bluuebunny/crossref_metadata_2025 huggingface dataset:
Plant functional types – a strategic perspective
Authors: Semenova Galina, V. , van der Maarel Eddy
Published: May 2006

Abstract. This paper discusses the use of Plant Functional Types to describe vegetation types – from plant communities to formations – in order to understand the ecological constraints of plants and plant communities on a higher level of abstraction. The terminology around plant functional types, traits and strategies is in need of further clarification and unification. The use of the term plant functional type is recommended. We are in need of a total environmental framework in which, hierarchically or reticulately, plant functional types can be compared and interpreted.
Common data standards for recording relevés in field survey for vegetation classification
Authors: Mucina Ladislav , Schaminée Joop H.J. , Rodwell John S.
Published: May 2006

Abstract. In the framework of the European Vegetation Survey common data standards are proposed for recording phytosociological relevés for syntaxonomical classification. The authors wish to establish the notion that common data standards for recording phytosociological data can only be advantageous for advancing the credibility and application of vegetation science, and may stimulate other projects.
Management of a semi‐natural grassland; results from a 15‐year‐old experiment in southern Sweden
Authors: Hansson Margareta , Fogelfors Håkan
Published: May 2006

Abstract. Vegetation changes in a semi‐natural grassland of wooded meadow type that had been grazed for centuries are described following the introduction of various management regimes: mowing each year, mowing every third year, burning, mechanical removal of woody plants, chemical treatment of woody plants, continuous grazing and abandonment. The experiment was established in southern Sweden in 1972 and has been in progress for 15 years. In 1972, 1980 and 1986 the botanical composition in these plots was investigated in permanent subplots. The study clearly demonstrates that mowing or grazing is necessary to preserve community structure and that mowing is to be preferred in cases where maintaining species richness is of primary concern. Mowing every third year delayed vegetation change and prevented woody species from spreading. Therefore, periodic mowing might be an alternative way to preserve the flora. In contrast, yearly burning does not seem to be a viable management in this type of semi‐natural grassland. To preserve the open landscape regeneration of woody plants has to be prevented. However, in plots where woody plants were removed the typical grassland flora declined. Abandonment resulted in closed forest.
Classification of vegetation: Past, present and future
Authors: Mucina Ladislav
Published: May 2006

Abstract. This paper is a report on the past, status‐quo and perspectives of vegetation classification, still a major occupation of many vegetation scientists. The history of vegetation classification is discussed against a background of several controversial issues such as the problem of continuum vs. discontinuum, naturalness vs. arbitrariness of the nature of plant communities, universality vs. ad hoc character of syntaxonomic schemes, as well as classical versus numerical approaches to data analysis for classification purposes.

The development of the methodology of vegetation science and the present image of vegetation classification is documented by a bibliometric analysis of the publication record of four majorjournals: Journal of Vegetation Science, Vegetatio, Phytocoenologia and Tuexenia. This analysis revealed a persisting controversy between traditional and numerical approaches to vegetation classification. A series of important changes in vegetation science (foundation of new journals, change of editorial policy by the established, important meetings) punctuate a period called the ‘Innovation period’.

Several trends in the development of methods of vegetation systematics are summarized under the headings formalism, pluralism, functionalism, pragmatism and indeterminism. Some new features, such as the development and improvement of numerical tools, use of large data banks and attempts to summarize the theory of vegetation classification are discussed. The new growth‐form system of Barkman initiated a revival of physiognomy‐based vegetation classification. Within this framework the use of the character‐type concept and the development of new numerical methods for studying the hierarchical structure of character‐set types seems to be a promising approach. The achievements of population biology and ecophysiology have affected vegetation science by emphasizing the functionality of species within plant communities. The use of guilds and other functional groups has experienced an increasing interest from vegetation scientists. Applied in vegetation science, fuzzy‐set theory has bridged the techniques of classification and ordination of plant communities.
Transect‐based patch size frequency analysis
Authors: Xiaobing Dai , van der Maarel Eddy
Published: May 2006

Abstract.A new, transect‐based patch size detection method for species pattern is proposed which improves results obtained with methods described earlier. The method was tested on an extensive artificial data set together with three of the existing methods considered best: Two and Three Term Local Quadrat Variance (T2LQV and T3LQV) and New Local Variance (NLV). The TLQV methods recovered only some of the existing patterns and were heavily dependent on inter‐patch distances, whereas NLV almost always produced curves with oscillations. In addition a significance test is proposed, while such a test is seldom found in the earlier methods.

Our method, PASFRAN, determines the frequencies of runs with 1, 2, 3, etc. quadrats containing a certain species and compares those with frequencies based on Monte Carlo simulated random configurations. The comparison is performed for each run length and the significance of the deviation between observed and expected frequencies can be calculated on the basis of a large number of simulations. Because this approach may be considered a case of multiple testing, a Bonferroni correction on the significance level was applied. The method can also be used for the detection of inter‐patch distances. In addition, run lengths can be grouped and the test can be applied to the frequencies of combinations of run lengths.

