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1. Pitfall trapping is one of the most widely used arthropod sampling techniques. However, relative species abundance in pitfall trap catches differs from that found using quadrat samples. This difference, here termed bias, reflects the fact that pitfall trap catch is influenced not only by abundance but also by other factors, including activity, which may be linked to body size. Here, we investigate whether the bias affecting pitfall trap catches of a particular species is related to the typical body mass of individuals of that species. 2. Data were extracted from five studies where pitfall trapping bias was quantified and covered 32 species of spiders and carabid beetles. Bias was expressed as the ratio of biomass captured by pitfall traps to that measured by quadrat counts (four field studies), or as the product of mean speed of movement and probability of capture per trap encounter, at standard density (one laboratory study). 3. Pitfall trapping bias and body mass were strongly related on a log–log scale, with log(body mass) explaining 78% of the variation in log(bias) (P

Archaeologists commonly utilize spatial technologies to determine the occurrence probability of archaeological sites over large areas. Heavily forested areas of the northern Great Lakes have proven to be especially difficult places to carry out archaeological surveys. In this study, paleoshoreline mapping and site location analysis was used to develop a predictive model to identify likely prehistoric site locations from the Archaic Period in the Pictured Rocks National Lakeshore. Field survey efforts targeted locations where modeling efforts indicated high site probability, discovering 23 new prehistoric sites within this National Lakeshore. Based on associations with Nipissing Phase (mid-Holocene age) paleoshorelines, the presence of distinct lithic artifact technologies, paired with limited radiometric dating, the newly found sites are thought to be Late Archaic in cultural affiliation. Analysis of site settings indicates a preference for lagoon, barrier, and estuarine environments. The application of these spatial technologies demonstrates a targeted yet successful approach to field archaeology with limited field time and expansive areas. © 2010 Wiley Periodicals, Inc.

Summary 1. Upland heaths in the UK are of significant conservation importance. Large areas are managed through prescribed burning to improve habitat and grazing for red grouse Lagopus lagopus scoticus, deer Cervus elaphus and sheep Ovis aries. Previous research has identified trends in vegetation development following burning, but has not linked this to variation in fire behaviour and severity. 2. We burned 15 experimental fires on an area of Calluna vulgaris-dominated moorland, and recorded pre- and post-fire vegetation structure and composition, fire behaviour characteristics, and several ‘proxy measures’ of fire severity. 3. We distinguished measures of fire severity, describing the immediate physical effects of burning, from the long-term ecosystem responses of substrate development and Calluna regeneration. Proxy measures of fire severity did not relate strongly to fire behaviour or ecosystem response. 4. Post-fire regeneration was strongly linked to stand age and post-fire substrate type. Fire behaviour and severity had little effect, though fire-induced ground-surface heating may promote Calluna seedling establishment. Vegetative regeneration of Calluna was extremely poor in older stands, as was seedling establishment in areas where the post-fire substrate was dominated by live or dead pleurocarpous moss mats. 5.Synthesis and applications. Significant nonlinearities exist in fire severity on heathlands, with step changes related to the depth and moisture content of moss/litter layers and peat. Younger stands, less than c. 30 cm tall, should be the focus of management if the objective is to maximize Calluna regeneration. Burning older and uneven-aged stands is discouraged except for the purposes of fire hazard management. Managers should develop landscape-level burn plans to target burning effectively and create diverse fire regimes.

Summary 1. Calluna-dominated heaths occur throughout Europe but are in decline across their range. There is growing interest in using prescribed burning for their management, but environmental and social change will impact future fire regimes. Understanding fire behaviour is vital for the sustainable use of fire, but no robust models exist to inform management. 2. Shrub fuels display complex fire behaviour. This is particularly true in UK moorlands which are unusual in their fuel structure and moisture regime, being dominated by live fuel and an oceanic climate. 3. We burnt 27 experimental fires in the Scottish uplands during the legal burning season using a replicated experimental design. Plots were assigned to one of three commonly identified growth phases. We estimated a range of prefire fuel characteristics, including heterogeneity in fuel structure. We recorded wind speed and direction and estimated rate of spread (RoS). 4. Redundancy analysis was used to investigate the relationship between fire behaviour parameters as a whole and control variables. Fuel structure and heterogeneity, wind speed and canopy fuel moisture content were strongly related to variation in fire behaviour. 5. Best subsets regression was used to generate models of fire spread based on wind speed, vegetation height, canopy fuel moisture and an index of fuel heterogeneity. RoS was determined largely by wind speed, but this interacted strongly with vegetation structure. Changes in fuel horizontal continuity and vertical structure reduced rates of spread in low wind speeds. 6. Synthesis and applications. Live fuel moisture and fuel heterogeneity play an important role in dampening fire behaviour, aspects of shrub fuels that have previously not been examined in detail. Careful use of fire for moorland management increases habitat diversity and creates fire-safe landscapes. Escaped prescribed fires burn large areas, homogenize landscapes and have severe impacts on ecosystem services. The complex relationship between fuel structure and wind speed implies that changes in behaviour can be rapid and unexpected. Models can be used to assess fire hazard prior to prescribed burning and to choose fuels that can be burnt safely under prevailing or forecast conditions.

