating water table. Vascular plant species that experienced most extreme water level fluctuations (Carex nigra, Juncus filiformis) have earlier been regarded as disturbance indicators. In addition, the difference between the piezometric water level and simultaneously measured water table depth reached the highest values within the habitats of those species (i.e., within Polytrichum commune aro wetlands) showing the downward direction of water movement in sandy mineral soil.     

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.     

Multiple gradients in mire vegetation: a comparison of a Swedish and an Italian bog

The major environmental gradients underlying plant species distribution were outlined in two climatically and bio-geographically contrasting mires: a Swedish bog in the boreo-nemoral zone, and an Italian bog in the south-eastern Alps. Data on mire morphology, surface hydrology, floristic composition, peat chemistry and pore-water chemistry were collected along transects from the mire margin (i.e., the outer portion of the mire in contact with the surrounding mineral soil) towards the mire expanse (i.e., the inner portion of the mire). The delimitation and the extent of the minerotrophic mire margin were related to the steepness of the lateral mire slope which, in turns, controls the direction of surface water flow. The mineral soil water limit was mirrored in geochemical variables such as pH, alkalinity, Ca²⁺, Mg²⁺, Al³⁺, Mn²⁺, and SiO₂ concentrations in pore-water, as well as Ca, Al, Fe, N and P contents in surface peat. Depending on regional requirements of plant species, different species were useful as fen limit indicators at the two sites. The main environmental factors affecting distribution of habitat types and plant species in the two mires were the acidity-alkalinity gradient, and the gradient in depth to the water table. The mire margin – mire expanse gradient corresponds to a complex gradient mainly reflected in a differentiation of vegetation structure in relation to the aeration of the peat substrate.     

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.     

The first pollen diagram from the Hoher Fläming, Brandenburg (Germany)

A 72 cm peat core from a spring mire reveals 3300 years of vegetation history in the Hoher Fläming, a landscape formed by the penultimate glaciation in southeastern Brandenburg. Primeval beech-oak forest dominated from a.d. 550 to 1200, prior to local forest clearance. Existing maps showing the natural and potential natural vegetation as pine and oak need to be revised. Local woodland cutting in the 12th century and grassland use since the 15th century affected the development of the helokrene (spring-fed) mire deposits from alder carr to mesotrophic fen vegetation and then to the present-day Sphagnum fallax-Juncus acutiflorus wet meadows. Vegetation and mire history link together the Hoher Fläming and adjacent landscapes on a northwest-southeast gradient of suboceanic to subcontinental climate. Moreover it represents a geographical and altitudinal transition of lowland and hill vegetation from 30 to 200 m a.s.l. to the montane belts of the palynologically well investigated Harz mountains. However, regarding some trees and herbs, the Hoher Fläming does not belong to the Hercynian region and type of vegetation.     

Recent changes in mire vegetation in Yawata,southwestern Japan

Recent changes of mire plant communities in the Yawata highland, southwestern Japan, are documented. The area and the boundary length of five important mires (range 1 to 6 ha) declined during past 24 years. Qualitative changes are primarily caused by human influences, e.g., accumulating debris from forest-harvest sites above the mires, from road construction, and increased drainage from man-made ditches. The Cirsieto-Molinietum japonicae, a characteristic mire community of temperate Japan climates, maintained its community structure and flora. However, 3 of 11 subordinate units of this community changed species composition and population structure, and 3 of them disappeared. The 28 mire plants classified as endangered in the 1950s were present in 1991.