bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plant communities in kettle‐holes in central Poland: chance occurrence of species?
Authors: Ka'mierczak Ewa , van der Maarel Eddy , Noest Vera 
Published: May 2006

Abstract. Plant communities occurring in kettle‐holes in the Ziemia ChemiÄska area, northern central Poland are described. These depressions of Late‐Glacial origin have gradually become part of the agricultural landscape, but many of them still have semi‐natural vegetation. 829 phytosociological relevés were made in 116 kettle‐holes; an environmental description included (a) for each relevé: soil type, depth of phreatic water table in summer, pH; and (b) for the depression as a whole: size, form, distance to nearest kettle‐hole, distance to nearest potential source of disturbance, actual occurrence of a severe disturbance, notably inflow of liquid manure.On the basis of various cluster analyses 120 basic clusters with 113 characterizing species (out of a total of 217 species) were obtained. No less than 29 clusters consist of only one relevé and 57% have no more than four relevés. Most clusters have only one constant ‐ and often dominant ‐ species. 49 species occur only once and 62 % occur in less than 1 % of the relevés. The clusters show little ecological coherence.Correspondence Analysis of the data set showed the occurrence of many outlier samples and species; a moisture and a eutrophication gradient were revealed by Canonical Correspondence Analysis.The lack of coherence between the variation in community types and variation in environmental factors is explained by assuming a chance occurrence of species, which appear and disappear as in the case of species‐rich grasslands where a large small‐scale species turnover takes place (described as the carousel model). The kettle‐holes may provide a small number of broad habitat types, within each of which several species may form short‐lived plant communities. Indeed, many locally dominant kettle‐hole species are short‐lived perennials or therophytes, which may come and go, while sharing the same habitat. This hypothesis has to be tested through repeated vegetation analysis.
Disturbance effects on herbaceous layer vegetation and soil nutrients in Populus forests of northern lower Michigan
Authors: Roberts M.R. , Gilliam F.S. 
Published: May 2006

Abstract. Recent disturbance models have identified changes in resource availability as factors that control plant community response. Soil nutrient resources typically are assumed to change following forest disturbance, usually with nutrient availablity increasing initially and subsequently decreasing through later stages of succession. We examined the effects of disturbance (clearcut harvesting with a brief recovery period) on soil organic matter, pH and extractable soil nutrients in successional aspen forests of northern lower Michigan to determine relationships of these variables to changes in herbaceous layer vegetation. Two site types were identified: drymesic (glacial outwash sands, low in organic matter) and mesic (calcareous clay till, high in organic matter). Extractable nutrient concentrations were 1.5 to 3 times higher in the A1 horizon of mesic sites than those of dry‐mesic sites. Soil pH and cations increased after disturbance on mesic sites, but not on dry‐mesic sites. Patterns of change with disturbance were less pronounced in lower horizons on both site types. Herblayer species diversity increased after disturbance on mesic sites, but with decreases in the importance of shade‐tolerant tree species and Maianthemum canadense. Species characteristic of open habitats (e.g. Pteridium aquilinum, Rubus spp., Fragaria virginiana, and Diervilla lonicera), increased in importance. Soil factors, species composition and diversity on dry‐mesic sites changed little after disturbance, with Pteridium aquilinum and ericaceous species remaining dominant in both mature (55–82 yr) and disturbed (≤ 15 yr) stands.These results suggest that soil nutrient resources do not always change through secondary succession and that patterns of change can be distinctly site‐dependent. Disturbance response patterns in the herbaceous layer of these aspen forests are also site‐dependent.
Pattern and process in the plant community: Fifty years after A.S. Watt
Authors: Van Der Maarel Eddy 
Published: May 2006

Abstract. This paper is a tribute to A.S. Watt who published his ‘Pattern and process in the plant community’ almost 50 years ago. Watt's interpretation of the plant community “as a working mechanism, which maintains and regenerates itself” is still highly relevant, although the keywords have changed. ‘Process’ in Watt's view involves both upgrade and downgrade aspects, whereas ‘Pattern’ was not specified, neither quantified. Nowadays, process is mainly approached as ‘disturbance’, that is natural disturbance and ‘pattern’ as patch structure. Together they make up the ‘patch dynamics’ of the community. Some implications of patch dynamics for phytosociology are discussed. A ‘Wattian’ concept of the plant community combines the Gleasonian idea of individualistic behaviour of species with the Clementsian (or rather Braun‐Blanquetian) notion of community dynamics. Later work by Harper (demography), Grubb (regeneration niche) and earlier work of Sernander (forest gap dynamics) is significant for the understanding of the patch‐dynamic nature of the community.Recent interest in plant species mobility can easily be linked to the concept of patch dynamics. Examples of mobility in a limestone grassland are given and a system of mobility types is proposed.Some perspectives for the study of patch dynamics are mentioned. Numerical pattern analysis should have a more prominent place in this type of study; the significance of the study of small permanent plots in a stand is emphasized, and unprejudiced demographic studies, as well as experimental studies of small‐scale species replacement are recommended.
The Dynamic keyhole‐key model of coexistence to explain diversity of plants in limestone and other grasslands
Authors: Gigon A. , Leutert A. 
Published: May 2006