The method can detect dominance patches when quantitative data on the occurrence of plant species are available. In the same way, it can detect multi‐species patterns using sample scores from an ordination analysis such as correspondence analysis. An extension towards composite, higher‐order patterns is under investigation. The new method appeared to be effective in recovering artificial patterns, while it is not influenced by the relative values of patch size and inter‐patch distance. When applied to the distribution of cow dung patches and certain plant species along a transect of 500 quadrats of 10 cm × 10 cm in an alvar limestone grassland, it produced straightforward and realistic results as compared with other methods and field impressions.
Similarity between seed bank and vegetation in Mediterranean grassland: a predictive model
Authors: Peco B. , Ortega M. , Levassor C.
Published: May 2006

Abstract. The similarity in species composition between seed bank and vegetation was analysed in Mediterranean grasslands in relation to altitude, topography and grazing. Soil samples were collected in permanent plots in autumn at the end of the summer drought period and in spring, before the new seed fall and after the natural winter seed stratification. The seed bank composition was determined by greenhouse germination over a nine‐month period. Presence/absence of species in the standing vegetation throughout the complete annual cycle, and the percentage area of bare ground in October, were recorded in the same plots. The species composition of the standing vegetation is clearly determined by altitude, topography and grazing, while the floristic composition of the seed banks is only related to altitude and topography in the case of autumn seed bank and with any of the three factors in the spring seed bank. Relative abundances of grasses, legumes and forbs also show different patterns in vegetation and seed bank data. Sørensen similarity between the autumn seed bank and the vegetation declines as altitude rises, but there are no significant differences for topography and grazing. This similarity decreases in the case of the spring seed bank and does not show any significant relationship with any of the factors. The perennial/ annual ratio and the proportion of bare soil in October are proposed as explanatory variables in a predictive model of similarity between the seed composition of the seed bank and vegetation.
On explicit formulas of edge effect correction for Ripley'sK‐function
Authors: Goreaud François , Pélissier Raphaël
Published: May 2006

Abstract.The analysis of spatial pattern in plant ecology usually implies the solution of some edge effect problems. We present in this paper some explicit formulas of edge effect correction that should enable plant ecologists to analyse a wider range of real field data.

We consider the local correcting factor of edge effect for Ripley'sK‐function, that can also be used for other statistics of spatial analysis based on the counting of neighbours within a given distance. For both circular and rectangular study areas, we provide a review of explicit formulas and an extension of these formulas for long and narrow plots. In the case of irregular‐shaped study plots, we propose a generalization of the method that computes edge effect correction by excluding triangular surfaces from a simple (rectangular or circular) initial shape.

An example in forest ecology, where the soil characteristics determine a study plot of complex shape, illustrates how this edge effect correction can be effective in avoiding misinterpretations.
Challenging Theophrastus: A common core list of plant traits for functional ecology
Authors: Weiher Evan , van der Werf Adrie , Thompson Ken , Roderick Michael , Garnier Eric , Eriksson Ove
Published: May 2006

Abstract. Ecologists need a common language of plant traits in order to make comparisons across regions and scales, pool data, and maximize the utility of the data. To develop such a set of traits we began with the primary challenges faced by plants: dispersal, establishment, and persistence in order to identify fundamental traits. Most of these traits are hard to measure, but advances in comparative ecology have suggested a number of easy to measure analogs. Unfortunately, some of the fundamental traits have no simple analog. The common core list includes: seed mass, seed shape, dispersal mode, clonality, specific leaf area, leaf water content, height, above‐ground biomass, life history, onset of flowering, stem density, and resprouting ability. Most of the traits can be measured quantitatively, but several traits on the list must still be measured qualitatively due to logistical problems or lack of an easy analog. Key problem areas include: dispersal ability, capacity for vegetative spread, germination, palatability, plasticity, and all the various below‐ground traits. Comparative studies need to address these problem areas. The common core list is suggested as a common starting point for studies of functional ecology. The idiosyncrasies of regional floras and specific research agendas will dictate which traits can be ignored and those that need to be added.
Vegetation development in dune slacks: the role of persistent seed banks
Authors: Bekker R.M. , Lammerts E.J. , Schutter A. , Grootjans A.P.
Published: May 2006

Abstract. The soil seed bank composition was determined at four sites in the dune slack ‘Koegelwieck’ on the Dutch Wadden Sea island of Terschelling. At three different sites in the slack, where sod‐cutting experiments down to the mineral sand had been carried out, the established vegetation and seed bank were assessed after 5, 9 and 39 yr of undisturbed development, respectively. In addition, a fourth site in the slack was investigated, where vegetation development had proceeded for 80 yr since plant colonization of bare soil and where nowadays a vegetation dominated by Calamagrostis epigejos and Salix repens occurs. Together these four sites can be regarded as a chronosequence of dune slack formation.

