Racomitrium Lanuginosum Research Articles

Climatic control of peat erosion in a North Wales blanket mire

Summary This study investigates the palaeoecology of a hummock‐and‐hollow complex from a partially eroded upland blanket mire at the Migneint, north Wales, UK. Three peat cores were collected and analysed for pollen and botanical macrofossils, two for peat humification and a third was radiocarbon‐dated. In the interpretation of the palaeoecological record particular attention was paid to the ecology of the moss Racomitrium lanuginosum. We delimit two periods in the development of the hummock‐hollow complex: an earlier period of climatically controlled blanket‐mire development; and a later period of mire erosion (initiated between c. 2000 and 1350 Cal. year BP) when ‘natural’ climatically controlled mire development was modified by excessive drying of the mire surface. The data support recent studies in suggesting that the development of British blanket mires is sensitive to climate change. However, climatically controlled blanket‐mire development appears to have been pre‐empted at the Migneint by the development of the erosion‐complex, the initiation of which coincides with the zenith of an extensive deforestation during the Late Bronze Age, Iron Age and Romano‐British periods.

Climatic control of blanket mire development at Kentra Moss, north‐west Scotland

Summary 1 Four peat cores were collected from Kentra Moss, north‐west Scotland, and analysed for botanical macrofossils and peat humification. The pollen record was used as a template for the identification of synchronous levels between cores. 2 A non‐random pattern of change in bryophyte macrofossils and humification was simultaneous between all four cores. Stratigraphic changes occurred independently of human land‐use and were best interpreted as palaeoclimatic events. Remains of Racomitrium lanuginosum and Sphagnum papillosum, in conjunction with changes in peat humification, provided the clearest indication of past increases in climatic wetness (‘wetshifts’) to impact upon mire hydrology and ecology. 3 Eight wetshifts were identified and radiocarbon‐dated, beginning at c. 3250, 2550, 2150, 1400, 1150, 875, 600 and 325 calibrated years BP (cal. BP). Seven of these wetshifts match closely with palaeoclimatic events from a range of mires previously examined in Britain and Ireland. We suggest that blanket mires may provide the best source of decade‐ to century‐scale palaeoclimatic information in oceanic north‐west Europe. 4 The proxy‐climatic evidence indicates that: (i) the extinction of Sphagnum imbricatum at Kentra Moss (at c. 1400 cal. BP) was caused by an increase in climatic and mire surface wetness, when it was replaced first by Racomitrium lanuginosum and then by Sphagnum papillosum; and (ii) that increased climatic wetness and human land‐use were responsible for the shift from an early minerotrophic peatland to ombrotrophic blanket mire at c. 4070 cal. BP. 5 Given the evidence for a prevailing climatic effect on the development of Kentra Moss, the effect of human‐induced global warming on Britain's blanket mire resource will probably be significant. British blanket mires have international conservation status, and future changes in their ecology will challenge conservationists, academics and politicians.

Rapid recovery of photosystems on rewetting desiccation-tolerant mosses: chlorophyll fluorescence and inhibitor experiments.

In the mosses Racomitrium lanuginosum, Anomodon viticulosus and Rhytidiadelphus loreus, after a few days air dry, F:(v)/F:(m) reached, within the first minute of remoistening in the dark, two-thirds or more of the value attained after 40 min. A fast initial phase of recovery was completed within 10-20 min after which further change was slow. Initial recovery of Phi(PSII) in the light was somewhat slower, but was generally substantially complete within a similar time. Remoistening with 0.3 mM cycloheximide (CHX) or 3 mM dithiothreitol (DTT) made little difference to this short-term (40 min) recovery of either F:(v)/F:(m) or Phi(PSII); 3 mM chloramphenicol (CMP) had little effect on recovery of F:(v)/F:(m), but resulted in substantial (though not total) depression of Phi(PSII) and (14)CO(2) uptake. Effects of the protein-synthesis inhibitors and DTT were much more clearly apparent in longer-term experiments (>20 h) but only in the light. In the dark, the three inhibitors had at most only slight effects over periods of 60-100 h. In the light, CMP-treated samples of all three species showed a progressive decline of dark-adapted F:(v)/F:(m), falling to zero within 1-5 d (possibly due to blocking of the turnover of the D1 protein of PSII) and accelerated by DTT. CHX-treated samples showed a similar but slower decline. In the shade-adapted and relatively desiccation-sensitive Rhytidiadelphus loreus, slow recovery of F:(v)/F:(m) continued in the dark even in the presence of CMP and CHX for much of the 142 h of the experiment. The results indicate that in desiccation-tolerant bryophytes recovery of photosynthesis after periods of a few days air dry requires only limited chloroplast protein synthesis and is substantially independent of protein synthesis in the cytoplasm.