Abstract. This paper is a tribute to A.S. Watt who published his ‘Pattern and process in the plant community’ almost 50 years ago. Watt's interpretation of the plant community “as a working mechanism, which maintains and regenerates itself” is still highly relevant, although the keywords have changed. ‘Process’ in Watt's view involves both upgrade and downgrade aspects, whereas ‘Pattern’ was not specified, neither quantified. Nowadays. process is mainly approached as ‘disturbance’, that is natural disturbance and ‘pattern’ as patch structure. Together they make up the ‘patch dynamics’ of the community. Some implications of patch dynamics for phytosociology are discussed. A ‘Wattian’ concept of the plant community combines the Gleasonian idea of individualistic behaviour of species with the Clementsian (or rather Braun‐Blanquetian) notion of community dynamics. Later work by Harper (demography), Grubb (regeneration niche) and earlier work of Sernander (forest gap dynamics) is significant for the understanding of the patch‐dynamic nature of the community.Recent interest in plant species mobility can easily be linked to the concept of patch dynamics. Examples of mobility in a limestone grassland are given and a system of mobility types is proposed.Some perspectives for the study of patch dynamics are mentioned. Numerical pattern analysis should have a more prominent place in this type of study; the significance of the study of small permanent plots in a stand is emphasized, and unprejudiced demographic studies, as well as experimental studies of small‐scale species replacement are recommended.
Vegetation succession in a floating mire in relation to management and hydrology
Authors: van Diggelen R. , Molenaar W.J. , Kooijman A.M. 
Published: May 2006

Abstract. The vegetation succession in a floating mire was studied in relation to management and hydrological conditions in a former peat cutting area in the northern part of the Netherlands. An existing map showed that in 1956 the vegetation consisted mainly of meadows, reedbeds and rich fen vegetation while a recent survey revealed that this picture had completely changed in 1989. The area had mainly become woodland but part had remained open, due to the continuation of a mowing regime. The timing of the mowing appears to be critical, especially during the earlier phases of the succession. Winter‐mowing favours the development of eutrophic reedbeds, while summer‐mowing promotes mesotrophic sedge communities. In the course of time these succession lines converge increasingly towards acidic vegetation types.The development from open water to embryonic bog differed greatly between sites with a similar management regime. Mostly this took only a few decades but in a few sites the vegetation had hardly changed since 1956. Whereas the former sites were acid throughout the profile, the latter showed a high pH from top to bottom. It is obvious that acidification does not occur as long as alkaline surface water can move freely underneath the floating mat. As soon as a given site becomes disconnected from the surface water the depletion of bases by infiltrating rainwater is no longer compensated. A rough estimate of the acidification rate shows that in an infiltration area three decades are sufficient for a floating mat of 40 cm to become completely decalcified. This corresponds well to the observed succession from rich fens to embryonic bogs in the same period. It is suggested that the best way to preserve rich fen vegetation is to start the succession anew by digging turf ponds.
Microclimatic convergence of high‐elevation tropical páramo and temperate‐zone alpine environments
Authors: Diemer Matthias 
Published: May 2006

Abstract. Plant microclimates of three tropical superpáramo sites at 4100–4600 m a.s.l. in Ecuador were monitored over a five‐month period and results were evaluated in local and biogeographical contexts. Soil temperatures tended to decrease with altitude, whereas quantum flux density (QFD) exhibited no consistent altitudinal pattern. Leaf temperatures of prostrate rosette and cushion plants exhibited diurnal amplitudes of 30 °C independent of altitude, while herbaceous perennials and woody shrubs, which were situated higher above the soil surface, had lower maxima and lower daily amplitudes as a result of aerodynamic coupling to the atmosphere. Long‐term growth measurements and an analysis of a stem cross‐section of the shrub Loricaria indicated that growth conditions at 4060 m a.s.l. were constant over a 4‐yr to > 25‐yr period.Means and frequency distributions of QFD as well as soil and leaf temperatures in the Ecuadorean Andes closely resemble growing season averages at high alpine sites in the European Central Alps at 2600 m a.s.l. Equivalent growth conditions in equatorial tropical páramo sites and seasonal temperate zone mountains extending to the arctic, suggest that, aside from the duration of the growing season, similar abiotic selection pressures operate on high elevation plants in humid mountain ecosystems, which are largely independent of latitude.
Effects of soil erosion on the floristic composition of plant communities on marl in northeast Spain
Authors: Guerrero‐Campo Joaquín , Montserrat‐Martí Gabriel 
Published: May 2006