There is a general consensus that functional traits are reliable indicators of adaptation of organisms to particular environmental characteristics. In this study we relate the combined distributions of species traits of plants and animals to disturbance regimes in chestnut forests of southern Switzerland affected by regular winter fires. We used co-inertia analysis for combining the trait response of 471 invertebrate species (117 001 individuals) and 81 plant species at 23 sites with different fire and cutting histories. Trait response was assessed by calculating the variation in weighted mean traits averaged over the communities and by using mean traits in multivariate analyses. The analysis showed a strong association between plant and animal traits under fire constraints (Monte-Carlo test, p=0.0045). Plants and animal distributions show parallel trends in responses to fire which selects traits relating to persistence (ability to survive), resilience (ability to recover) and mobility. Warmth-demanding insects, herbivores, flying carnivores and pollinators were associated with recent fires, as were annual, ruderal and light-demanding plant species with long flowering duration. Small arthropods feeding on dead wood and those with narrow habitat requirements were associated with low fire frequency and unburnt sites, as were competitive plants with large seeds favoring moist sites. The spatial association between plant and animal traits reflected adaptations that promote survival in the disturbance regime, while the disturbance acts as an environmental filter on the distribution and assemblage of the trait values within communities. This combined analysis of plant and invertebrate traits distributions illustrates how community and ecosystem responses can be monitored and the results generalized across localities and disturbance types. Analyses of traits that cross trophic levels provide powerful and promising tools for validating management procedures and controlling ecosystem functions.

Question: Can cation analyses of water samples within a peatland site be used to infer solute sources to the samples, and so provide an objective criterion of ombrotrophy? Location: Mire complexes within native Pinus sylvestris forest, in Abernethy Forest, north of the Cairngorm Mountains, Scotland, UK. Methods: Chemical analyses of major cations in 200 water samples, and χ2 analysis of contingency tables relating species occurrence in the corresponding quadrat samples to the ombrotrophic-telluric division. Results and conclusions: The chemical data (especially the ratios Ca2+/Mg2+ and Na+/Mg2+) indicated a separation of about 140 essentially ombrotrophic samples from about 60 showing clear telluric influence; these conclusions are consistent with published rainwater analyses. For hydrological and meteorological reasons, a sharp separation cannot be expected, so the limit adopted here (Ca/Mg=1.0) is to some extent arbitrary, but the methods described provide a more objective criterion of ombrotrophy than any other. Contingency tables showed highly significant associations between species occurrence and the ombrotrophic-telluric division. The strongest associations included: (ombrotrophic) Eriophorum vaginatum, Odontoschisma sphagni and Sphagnum cuspidatum; (telluric) Carex panicea, Potentilla erecta, Carex echinata, Narthecium ossifragum, Sphagnum auriculatum s.l., Agrostis canina, Molinia caerulea, Eriophorum angustifolium, and Sphagnum recurvum s.l. The Abernethy mires are arguably more comparable with mire complexes on base-poor rocks in southern Scandinavia than with most ombrotrophic sites further south and west in Britain. As in Sweden, Narthecium ossifragum and Eriophorum angustifolium, generally ubiquitous on British and Irish ombrotrophic bogs, are “fen” plants at Abernethy.

