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The study site is the Honghe National Nature Reserve, a Ramsar designated site on the Sanjiang Plain in Northeast China. We present results regarding the spatial pattern and structure of plant communities in these most important natural but continually diminishing freshwater wetlands of China to help promote both protection and restoration. By investigating three ecological levels (landscape, ecosystem and community), this paper quantifies the characteristics of spatial pattern with the aim to identify specific ecological correlations with different hydrogeomorphic features. Specifically, the research involves hierarchical mapping of vegetation types by use of remote sensed data, and the coupling of landscape indices with fluvial topographic zones that have been deduced by GIS from DEM. Statistics from historical survey data are also used to measure the degradation of marshes as well as the historical change of the hydrological regime. We found that dominant is the Calamagrostis angustifolia — Carex spp. community type, a wet meadow and marsh complex within the prevailing landscape mosaic of shrubland and meadow. The results suggest that the sites’ hydro-geomorphic character has decisive influence on plant community structure and composition. There is only limited direct human interference in the sites and, as a consequence, the spatial pattern of vegetation distribution is natural. However, changes to the hydrological regime as the result of extensive irrigation activity in the surrounding area has led to rapid degradation of marsh wetlands within the sites, which threatens the ecological status in this storehouse of “Natural Genes” in the reserve.

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A detailed analysis of the relationship between woody types and environmental variables (pedological and topographical) was carried out inside the city of Rome. Twenty-three sample sites 100 m2 each were selected according to the principle that they were inside woody vegetation patches greater than 2.3 ha. Presence-absence data were analysed through hierarchical classification and principal coordinates analysis in order to detect woody vegetation types. The six groups identified were then analysed according to thirty-four variables: a spatial discriminant analysis was performed using soil physical and chemical variables measured in the A1 and A2 horizons, topographical variables (altitude, slope and aspect), and annual potential irradiation. This procedure was able to quantify the contribution of the spatial distribution of the samples with respect to that of the environmental variables, thus improving the discriminant model. The combination of three variables: aspect, organic matter A2 and exchangeable cations A2 is the most effective in discriminating the woody types allowing a hypothesis for the planning and management of these communities.

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Community Ecology
Authors: F. Attorre, M. Alfó, D. Bottini, and et al.

A detailed analysis of the relationship between woody types and environmental variables (pedological and topographical) was carried out inside the city of Rome. Twenty-three sample sites 100 m2 each were selected according to the principle that they were inside woody vegetation patches greater than 2.3 ha. Presence-absence data were analysed through hierarchical classification and principal coordinates analysis in order to detect woody vegetation types. The six groups identified were then analysed according to thirty-four variables: a spatial discriminant analysis was performed using soil physical and chemical variables measured in the A1 and A2 horizons, topographical variables (altitude, slope and aspect), and annual potential irradiation. This procedure was able to quantify the contribution of the spatial distribution of the samples with respect to that of the environmental variables, thus improving the discriminant model. The combination of three variables: aspect, organic matter A2 and exchangeable cations A2 is the most effective in discriminating the woody types allowing a hypothesis for the planning and management of these communities.

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Ad hoc decisions during fieldwork reduce the accuracy and reliability of vegetation maps. A method is proposed to objectify vegetation (thematic aspects) mapping (spatial aspects) for monitoring (temporal aspects). The most accurate and reliable description of the vegetation is a list of all plant species found within a plot. Therefore, the proposed method is an interpolation of a spatially representative sample of permanent plots combined with aerial photo interpretation. The method is objective because surveyors do not have to make decisions during fieldwork based on their personal judgement. Moreover, it is flexible, because the classification and interpolation methods can be adapted to specific views or needs depending on the aim of a study. The method was applied to an area in the north of the Netherlands in 1998. A sampling design with a density of 1 plot/ha was used, and interpolated with a perpendicular bisector. In 2002, the number of plots/ha was doubled. The influence of sample density on the mapping results was studied because it is an important decision to be made before fieldwork. Two plots/ha seem to be sufficient in order to obtain reliable information on patterns of plant species composition and vegetation types of the area, and their change over time. However, in patches where vegetation varies on a very small spatial scale this plot density was insufficient.

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Due to its nearly 1.5 million ha extension and the aimed fine mapping resolution, classical vegetation mapping was not suitable method to prepare the habitat map of Duna-Tisza köze region (Hungary). We developed a novel mapping method. By this method the actual status of more than 12,000 patches of semi-natural vegetation was recorded, documented previously as grasslands, wetlands, open forests and grasslands with scattered trees and shrubs in the middle of the 1980s. A digital layer of 272,387 ha at 1 : 25,000 resolution was created as the background of the analysis. Vegetation type was classified at 46,930 points in the mapping area. The collaboration of 59 colleagues resulted in the development of the digital geographical database of the study area (D-TMap GIS Point database). One-third of the data relies on field data, while the other two-thirds on satellite interpretation. Landscape pattern and the accuracy of the statistical data of the habitats, generated from the point database, are improved by the polygonised version of the point database (D-TMap GIS Polygon database). In this paper we show how the GIS Point database was generated, and summarise the ecological content, availability, and limitation of the derived point and polygon based actual habitat maps. Analysis of the database and the landscape scale pattern of the habitats are discussed in a further paper.