Clear time sequences were detected in the seed bank data. Many late successional species showed a significant increase in the number of seeds during the succession. Some of the early successional basiphilous pioneer species such as Anagallis minima, Centaurium littorale, Littorella uniflora, Radiola linoides and Samolus valerandi, showed either a decrease during the time of succession or an optimum in the vegetation while remaining present in the seed bank in low but detectable numbers. They could, therefore, play a role in re‐establishment of the vegetation after sod‐cutting. One of the target species, Schoenus nigricans, established within a few years after removal of the sod. However, no seeds of this species have been detected in the soil below either of the successional stages. Based on the species disappearance from the established vegetation and based on the independent data of Thompson et al. (1997) an estimation of seed longevity could be made for several Red List species of wet dune slacks.
Sampling strategies for the assessment of tree species diversity
Authors: Gimaret‐Carpentier Clémentine , Pélissier Raphaël , Pascal Jean‐Pierre , Houllier François
Published: May 2006

Abstract. This paper aims at proposing efficient vegetation sampling strategies. It describes how the estimation of species richness and diversity of moist evergreen forest is affected by (1) sampling design (simple random sampling, random cluster sampling, systematic cluster sampling, stratified cluster sampling); (2) choice of species richness estimators (number of observed species vs. non‐parametric estimators) and (3) choice of diversity index (Simpson vs. Shannon). Two sites are studied: a 28‐ha area situated in the Western Ghats of India and a 25‐ha area located at Pasoh in Peninsular Malaysia. The results show that: (1) whatever the sampling strategy, estimates of species richness depend on sample size in these very diverse forest ecosystems which contain many rare species; (2) Simpson's diversity index reaches a stable value at low sample sizes while Shannon's index is affected more by the addition of rare species with increasing sample size; (3) cluster sampling strategies provide a good compromise between cost and statistical efficiency; (4) 300 ‐ 400 sample trees grouped in small clusters (10–50 individuals) are enough to obtain unbiased and precise estimates of Simpson's index; (5) the local topography of the Western Ghats has a major influence on forest composition, the steep slopes being richer and more diverse than the ridges and gentle slopes; (6) stratified cluster sampling is thus an interesting alternative to systematic cluster sampling.
Response patterns of Vaccinium myrtillus and V. vitis‐idaea along nutrient gradients in boreal forest
Authors: Mäkipää Raisa
Published: May 2006

Abstract. The relationships between biomass of dwarf shrub species and nutrient gradients of forest soils was studied under field conditions in boreal forests. The biomass‐response curves of Vaccinium myrtillus and V. vitis‐idaea were fitted against soil nutrient gradients using Generalized Linear Models (GLM). Ecological niches of Vaccinium myrtillus and V. vitis‐idaea were evaluated, and effects of nitrogen addition (manipulation of the nutrient gradient) on response function were tested.

The Vaccinium species showed statistically significant Gaussian responses along soil nitrogen, phosphorus and calcium gradients, but not along other gradients (K and Mg). Furthermore, manipulation of the nitrogen gradient seemed to have a minor effect on response functions, i.e. addition of nitrogen did not change ecological niches of these species. Ecological optima of V. myrtillus and V. vitis‐idaea on the nutrient gradients were about the same. This study suggests that differences in dominance between Vaccinium myrtillus and V. vitis‐idaea in boreal forest is not determined by nutrient gradients, but may rather be explained by light conditions and/or moisture availability.
Predictive mapping of alpine grasslands in Switzerland: Species versus community approach
Authors: Zimmermann Niklaus E. , Kienast Felix
Published: May 2006

Abstract. Separate logistic regression models were developed to predict the distribution and large‐scale spatial patterns of dominant graminoid species and communities in alpine grasslands. The models are driven by four bioclimatic parameters: degree‐days of growing season (basis 0 °C), a moisture index for July, potential direct solar radiation for March, and a continentality index. Geology and slope angle were used as a surrogate for nutrient availability and soil water capacity. The bioclimatic parameters were derived from monthly mean temperature, precipitation, cloudiness and potential direct solar radiation. The environmental parameters were interpolated using a digital elevation model with a resolution of 50 m. The vegetation data for model calibration originate from field surveys and literature. An independent test data set with samples from three different climatic zones was used to test the model. The degree of coincidence between simulated and observed patterns was similar for species and communities, but the κ‐values for communities were generally higher (κ= 0.539) than for species (mean individual κ= 0.201). Information on land use was detected as a major factor that could significantly improve both the species and the community model. Nevertheless, the climatic factors used to drive the model explained a major part of the observed patterns.
Species diversity, niche metrics and species associations in harvested and undisturbed bogs
Authors: Soro Antonella , Sundberg Sebastian , Rydin Håkan
Published: May 2006

Abstract. Competition is considered an important force in structuring plant communities and in governing niche relations, but communities recovering from disturbance, may be less governed by species interactions and less orderly organized. To address this issue, we studied species richness, abundance and patterns of association between plant species at three spatial scales (1 m2, 1/25 m2, 1/625 m2) in two ombrotrophic mires in east‐central Sweden. One was at a secondary successional stage following peat extraction 50 yr ago and the other was undisturbed. Peat extraction leads to a change in hydrology which is slowly restored by the formation of new peat. Niche breadth and niche overlap along the gradient of height above the water table were calculated for the five common Sphagnum species occurring at both mires in an attempt to better understand differences in species co‐occurrence at each mire.

