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A model where a dictator decides on both the level of public-sector capital and whether to democratize is constructed. Under dictatorship the labour market is monopsonistic; democratization involves instituting a competitive labour market. Workers sometimes have a credible threat of revolution and this may affect the dictator's investment decision; it may also induce democratization. The possibility of a 'political development trap', where the dictator stifles development to stay in power, emerges. The model is used, inter alia, to explain the effects of the 1832 Reform Act in the UK and the worldwide positive correlation between income and democracy. [ABSTRACT FROM AUTHOR]

Question Is the succession of cryptogamic epiphyte communities (lichens) consistent with autogenic processes and life-history trade-offs? Location Northern Britain ( Scotland). Methods We subsampled epiphytes from the lower bole of aspen ( Populus tremula L.) and tested for two signatures in community succession. First, we used resampling among microhabitats to estimate species richness ( sR) and species density (ρ) for trees along a chronosequence. We tested sR and ρ against patterns consistent with autogenic and life history-mediated succession. Second, we constructed null model communities from a regional species pool to test for significant dispersion in multivariate trait diversity. Results We show that species density ( ρ) declined along the tree age chronosequence. This decline was consistent with the observed unimodal pattern in species richness ( sR) for a habitat that has a non-stationary area (increasing lower bole habitat area with tree age). We found under-dispersed trait diversity for younger trees, tending towards equilibrium between the regional species pool and local community for mid- and older-aged trees. Over-dispersion was evident for communities with the highest species richness. Conclusions We conclude that lichen epiphyte communities undergo succession structured by autogenic processes (interference competition) and may also be structured by life-history trends, e.g. the competition-colonization trade-off. However, we suggest that the stochastic extirpation of competitive and dominant species may allow pioneer species to persist in the long term, explaining equilibrium in trait diversity observed for older-aged trees. [ABSTRACT FROM AUTHOR]

This review positions the biodiversity response to climate change within a social-sciences risk-based framework, integrating the parameters of hazard, exposure, and vulnerability. It uses lichen epiphytes as a case study. In treating human-induced climate change as a hazard, the exposure of lichen epiphytes is considered as their sensitivity to spatial climatic variation, while also seeking congruence between bioclimatic models and observational data supporting distributional change. Improved understanding of exposure could be generated through functional response models, and climate sensitivity should be carefully interpreted against co-occurring hazards (pollution, habitat degradation). Where negative impacts result from exposure to climate change, species vulnerability may be reduced through adaptive forest management. This opportunity is based on a cross-scale interaction between microhabitat specificity and macroclimatic setting. Certain stand types (e.g., old-growth stands) offer greater opportunity for establishment and growth in suboptimal climates, because high microhabitat heterogeneity generates a broader spectrum of microclimatic niches, which buffer an unsuitable macroclimate. Lichen epiphyte vulnerability will nevertheless be dependent on an amalgam of ecological processes considered at the stand scale, including trophic interactions, acclimation, and evolutionary adaptation, and at the landscape scale, including gene flow and dispersal limitation. A trait-focused approach could provide an opportunity to generalize these processes. [ABSTRACT FROM AUTHOR]

Objective: Coronary computed tomography (CT) angiography is an advanced cardiac imaging test commonly used for diagnosing early signs of ischemic heart disease. Despite its importance in cardiology, little is known about its psychological effect on patients. The present study sought to examine these effects in relation to illness perceptions, cardiac health behavior intentions, and subsequent health behaviors. Methods: Forty-five nonacute cardiac patients who were referred for diagnostic coronary CT angiography completed questionnaires prior to testing and following the receipt of test results, at which point illness perceptions and intentions to take cardiac medication, as well as diet and exercise intentions were measured. Exercise and dietary behaviors were measured at follow-up 6 weeks later. Changes on these variables were then compared between patients diagnosed with normal arteries and patients diagnosed with diseased arteries. Results: Compared to positive-testing patients, patients with normal test results reported significant changes toward more positive illness perceptions following testing, with improvements in emotional effect of illness, illness concern, consequences, and personal control of illness. The illness perception of treatment control was seen as more important among positive-testing patients, whereas both groups reported increases in illness coherence. Health behavior intentions (cardiac medication intentions and exercise intentions) increased for positive-testing patients only, as did physical activity at follow-up. Conclusions: Diagnosis-dependent psychological effects can be detected following coronary CT angiography. These effects have important implications for patient health and health care in diagnostic contexts, and the results from this study can be used to guide further research in this area. [ABSTRACT FROM AUTHOR]