Measurement and Modeling of the Spectral and Directional Reflection Properties of Lichen and Moss Canopies

Both spectral and directional reflection characteristics of terrestrial surfaces are of interest for remote sensing applications. We report on detailed laboratory measurements of the Cladina stellaris and Flavocetraria nivalis lichens and the Racomitrium lanuginosum moss canopies carried out at the European Goniometer facility at the Joint Research Center, Ispra, Italy. we present bidirectional reflectance factor data in the blue, green, red, and near-infrared parts of the spectrum. The moss had enhanced backscatter in the visible spectrum and was strongly backscattering in the near-infrared. We successfully fitted the low-dimensional parametric model of Rahman, Pinty, and Verstraete to our experimentally determined bidirectional reflectance factors. By means of cross-validation, we assessed the number of randomly sampled data points necessary to guarantee reliable model inversions. We found that approximately 100 measurement points were needed for our experimental data. Finally, we applied bootstrap techniques to show that the root-mean-square modeling error was as low as 5.7% for our chosen targets and model. Our findings, combined with digital elevation models and atmospheric radiative transfer models, may result in enhanced detection of lichens from optical satellite data. The complete dataset is available from the first author.

The levels of cesium radionuclides in mosses collected from akçaabat, maçka and sürmene in the eastern black sea region of Turkey, 1997

Radiocesium levels in mosses collected from Akçaabat, Maçka and Sürmene in the Eastern Black Sea Region of Turkey were determined 9 years after the Chernobyl accident occurred. Cs‐134 and Cs‐137 radionuclides were detected in all samples. The measured levels of Cs‐134 and Cs‐137 ranged between 28–207 and 117–8431 Bq/kg depending on moss genera and species dry weight respectively. The highest concentrations of Cs‐137 were found in Anomodon viticulosus, Racomitrium lanuginosum and Leucobryum glaucum while the lowest activity was detected in Calliergon cuspidatum, Dicranum majus and Pseudoscleropodium purum.

Water-relations parameters of some bryophytes evaluated by thermocouple psychrometry

Water-relations parameters are presented for four mosses, and for four leafy and four thalloid liverworts. Osmotic potentials of mosses and leafy liverworts at full turgor mostly lie in the range −1.0 to −1.5 MPa; multistratose thalloid liverworts generally give values in the range −0.5 to −1.0 MPa. These figures are less negative than older measurements based on plasmolysis, which more nearly reflect osmotic potential at turgor loss. Full-turgor water content can generally be estimated with fair accuracy from the graph of water content against water potential; careful blotting of saturated material may give acceptable approximate values for many purposes. Mosses and leafy liverworts of well-drained habitats generally have full-turgor water contents in the range 100-300% dry weight; values for thalloid liverworts may be much higher. Full-turgor water content (as % d.w.) varies seasonally, being high in new growth, and falling progressively through the growing season. The bulk modulus of elasticity (εB) is low (implying highly extensible cell walls) in most thalloid liverworts, and in such desiccation-tolerant mosses as Syntrichia ruraliformis and Racomitrium lanuginosum, but reaches values of 12-20 or more in some leafy liverworts with more rigid cells. Variation in water-relations parameters shows less relation to habitat than might be expected, probably because even in dry habitats bryophytes are fully hydrated for most of the time they are metabolically active, and only suffer water stress transiently as they dry out.