Species cover differed between the mires, and the number of species per plot was higher in the undisturbed community at all scales, suggesting that the degree of species intermingling was greater than at the harvested site. At all scales, the number of non‐random associations was higher, and niche overlap lower among ecologically similar species (e.g. hollow Sphagnum species) in the undisturbed mire. These differences indicate that random events are important in colonization, and that biotic interactions between neighbours later result in a higher degree of non‐randomness.

In addition, we surveyed a number of abandoned peat pit sites to test the effect of disturbance for species composition at a regional scale. Ombrotrophic peat pits contained several Sphagnum species normally associated with minerotrophic mires, and species of wooded mires occurred frequently in peat pits, making them more species‐rich than undisturbed bogs. There were also Sphagnum species new to, or rare in, this part of Sweden which indicates effective long‐distance dispersal. Even 50 yr after peat extraction had ceased, the vegetation had not recovered to its original composition.
Community structure of epilithic and endolithic algae and cyanobacteria on cliffs of the Niagara Escarpment
Authors: Matthes‐Sears U. , Gerrath J.A. , Gerrath J.F. , Larson D.W.
Published: May 2006

Abstract. In order to understand how communities of rock‐inhabiting micro‐organisms are spatially organized, rock samples and environmental variables were collected from five cliff sites in Ontario, Canada. Algae and cyanobacteria were extracted from the epilithic zone (rock surface) and endolithic zone (subsurface) of 180 samples, and the frequency of each taxon (genus or larger) was determined. Multivariate statistical analyses were used to determine (1) the variation in community composition on different spatial scales; (2) differences in community composition between surface and subsurface; and (3) the environmental constraints of community structure. 13 taxa of cyanobacteria and 12 taxa of eukaryotic algae were identified in the endolithic zone, and 17 and 14 in the epilithic zone, respectively. The most frequent taxa were similar in both zones, but MANOVA of species frequencies showed significant differences between endolithic and epilithic communities. DCA and CCA showed that geographic‐scale variation in community composition was the dominant trend in the data for both surface and subsurface. Cyanobacteria and eukaryotic algae showed a clear separation on the first ordination axis. When the geographic‐scale variation was removed in a partial ordination, the separation of organisms by kingdoms disappeared and epi‐ and endolithic ordinations were no longer similar. Light then appeared to control the endolithic species composition, while other factors, possibly moisture‐related, were suggested for the epilithic community. Despite biomass and productivity that varies mostly at scales of < 1m2, we conclude here that species composition and its environmental constraints vary at small as well as larger scales.
Future wildfire in circumboreal forests in relation to global warming
Authors: Flannigan M.D. , Bergeron Y. , Engelmark O. , Wotton B.M.
Published: May 2006

Abstract. Despite increasing temperatures since the end of the Little Ice Age (ca. 1850), wildfire frequency has decreased as shown in many field studies from North America and Europe. We believe that global warming since 1850 may have triggered decreases in fire frequency in some regions and future warming may even lead to further decreases in fire frequency. Simulations of present and future fire regimes, using daily outputs from the General Circulation Model (GCM), were in good agreement with recent trends observed in fire history studies. Daily data, rather than monthly data, were used because the weather and, consequently, fire behavior can change dramatically over time periods much shorter than a month. The simulation and fire history results suggest that the impact of global warming on northern forests through forest fires may not be disastrous and that, contrary to the expectation of an overall increase in forest fires, there may be large regions of the Northern Hemisphere with a reduced fire frequency.
Seedling establishment in relation to microhabitat variation in a windthrow gap in a boreal Pinus sylvestris forest
Authors: Kuuluvainen Timo , Juntunen Pauli
Published: May 2006

Abstract. The characteristics of microhabitats of established Pinus sylvestris and Betula seedlings were studied in a small windthrow gap in a mature P. sylvestris‐dominated forest in the Petkeljärvi National Park in eastern Finland. Seedlings were strongly clustered in disturbed microhabitats, particularly uprooting pits and mounds, formed by tree falls. They covered 3% of the 0.3.ha study area consisting of the gap and some of the forest edge. Although Betula occurred only as scattered individuals in the dominant canopy layer of the forest, it accounted for 30% of the seedlings found in the study area. Betula regeneration was almost completely restricted to pits and mounds, where 91% of the seedlings were found. Uprooting spots were also the most important regeneration microhabitats for Pinus, where 60% of the seedlings grew, even though the seedlings were found in other substrates as well, particularly on sufficiently decomposed coarse wood. Undisturbed field‐ and bottom‐layer vegetation had effectively hindered tree seedling establishment, which emphasises the role of soil disturbance for regeneration. While the establishment of seedlings was found to be clearly determined by the availability of favourable regeneration microhabitats, the early growth of seedlings was affected by a complex interaction of environmental variables, including the type of microhabitat, radiation environment and interferences caused by competing seedlings and adjacent trees. In the most important regeneration microhabitats, i.e. in uprooting pits and on mounds, the distributions of the local elevations of Pinus and Betula seedlings were different. Pinus seedlings occurred closer to ground level, i.e. on the fringes of pits and lower on mounds, while Betula seedlings grew deeper in pits and higher on mounds. The position of the Betula seedlings indicate that they may have a competitive advantage over Pinus seedlings in the dense seedling groups occurring in uprooting spots. We suggest that this initial difference in Pinus and Betula establishment may affect the subsequent within‐gap tree species succession and can, in part, explain the general occurrence of Betula in conifer‐dominated boreal forests.
Simulated pattern formation around artificial waterholes in the semi‐arid Kalahari
Authors: Jeltsch Florian , Milton Suzanne J. , Dean W. Richard J. , van Rooyen Noel
Published: May 2006

