bluuebunny/crossref_metadata_2025_split huggingface dataset:
Habitat associations of Sterculiaceae trees in a Bornean rain forest plot
Authors: Yamada Toshihiro , Tomita Akemi , Itoh Akira , Yamakura Takuo , Ohkubo Tatsuhiro , Kanzaki Mamoru , Tan Sylvester , Ashton Peter S. 
Published: February 2009

Abstract.Questions: 1. Are trees in a Bornean tropical rain forest associated with a particular habitat? 2. Does the strength of habitat association with the species‐specific optimal habitat increase with tree size?Location: A 52‐ha plot in a mixed dipterocarp forest in a heterogeneous landscape at the Lambir Hills National Park, Sarawak, East Malaysia.Methods: Ten species from the Sterculiaceae were chosen as representative of all species in the plot, on the assumption that competition among closely related species is more stringent than that among more distantly related taxa. Their habitat associations were tested using data from a 52‐ha plot by a torus‐translation test.Results: The torus‐translation test showed that eight out of the ten species examined had significant association with at least one habitat. We could not find negative species‐habitat associations for rare species, probably due to their small sample sizes. Among four species small trees were less strongly associated with habitat than large trees, implying competitive exclusion of trees in suboptimal habitats. The other four species showed the opposite pattern, possibly owing to the smaller sample size of large trees. A habitat had a maximum of three species with which it was significantly positively associated.Conclusions: For a species to survive in population equilibrium in a landscape, habitats in which ‘source’ subpopulations can be sustained without subsidy from adjacent habitats are essential. Competition is most severe among related species whose source subpopulations share the same habitat. On the evidence of source subpopulations identified by positive species‐habitat association, species‐habitat association reduces the number of confamilial competitors. Our results therefore indicate that edaphic niche specialization contributes to coexistence of species of Sterculiaceae in the plot, consistent with the expectations of equilibrium hypotheses.
Causes of pattern in plant communities where environmental change is rapid and species longevity is short
Authors: Cousens Roger D. , Dale Mark R.T. , Taylor James , Law Richard , Moerkerk Michael , Kembel Steven W. 
Published: February 2009

Abstract.Questions: To what extent can spatial structure and its causes be determined in a highly disturbed environment? What are the main determinants of pattern and are these species‐specific? How much do spatial patterns change over generations?Location: Wimmera region of southern Australia.Methods: Broad‐leaved weeds were counted in 225 000 contiguous 20‐cm square quadrats. A substantial number of these quadrats were recorded again after two and four years. An hierarchical ‘adaptive analysis’ approach was used to select spatial analytical methods to examine specific aspects of pattern and variation in pattern from year to year.Results: Patterns varied among species and included both dense and sparse patches surrounded by areas of zero density, diffuse gradations of density and clear anisotropy. Patterns inErodium botrysandOxalis pes‐capraepersisted over years, whereas patterns inArctotheca calendulawere less pronounced and varied over time. Edaphic factors appeared to have only a minor influence over the spatial distribution of the weed community as a whole. InOxalis pes‐caprae, whose patches were hypothesized to have been shaped by cultivation, there was no spread in four years, despite further tillage. Outlying plants ofO. pes‐capraefailed to establish new patches, even in the year of greatest population increase. Little evidence of localised recruitment events was found.Conclusions: Despite repeated annual disturbances by natural and anthropogenic mechanisms, clear and interpretable spatial structure develops in annual weeds over a range of spatial resolutions. Adaptive analysis is a useful approach to the characterization of such patterns.
Seed bank, seed dispersal and vegetation cover: Colonization along a newly‐created river channel
Authors: Gurnell A.M. , Boitsidis A J. , Thompson K. , Clifford N J. 
Published: February 2009