A macrofossil flora from early Aranuian lake-bed deposits, Doubtful River, Waiau-uha catchment, North Canterbury, New Zealand

Sediments deposited in an early Aranuian lake in a mountain valley contain abundant, well-preserved fossil wood, leaves, and seeds. Radiocarbon dates ranging from 13 300 to 10 800 yr B.P. have been obtained for wood samples. The macrofossil species represented all grow in the region today. By analogy with modern plant communities, the fossil assemblage appears to be drawn from two main kinds of vegetation complex: hillside scrub, with Phyllocladus alpinus a major component; and valley-floor communities, including river floodplain, with Racomitrium lanuginosum abundant and associated grassland with dwarf shrubs (Leucopogon fraseri) and thorn scrub (Discaria toumatou). The scarcity of Podocarpus hallii fossils suggests that the climate was cooler than now. Archeria traversii fossils indicate that precipitation was at least as high as now.

Relationships of geothermal bryophyte communities to soil characteristics at Thermal Meadow, Hotsprings Island, Queen Charlotte Islands, Canada

To determine the responses of cryptogams to the variations in temperature, pH, and humidity, we studied the vegetation of Thermal Meadow, Hotsprings Island, Queen Charlotte Islands, B.C., Canada. Only seven cryptogamic taxa were present in the samples: five mosses, one liverwort, and one lichen. Humidity limited the distribution, with Racomitrium lanuginosum and Cladina ciliata preferring the warmer, drier sites and Pleurozium schreberi and Dicranum scoparium preferring cooler, more moist sites. Polytrichum formosum was the most frequent taxon, occurring under both cool, moist conditions and warm, dry conditions. Aulacomnium palustre occurred in the mid temperature range mostly where humidity was fairly high. The pH ranged 6.8–7.2, providing insufficient variation for us to delimit species preferences.

Short-term physiological responses of mosses to atmospheric ammonium and nitrate

Many bryophytes rely to a large extent on atmospheric deposition for their nutrient uptake. However, increasing levels of atmospheric ammonium (NH 4 + ) and nitrate (NO 3 - ) attract concern as to the possible harmful effects on bryophytes from these two nutrient sources. Changes in nitrate reductase (NR) activities, cation (Ca, K and Mg), total nitrogen (N) and organic acid concentrations were investigated for the mosses,Racomitrium lanuginosum, Rytidiadelphus loreus andPhilonotis fontana, in response to a single field misting with 3 mol−3 NH 4 + and NO 3 - . Increases of 20% were recorded for tissue N content, 48 hr after misting with N containing solutions. When labelled15NH 4 + or15NO 3 - were applied toR. Lanuginosum at 1, 3 and 6 mol m−3 concentrations, partitioning of incorporated15N between different tissue regions occured, with the highest N uptake in the upper stem and leaves. High concentrations of applied N resulted in reduced efficiency of N uptake. NH 4 + applications caused declines in NR activities, organic acids and cations, whereas, NO 3 - treatments caused the reverse response. Changes in cation contents, organic acids and NR activity reflect short-term regulation of N metabolism in the presence of defined N sources, as well as potential mechanisms of regulating cell pH homoeostasis. The consistency of physiological responses, especially NR activities, over short-term pollution episodes, provides evidence for their use as indicators of both NH 4 + and NO 3 - pollution.