Background:Bioclimatic models are widely applied in biogeography and conservation biology; however, the functional relevance of macroclimate as an explanation for species performance (e.g. establishment, growth and survival, fecundity) has been challenged. Aims:In this study, we aimed to determine whether the ecological performance of an epiphytic lichen is related to coarse-grained macroclimate. Methods:A meta-analysis was carried out to compare local growth rates for a lichen epiphyte,Lobaria pulmonaria, to coarse-grained interpolated climate surfaces. Growth rates were sampled from small-scale experiments conducted within different forest settings and for different regions of the world. Generalised linear mixed models were used to compare thallus growth (response) to a suite of climatic variables derived from the WorldClim dataset. Results:A significant relationship between thallus growth measured for experimental forest microhabitats and macroclimatic variables (total precipitation and annual mean temperature) was found. This relationship was validated through a comparison withL.pulmonaria's North American range for which projected growth rates were higher and lower where the species tended to be present and absent, respectively. Conclusions:The ecological relevance of coarse-grained macroclimate applied in bioclimatic modelling has been challenged. We show that the use of macroclimatic data may be functionally defensible where correlated with independent measures of local ecological success. [ABSTRACT FROM PUBLISHER]

This paper describes a novel archaeological resource--preserved epiphytes on the timber structure of vernacular buildings--used, to our knowledge, for the first time to quantify a loss of biodiversity between pre-industrial and post-industrial landscapes. By matching the confirmed occurrence of epiphyte species for the pre-industrial period, with a statistical likelihood for their absence in the present-day landscape (post- 1960), we robustly identified species that have been extirpated across three contrasting regions in southern England. First, the scale of biodiversity loss observed--up to 80 per cent of epiphytes--severely challenges biodiversity targets and environmental baselines that have been developed using reference points in the post-industrial period. Second, we examined sensitivity in the present-day distribution of extirpated species, explained by three environmental drivers: (i) pollution regime, (ii) extent of ancient woodland, and (iii) climatic setting. Results point to an interacting effect between the pollution regime (sulphur dioxide) and changed woodland structure, leading to distinctive regional signatures in biodiversity loss. [ABSTRACT FROM AUTHOR]

Abstract: The Late Pleistocene archaeological record of the Great Lakes drainage area shows that there were several, albeit spatially variable, changes in that record in a time period corresponding to the Younger Dryas (YD) climatic reversal at ca. 10,800–10,000 14C BP. Notable here are declines in some areas in the mobility of Paleoindian groups as measured by distance to the main lithic source employed, declines in the overall frequency of sites/findpots, particularly in the western Great Lakes where some northern areas seem to have been largely abandoned, and an increasing association of occupation locales with glacial lake shores or extensive wetlands left by recently drained glacial lakes. Some of the changes, as in range mobility, most likely relate to the colonization of new areas rather than directly to the YD. Specifically, the earliest groups were able to target rich, but widely dispersed, resource locales due to an absence of competing groups. However, the declines in locale frequencies and shifting distributions of those locales may be due to YD influence, notably to an eventual drying out of the area that resulted in less productive environments overall and made the lake shores and wetland areas more attractive environmental niches for human occupation. [Copyright &y& Elsevier]

The article presents a research study which tested the utility of DNA barcoding across eight orders of lichen-forming fungi. The author indicates that around 92% of species possess a barcode gap when using the internal transcribed spacer of nuclear ribosomal DNA, and that DNA barcoding in a floristic context has a high potential to identify specimens to the correct species.