Abstract. Sinking boreholes to tap groundwater supplies facilitated expansion of all‐year round livestock production into the semi‐arid Kalahari. Increased grazing and trampling pressure around the boreholes often caused vegetation changes and range degradation. The long‐term influences of cattle grazing on vegetation pattern around watering points in the southern part of the semi‐arid Kalahari are investigated using a grid‐based simulation model. Shrub‐grass dynamics are modelled for two regimes with high and low rainfall and under various stocking rates. Results indicate the formation of distinct vegetation zones (‘piosphere’ zones) at the high rainfall site. Under all tested stocking rates distinct zones of bare soil, woody shrubs and a mixed grass‐shrub savanna develop. The piosphere zones expand outwards at a rate correlated with the grazing pressure. At the lower‐rainfall site zone development is limited and influenced by rainfall. Under abnormally high stocking rates an increase in shrub cover occurs within 50 yr under the low rainfall regime, leading to less distinct zones than under the high rainfall scenario. Modelling results suggest that the recovery potential of shrub‐encroached piosphere zones after withdrawal of cattle is negligible in a time span of 100 yr.
A long‐term study of Pinus banksiana population dynamics
Authors: Kenkel N.C. , Hendrie M.L. , Bella I.E.
Published: May 2006

Abstract. The long‐term population dynamics of a pure, naturally‐established stand of Pinus banksiana (jack pine) in southeastern Manitoba, Canada is described. The study was initiated at stand age 15, when all 468 trees in a plot were mapped and their trunk diameter at breast height (DBH) measured. The plot was remeasured eight times — every five years (six years in one case) — and mortality and DBH changes recorded. Total mortality over the 41‐yr study period was ca. 84 %. Mortality was initially very low, increased once the stand entered the self‐thinning stage from ages 25–46, and declined at ages 46–56. Mortality was restricted to the smallest size classes throughout. The stand reached the self‐thinning line at ca. age 30. The self‐thinning slope was significantly less steep than the theoretically expected value of −0.5.

The distribution of DBH values was initially symmetric, showed increasing positive skewness during the period of highest mortality, and became symmetric again at later stages. Size (DBH) inequality was highest just prior to the onset of density‐dependent mortality, and subsequently declined. Tree DBH values were positively autocorrelated both initially and at later stages of stand development, but were spatially independent during the period of highest density‐dependent mortality. The stand initially had a strongly clumped pattern at all spatial scales. Patterns of mortality were non‐random during stand development, however, resulting in increased spatial regularity over time. Mortality was initially restricted to high density patches of the stand, but occurred throughout the plot once the self‐thinning line was reached. Mortality during the self‐thinning stage deviated from random expectation at local spatial scales (1–2m radius), suggesting that individuals were competing with their immediate neighbours. It is argued that an integrated approach, incorporating both population size and spatial structures, is essential in improving our understanding of long‐term plant population dynamics.
Seed floating ability and distribution of alpine plants along a northern Swedish river
Authors: Danvind Maria , Nilsson Christer
Published: May 2006

Abstract. In this study we tested the hypothesis that diaspore buoyancy is an important factor in determining the distribution range of riparian plants, by measuring the floating capacity of fruits and seeds from 17 alpine vascular plant species during 1 yr. Minimum, median, mean, and maximum (≤ 1 yr) floating times of fruits and seeds were then related to the downstream distribution of plants along the free‐flowing Vindel River in northern Sweden. The distances from the alpine headwater region to the most downstream occurrence of plants, and to the cessation of a more continuous distribution, were evaluated. The variation in downstream limits of plants could not be statistically explained by variation in seed buoyancy between species, indicating that floating ability of seeds is not important for plant distribution patterns. There may be several reasons for this, and they may differ between species.
Resprouting of Quercus suber in NE Spain after fire
Authors: Pausas Juli G.
Published: May 2006

