bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vegetation of a coastal sand dune system in southern New Zealand
Authors: Sykes Martin T. , Wilson J. Bastow 
Published: May 2006

The introduction of vigorous exotic species has destroyed much of the native sand dune vegetation along the coasts of South Island, New Zealand. However, some dunes built by the native cyperad Desmoschoenus spiralis still remain in the southwest.The dunes at Cole Creek, on the West coast of South Island, were chosen as a relatively pristine study area. 15 transects were laid through semi‐fixed dunes into dwarf forest. Environmental measurements were taken at regular intervals through the dunes: pH, soil moisture, organic matter, conductivity, nutrient status and elevation. Classification and ordination of these data demonstrated that two major environmental areas were present ‐ open dune and dwarf forest ‐ with an abrupt ecotone between them. Vegetation analyses revealed a loosely‐banded pattern, parallel to the sea. Vegetation types with few but constant species such as Desmoschoenus spiralis and Calystegia soldanella, predominated in the open dune. Forest species were rarely found seaward of the dune/forest boundary, though there was evidence the Spatial Mass Effect was operating.Multiple regression and canonical correlation of the vegetation and environmental factors showed that the main factors affecting vegetation patterns were the environmental complex related to distance from the sea, elevation above mean tide, soil alkalinity and moisture.
Simulation modeling of the effects of site conditions and disturbance history on a boreal forest landscape
Authors: Fulton Mark R. 
Published: May 2006

Abstract. Computer simulations were used to elaborate hypotheses about controls on forest structure and composition in a 0.7 km ≤ area of boreal forest in Central Sweden. DBH and species of all adult trees and stand conditions were recorded for 57–10 m radius plots. Ordination of these data suggested that nutrient‐availability and time‐since‐disturbance were the main controls of forest composition and structure within the area.The simulation model couples equations representing the effect of tree canopy structure and biomass on light and soil conditions with equations representing the effect of these conditions on reproduction, growth and mortality in height cohorts of trees on a 0.1 ha patch. Nitrogen‐availability levels for each modeled plot were simulated by species‐specific growth multipliers. The model was run for 400 simulated yr at six levels of N availability. Age and N status of each study plot were inferred by matching with the most similar model output. Inferred ages agreed with what is known of the disturbance history, and site factors related to soil fertility were correctly correlated with the inferred N status.The consequences of size‐selective disturbance were explored by model experiments. Biomass was removed from large or small size classes at 100 ‐ 200 yr and the simulations were run for an additional 300 yr. Disturbed stands of high N status often became similar to undisturbed stands of different N status. Size‐selective disturbances produced stands that were different from any in the undisturbed succession, but these differences disappeared within 50 ‐ 100 yr, implying successional convergence in stand structure and composition. Plots of simulated basal area against time and nitrogen‐availability for the four species illustrate the time dependence of species performance along a fertility gradient.
Towards unification of national vegetation classifications: A comparison of two methods for analysis of large data sets
Authors: Bruelheide Helge , Chytrý Milan 
Published: May 2006

Abstract. In European phytosociology, national classifications of corresponding vegetation types show considerable differences even between neighbouring countries. Therefore, the European Vegetation Survey project urgently needs numerical classification methods for large data sets that are able to produce compatible classifications using data sets from different countries. We tested the ability of two methods, TWINSPAN and COCKTAIL, to produce similar classifications of wet meadows (Calthion, incl. Filipendulenion) for Germany (7909 relevés) and the Czech Republic (1287 relevés) in this respect.In TWINSPAN, the indicator ordination option was used for classification of two national data sets, and the extracted assignment criteria (indicator species) were applied crosswise from one to the other national data set. Although the data sets presumably contained similar community types, TWINSPAN revealed almost no correspondence between the groups derived from the proper classification of the national data set and the groups defined by the assignment criteria taken from the other national data set. The reason is probably the difference in structure between the national data sets, which is a typical, but hardly avoidable, feature of any pair of phytosociological data sets. As a result, the first axis of the correspondence analysis, and consequently the first TWINSPAN division, are associated with different environmental gradients; the difference in the first division is transferred and multiplied further down the hierarchy.COCKTAIL is a method which produces relevé groups on the basis of statistically formed species groups. The user determines the starting points for the formation of species groups, and groups already found in one data set can be tested for existence in the other data set. The correspondence between the national classifications produced by COCKTAIL was fairly good. For some relevé groups, the lack of correspondence to groups in the other national data set could be explained by the absence of the corresponding vegetation types in one of the countries, rather than by methodological problems.
Soil seed bank and community dynamics in an annual‐dominated Mediterranean salt‐marsh
Authors: Marañón T. 
Published: May 2006