We combine Acemoglu and Robinson's model of the economic origins of democracy with Lohmann's model of political mass protest. This allows us to analyse the economic causes of political regime change based on the microfoundations of revolution. We are able to derive conditions under which democracy arises peacefully, when it occurs only after a revolution and when oligarchy persists. We model these possibilities in a world of asymmetric information, where information cascades are possible, and where these cascades may involve errors in the sense that they make everyone worse off. [ABSTRACT FROM AUTHOR]

Bioclimatic envelope models are frequently used to project the species response to climate change scenarios. Development and improvement of bioclimatic models has focussed on data properties and statistical tools, while significant criticism continues to challenge the ecological framework of model assumptions. We hypothesised that a potential for model improvement emerges from linkage across scales, between macroclimate and variation in local habitat quality: i.e. a species' habitat specificity may shift along macroclimatic gradients. We first sampled two test-case epiphytic lichen species across a steep climatic gradient, and second developed standard bioclimatic models accompanied by a threshold likelihood value for discriminating presences and absences. We used the difference between predicted model values and the threshold as a response variable ( D): we show that values for D are explained by an interaction between the climatic setting and habitat quality. A potential error in bioclimatic models is then quantified as the region of false absences or presences, which would be incurred as a consequence of sensitivity to variable habitat. This signature habitat effect occurs at a species' range-edge, and, as a corollary, provides quantification in support of conservation: i.e. information is provided on how a habitat may be managed in marginal climatic regions (leading or trailing range-edge boundaries) in order to promote species protection. [ABSTRACT FROM AUTHOR]

Question: How does an improved understanding of species interactions, combined with an additional ecological variable (wind speed), alter the projected vegetation response to variation in altitudinal temperature? Location: Cairngorm Mountains, Scotland. Methods: Montane heathland vegetation was sampled from 144 plots (432 quadrats) comprising eight altitudinal transects. Ordination by partial DCA and path analysis was used to confirm: (1) the effect of wind speed and altitude (≈ temperature) on vegetation structure, i.e. canopy height and cover of bare ground, and (2) the control of arctic/alpine macrolichen occurrence by vegetation structure. Nested regression analysis was used to project the response of vegetation structure and lichen occurrence to temperature change scenarios with and without a step-wise change in future wind speed. Results: Warming trends shifted vegetation zones upwards, with a subsequent loss of suitable habitat for arctic/alpine lichens. However, incorporating wind speed as an additional explanatory variable had an important modifying effect on the vegetation response to temperature: decreasing wind speed exaggerates the effects of increased temperature and vice versa. Our models suggest that for the wind-driven heath examined, a 20% increase in mean wind speed may negate the effect of increased temperature on vegetation structure, resulting in no net change in lichen occurrence. Conclusions: We caution that an improved understanding of species interactions in vegetation response models may force the consideration of locally variable environmental parameters (e.g. wind speed), bringing into question the predicted vegetation response based on standard projections of temperature change along altitudinal gradients. [ABSTRACT FROM AUTHOR]

The interpretation of natural plant communities frequently invokes species-sorting controlled by niche differences along spatial environmental gradients. This process of niche structuring can be explained by reference to functional traits, which provide a mechanistic explanation for community structure. In contrast, models explaining species coexistence obviate the limiting effect of niche difference, by invoking processes which cause species-level drift, e.g. demographic stochasticity. This paper investigates a simple habitat with strong gradients (moss communities in a patterned arctic wetland) to identify signature-patterns under-pinning the relative importance of deterministic assembly and stochastic drift in a natural community. First, ordination analysis was used to confirm community composition structured by a range of nine carefully selected functional traits. Second, to determine whether traits explaining community composition might also explain species richness, local species richness (sR) was compared to (1) observed trait diversity and (2) expected trait diversity based on permutation tests, which are used to simulate null community assembly for different values of sR. Traits explaining species composition, consistent with deterministic niche structuring, do not appear to maintain sR. This surprising result was explained by decomposing the community into individual pair-wise comparisons, i.e. species niche-differences and association (χ2). Results support deterministic processes via the sorting of species with similar and contrasting niches, at opposite ends of a composite environmental gradient. Nevertheless, stochastic drift is apparent in the random structure of a majority of pair-wise associations; in addition, a species’ abundance was in general not related to environmental distance from response-optima. We suggest therefore that spatial pattern in the moss community is a balance between deterministic forces with respect to species traits and controlling environmental gradients, and stochastic drift, which weakens this deterministic structure. [ABSTRACT FROM AUTHOR]