AbstractQuestion: What is the relative importance of the initial seed bank and subsequent seed dispersal for floristic composition of bank vegetation two years after creation of a newly‐cut reach of a river channel?Location: River Cole, West Midlands, United Kingdom.Methods: We took bank and bed sediment samples from a 0.5‐km reach of a new river channel cut into intact flood‐plain. After river diversion, seed samples deposited on artificial turf mats placed on the river banks and flood‐plain edge were taken in summer and winter 2002 and 2003. Seed rain samples from funnel traps were taken during summer 2002 and 2003. We undertook greenhouse germination trials to assess viable seed species within these samples. In summer 2004, we surveyed river bank vegetation.Agglomerative cluster analysis was used to investigate floristic similarity between seed bank, seed rain, seed deposition samples and final bank vegetation cover. DCA was used to explore contrasts between the samples and to assess whether these reflected interpretable environmental gradients.Results: Seed rain samples contained a small subset of species in the summer depositional samples. 38 species were found within the final vegetation, the seed bank, and at least one of the four sets of depositional samples; a further 30 species not present in the seed‐bank samples were present in at least one of the four sets of depositional samples and the final vegetation. Floristic composition of the vegetation was most similar to the depositional samples from winter 2002 and 2003 and summer 2003. DCA axis 1 reflected a time sequence from seed‐bank samples through depositional samples to the final vegetation.Conclusions: Newly cut river banks were colonized rapidly. Seed remobilization and hydrochorous transport from the upstream catchment are important for colonization. Species richness was highest in samples deposited during winter when high river flows can remobilize and transport viable seeds from upstream. This process would also have enhanced the species richness of seed production along the banks during the second summer (2003).
Influence of rocky landscape features and fire regime on vegetation dynamics in AppalachianQuercusforests
Authors: Signell Stephen A. , Abrams Marc D. 
Published: February 2009

AbstractQuestion: How do interactions between rocky landscape features and fire regime influence vegetation dynamics?Location: Continental Eastern USA.Methods: We measured vegetation, disturbance and site characteristics in 40 pairs of rocky and non‐rocky plots: 20 in recently burned stands, and 20 in stands with no evidence of recent fire (‘unburned’ stands). Two‐way analysis of variance (ANOVA) was used to assess the main and interaction effects of fire and rock cover on plant community composition.Results: In burned stands, rock cover had a strong influence on vegetation. Non‐rocky ‘matrix’ forests were dominated byQuercus, and had abundant ground cover and advance regeneration of early and mid‐successional tree species. Burned rocky patches supported greater density of fire‐sensitive species such asAcer rubrum, Sassafras albidumandNyssa sylvaticaand had little advance regeneration or ground cover.Quercushad fewer fire scars and catfaces (open, basal wounds) on rocky patches, suggesting that rocky features mitigate fire severity. In unburned stands, differences between rocky and non‐rocky patches were less distinct, with both patch types having sparse ground cover, little tree regeneration, and high understorey densities of relatively shade tolerantA. rubrum, N. sylvaticaandBetula lenta.Conclusion: Under a sustained fire regime, heterogeneity in rock cover created a mosaic where fire‐adapted species such asQuercusdominate the landscape, but where fire‐sensitive species persisted in isolated pockets of lower fire severity. Without fire, species and landscape richness may decline as early‐mid successional species are replaced by more shade tolerant competitors.
Controls over invasion of Bromus tectorum: The importance of climate, soil, disturbance and seed availability
Authors: Bradford John B. , Lauenroth William K. 
Published: February 2009

AbstractQuestion: Predicting the future abundance and distribution of invasive plants requires knowing how they respond to environmental conditions. In arid and semi‐arid ecosystems where water is a limiting resource, environmental conditions and disturbance patterns influence invasions by altering acquisition and utilization of water over space and time. We ask: 1. How do variations in climatic and soil properties influence temporal soil water dynamics? 2. How does this variation affect the establishment of Bromus tectorum (cheatgrass), a cool‐season annual grass that has successfully colonized much of the U.S. Great Basin?Location: Short‐grass Steppe in northeastern Colorado, USA; Arid Lands Ecology reserve in southeastern Washington, USA; and the Patagonian steppe of the Chubut province in Argentina.Methods: We utilized a soil water model to simulate seasonal soil water dynamics in multiple combinations of climatic and soil properties. In addition, we utilized a gap dynamics model to simulate the impact of disturbance regime and seed availability on competition between B. tectorum and native plants.Results: Our results suggest that climate is very important, but that soil properties do not significantly influence the probability of observing conditions suitable for B. tectorum establishment. Results of the plant competition model indicate that frequent disturbance causes more Bromus tectorum in invaded areas and higher seed availability causes faster invasion.Conclusions: These results imply a general framework for understanding Bromus tectorum invasion in which climatic conditions dictate which areas are susceptible to invasion, disturbance regime dictates the severity of invasion and seed availability dictates the speed of invasion.
Regeneration of a marginal Quercus suber forest in the eastern Iberian Peninsula
Authors: Pausas J.G. , Ribeiro E. , Dias S.G. , Pons J. , Beseler C. 
Published: February 2009