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The phylogenetic relationship among species may influence the mechanisms controlling local community assembly in ecological time. We analyzed the degree of recurrence of phylogenetic structure patterns in woody plant communities distributed along grassland-forest ecotones, across different vegetation types in southern Brazil, and the effect of phylogenetic pool size used to assess such patterns. Species frequency in quadrats distributed along grassland-forest ecotones was surveyed in different phytogeographic regions, where forests tend to expand over grasslands. We used principal coordinates of phylogenetic structure (PCPS) to evaluate the structure within vegetation quadrats divided into three habitat categories: grassland, forest edge and forest interior. Furthermore, phylogenetic structure measures were computed using different phylogenetic pool sizes. Our analyses showed consistent patterns in relation to habitat categories and to different phylogenetic pool sizes. Basal clades of angiosperms were associated with forest areas, while late-divergence clades were associated with grasslands. These results suggest that grasslands act as phylogenetic habitat filters to forest woody species, independently of species composition at each site and the phylogenetic pool. Rosanae and Asteranae act as vanguards of forest expansion over grasslands, while Magnolianae species tend to be restricted to forest. Our results shed light on the organization of ecological systems, providing evidence of recurrent phylogenetic structure patterns in ecotone plant communities at regional scale.

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The objective of the work reported is the development of red-edge methodology in order to characterize agricultural vegetation types and the determination of relationships between different vegetation (high biomass, low biomass) and thermal images. Therefore, the aim was to calculate red-edge position (REP) values and compare them to traditional vegetation indices (NDVI) and thermal images. Images were taken by a DAIS 7915 airborne imaging spectrometer that was equipped with an additional thermal imaging system. An exponential relationship was found between the on-curve-evaluation based (REP) and the broad band vegetation indices (NDVI). A linear relationship was determined between surface temperature differences ( ΔT s ) of the vegetation and NDVI values. A logarithmic relationship was found between surface temperature differences ( ΔT s ) of the vegetation of the canopy and red-edge position (REP). NDVI and REP are suitable vegetation indices when there are several bands available in the spectral range of 600-800 nm. REP was found to be a suitable method for analyzing and characterizing vegetated surfaces.

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Community Ecology
Authors: F. Attorre, M. Alfó, D. Bottini, and et al.

A detailed analysis of the relationship between woody types and environmental variables (pedological and topographical) was carried out inside the city of Rome. Twenty-three sample sites 100 m2 each were selected according to the principle that they were inside woody vegetation patches greater than 2.3 ha. Presence-absence data were analysed through hierarchical classification and principal coordinates analysis in order to detect woody vegetation types. The six groups identified were then analysed according to thirty-four variables: a spatial discriminant analysis was performed using soil physical and chemical variables measured in the A1 and A2 horizons, topographical variables (altitude, slope and aspect), and annual potential irradiation. This procedure was able to quantify the contribution of the spatial distribution of the samples with respect to that of the environmental variables, thus improving the discriminant model. The combination of three variables: aspect, organic matter A2 and exchangeable cations A2 is the most effective in discriminating the woody types allowing a hypothesis for the planning and management of these communities.

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Definitions of seed banks are discussed in the introductory part of the paper. In the second part, a literature review regarding sampling problems in soil seed bank ecology is presented. Regarding sampling depth, a rapid decline in soil seed content is demonstrated from example studies. The use of soil cores with 5 cm or 10 cm depth is suggested to ensure comparability of results. For determination of optimal sample volumes for various communities, the species saturation model is suggested such that “minimal volume” can be defined for soil seed banks in the same way that “minimal area” can be defined in phytosociological studies. Although sampling time may depend on research goals for vegetation types with a winter standstill period, late autumn sampling is suggested for detecting the entire soil seed bank, whilst late spring sampling is recommended for the examination of its persistent part. Studies looking at medium (plant community level) and fine scales (patch level) have demonstrated that soil seed bank distributions show horizontal aggregation for most of the cases and for most of the species. Seed dispersal processes which are among major factors responsible for such aggregated patterns are also discussed.

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The recruitment patterns of trees, shrubs and climbers were studied in two contrasting geographical areas in Venezuela: the Venezuelan Central Plain (VCP), and shrubland. The main purpose was to determine whether recruitment was simultaneously affected by adult plant abundance and relative fecundity in two different geographical areas, and if such relationships were influenced by life forms, vegetation types, dispersal syndromes, and within and between habitats in the VCP. Multiple regressions were used to determine the effect of adult plant abundance and relative fecundity on seedling and juvenile plant abundance. The relative abundance of juvenile plants increased significantly with the simultaneous increment of relative adult abundance and relative fecundity. However, the best predictor of plant recruitment was adult plant abundance. The effect of adult abundance and the fecundity of life forms on recruitment varied according to habitat in the VCP. Significant regressions were also found for species with animal dispersed plant species in the VCP and animal and wind dispersed species in the shrubland. This agrees with the associations between shrubs with animals dispersal in the VCP. Although plants tended to recruit mainly in those habitats where the parent plants were found, recruitment also depended upon the fecundity and adult abundance of plants from different habitats. It is suggest that there is a progressive colonization from the forest to the forest border and from the border to the savanna, and that there is a high interdependence between adjacent habitats for recruitment in the VCP.

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