Aim To quantify the role of multiple biodiversity drivers – pollution, woodland structure and climate – controlling lichen epiphyte composition and diversity. Location  Scotland, north-west Europe. Methods Four compatible datasets were assembled: site-scale species distribution data (response) and base-line modelled data on climate, pollution loads and extent of old-growth woodland (explanatory variables). First, partial-canonical correspondence analysis was used: (1) to compare the importance of environmental variables to pure spatial effects and (2) to partition the importance of environmental variables in explaining species composition. Secondly, patterns of species richness were investigated using multiple least-squares regression. Results Old-growth woodland was the most important control of species richness. Pollution was the most important explanatory variable for species composition. The impact of pollution on composition (and to a lesser extent on richness) is explained: (1) By recovery of lichens with declining SO2 pollution, although with epiphyte composition shifted by the recent effects of N-pollution and (2) By the limited spatial extent of severe pollution, and generally low-to-moderate pollution loads across our study area, combined with the positive effect of old-growth woodland extent in controlling species richness. The effect of climate and old-growth woodland on species composition covaried, supporting an interaction between habitat quality and climatic setting, which may be important in understanding the epiphyte response to climate change. Conclusions Advances in conservation planning will likely require an integrated approach to understanding simultaneous effects of multiple drivers, providing opportunities for integrated management strategies. Our study provides a preliminary example of this approach by combining three key biodiversity drivers into a single framework for lichen epiphytes. Thus, reducing pollution loads may make old-growth woodland that currently exists in a polluted landscape available for colonization, thereby extending the available habitat for epiphytes, and facilitating an effective species response to climate change. [ABSTRACT FROM AUTHOR]

The Crowfield site, excavated in 1981-82, would be a small typical Early Paleoindian campsite except for the added presence of a plough-truncated pit feature containing 182+ burned and destroyed stone artifacts. This paper reports on the latest insights into the feature contents based on continuing attempts to cross-mend fragments, as well as detailed analyses of the spatial distribution of artifact pieces within the feature itself These results reinforce earlier conclusions that the items were burned where found, represent a cache of still functional tools and preforms, and were purposefully destroyed. They confirm that the site represents the best evidence to date for sacred ritual by eastern North American fluted point users. Contrasts with other reported early sacred and secular caches are documented that highlight the uniqueness of the assemblage. It is argued that these contrasts indicate the Crowfield feature assemblage more closely approximates a transported, functioning tool kit, as opposed to the surplus, seasonal and insurance gear or offerings, that dominate other early caches. [ABSTRACT FROM AUTHOR]

Aim To quantify the interaction between climate and woodland continuity in determining the bioclimatic response of lichen epiphytes. Location Northern Britain (Scotland). Methods Indicator-species analysis was used to pre-select lichen epiphytes along parallel gradients in climate and the extent of old-growth woodland. Nonparametric multiplicative regression was used to describe in a predictive model the individualistic response of selected species, which were projected based on climate-change scenarios and contrasting patterns of simulated woodland loss or gain. Species with a similar response were grouped using a novel application of cluster analysis to summarize the potentially huge number of projected outcomes. Projected patterns of occurrence under climate-change scenarios were examined for different levels of old-growth woodland extent. Results Forty-two lichen species were statistically significant indicator species in oceanic woodlands, and old-growth indicators under suboptimal climatic conditions. Responses to climate-change scenarios were contrasting, with one group comprising species projected to increase in extent in response to climate warming, and other response groups projected to decrease in occurrence, possibly in response to shifting rainfall patterns. The occurrence of all response groups had a positive relationship with old-growth woodland extent. Main conclusions An ‘oceanic’ biogeographical group of epiphytes identified using the baseline climatic and present-day woodland setting comprised species with a cyanobacterial photobiont or tropical phytogeographical affinities. However, within this group the individual species responses to climate-change scenarios were contrasting. Additionally, group responses may be poorly matched with simple ecological traits. However, the studied interaction between climate and habitat continuity suggests that the impact of climate change might be offset for certain lichen epiphytes by appropriate management of woodland resources, for example, expansion of native woodland around remnant old-growth stands. [ABSTRACT FROM AUTHOR]