AbstractQuestion: Small and marginal forest populations are a focus of attention because of their high biodiversity value as well as the risk of population decline and loss. In this context, we ask to what extent a small, marginal Quercus suber (Cork oak) population located in the eastern Iberian Peninsula (Valencia, Spain) has the capacity for self‐regeneration and what are the factors that determine its recruitment variability.Location: Quercus suber forest in Pinet (Valencia, Spain).Methods: We performed a spatially explicit sampling both of the recruitment and of the potential parameters that could account for the recruitment variability. Using regression techniques we model the recruitment occurrence and abundance, and then we test to what extent the model obtained is still constrained by the spatial dependence.Results: Quercus suber recruitment density ranges from 0 to 18.66 individuals/25m2 (mean = 1.46, SD = 2.8), with a very skewed distribution. Recruitment is similar under Q. suber forests and under Pinus forests, but it is almost absent under shrublands. Thus the parameters that explain most of the recruitment variability in local vegetation types are: the presence and cover of shrubs (negative relationship with recruitment), the basal area of Q. suber and Pinus and the amount of bare soil (all positively related to recruitment). These parameters are strongly related to the ecological processes driving recruitment (i.e. dispersal and predation) and they remove most of the spatial dependence of recruitment. Most recruiters, however, are small, forming a seedling bank rather than growing to successfully colonize new habitats.Conclusion: The results suggest that although recruitment densities are not very high, they do not limit potential regeneration in the Pinet Q. suber forest. However, successful regeneration is not observed. If we aim to increase the Pinet Q. suber population size, land management measures need to provide appropriate conditions for both seedling establishment in shrublands (e.g. shrub clearing) and seedling growth in woodlands (e.g. Pinus logging).
Application of palynology to describe vegetation succession in estuarine wetlands on Great Barrier Island, northern New Zealand
Authors: Deng Y. , Ogden J. , Horrocks M. , Anderson S. 
Published: February 2009

AbstractQuestion: This paper compares published palynological studies from coastal swamps containing the same suite of species. We ask the following questions: (1) does succession follow the same pathways in different swamp systems, or (2) at different times? If not, (3) how variable are the patterns and (4) what are the likely driving factors?Location: Great Barrier Island, Northern New Zealand.Methods: Eighteen pollen profile diagrams were studied from four estuarine wetlands, ranging from mangroves to swamp forest. Recognition of a transition between vegetation stages was by subjective consideration of the relative abundances of pollen of key indicator species at different depths in the sedimentary sequence.Results: A linear sequence of vegetation communities beginning with mangroves and followed by estuarine marsh communities composed of Juncus kraussii, Leptocarpus similis and Baumea juncea was recognised in almost all pollen diagrams. Further transitions, from Baumea to a terrestrial system of Leptospermum shrubland or Cordyline/Dacry‐carpus swamp forest, followed two main pathways associated with autogenic accumulation of peat and terrigenous sediment input respectively. At Kaitoke and Awana the marine/freshwater transition occurred before the arrival of humans on Great Barrier Island. At Whangapoua, increased sedimentation followed anthropogenic burning of adjacent forest, and this transition was faster and is still in progress.Conclusion: Palynology and current vegetation zonation patterns concur to demonstrate that the marine sedimentation phase of estuarine succession is predictable and linear. Baumea marks the transition to the freshwater phase, in which varied successional patterns are determined by interactions between hydrology, sediment input, and peat accumulation. Natural and human disturbances drive sedimentation rates, and interact with autogenic factors, to dictate vegetation transitions in these later stages. The intensive impact (mainly burning) during Polynesian times had a much greater effect on estuaries and swamps than the pre‐Polynesian natural processes, greatly accelerating plant succession.
On the evaluation of ordinal data with conventional multivariate procedures
Authors: Ricotta Carlo , Avena Giancarlo 
Published: February 2009