Abstract. This study explored the validity of three responses of vegetation to increased soil erosion: reduction of vegetation cover, number of species and reduced substitution of species.201 relevés, including edaphic and geomorphological data, were surveyed in the intensely eroded Eocene marls of the Prepyrenees (NE Spain). Changes in plant species’ presence in relevés from different degradation stages were compared. The level of vegetation degradation was defined as the total phanerogam cover which, in the studied area, was correlated to the degree of soil erosion. The considered trends were validated. Reduction of phanerogam cover and species number were gradual from low to high‐eroded areas. Vegetation degradation explained 48% of the species number variance. In the later stages of degradation a significant substitution of species was not observed, only a lower frequency of occurrence of several species that appeared in the whole set of relevés. Through the process of degradation, 47% of species displayed significantly reduced frequencies as degradation increased, none showed a significant increase in frequency.It is concluded that there are no characteristic species in these plant communities that survive in the severely eroded marls. Among the few species that had increased in frequency, most only colonised favourable micro‐environments.
Availability of coarse woody debris in a boreal old‐growth Picea abies forest
Authors: Jonsson Bengt Gunnar 
Published: May 2006

Abstract. This study reports temporal (based on cross‐dated dead trees) and spatial patterns of availability of coarse woody debris (CWD) from Picea abies in a Swedish boreal landscape with discrete old‐growth forest patches in a wetland matrix. Data were collected from 29 patches ranging in size from 0.3 to 28 ha. A total of 897 dead trees with a minimum diameter of > 15 cm occurred on the 7.2 ha area analysed. The year of death was established for 50% of these trees.CWD volume ranged from 17 to 65 m3/ha for downed logs and from 0.5 to 13 m3/ha for standing snags. CWD of all decay stages and diameter classes occurred abundantly and the probability of finding logs of all decay stages and sizes was very high at the scale of single hectares. Tree mortality differed among 5 yr periods. However, during the last 50 yr no 5 yr period produced less than 3 logs/ha. Decay rates were highly variable among different logs. Logs with soft wood and some wood pieces lost (decay stage 5) died ca. 34 years ago. This suggests a fairly rapid decay in this northern forest. The data indicate a high and continuous availability of CWD of all types. It is likely, therefore, that selection pressures for efficient dispersal among CWD dependent species may not be very high. Consequently, species with narrow habitat demands and/or low dispersal ability may have evolved and this may contribute to the decrease of certain species in the managed landscape.
Distribution of plant species in Israel in relation to spatial variation in rainfall
Authors: Kadmon Ronen , Danin Avinoam 
Published: May 2006

Abstract. Relations between the distribution of herbaceous and woody species from the flora of Israel and the variation (25–900 mm) in mean annual rainfall are described using a grid‐based approach integrating multivariate techniques (cluster analysis and DCA‐ordination) and GIS. The analysis was based on an extensive data base of vascular plant records in 10 km × 10 km grid cells representing the climatic zones of Israel. Cluster analysis revealed three geographically distinct clusters of grid cells which could be arranged along the main rainfall gradient in the study area. The main subdivision is between cells from the Mediterranean region and cells from the more arid region. The second subdivision separated cells from the arid region into two distinct groups which differed significantly in rainfall. Clustering of herbaceous and woody species was similar, but boundaries separating adjacent clusters based on woody species were consistently linked to more rainy areas. Cell scores on the first DCA‐axis were significantly correlated with mean annual rainfall, but this relationship was not linear. Log‐transformation of the rainfall data resulted in a higher correlation between the DCA‐scores and rainfall, indicating that variation in rainfall had a stronger effect on species composition in relatively dry than in more mesic regions. Slopes of linear regression models relating cell scores on the first DCA‐axis to mean annual rainfall, as well as the corresponding R2‐values, were highest in the desert, intermediate in the dry Mediterranean, and lowest in the mesic Mediterranean territory. These results indicate that both the per‐unit effect of rainfall on plant species composition and its relative importance as a determinant of compositional variation decreased from relatively dry to more mesic regions.The length of the first axis, as well as the slopes of regression models relating cell scores on the first DCA‐axis to mean annual rainfall were consistently higher in the case of woody species which are characterized by a higher rate of compositional variation. Due to lack of comparable data, it is difficult to evaluate whether our results can be generalized to other regions. However, an analysis of data obtained from different parts of the world points to a considerable variability in the degree to which rainfall affects patterns of floristic variation. Our findings that compositional responses to rainfall may vary between different groups of species and may depend on the part of the rainfall range which is being considered may partially explain this inconsistency.
Distribution of plant functional types along gradients of disturbance intensity and resource supply in an agricultural landscape
Authors: Kleyer Michael 
Published: May 2006