Separating the Effects of Litter Quality and Microenvironment on Decomposition Rates in a Patterned Peatland

Decomposition rates, measured as proportion of original ash-free dry mass lost from litter bags, were studied on four microhabitats of an ombrogenous peatland in southwestern Scotland: a Racomitrium lanuginosum hummock (HR), a Sphagnum capillifolium hummock (HS), a Sphagnum papillosum lawn (L), and a Sphagnum cuspidatum hollow (H). Reciprocal transplant experiments, in which litter bags were swapped among depths both within and among microhabitat types, separated the effects of litter quality (litter type and degree of humification of the peat) and microenvironment (water table position and microhabitat type). All were important determinants of mass loss. Decomposability of the litter from different microhabitats increased in the order HR < HS < L < H. Chemical 'ageing' of the peat reduced rates of decay in highly humified peat, although a history of decay was associated with maximum decomposability of peat from HR hummocks. The suitability of hollows for decay was significantly less than for HR and HS hummocks and lawns. Peat lost mass most slowly when placed below the lowest water table, but the highest mass losses were for peat placed in, or slightly above, the zone of water table fluctuation. Mass loss decreased with depth for peat decaying in its natural position in hollows and lawns and the oxic layer of HS hummocks. A peak in mass loss occurred within the zone of water table fluctuation in HS hummocks, and just above the highest water table in HR hummocks. The results support earlier suggestions that differences due to chemical ageing of peat contribute to differences in decomposition rates between hummocks and hollows, and that hummock species are intrinsically more resistant to decay than hollow species. The pattern was complicated further, however, by the effects of water table position and microhabitat type. The combined effects of litter quality (species composition and degree of humification of the litter) and environment (microhabitat of incubation and position of incubation relative to water table) are complex, and these complexities must be incorporated into models of decomposition.

Climate and Erosion Signals in British Blanket Peats: The Significance of Racomitrium Lanuginosum Remains

1 British and world distribution patterns of the moss Racomitrium lanuginosum (Hedw.) Brid. are used to deduce the likely conditions governing the occurrence of its preserved leaves in the upper layers of British blanket peats. It is suggested that R. lanuginosum dominates in blanket mires only under conditions of lowered water table and high atmospheric humidity. 2 Detailed stratigraphic records from blanket mires in the Southern Pennines (Northern England) and the Berwyn Mountains (North Wales) show remains of R. lanuginosum preserved in the peat columns of both eroded and uneroded sites. At uneroded sites in the Southern Pennines, Racomitrium remains predominate between about AD1250 and 1450 and again in the mid-Eighteenth Century. At hummock sites in both regions, and at gullied sites in the Southern Pennines, Racomitrium remains are continuously present in the peat column from about AD 1250-1800. 3 It is concluded that the presence of Racomitrium remains in the peat column constitutes a clear proxy-climate signal, signifying, in uneroded areas, a prolonged period of drier climate succeeded by a return to a wetter, more humid climate (though that signal may be blurred by superimposed effects of burning and grazing of the mire surface). 4 The macrofossil record demonstrates the marked effects on the blanket mire vegetation of both study regions of the documented period of drier climate from c. AD 1150-1300 (the 'Early Mediaeval Warm Period'). 5 Possible consequences of that episode on the blanket mires of the two regions include the onset of gully erosion and the development of a 'stagnation complex' in pool-and-hummock systems. The extension of these findings to other blanket mire regions of the British Isles is discussed.

Fate of added nitrogen in a moss-sedge Arctic community and effects of increased nitrogen deposition

Although nitrogen deposition has not increased as drastically in the Arctic as in the highly industrialized countries, this area has not been left unaffected. Several studies indicate at least twofold increases in the N-deposition in the Arctic during the last 100 years. Arctic plants are generally adapted to low availability of nutrients; thus arctic plant communities may be sensitive even to small changes in the nutrient input. Based on two field studies in Iceland, this paper discusses the effects of increased nitrogen deposition on a simple two-species plant community,Racomitrium lanuginosum moss-heath withCarex bigelowii. The paper also discusses the implications for community structure based on the interactions between the two major growth forms, the moss and the clonal graminoid, that are adapted to take up nitrogen from different sources.