AbstractIn a recent Forum paper, it is argued that, in most studies, ordinal data such as the Braun‐Blanquet abundance/dominance scale are not properly treated by multivariate methods. This is because conventional multivariate methods are generally adequate for ratio‐scale variables only, while for ordinal variables differences between states and their ratios are not interpreted. Conversely, in this paper it is shown that using conventional multivariate procedures for evaluating ordinal data should imply a shift from a metric space to a topological data space; as such the use of ordinal data does not represent a serious methodological error, provided that results are interpreted accordingly.
PC‐ORD version 5: A user‐friendly toolbox for ecologists
Authors: Grandin Ulf 
Published: February 2009

AbstractRecently, version 5 of PC‐ORD, one of the major commercial software packages for multivariate ecological community data analyses, was released. The new version offers a whole range of techniques and methods for analyses of ecological data. It includes modules for different types of ordination and classification, as well as other exploratory techniques such as species‐area curve analysis and indicator species analysis. Data are stored in spreadsheets and can be easily manipulated in various ways. In essence, version 5 of PC‐ORD offers the user a full toolbox for exploration and analysis of ecological data, packed in a user‐friendly environment.
Johansson revisited: the spatial structure of epiphyte assemblages
Authors: Zotz Gerhard 
Published: February 2009

AbstractQuestion: Vertical zonation schemes are widely used in biodiversity studies with vascular epiphytes as a tool to capture spatial distribution patterns, the one most commonly used was proposed by Johansson more than 30 years ago. Does a survey of the epiphytes found on larger trees really yield a representative sample of the local community?Location: Lowland rainforest of the San Lorenzo Crane Plot, Republic of Panama.Methods: A complete census of the vascular epiphytes on all trees > 1 cm DBH in 0.4 ha of undisturbed lowland forest was analysed with both cluster and discriminant analysis to detect groupings of epiphyte species.Results: Six different groups of species were detected, five of them preferring different substrates on larger trees (as defined by (1) the height above ground at the attachment site, (2) the diameter of the substrate and (3) the occurrence on stem vs branches/twigs) and resembling to some extent the original Johansson zones. A sixth group of epiphytes, comprising ca. 10% of all taxa, was almost always found on small diameter stems and branches of trees with small DBH at lower and intermediate heights within the forest.Conclusions: Applying pre‐established zonation schemes may lead to misleading results in biodiversity studies with epiphytes. Important aspects of spatial distribution patterns may be missed, and the determination of relative species abundances may carry a strong quantitative and qualitative bias when analyses rely completely on epiphytic plants found on larger trees.
A functional analysis of vegetation dynamics in abandoned and restored limestone grasslands
Authors: Dzwonko Zbigniew , Loster Stefania 
Published: February 2009