Question: How does regular management burning of a northern, Calluna vulgaris-dominated heathland affect the lichen diversity at the patch and landscape scale? Location: Mar Lodge Estate, Scottish Highlands, United Kingdom. Methods: 26 fire sites of different ages and 11 long-term unburnt stands were surveyed to create a chronosequence of changing lichen diversity following burning. Data were analysed graphically, with a GLM and using a CCA. Results: Though the immediate effect of fire was to significantly reduce lichen diversity, it generally recovered within 20 years. There was a significant difference in the population dynamics between wet and dry moorland areas with terricolous lichens in the former site being replaced by pleurocarpous mosses. Older stands, unburnt for 25 years or more, generally had lower diversity than stands 10 to 15 years old. Changes in lichen diversity and community composition can be attributed to the development of Calluna stand structure following burning. Conclusion...

For the past two decades, archaeologists have been constructing predictive archaeological models to determine the occurrence probability of archaeological sites. Here, the technique has been used to explore the environmental factors that may have had an influence on the distribution of ringforts in Ireland. In the Inny River catchment of the Irish midlands, locational information, together with corresponding environmental variables, were assembled in a geographic information system. The analysis showed that ringfort sites have a distinctive locational pattern and cluster on moderately fertile, well-drained soils on gently sloping land surfaces (slopes of 4–9%) between 80 and 150 m above mean sea level. To test the practical applicability of the model, the results were extended to two separate areas adjoining the Inny River catchment (Blackwater valley and Lough Ramor catchment) in the form of a probability surface. The model predicts relatively low densities of ringforts in the Blackwater valley and much higher probabilities of occurrence in the Lough Ramor catchment. These predictions are broadly consistent with recorded site distributions. © 2006 Wiley Periodicals, Inc.

The spatial pattern of defoliation by mammalian herbivores across vegetation mosaics bas been frequently discussed, but rarely spatially quantified. Here we considered the role of plant-herbivore interactions in determining the spatial distribution of shrub defoliation by a large mammalian herbivore across a grass-shrub mosaic. We investigated the spatial pattern of heather defoliation by sheep in heather-grass mosaics. Heather-grass mosaics are two-phased vegetation mosaics, in which a spatially localized plant community (grass) fulfils nutritional needs, whilst a spatially extensive plant community (heather) meets energy requirements but is nutritionally marginal. We used a spatial analysis method, originating from human geography, to show that heather defoliation was not spread across the mosaic homogeneously, but that the spatial pattern was determined by geometric characteristics of the mosaic, grazing intensity, and the contrast between preferred and less preferred communities. The spatial analysis method proved to be a powerful tool to describe the spatial pattern of shrub defoliation. Applications of the method are explored and the implications of the spatial distribution of shrub defoliation are discussed.

○ Experiments were conducted to determine the genetic relationship between the alpine fern Athyrium distentifolium and the Scottish endemic taxon A. distentifolium var. flexile. ○ Segregation of the taxa was studied after growing sporophytes from spore families, and after selfing and crossing gametophytes. The growth of both gametophytes and sporophytes was measured under a range of nutrient regimes. ○ The distinction between the two taxa is due to variation at a single gene with pleiotropic effects expressed at both the sporophyte and gametophyte stages. A. distentifolium sporophytes (genotypes A D /A D or A D /A F ) are taller, have fewer fronds, and produce fewer spores than A. distentifolium var. flexile sporophytes (genotype A F /A F ). Gametophytes containing the A F allele have a 50% higher growth rate than those with the A D allele on a range of media. ○ The polymorphism may be maintained by a balance between selection for and against the A F allele at the gametophyte and sporophyte stages of the life cycle, respectively. Implications for the conservation of the A. distentifolium var. flexile taxon are discussed.

The coefficient of turbulent diffusion was measured in a 1·25m tall wheat canopy using a uniform release of nitrous oxide, the energy and momentum balance methods, and the humidity profile. The nitrous oxide profile gave the most accurate values, KN in the lower two thirds of the canopy, and a regression of the energy balance estimates, KE, against KN had a slope of 1·17 ± 0·10 with a non-significant intercept of 17cm2s−1. The mean day time profile of KN was exponential, K(z) = K(h) exp(−γ(1-z/h)) with γ = 3·9 when u(h) 1·2m s−1. But analysis of KN for the height interval 0·3 to 0·8m shows the importance of thermal stability, and the results are related to the non-dimensional stability parameter g/T(ΔT/Δz/(u(h)h2) where ΔT/Δz is the temperature gradient and u(h) is the windspeed at crop height, h. The large scatter in the results was attributed to the heterogeneity of the crop. Also the wind profile was frequently S-shaped defying a simple one-dimensional analysis and causing the momentum balance to give nonsensical results. Hence it seems unlikely that one-dimensional analysis of transfer can give values of K allowing an accurate estimate of the source and sink distributions within a dense crop canopy.