Abstract. The seed bank in the soil and litter of an annual grassland in the upper salt marsh of the Guadalquivir delta (SW Spain) contained on average 49110 seeds/m2; 29 species were represented. Field censuses of the grassland, in two consecutive springs, yielded 7 410 and 9 520 plants/m2 respectively. A combined Correspondence Analysis of the seed bank samples and field censuses showed differences in grassland composition between wet and dry years. The environmental changes induced different expressions of the soil seed bank, mediated by demographic processes.The effect of salinity (25 dS/m of NaCl) was studied on intact soil blocks transplanted to a greenhouse. Salinity did not affect the emergence of seedlings, but reduced the growth of the dominant species, Trisetaria panicea.The importance of the role of seed banks in community dynamics and their use for conservation management are discussed.
Stand and neighbourhood parameters as determinants of plant species richness in a managed forest
Authors: Skov Flemming 
Published: May 2006

Abstract. Patterns of species richness in a managed forest were related to ecological factors at two spatial scales. Local variables within a plot (5 m × 5 m) included 13 soil classes and nine stand classes. Neighbourhood variables were defined within a 25 m radius from the focal plot and were measured using a Neighbourhood Diversity Index (NDI ‐ total diversity of different stand classes) and nine Neighbourhood Scores (NS ‐ relative dominance of a given stand class).224 species were registered in the survey of which 138 were true forest species. Local parameters (stand and soil class) were weak predictors of total and forest species richness. High total and forest species richness were significantly related to high values of NDI (i.e. heterogeneous neighbourhoods). Regression trees showed that total species richness was best predicted by the amount of roadside habitat in the neighbourhood and NDI. Forest species richness was positively related to NDI and negatively related to the amount of coniferous stands in the neighbourhood.
Tree regeneration and future dynamics of the laurel forest on Tenerife, Canary Islands
Authors: Arévalo José Ramón , Fernández‐Palacios María José , Palmer Michael W. 
Published: May 2006

Abstract. We studied two sites in the laurel forest of Tenerife to predict future changes in canopy composition. We used two projection methods: Horn's ‘Markovian Projection’, which utilizes information on juveniles in the vicinity of canopy trees, and a 'Stand Projection’, which ignores such information. We performed these projections both including and excluding a‐sexual regeneration. Although all of our projections predict a change in species composition, inclusion of a‐sexual reproduction decreased the magnitude of successional change. The persistence of Prunus lusitanica and Ilex canariensis appears to be highly dependent on a‐sexual regeneration.Both the Markov‐ and stand projections predict a slight convergence in species composition between the two sites when only sexual regeneration is considered, and also a higher dominance of the shade‐tolerant species Laurus azorica. When a‐sexual regeneration is also considered, some divergence is shown, with less projected change in the stand projection than in the Markov projection. In spite of some differences between the models, general patterns such as an increase of shade‐tolerant species (Laurus azorica and Prunus lusitanica) and a decrease of shade‐intolerant species (Erica arborea, Erica scoparia and Myrica faya) are consistent.
Becoming Messenian
Authors: Luraghi Nino 
Published: May 2006

AbstractThe article is an enquiry into the identity of two groups who called themselves Messenians: the Helots andperioikoiwho revolted against Sparta after the earthquake in the 460s; and the citizens of the independent polity founded by Epameinondas in 370/69bcin the Spartan territory west of the Taygetos. Based on the history of the Messenians in Pausanias Book 4, some scholars have thought that those two groups were simply the descendants of the free inhabitants of the region, subdued by the Spartans in the Archaic period and reduced to the condition of Helots. According to these scholars, the Helotized Messenians preserved a sense of their identity and a religious tradition of their own, which re-emerged when they regained freedom. One objection to this thesis is that there is no clear archaeological evidence of regional cohesiveness in the area in the late Dark Ages, while the very concept of Messenia as a unified region extending from the river Neda to the Taygetos does not seem to exist prior to the Spartan conquest. Furthermore, evidence from sanctuaries dating to the Archaic and Early Classical periods shows that Messenia was to a significant extent populated byperioikoiwhose material culture, cults and language were thoroughly indistinguishable from those documented in Lakonia. Even the site where Epameinondas later founded the central settlement of the new Messenian polity was apparently occupied since the late seventh century at the latest by a perioikic settlement. Some of theseperioikoiparticipated with the Helots in the revolt after the earthquake, and the suggestion is advanced, based on research on processes of ethnogenesis, that they played a key role in the emergence of the Messenian identity of the rebels. For them, identifying themselves as Messenians was an implicit claim to the land west of the Taygetos; therefore the Spartans consistently refused to consider the rebels Messenians, just as they refused to consider Messenians – that is, descendants of the ‘old Messenians’ – the citizens of Epameinondas' polity. Interestingly, the Spartan and the Theban-Messenian views on the identity of these people agreed in denying that the ‘old Messenians’ had remained in Messenia as Helots. Messenian ethnicity is explained as the manifestation of the will ofperioikoiand Helots living west of the Taygetos to be independent from Sparta. The fact that most Messenian cults attested from the fourth century onwards were typical Spartan cults does not encourage the assumption that there was any continuity in a Messenian tradition going back to the period before the Spartan westward expansion.
Athens and Chalkis: a study in imperial control
Authors: Ostwald Martin 
Published: May 2006