AbstractQuestion: How do various plant functional groups and types are related to regeneration of limestone grasslands and to temporal changes in cover of trees and shrubs? Which mechanisms are responsible for changes in differently treated grasslands?Location: Southern Poland, 50° 01'N, 19° 50'E.Methods: A 12‐year restoration experiment after the clearing of a 35‐yr‐old secondary pine wood developed on limestone grassland, and a parallel observation of succession in neighbouring abandoned grassland were carried out. Changes in cover of species with different functional traits and established strategies in relation to time and cover of shrub layer were analysed using multiple linear regression.Results: Over 12 years the composition and cover of species changed in the studied grasslands, but significant differences still occurred between the old grassland and the grassland restored in former wood gaps and that developed in former closed wood. Despite the very close proximity of the old grassland, the composition of restored grasslands was still much determined by initial conditions. In these grasslands, the cover of Festuco‐Brometea species was significantly lower than in the old grassland. In all sites, the cover of species with large leaves and with leaves distributed regularly along the stem, and the cover of CS strategists increased. With increasing shrub cover in restored grasslands, the cover of annuals and biennials, tall species, and R and CS strategists decreased.Conclusions: Limited availability of seeds seems the principal reason for the weak regeneration of xerothermic limestone grasslands. Trees and shrubs inhibit the developed of both early successional species and perennials occurring in established communities. They significantly hinder regeneration of grasslands and should be cut every five or six years.
Seed dynamics linked to variability in movement of tidal water
Authors: Chang E.R. , Veeneklaas R.M. , Bakker J.P. 
Published: February 2009

AbstractQuestion: Community structure may be influenced by patterns of dispersed seeds (seed rain) because they contribute to the template of plant community development. We explored factors influencing seed rain in a system dominated by tidal water, where direction and magnitude of water flow are difficult to predict, unlike many other hydrochorous systems where water flow is directional. We posed three main questions: (1) are patterns in seed rain linked to effects of hydrodynamic variability; (2) do these patterns in seed rain reflect distribution of seed sources and seed production; and (3) what are the implications for the assembly of tidal communities?Location: Salt marshes on the Wadden island of Schier‐monnikoog, The Netherlands.Methods: Species compositions of vegetation, seed rain, seed production and driftlines along a chronosequence of communities were compared. We also studied seed movement by sowing Astroturf® mats with seeds and checking for seeds remaining after a single tidal inundation.Results: Storm surges had a significant effect on seed‐rain patterns as the highest density and diversity of captured seeds were found during a stormy period. Seed rain of the youngest communities was more influenced by storms than that of older communities. Patterns in seed rain generally followed similar patterns in the distribution of established plants, and seed production.Conclusions: Results suggested mostly local dispersal of seeds. However, there was some evidence of long‐distance dispersal occurring during storm surges in younger communities that are regularly inundated with tidal water. The possible role of seed retention in constraining community development, rather than dispersal per se, is further discussed.
The importance of shrub cover for four cactus species differing in growth form in an Andean semi‐desert
Authors: López Ramiro Pablo , Valdivia Sergio 
Published: February 2009

AbstractQuestion: Factors influencing seedling establishment are known to vary between open sites and those protected by plant cover. In many desert regions, protected microhabitats below shrubs are essential for establishment of many cactus species. Very little is known about these factors for Andean cacti and how the importance of vegetation cover varies with cactus species. Are Andean cacti associated more frequently to vegetation cover than to open ground? Are they associated to certain shrub species? Is the distributional pattern in relation to cover similar for different cactus species? In what microhabitat (below or away from shrubs) are cactus seeds more abundant? These questions are addressed for the case of an Andean semi‐desert.Location: Semi‐arid tropical Andes, La Paz department, Bolivia.Methods: We examined 132 isolated shrubs = 50 cm along a line across two microhabitats: areas below and away from shrubs/trees. Shrub crown size was measured. The among‐shrub samples were taken from open spaces contiguous to each of the sampled shrubs. In both microhabitats, all cactus species were recorded. The cardinal direction of the cacti was also registered. Correlation between canopy diameter and number of beneficiaries was evaluated for Prosopis flexuosa. The cactus seed bank in each microhabitat was also studied.Results and Conclusions: The four cactus species found behaved differently in relation to shrub canopies. These distributional differences could be due to differences in growth form. Columnar cacti apparently need the shade of shrubs. Only the columnar species is able to grow near the base of the tallest nurse species. The opuntioid cacti studied seem more facultative: although apparently preferring shrub un‐der‐canopies, they are able to establish in open ground. The globose cactus is the most indifferent to the presence of plant cover. These patterns parallel others found in North America. The capacity of different cacti to appear in open spaces could be related to vegetative propagation, and not necessarily to seedling tolerance of heat.