Abstract. Many Mediterranean species have evolved strategies that allow them to survive periodic wildfires. Quercus suber trees resprout after fire, some from stem buds and others from basal buds only. In the former case the canopy recovers quickly. In the latter case the stem dies but the tree survives and regrows from basal sprouts. The probability of stem death and the degree of height recovery were studied after a fire in a Q. suber forest in NE Spain using logistic regression analysis. The results suggest that most trees survive after fire; the probability of stem death is negatively related to tree diameter; and recovery is positively related to tree diameter and to bark thickness. Implication for management and conservation of cork‐oak forests are discussed.
Can we trust gradients extracted by Detrended Correspondence Analysis?
Authors: Ejrnæs Rasmus
Published: May 2006

Abstract. In this study, data from dry temperate grassland vegetation in Denmark are used to compare the predictive power of gradients obtained by ordination. One of the problems of ordination methods based on weighted averaging, namely the assumption of symmetric, unimodal response curves, is investigated by smoothing species responses to simple and complex gradients respectively.

It was found that species response types to a pH gradient are diverse and often deviate from a unimodal, symmetrical shape. Bimodal responses were also found, but they disappeared when more influential gradients were considered. Many species showed truncated responses with optima near gradient ends.

In order to assess the impact of unrealistic response assumptions and reported problems with instability on the performance of DCA, the predictive potentials of measured variables and coenoclines extracted by DCA were compared. Despite field data violating the assumption of unimodal response, DCA was found to extract gradients predicting species abundance better than the environmental variables available. Shortcomings and advantages of indirect and direct methods in plant ecology are discussed.
Classification of dry grassland vegetation in Denmark
Authors: Bruun Hans Henrik , Ejrnæs Rasmus
Published: May 2006

Abstract. A hierarchic classification of Danish semi‐natural grassland vegetation on well‐drained soils is presented. TWINSPAN was used for clustering of 614 samples of grassland vegetation showing floristic gradients and turnover in species composition in more dimensions. The optimal hierarchic level of clustering was determined by indicator species analysis. The classification was interpreted in terms of variables relating to abiotic environment and vegetation structure and to major ecoclines previously identified by gradient analysis. The 12 final clusters were compared to syntaxa of formal phytosociology and to communities in the British Vegetation Classification. Criteria for achieving floristically homogeneous clusters without sacrificing the ecological interpretability and validity of the clusters in time and along geographical gradients are discussed.
Three Catilinarian Dates
Authors: Holmes T. Rice
Published: May 2006

I. The date of the consular election in 63 B.C.—Cicero in his speech Pro Murena, which was delivered in November, 63 B.C, after Catiline quitted Rome, said that before the consular election of that year Catiline used to appear in public surrounded by troops from Faesulae and Arretium, and that in a private gathering (contione domestica) he had declared that the only true champion of the wretched was one who shared their wretchedness, that they should put no trust in the promises of the well-to-do, and that their destined leader must be utterly fearless and conspicuously miserable. The Senate, he reminded the jury, decreed therefore on his motion that the election, which had been fixed for the following day, should be postponed, in order that there might be an opportunity of discussing Catiline's conduct. On the following day, accordingly, he challenged Catiline to explain; and Catiline made the reply, which has been so often quoted, that in the State there were two bodies, one feeble with a weak head, the other strong but without a head. The Senate, Cicero thought, did not on this occasion act with sufficient vigour, for some could not realize that there was any danger, while others were too timid; and Catiline stalked triumphantly out of the House. Cicero, taking alarm at the slackness of the Senate and knowing that Catiline was bringing armed conspirators to the Field of Mars, went thither himself wearing a breastplate and accompanied by a bodyguard; whereupon all the respectable electors, seeing, as he had intended, that he was in peril, rallied round Murena. Then followed the election, in which Murena and Silanus were returned.
An Editor Recalls Some Hopeless Papers
Authors: Hodges Wilfrid
Published: May 2006

§1. Introduction. I dedicate this essay to the two-dozen-odd people whose refutations of Cantor's diagonal argument (I mean the one proving that the set of real numbers and the set of natural numbers have different cardinalities) have come to me either as referee or as editor in the last twenty years or so. Sadly these submissions were all quite unpublishable; I sent them back with what I hope were helpful comments. A few years ago it occurred to me to wonder why so many people devote so much energy to refuting this harmless little argument—what had it done to make them angry with it? So I started to keep notes of these papers, in the hope that some pattern would emerge.

These pages report the results. They might be useful for editors faced with similar problem papers, or even for the authors of the papers themselves. But the main message to reach me is that there are several points of basic elementary logic that we usually teach and explain very badly, or not at all.