Himalayan forests are biodiverse and support the cultural and economic livelihoods of their human communities. They are bounded to the south by the Indo-Gangetic Plain, which has among the highest concentrations of atmospheric ammonia globally. This source of excess nitrogen pushes northwards into the Himalaya, generating concern that Himalayan forests will be impacted. To estimate the extent to which atmospheric nitrogen is impacting Himalayan forests we focussed on lichen epiphytes, which are a well-established bioindicator for atmospheric nitrogen pollution. First, we reviewed published literature describing nitrogen thresholds (critical levels and loads) at which lichen epiphytes are affected, identifying a mean and confidence intervals based on previous research conducted across a diverse set of biogeographic and ecological settings. Second, we used estimates from previously published atmospheric chemistry models (EMEP-WRF and UKCA-CLASSIC) projected to the Himalaya with contrasting spatial resolution and timescales to characterise model variability. Comparing the lichen epiphyte critical levels and loads with the atmospheric chemistry model projections, we created preliminary estimates of the extent to which Himalayan forests are impacted by excess nitrogen; this equated to c. 80–85% and c. 95–98% with respect to ammonia and total nitrogen deposition, respectively. Recognising that lichens are one of the most sensitive bioindicators for atmospheric nitrogen pollution, our new synthesis of previous studies on this topic generated concern that most Himalayan forests are at risk from excess nitrogen. This is a desk-based study that now requires verification through biological surveillance, for which we provide key recommendations. • We reviewed nitrogen critical levels and loads for lichen biodindicators. • These thresholds were applied to Himalayan forests based on modelled nitrogen. • Over 80% of Himalayan forests exceeded critical levels and loads. • Lichen bioindicators signal potential for widespread negative effects associated with atmospheric nitrogen pollution. [ABSTRACT FROM AUTHOR]

The formation of many arctic wetlands is associated with the occurrence of polygon- patterned permafrost. Existing scenarios to describe and explain surface landforms in arctic wetlands (low-center and high-center polygons and polygon ponds) invoke competing hypotheses: a cyclic succession (the thaw-lake hypothesis) or a linear succession (terrestrialization). Both hypotheses infer the predictable development of polygon-patterned wetlands over millennia. However, very few studies have applied paleoecological techniques to reconstruct long-term succession in tundra wetlands and thereby test the validity of existing hypotheses. This paper uses the paleoecological record of diatoms to investigate long-term development of individual polygons in a High Arctic wetland. Two landform processes were examined: (1) the millennial-scale development of a polygon-pond, and (2) the transition from low-center to erosive high-center polygons. Diatom assemblages were quantified from habitats associated with contrasting landforms in the present-day landscape, and used as an analog to reconstruct past transitions between polygon types. On the basis of this evidence, the paleoecological record does not support either of the existing models describing the predictable succession of polygon landforms in an arctic wetland. Our results indicate a need for greater paleoecological understanding, in combination with in situ observations in present-day geomorphology, in order to identify patterns of polygon wetland development and elucidate the long-term drivers of these landform transitions. [ABSTRACT FROM AUTHOR]

Question: How might contrasting plant groups interact to confer ecosystem stability during the development of a wet heath: i.e. in response to two major environmental drivers, past hydrologic change and burning? Location: Rannoch Moor, Scotland. Methods: Three peat cores were used to reconstruct vegetation change, surface moisture and burning phases, during wet heath development for a radiocarbon-dated period from ca. 9500-1000 yr BP. Results: Statistical analysis of peat cores revealed significant relationships between burning phases and past periods of inferred surface dryness. Vegetation elements were related in the palanoecological record to surface dryness (Ericaceae), wetness (Sphagnum, monocotyledons, and Racomitrium) and periods of burning (i.e. negative correlation of Racomitrium and monocotyledon remains with charcoal). However, correlations between plant groups could not be adequately explained by their equivalent direct response to hydrology and burning, and the effects of species interactions are invoked. Conclusions: The results indicate millennial-scale stability of the wet heath ecosystem in response to past environmental change (i.e. hydrology and burning). This stability is conferred by interaction between a diversity of plant groups, enabling local shifts in vegetation composition in response to environmental drivers. This long-term stability of the mire ecosystem forms a template against which present-day threats (e.g. pollution, climate change) should be critically assessed. [ABSTRACT FROM AUTHOR]