Pool-and-Hummock Patterning in a Southern Pennine Blanket Mire II. The Formation and Erosion of the Pool System

1 Inferences about the processes leading to surface patterning, pool formation and gully erosion in a Southern Pennine blanket mire are drawn from the 15-m stratigraphic profile from Alport Moor described in Part I. 2 Four successive stages in the development of the present mire surface are recognized: a topographically differentiated dry bog vegetation c. 2800 years ago, which then developed into a wet rather featureless mire surface by c. 200 Cal BC; an extended phase between c. 200 Cal BC and 1250 Cal AD when hummock-hollow differentiation was taking place over the mire surface; and drier bog vegetation since c. 1250 Cal AD, probably following incision of the main drainage gullies. 3 Preserved remains of Sphagnum occurred in 52% of the peat samples analysed for macrofossils. In the peat profile the Sphagnum remains were concentrated into five essentially continuous and nearly horizontal bands, separated by intervening regions where Sphagnum was scarce or absent. 4 The temporally discontinuous distribution of Sphagnum in the stratigraphic profile is shown to be an overall response to climate change (Sphagna increasing in abundance during periods of wetter climate), modified by site-specific responses to ongoing topographic differentiation and the incidence of erosion. 5 It is suggested that high pollen values of Cyperaceae found in the pollen record from Alport Moor and some other Southern Pennine sites might record the local spread of Eriophorum angustifolium across bare wet peat, and might thus indicate times when the mire surface was under stress. 6 Site-specific differences in the patterns of Sphagnum abundance over the last 1200 years in the study area and on the nearby Featherbed Moss are used to follow the development of the erosion system on Alport Moor. 7 The currently eroded mire surface on much of Alport Moor has arisen from at least three processes acting on the pool-and-hummock system: (a) the drawing-off of water from the pools by endotelmic streams extending headwards from the main streams of the catchment area, probably at least 1000 years ago; (b) extensive drying-out of pools and hummocks during the drier climatic conditions between c. AD 1150 and 1300; (c) subsequent human modification of the mire vegetation by burning, grazing and, latterly, air pollution. 8 Sphagnum was lost from the mire surface generally on Alport Moor by 400-500 years ago. Only the disappearance of the moss Racomitrium lanuginosum from the hummocks might be attributed to the deleterious effects of air pollution.

Regional and historical variation in the nitrogen content of Racomitrium lanuginosum in Britain in relation to atmospheric nitrogen deposition.

The moss Racomitrium lanuginosum (Hedw.) Brid. is an important component of the drier parts of ombrotrophic mires and montane heaths in north-western Britain. The extent and quality of the montane heaths dominated by R. lanuginosum has declined in recent decades, perhaps in part due to the effects of acidic deposition at high elevations. This paper examines the effect of atmospheric nitrogen deposition, which has increased during this century, on the nitrogen content of R. lanuginosum in Britain. The nitrogen content of the moss reflects the magnitude of the atmospheric supply being least in north-western Scotland and greatest (as much as six-fold greater) near to urban centres in northern England. This regional difference was less marked (only approx. two-fold) during the 19th century (as revealed from the analysis of herbarium specimens) when nitrogen concentrations were appreciably lower. Transplant studies both between regions and between sites within a mountain system demonstrated the importance of atmospheric deposition in determining the tissue nitrogen concentration of the moss. The results are discussed in relation to the potential importance of the enhanced atmospheric nitrogen supply to the normally nitrogen-impoverished montane heaths, and to the growth and persistence of the moss.