A new method is described for measuring the vertical component of the coefficient of turbulent diffusion, K, within a wheat canopy. A uniform controlled flux of nitrous oxide was released from a network of nylon tubes at ground level, and K was calculated from the concentration gradient measured at the centre of the network. The method was first used above the canopy when the crop was short, and the results agreed with those obtained from the wind profile and energy balance. Experiments with different sizes of distribution area showed that in most conditions a radius of only 12m was adequate to give a vertical flux that was constant within 15% to a height of 1m in a canopy 1·25m tall. The possible error in K was estimated to be 10 to 15% in the lower half of the canopy increasing to 30 to 40% above 1·0m. This is a useful complement to the energy and momentum balance methods that are very inaccurate in the lower half of the canopy.

Carbon dioxide is transported from the atmosphere to leaf surfaces very efficiently, and atmospheric diffusion resistances rarely affect photo-synthetic rates by more than 10%. The largest single resistance is in the boundary layer of individual leaves, and this is a well-known function of leaf size, wind speed, and leaf to air temperature difference. For uniform vegetative canopies a fully turbulent boundary layer exists above; this layer is also well understood and well-proven equations can be used to relate the carbon dioxide flux to the concentration gradient. Transport in the air within and just above vegetative canopies is less well understood. Turbulent diffusion theory has been shown to be inadequate, and consequently the diffusion resistance analogy cannot be used. Recent work, however, shows that Lagrangian theories of dispersion offer an alternative and more accurate description of transport within canopies.

A Markov chain model that simulates the trajectories of fluid particles in turbulent flow is described. It incorporates fluctuations in vertical and streamwise velocity, and can be used with velocities that have a skewed probability distribution. The model is used to estimate the distribution of heat downwind from an elevated line source in the boundary layer above a rough surface, and the results are compared with those from a wind tunnel experiment. The simplest model, with fluctuations in vertical velocity only, underestimates the plume depth by 4% to 22% at various distances downwind, and underestimates the rise in the mean height of the plume by 1·5 mm in 25·5 mm. The inclusion of streamwise velocity fluctuations increases the vertical plume width by 6% and also improves the prediction of the mean height of the plume. The model also gives profiles of streamwise eddy flux of heat u'θ that agree closely with those measured. Skewed velocity distributions can be included in the model, but in the boundary layer above a rough surface Gaussian velocity distributions are quite adequate.

SUMMARY The rain tower/wind tunnel complex at Rothamsted consists of a rain tower (height 11 m, cross-section 1 m2) linked to the upwind end of a wind tunnel (length 12 m, cross-section 1 m2), which may be operated in either an open or a closed configuration. At the top of the rain tower, water drops with diameters of 2.5 to 5 mm are produced by a drop generator, which can be fitted with different nozzles. Simulated rain with a drop diameter of 1 to 3 mm is produced at a rate of 8 to 12 mm h-1 by a rain generator with an area of 52 × 67 cm. The rain tower may be operated in conjunction with the wind tunnel in an open configuration. The windspeed can be decreased from a maximum of 8 m s-1 by decreasing the speed of the fan. The wind tunnel has its own internal lighting. When the wind tunnel is in a closed configuration, temperature and humidity can be controlled in the range 12 oC (62–80% r.h.) to 35 oC (22–50% r.h.). Data presented illustrate the use of this rain tower/wind tunnel complex to study dispersal of plant pathogen spores by rain-splash or wind.

An Oldershaw column has been operated with two negative systems; ethylene dichloride/toluene, and ethylene dichloride/224 trimethylpentane. The difference in surface tension between ethylene dichloride and toluene at 90°C. is about one-seventh of the difference between ethylene dichloride and 224 trimethylpentane at the same temperature. It is shown that this surface tension difference does not significantly effect the overall performance of a perforated plate column. Photographs taken show no apparent change in foam structure for the two systems at all boil up rates. Vapor-liquid equilibrium data has been determined for the system ethylene dichloride/224 trimethylpentane at 750 mm. mercury pressure. There is an azeotrope of composition, 77.0 mole % ethylene dichloride.