AbstractThe basic contention of this article is that, contrary to a widely held and influential view, the Chalkis Decree does not constitute evidence that Athens tried to impose democracies on rebellious allies after their subjugation. It contains an exchange of oaths between Athens and Chalkis, confirming an ‘agreement’ (homologia), the contents of which are lost. The oaths show Athenian concern for the protection of the Athenian democracy and its friends at Chalkis, and impose some judicial but no political restrictions on Chalkis to secure Athenian domination and assure the priority of Athenian interests. In fact, the Athenians acknowledge the right of the Chalkidians to insist on the performance of civic duties in Chalkis on the part of aliens (xenoi) resident there. The Athenians among these residentxenoi, who are exempted from these obligations, are neither colonists nor kleruchs, as is sometimes alleged, but most probably individual settlers who had been given land in Chalkidian territory by Tolmides in the 450s.
A transitional xerophytic tropical plant community of the Cape Region, Baja California
Authors: de la Luz León , Luis José , Navarro Pérez , Juan José , Breceda Aurora 
Published: May 2006

Abstract. Our main objective was to use comparative floristic and structural criteria in order to understand the differences in assemblages brought about by the meeting of arid and dry‐tropical environments. We sampled 33 vegetation plots and recorded all perennial species. The data were subjected to multivariate analysis, including Principal Component Analysis (PCA).The floristic variation detected by the PCA was strongly related to altitude and rainfall. The gradient detected by the ordination procedure had Tropical deciduous forest (TDF) and Sonoran Desert (SD) at opposite extremes and Cape sarcocaulescent shrubland (CSCS) in an intermediate position. The numerical classification algorithm detected six distinct groups of species with clearly identifiable field distributions. Vegetation structure also differed significantly between the regions. SD had the lowest species‐richness (α‐diversity) and inter‐site similarity in the CSCS was highest, indicating that this environment is relatively uniform and has low species turnover (β‐diversity).It is concluded that the CSCS is distinctly different from the sarcocaulescent shrublands of the more northern plant communities of the peninsula, where Sonoran Desert floristic affinities prevail. The floristic composition of the CSCS is rich in dry‐tropical affinities, its species richness is higher, it is homogeneous in its species content and turnover and is more dense with a taller canopy than the northern desert scrubs. It is proposed that the boundary line separating the Cape sediments of granitic origin from the basalt‐derived sediments of the northern‐lying Sierra de la Giganta should be used as an easily identifiable landscape trait to delimitate this unique community.
Logical Consequence Revisited
Authors: Sagüillo José M. 
Published: May 2006

Tarski's 1936 paper, “On the concept of logical consequence”, is a rather philosophical, non-technical paper that leaves room for conflicting interpretations. My purpose is to review some important issues that explicitly or implicitly constitute its themes. My discussion contains four sections: (1) terminological and conceptual preliminaries, (2) Tarski's definition of the concept of logical consequence, (3) Tarski's discussion of omega-incomplete theories, and (4) concluding remarks concerning the kind of conception that Tarski's definition was intended to explicate. The third section involves subsidiary issues, such as Tarski's discussion concerning the distinction between material and formal consequence and the important question ofthe criterion for distinguishing between logical and non-logical terms.§1. Preliminaries. In this paper an argument is a two-part system composed of a set of propositions P (the premise-set) and a single proposition c (the conclusion). The expression ‘c is a [logical] consequence of P’ is used with the same meaning as the expression ‘c is [logically] implied by P’. The expressions ‘is a logical consequence of’ and the converse ‘implies’ are relational. Often, I shall be talking in the same sense of validity of an argument. Validity is a property of arguments; an argument with premise-set P and conclusion c is valid if and only if P implies c; i.e., c is a logical consequence of P. Notice that this notion of argument is strictly ontic; it does not involve any agent that thinks, determines or establishes that a given proposition is or is not a consequence of a given set of propositions.
Hermann Weyl's Intuitionistic Mathematics
Authors: van Dalen Dirk 
Published: May 2006