Abstract. In this study, plant functional types are understood as groups of plants with similar biological traits displaying significant optima or maxima on a gradient plane of resource supply and disturbance intensity. The biological traits refer to expansion, vegetative regeneration, generative reproduction, dispersal and seed bank longevity.129 vegetation samples were taken in an agricultural landscape in southwestern Germany, covering a wide range of terrestrial vegetation types – but with the exception of forests and wetlands. For each site, also soil data were recorded. Mean daily soil moisture was estimated with a simple model. Soil moisture, balanced nitrogen supply and available phosphorus were combined into a factor ‘resource supply’. In addition, disturbance intensity was estimated for each site. This factor was based on (1) frequency of disturbance, (2) disturbance depth below or above the soil surface, and (3) proportion of the area affected by a discrete disturbance event. 30 plant groups with similar biological characteristics resulted from a cluster analysis, based on a compilation of 19 biological traits for a regional species pool. Logistic regression on a gradient plane of disturbance intensity and resource supply yielded response curves for 28 groups. The dependent variable was defined as the probability of encountering all members of a group in a sample. 17 groups display a significant response curve on the gradient plane. Plants with a potential for long‐ range dispersal are concentrated on sites with low or high disturbance intensities (e.g. fallow land, fields, lawns). On sites with medium disturbance intensity (e.g. meadows) and low to medium resource supply, small‐range dispersal predominates. There are no distinct trends concerning seed bank longevity. The potential for vertical and lateral expansion increases with decreasing disturbance intensity. Only at medium disturbance intensities does vertical expansion correlate positively with resource supply. Rapid detachment of daughter individuals occurs more often on productive sites than on less productive sites. Diversity of groups with similar biological traits is highest on sites with medium disturbance intensities.
Compositional dynamics of natural forests in the Bialowieza National Park, northeastern Poland
Authors: Bernadzki Eugeniusz , Bolibok Leszek , Brzeziecki Bogdan , Ząjaczkowski Jacek , Żybura Henryk 
Published: May 2006

Abstract. This paper presents results of a long‐term study on natural forest dynamics in the Białowieza National Park (BNP), northeastern Poland. Five permanent sample areas were used, each consisting of a transect of varying width (40 ‐ 60 m) and length (200 ‐ 1380 m). The total sample area is 14.9 ha. The study covers the period 1936–1992. During this period measurements were made on five occasions at approximately 10‐yr intervals. On each measurement date all trees with DBH > 5 cm were identified and their spatial location, diameter, crown condition and position in the canopy determined.During the study period the stands underwent noticeable changes, mainly in terms of tree species composition. The major change was a quantitative increase of the late‐successional species: Tilia cordata and Carpinus betulus, also to a lesser degree Fraxinus excelsior and, in the last period, of the early successional Alnus glutinosa. Declining species included both early‐ and late‐succession species. Among the latter group, Picea abies ranked first. This species lost much of its importance during the last few decades. P. abies was followed by Pinus sylvestris which is an important component of the climax vegetation under the conditions prevailing in Bialowieza, at least on more oligotrophic sites. Still, this species has not been able to regenerate during the whole study period. Some other late‐succession species, Acer platanoides and Quercus robur, were also amongst the declining species. Although the basal area of Q. robur increased, its population was getting older and the process of natural regeneration was markedly impeded.All typical pioneer, short‐lived species: Betula pendula and B. pubescens, Salix caprea and Populus tremula also decreased, which was probably caused by a lack of major disturbances during the study period.In general, the results obtained for the semi‐natural conditions of Bialowieza during the 56‐yr observation period suggest a rather high compositional instability of the forest stands there. A more precise identification of the role of particular factors in the observed stand dynamics is difficult because of the paucity of appropriate historical and environmental data which refer directly to the study plots; moreover, the data are generally incompatible and of different resolution.
Plant functional types in coastal foredunes in relation to environmental stress and disturbance
Authors: García‐Mora M. Rosario , Gallego‐Fernández Juan B. , García‐Novo Francisco 
Published: May 2006

Abstract. The foredune vegetation in the Gulf of Cadiz (SW Spain, S Portugal) was studied by means of morphological characters and functional traits of plants. The 55 vascular species recorded in the area were classified into three functional types: Type I consists mainly of winter annuals of moderate size with soft leaves, showing no presumed adaptations to the dune environment. Plants of Type II are mostly perennials with a below‐ground spreading root network and leaves with presumed adaptations to coastal environmental stress. Type III includes plants mostly capable of being dispersed by sea‐water and of withstanding sand burial.In relatively unstable soil, Type II and Type III plants were found to be more abundant, their relative proportion depending on the dominance of accretion/erosion processes. Increasing cover of Type I plants was associated with relatively more stable soils. The ratios in occurrences of the three types can be used as an indicator of foredune dynamics.