In 1995 an engineer named William Dilworth, who had published a refutation of Cantor's argument in the Transactions of the Wisconsin Academy of Sciences, Arts and Letters, sued for libel a mathematician named Underwood Dudley who had called him a crank ([9] pp. 44f, 354).
Completely Additive Liftings
Authors: Farah Ilijas
Published: May 2006

The purpose of this communication is to survey a theory of liftings, as developed in author's thesis ([8]). The first result in this area was Shelah's construction of a model of set theory in which every automorphism ofP(ℕ)/ Fin, where Fin is the ideal of finite sets, istrivial, or inother words, it is induced by a function mapping integers into integers ([33]). (It is a classical result of W. Rudin [31] that under the Continuum Hypothesis there are automorphisms other than trivial ones.) Soon afterwards, Velickovic ([47]), was able to extract from Shelah's argument the fact that every automorphism ofP(ℕ)/ Fin with a Baire-measurable lifting has to be trivial. This, for instance, implies that in Solovay's model ([36]) all automorphisms are trivial. Later on, an axiomatic approach was adopted and Shelah's conclusion was drawn first from the Proper Forcing Axiom (PFA) ([34]) and then from the milder Open Coloring Axiom (OCA) and Martin's Axiom (MA) ([48], see §5 for definitions). Both shifts from the quotientP(ℕ)/ Fin to quotients over more general idealsP(ℕ)/Iand from automorphisms to arbitrary ho-momorphisms were made by Just in a series of papers ([14]-[17]), motivated by some problems in algebra ([7, pp. 38–39], [43, I.12.11], [45, Q48]) and topology ([46, p. 537]).
Domains for Computation in Mathematics, Physics and Exact Real Arithmetic
Authors: Edalat Abbas
Published: May 2006

We present a survey of the recent applications of continuous domains for providing simple computational models for classical spaces in mathematics including the real line, countably based locally compact spaces, complete separable metric spaces, separable Banach spaces and spaces of probability distributions. It is shown how these models have a logical and effective presentation and how they are used to give a computational framework in several areas in mathematics and physics. These include fractal geometry, where new results on existence and uniqueness of attractors and invariant distributions have been obtained, measure and integration theory, where a generalization of the Riemann theory of integration has been developed, and real arithmetic, where a feasible setting for exact computer arithmetic has been formulated. We give a number of algorithms for computation in the theory of iterated function systems with applications in statistical physics and in period doubling route to chaos; we also show how efficient algorithms have been obtained for computing elementary functions in exact real arithmetic.
Sepulchral Relief from Attica, at Winton Castle, Haddingtonshire
Authors: Brown G. Baldwin
Published: May 2006

The Attic sepulchral relief reproduced on Plate B, is the principal object in an interesting collection of antiques formed by the late Baroness Ruthven of Winton Castle, Haddingtonshire, and assigned by her to the Museum of the Society of Antiquaries of Scotland. The bulk of the collection, consisting of vases, mostly of a small size and of the black figured kind, but including several good Attic lekuthoi, is now deposited in the Museum, but the most notable objects remain still at Winton Castle. These comprise a fine hydria 13½ inches high, with a red-figured design (Paris, Helen and other figures with Erotes, etc.) very delicately drawn in the best style, and two sepulchral reliefs, of which one is small and of poor workmanship, and the other, now for the first time published, an interesting and charming work.
Recent discoveries in Eastern Cilicia
Authors: Bent J. Theodore
Published: May 2006

Hearing of extensive and unidentified ruins on the banks of the river Jeihan (the ancient Pyramus) at a spot now called Bodroum to the east of the Cilician plain, just as the river enters the plain from the gorges of the Anti-Taurus, we determined to visit the site. The result of our explorations, made in the early months of this year, are as follows.

Our route took us past the rock of Anazarba and Kars Bazaar, at which places we decided to spend a few days, and though the spots have both been previously described we were able to add a few points to the information concerning them, both epigraphical and topographical.

Anazarba.—Caesarea penes Anazarbum, as Ptolemy calls it, was second only in importance to Tarsus of the cities of Cilicia during the days of imperial Rome, and was the metropolis of the eastern portion of the great plain. The town was built at the foot of a long rocky mountain, rising like an island out of the plain for the extent of three miles and attaining an altitude of 2,000 feet. The walls as they at present stand are of Armenian and Saracenic construction, enclosing a parallelogram, one side of which is protected by the mountain; but they contain many portions of Roman work, notably the great southern gate formed by a triumphal arch erected in the time of Justinian, when that emperor restored the town after it had been ruined by an earthquake.
The Homeric Talent, its Origin, Value, and Affinities
Authors: Ridgeway William
Published: May 2006

This paper is an endeavour to discover (1) the origin, (2) the value, and (3) the affinity of the Talent of the Homeric Poems to other systems. In those Poems we find two systems of denominating value, the one by the ox (or cow), or the value of an ox, the other by the talent (τάλαντον). The former is the one which has prevailed and does still prevail in barbaric communities, such as the Zulus, where the sole or principal wealth consists in herds and flocks. For several reasons we may assign to it priority in age as compared with the talent. For as it represents the most primitive form of exchange, the barter of one article of value for another, before the employment of the precious metals as a medium of exchange, consequently the estimation of values by the ox is older than that by a talent or ‘weight’ of gold, or silver, or copper. Again in Homer all values are expressed in so many beeves, e.g.

(Il. vi. 236.)