Question: How will changing climate and habitat structure interact to control the species diversity of lichen epiphytes? Location: Scotland. Method: Species richness (=diversity) of the epiphyte lichen community known as Lobarion (named after Lobaria pulmonaria) was quantified for 94 Populus tremula stands across Scotland, and compared in a predictive model to seven climate variables and eight measures of woodland structure. An optimum model was selected and used to project Lobarion diversity over the geographic range of the study area, based on IPCC climate change scenarios and hypothetical shifts in woodland structure. Results: Species diversity of the Lobarion community was best explained by three climate variables: (1) average annual temperature; (2) autumn and winter precipitation; in combination with (3) historic-woodland extent. Projections indicate a positive effect of predicted climate change on Lobarion diversity, consistent with the physiological traits of cyanobacterial lichens comprising the Lobarion. However, the general response to climate is modified significantly by the effect on diversity of historic-woodland extent. Conclusions: Historic-woodland extent may exert an important control over local climate, as well as impacting upon the metapopulation dynamics of species in the Lobarion. In particular, a temporal delay in the response of Lobarion species to changed woodland structure is critical to our understanding of future climate change effects. Future Lobarion diversity (e.g. in the 2050s) may depend upon the interaction of contemporary climate (e.g. 2050s climate) and historic habitat structure (e.g. 1950s woodland extent). This is supported by previous observations for an extinction debt amongst lichen epiphytes, but suggests an extension of simple climate-response models is necessary, before their wider application to lichen epiphyte diversity. [ABSTRACT FROM AUTHOR]

Axioms developed from island biogeography theory (i.e. species–area relationships, effects of fragmentation and isolation) are central to the development of conservation strategy. Within this context, the ‘extinction debt’ hypothesis brings into question an often assumed relationship between species richness and present-day spatial habitat structure (i.e. extent, fragmentation), suggesting instead that the richness and composition of biological communities may lag behind spatial changes in habitat. We examined evidence for an extinction debt among epiphytic lichens, a highly diverse biological group of significant conservation concern. Using sites in Scotland, we compared epiphyte species richness in smaller-scale habitat units (aspen stands) to larger-scale woodland structure (extent and fragmentation) measured at two spatial scales (1 km2 and 4 km2) and for two timeframes, modern (1990s to 2000s) and historic (1860s to 1880s). Species richness was positively related to woodland extent and negatively related to woodland fragmentation; however, richness was explained better by historic woodland structure at a 1-km2 scale, than by modern woodland structure. The results indicate: (1) a coupling of stand-scale epiphyte assembly and dynamics of the wider woodland ecosystem, and (2) a significant lag in the response of epiphyte species richness to habitat spatial structure. However, the effect of spatial habitat structure is different between species groups with contrasting traits. The effect of decreasing woodland extent on epiphyte richness is generally more severe for microlichens (comprising a greater number of rare and specialist species) than the more generalist macrolichens. [ABSTRACT FROM AUTHOR]

Aim Lichen epiphytes are important for biodiversity conservation and are also widely applied as environmental indicators. However, biogeographical and ecological knowledge underpinning lichen epiphyte conservation, and the use of lichens as indicators, is based primarily on a limited range of ‘macrolichen’ species. Wider trends in epiphyte biodiversity remain largely unexplored. This paper examines the community structure of lichen epiphytes on aspen ( Populus tremula L.) in Scotland, including species across all functional groups and comprising, therefore, taxonomically difficult ‘microlichens’. Location Northern Britain (Scotland). Methods Epiphytes were sampled from 12 sites throughout Scotland and examined at two scales: between and within aspen stands. Species were classified into contrasting functional groups and ordination by detrended correspondence analysis was used to summarize community structure. Results Within aspen stands (between trees) epiphyte communities showed successional patterns related to tree age. These successional patterns changed predictably for stands aligned along a climatic gradient (between stands). Main conclusions A dual climatic–successional trend in epiphyte community structure is presented. Large-scale trends in epiphyte diversity are explained as the local response of species with contrasting functional traits to climate and autogenic succession. Turnover of functional groups between stands is positively related to β-diversity, and ecological limits to the frequency of contrasting functional groups are presented. Accordingly, the study and application of lichen species with similar functional traits may inadequately represent patterns of biodiversity. This prompts criticism of the currently accepted conservation strategy, i.e. (1) an emphasis in the conservation literature on ‘macrolichen’ species with similar ecologies and (2) the application of lichen indices over climatically variable geographical areas. [ABSTRACT FROM AUTHOR]