Dedicated to Dana Scott on his sixtieth birthday.It is common knowledge that for a short while Hermann Weyl joined Brouwer in his pursuit of a revision of mathematics according to intuitionistic principles. There is, however, little in the literature that sheds light on Weyl's role and in particular on Brouwer's reaction to Weyl's allegiance to the cause of intuitionism. This short episode certainly raises a number of questions: what made Weyl give up his own program, spelled out in “Das Kontinuum”, how did Weyl come to be so well-informed about Brouwer's new intuitionism, in what respect did Weyl's intuitionism differ from Brouwer's intuitionism, what did Brouwer think of Weyl's views,…? To some of these questions at least partial answers can be put forward on the basis of some of the available correspondence and notes. The present paper will concentrate mostly on the historical issues of the intuitionistic episode in Weyl's career.Weyl entered the foundational controversy with a bang in 1920 with his sensational paper “On the new foundational crisis in mathematics”. He had already made a name for himself in the foundations of mathematics in 1918 with his monograph “The Continuum” [18]; this contained in addition to a technical logical-mathematical construction of the continuum, a fairly extensive discussion of the shortcomings of the traditional construction of the continuum on the basis of arbitrary—and hence also impredicative—Dedekind cuts.
The Mathematical Development of Set Theory from Cantor to Cohen
Authors: Kanamori Akihiro 
Published: May 2006

Set theory is an autonomous and sophisticated field of mathematics, enormously successful not only at its continuing development of its historical heritage but also at analyzing mathematical propositions cast in set-theoretic terms and gauging their consistency strength. But set theory is also distinguished by having begun intertwined with pronounced metaphysical attitudes, and these have even been regarded as crucial by some of its great developers. This has encouraged the exaggeration of crises in foundations and of metaphysical doctrines in general. However, set theory has proceeded in the opposite direction, from a web of intensions to a theory of extensionpar excellence, and like other fields of mathematics its vitality and progress have depended on a steadily growing core of mathematical structures and methods, problems and results. There is also the stronger contention that from the beginning set theory actually developed through a progression ofmathematicalmoves, whatever and sometimes in spite of what has been claimed on its behalf.What follows is an account of the development of set theory from its beginnings through the creation of forcing based on these contentions, with an avowedly Whiggish emphasis on the heritage that has been retained and developed by current set theory. The whole transfinite landscape can be viewed as the result of Cantor's attempt to articulate and solve the Continuum Problem.
Two Applications of Inner Model Theory to the Study of Sets
Authors: Hjorth Greg 
Published: May 2006

§0. Preface. There has been an expectation that the endgame of the more tenacious problems raised by the Los Angeles ‘cabal’ school of descriptive set theory in the 1970's should ultimately be played out with the use of inner model theory. Questions phrased in the language of descriptive set theory, where both the conclusions and the assumptions are couched in terms that only mention simply definable sets of reals, and which have proved resistant to purely descriptive set theoretic arguments, may at last find their solution through the connection between determinacy and large cardinals.Perhaps the most striking example was given by [24], where the core model theory was used to analyze the structure of HOD and then show that all regular cardinals below ΘL(ℝ) are measurable. John Steel's analysis also settled a number of structural questions regarding HODL(ℝ), such as GCH.Another illustration is provided by [21]. There an application of large cardinals and inner model theory is used to generalize the Harrington-Martin theorem that determinacy implies )determinacy.However, it is harder to find examples of theorems regarding the structure of the projective sets whose only known proof from determinacy assumptions uses the link between determinacy and large cardinals. We may equivalently ask whether there are second order statements of number theory that cannot be proved under PD–the axiom of projective determinacy–without appealing to the large cardinal consequences of the PD, such as the existence of certain kinds of inner models that contain given types of large cardinals.
An Elementary Approach to the Fine Structure of L
Authors: Friedman Sy D. , Koepke Peter 
Published: May 2006

We present here an approach to the fine structure of L based solely on elementary model theoretic ideas, and illustrate its use in a proof of Global Square in L. We thereby avoid the Lévy hierarchy of formulas and the subtleties of master codes and projecta, introduced by Jensen [3] in the original form of the theory. Our theory could appropriately be called ”Hyperfine Structure Theory”, as we make use of a hierarchy of structures and hull operations which refines the traditional Lα -or Jα-sequences with their Σn-hull operations.§1. Introduction. In 1938, K. Gödel defined the model L of set theory to show the relative consistency of Cantor's Continuum Hypothesis. L is defined as a unionof initial segments which satisfy: L0 = ∅, Lλ = ∪α<λLα for limit ordinals λ, and, crucially, Lα + 1 = the collection of 1st order definable subsets of Lα. Since every transitive model of set theory must be closed under 1st order definability, L turns out to be the smallest inner model of set theory. Thus it occupies the central place in the set theoretic spectrum of models.The proof of the continuum hypothesis in L is based on the very uniform hierarchical definition of the L-hierarchy. The Condensation Lemma states that if π : M → Lα is an elementary embedding, M transitive, then some ; the lemma can be proved by induction on α. If a real, i.e., a subset of ω, is definable over some Lα,then by a Löwenheim-Skolem argument it is definable over some countable M as above, and hence over some , < ω1. This allows one to list the reals in L in length ω1 and therefore proves the Continuum Hypothesis in L.