The talent on the other hand is only mentioned in relation to gold; for we never find any mention of a talent of silver. But the names of monetary units hold their ground long after they themselves have ceased to be in actual use, as we observe in such common expressions as ‘bet a guinea,’ or ‘worth a crown,’ although these coins themselves are no longer in circulation.
Sculpture in Sicilian Museums
Authors: Farnell L. R.
Published: May 2006

On travelling through Sicily in the spring of last year, I studied as carefully as my time allowed the classical remains in the museums of Palermo, Girgenti, Catania and Syracuse, and in the lack of any general catalogue of those antiquities and of any accessible information concerning them, the following notices accompanied by a few sketches from photographs I was able to take may be of slight service. I only wish to speak of the more important objects that, as far as I know, have not yet been at all or sufficiently published. Valuable as these objects are, I have been greatly surprised at the paucity of literary reference to them. The coin-collections and the architecture of the island have been carefully studied and written on: but an Englishman might seek in vain for much enlightenment in the archaeological publications of Sicily itself concerning its other antiquities. The art-journal entitled La Sicilia artistica ed archeologica refers almost entirely to mediaeval and modern paintings; and has published nothing classical except the Venus of Syracuse with two or three other statues of the goddess. Possibly the Bulletino della commissione di Antiquità e belle arti di Sicilia may have contributed much to classical archaeology, but unfortunately nothing of this publication is to be found in England except an isolated number of the year 1864 in the British Museum Library.
The Ram in Aeginetan Sculpture
Authors: Murray A. S.
Published: May 2006

Pausanias (X. 17, 6) seeks to convey a definite notion of the rams in Sardinia by saying that they had the form which an Aeginetan sculptor would give a wild ram, except for a shagginess on the breast which was too thick for Aeginetan art. The spareness of form implied here, and still more distinctly in the extraordinary swiftness which he ascribes to these rams, seems to agree very well with what remains of the sculpture of Aegina; and in calling attention to this circumstance (Greek Sculpture, p. 187) I supposed that Pausanias had in his mind only the general characteristic of the Aegina school, to which he refers on other occasions. But it occurs to me now that he may have been thinking specially of Onatas and the statue of Hermes Kriophoros, which he had seen at Olympia and described (v. 27,8). Onatas receives great praise from Pausanias (v. 25, 7), and no doubt was to him a representative of the school of Aegina.
Actors with Bird-Masks on Vases
Authors: Smith Cecil
Published: May 2006

Plate XIV. B represents an unpublished vase of the British Museum, which originally formed part of the Burgon Collection: it appears to have been found in Italy in 1835. It is an oinochoè with black figures on a red panel, and may be assigned to a period between about 500 and 450 B.C.

A representation upon an amphora published by Gerhard in his Trinkschalen, Pl. XXX. Figs. 1—3, so evidently relates to a similar subject, that it is here reproduced for comparison on the same plate (Fig. A). This picture shows us an auletes playing upon the double flutes in the presence of two grotesque-looking figures, apparently human, who are closely draped in long cloaks, himatia, and to whom his back is turned. That the heads of these two figures are intended to represent the heads of some sort of bird is evident from the beak-like conformation of the features, and by the purple crests which rise vertically from the crown. Gerhard, in publishing this vase, has for want of any better explanation described this scene as representing a parody or a mummery symbolical of a cock-fight. Viewed, however, in the light of the evidence afforded by the British Museum vase, this theory seems to me improbable: yet I am bound to say that I am unable to advance any explanation which seems entirely satisfactory.
A Summer in Phrygia: Part II
Authors: Anderson J. G. C.
Published: May 2006

After exploring the north side of the Lycos valley, and before proceeding down the right bank of the Maeander towards Ortakche (see Part I. init.), we spent a short time in the Phrygo-Lydian borderland, seeking for some evidence to clear up the uncertainties attaching to the situation of Sala, Tralla, Aetos, Kallatebos, and Apollonos-Hieron. (See Plate IV.)

In discussing this district, I enjoy the advantage of having before me the work of three previous explorers, Prof. Ramsay, Prof. Radet, and the late Dr. Karl Buresch. I have been careful to quote the opinions of these critics, though I must sometimes differ from them, because it is convenient for the reader to have before him all the views that are, or have been, held in regard to each town. Amid a few differences, I find myself in general agreement with Prof. Ramsay and Dr. Buresch. In the development of their views from the earliest to the latest stage there is, happily, a steady approximation towards the same results; and yet, by a strange accident, this approximation was quite unconscious, for Dr. Buresch knew only Prof. Ramsay's earliest views, while Prof. Ramsay in his latest work had only a very imperfect knowledge of Dr. Buresch's earliest opinions. I regret that I am obliged to differ more widely from the results reached by M. Radet, and, as some readers might put a wrong construction on such expressions of dissent, I would here record my appreciation of the value of his fresh and suggestive work. When a subject is in process of growth, every suggestion and every fresh point of view are valuable, and it is only by due consideration and open criticism of all proposed combinations that we can cherish the hope of ultimately reaching, or approximating to, the truth.