1 The response of peat-rich permafrost soils to human-induced climate change may be especially important in modifying the global C-flux. We examined the Holocene developmental record of a High Arctic peat-forming wetland to investigate its sensitivity to past climate change and aid understanding of the likely effects of future climate warming on high-latitude ecosystems. 2 The microhabitat of mosses was quantified in the present-day polygon-complex at Bylot Island (73° N, 80° W) and used to interpret the radiocarbon-dated macrofossil record of three cores, comprising c. 3500 years of wetland development. Recurrent wet and dry phases in the reconstructed palaeohydrological record indicated pronounced temporal variability. Wet and dry phases were compared between cores and with palaeoclimatic proxy values, measured as percentage melt and δ18O in nearby ice cores. 3 Periodic wet and dry phases appear unrelated to past climate over c. 50% of the combined stratigraphic records, and are attributable instead to geomorphological mechanisms. At other times, association of wet and dry phases with significantly lower and higher values of percentage melt and δ18O indicate a possible effect of past climate change on polygon hydrology and vegetation, although inconsistencies between cores suggest that local geomorphological processes continued to modify a regional climatic effect. However, during a period incorporating the Little Ice Age ( c. 305–530 cal. yearsbp), reconstructed moisture and vegetation change is pronounced and consistent among all three cores. 4 The results provide strong evidence for the sensitivity of a High Arctic terrestrial ecosystem to past climate change during the Holocene. The estimated magnitude of changes in soil moisture between wet and dry phases is sufficient to imply recurrent shifts in wetland function, periodically impacted upon by pronounced climatic variability, although controlled principally by autogenic processes. The structure and function of such wetlands may therefore be susceptible to predicted, human-induced climate warming. [ABSTRACT FROM AUTHOR]

This article describes the sale and optimal regulation of a sequence of public utilities, where monitoring of regulatory compliance is costly. The government is concerned with the revenue raised by successive privatizations as well as the standard objective of efficiency in production. The costs of monitoring are private information to the government. At each stage in the sequence of privatizations, the public Bayes updates its distribution of posterior beliefs over the government's regulatory enforcement strategy. The government knows that this "learning" is taking place and chooses the time path of monitoring levels accordingly. [ABSTRACT FROM AUTHOR]

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Natural abundance of 15N and [N] was studied in thalli of mat-forming lichens collected from tundra and heathland sites in the northern and southern hemispheres. The study includes samples of British Cladonia portentosa from sites in regions of high and low N-loading and in heathland growing both directly on peat and independently of the soil substratum, in a canopy of prostrate gorse (Ulex minor). In the mat-forming lichens examined, a non-random pattern in [N] and δ15N was characterised by a minimum in δ15N, which occurred most frequently at 20–40 mm below the thallus apex. Nitrogen concentration increased above this point, towards the apex, though remained invariably low towards the thallus base. We discuss the significance of the pattern in [N] and δ15N for current theories describing the uptake and recycling of nitrogen by mat-forming lichens in oligotrophic habitats. Our data are incompatible with the suggested uptake of soil organic-N depleted in 15N, though are consistent with possible internal recycling and the development of a structural necromass. The study emphasises the internal fractionation of nitrogen isotopes and provides a caveat against the assumption that values of δ15N provide an unequivocal indicator of source-sink relationships in nitrogen cycling. [ABSTRACT FROM AUTHOR]

Presents palaeoecological evidence of the active role of Racomitrium (R.) lanuginosum in mire drying and degradation in Great Britain. Introduction to the ecology of R. lanuginosum; Description of the study sites; Role of the plant species in the development of Kentra Moss and the Migneint.

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 macro-fossils, 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. [ABSTRACT FROM AUTHOR]

Presents a study which focused on Caradoc site in southwestern Ontario, Canada, which provides evidence of ritual behavior associated with unfluted lanceolate point assemblages of the Caradoc site. Background of the site; Artifactual material recovered from the site; Conclusions.