Diet and habitat use of the Dotterel Charadrius morinellus in Scotland

The feeding ecology of Dotterel Charadrius morinellus adults and chicks was studied on three Scottish breeding areas. On the basis of 2324 prey items identified from 234 faeces, we show that (i) birds feed selectively and (ii) age‐related and seasonal differences in food selection occur.The diet comprised mainly beetles (Coleoptera), sawflies (Symphyta) and the adults and larvae of Tipula montana. The faeces of adult Dotterel contained a high proportion of beetles, whereas chick faeces had more soft‐bodied prey. However, when T. montana adults emerged en masse (every second year) both adults and chicks took more tipulids. On one area, larval T. montana comprised much of the diet soon after the birds arrived on their breeding grounds and just before leaving in autumn. The preferred feeding habitats were flat or gently sloping Racomitrium lanuginosum or Juncus trifidus heaths or the transition zone between moss heath and montane bog. Dwarf‐shrub, grass‐dominated and single bog communities were avoided. The preferred feeding habitats were those in which pitfall trap catches of the main prey were highest. A close juxtaposition of montane bog and R. lanuginosum heaths met the feeding requirements of both chicks and adults, respectively. Recent changes in the breeding distribution of Dotterel in Britain may be related to de‐ terioration in feeding and breeding habitat due to overgrazing by sheep and greater habitat acidification.

The carbohydrates of bryophytes in relation to desiccation tolerance

The major soluble carbohydrate in shoots of the mosses Dicranum majus, Hookeria lucens, Polytrichum commune, Racomitrium lanuginosum, Thuidium tamariscinum and Tortula ruraliformis is sucrose, whose content varied between 100 and 500 f.Lmolg dry weight−1. Sucrose content was unaffected by desiccation. Glucose and fructose are present at less than one-tenth the sucrose cop.tent in each species and, in T. ruraliformis, desiccation causes a decrease in their concentration. Comparison with published data suggests that the above features, along with low levels of starch, are characteristic of mosses. It is suggested that high sucrose content, allied with low levels of reducing sugars, contributes to the desiccation tolerance of mosses.

Effects of Grazing on Tiller Size and Population Dynamics in a Clonal Sedge (Carex bigelowii)

The clonal sedge, Carex bigelowwi Torr. ex Schwein., is common in the subarctic range lands of the Icelandic Highlands, which are grazed during summer, mainly by sheep. The effects of grazing on tiller and the population dynamics were studied by comparing grazed and ungrazed sites at two altitudes. On a tiller basis, C. bigelowii responded to grazing by decreased tiller size and reduced probability of flowering while on a unit area basis, both density and biomass increased. The moss Racomitrium lanuginosum (Hedw.) Brid., also abundant at the study sites, is not grazed but sensitive to trampling. The moss dry weight was four times greater at an ungrazed site than at a comparable grazed site

Primary production and nitrogen economy of Racomitrium lanuginosum at the subalpine lava field of Mt. Fuji

Primary production and nitrogen economy of Racomitrium lanuginosum at the subalpine lava field of Mt. Fuji

The vegetation of ultrabasic soils on the Isle of Rhum II. The causes of the debris

Summary The relationship between the Rhum ultrabasic skeletal soils and their debris vegetation was investigated by plant analyses and field and laboratory experiments. Samples of Agrostis vinealis, Arenaria norvegica ssp norvegica, Calluna vulgaris, Festuca vivipara, Plantago maritima and Racomitrium lanuginosum from these soils usually had low concentrations of potassium and calcium, and high concentrations of sodium, magnesium (and high Mg/Ca quotients), iron and nickel. There were instances of very high iron concentrations (up to 22.4mg g−1 in Plantago maritima), very high Mg/Ca quotients (up to 27.8 in Arenaria novegica spp. norvegica) and high nickel concentrations (up to 0.48mg g−1 in Plantago maritima). A nutrient addition experiment which was set up in 1965 on an exposed barren area had in 1982 over twice as many species as originally recorded and a nearly complete plant cover. Shorter-term work has confirmed that nutrient availability limits the ultrabasic vegetation. An experiment on Agrostis v...

Biflavones from some mosses

From Antitrichia curtipendula and Racomitrium lanuginosum 5′,3‴-dihydroxyrobustaflavone and 5′, 8″-biluteolin were isolated. In Plagiomnium elatum the new biflavone 5′-hydroxyamentoflavone was detected