bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative studies of phenology and early effects of non‐grazing in Cretan phrygana vegetation
Authors: Bergmeier Erwin , Matthäs Ursula
Published: May 2006

Abstract. The phenology of five types of phrygana vegetation situated at various altitudes in SW Kríti (Crete), Greece, was studied over a period of 17 months. Two treatments were compared ‐ traditional pasturing and non‐grazing since spring 1993. The numbers of species in blossom and the numbers of flowering units were recorded. For each site, management type and year were displayed in symphenological diagrams. Differences in phenology were mainly related to altered management or the weather regime, or both. The numbers of flowering units were more evident than those of species in blossom for describing the early response of phrygana vegetation to non‐grazing. Increases in numbers of flowering units in the ungrazed areas are mainly due to certain abundant therophytes. Unfavourable weather conditions in late winter or early spring may cause a temporary decline in annual species. Rainfall in May at low altitudes promotes resprouting and reflowering of annuals.
Composition and ecology of vascular epiphyte communities along an altitudinal gradient in central Veracruz, Mexico
Authors: Hietz Peter , Hietz‐Seifert Ursula
Published: May 2006

Abstract. Vascular epiphytes were studied in forests at altitudes from 720 to 2370 m on the Atlantic slope of central Veracruz, Mexico. The biomass of all trees of each species > 10 cm diameter at breast height within plots between 625 and 1500 m2 was estimated. The number of species per plot ranged between 22 and 53, and biomass between 9 and 249 g dry weight/m2. The highest values, both of species and biomass, were found at an intermediate altitude (1430 m). Habitat diversity may contribute to epiphyte diversity in humid forests, but the importance of this effect could not be distinguished from the influence of climate. A remarkably high number of bromeliads and orchids grew in relatively dry forests at low altitudes. In wet upper montane forests, bromeliads were replaced by ferns, while orchids were numerous at all sites, except for a pine forest. The number of epiphytic species and their biomass on a tree of a given site were closely related to tree size. According to Canonical Correspondence Analysis, the factor determining the composition of the epiphytic vegetation of a tree was altitude and to some extent tree size, whereas tree species had practically no influence. The only trees which had an evidently negative effect on epiphytes were pines, which were particularly hostile to orchids and to a lesser degree to ferns, and Bursera simaruba, which generally had few epiphytes due to its smooth and defoliating bark.
Shoot and leaf demography of Carex curvula ssp. Curvula and Carex curvula ssp. rosae in the Central Alps
Authors: Erschbamer Brigitta , Winkler Josef
Published: May 2006

Abstract. Populations of Carex curvula ssp. curvula, C. curvula ssp. rosae and their intermediate form were investigated in the Central Alps over a three‐year period. The closely related taxa showed a different dominance behaviour in their respective communities. This may be caused by different growth strategies and a different reproduction biology. Therefore, the main aim of the study was to compare the demography of the three taxa. Shoot and leaf turnover, flower and seed production and population half‐lives were determined.

Differences in growth dynamics were less pronounced between the two species of Carex curvula than between these taxa and their intermediate form which showed the highest shoot turnover, highest number of fertile inflorescences and highest number of seeds per inflorescence. Carex curvula ssp. rosae showed a slightly higher shoot and leaf production but a lower reproduction capacity than Carex curvula ssp. curvula.

Recruitment of populations of the three Carex‐forms was only by vegetative shoots. Flowering had a striking effect on the shoot dynamics of the species grown in the grassland sites: up to about 70 % of all dead shoots could be identified as dead flowering shoots from the previous year.

The different dominance behaviour of the three taxa could not be explained by their demographical features. Interspecific interactions and the occurrence of microniches might affect the growth and reproduction processes of the taxa.
A vegetation map of tropical continental Asia at scale 1:5 million
Authors: Blasco F. , Bellan M.F. , Aizpuru M.
Published: May 2006

Abstract. A vegetation map at scale 1:5 million is presented.* It covers Bangladesh, Burma (Myanmar), India, Cambodia, Laos, Thailand, Vietnam and Sri Lanka and fills a conspicuous gap in the cartography of tropical vegetation, following the publication of vegetation maps of South America, Africa and Malaysia. For conformity, it is presented as one sheet at a scale of 1:5 million. It uses the basic map of the American Geographical Society (1942; bipolar oblique conformal projection) which forms the base for FAO's Soil map of the world. Basic information was obtained from many published maps, unpublished observations and satellite data. The limits of the main vegetation types have been updated with a complete set of Landsat MSS images (369 scenes) with a mosaic of Landsat TM data for 1991 and with recent forest maps from Asia.

Nine main vegetation units, which are groups of forest formations, have been identified and mapped, including woodlands, thickets and wooded savannas. Agricultural land has been shown in a uniform pale green colour in order to clearly express the extent of human impacts on woody vegetation.

In spite of the necessary oversimplification of the ground data, this map is probably the most explicit expression of the remaining forest stands and of the regression of natural vegetation in the region. It can be considered as a benchmark for future monitoring of tropical vegetation.
High‐elevation rock outcrop vegetation of the Southern Appalachian Mountains
Authors: Wiser Susan K. , Peet Robert K. , White Peter S.
Published: May 2006

Abstract.Species composition patterns and vegetation‐environment relationships were quantified for high‐elevation rock outcrops of the Southern Appalachian Mountains, an infrequent and insular habitat in a forested landscape. Outcrops occur over a wide geographic range encompassing extensive variation in both geology and climate. Geographic‐scale factors interact with site‐scale factors to produce variation in vegetation among outcrops. Similarly, site‐scale factors interact with micro‐scale factors to produce variation in vegetation within outcrops. To provide a quantitatively‐based classification of outcrop vegetation we used a TWINSPAN analysis of 154 100‐m2plots. We recognized nine communities that primarily correspond to different combinations of elevation, bedrock type, geography, and moisture. Within outcrops of a single bedrock type, vegetation composition of 100‐m2plots was consistently correlated with elevation and solar radiation, but relationships to soil nutrients varied with bedrock type. Both site‐scale (100 m2) factors (e.g. elevation, slope, aspect, and bedrock type) and plot‐scale (1‐m2) microsite factors (e.g. soil depth, vegetation height, soil nutrients) were strongly correlated with species composition at the 1‐m2level. Environment can be used to predict composition more effectively for 100‐m2plots on a single bedrock type than either across bedrock types or at a 1‐m2scale. Composition‐environment relationships resemble those described for outcrop systems from other regions with pronounced topographic relief more than they do those described for the nearby but flatter and lower‐elevation outcrops of the Southeastern Piedmont. There is strong spatial autocorrelation in this community, perhaps owing to dispersal limitation. Consequently, a comprehensive conservation strategy must include reservation of both a range of geologic types and a range of geographic locations.
The effect of gap dynamics on the size and spatial structure of Solidago sempervirens on primary coastal dunes
Authors: Lee Philip C.
Published: May 2006

Abstract. The role of gap dynamics in shaping the spatial and size distributions of the gap specialist Solidago sempervirens (seaside goldenrod) were examined on the primary dune grassland (Ammophila breviligulata, American beachgrass) of an Atlantic barrier island. Results suggest that coastal dune blowouts are patchy disturbances that allow S. sempervirens to temporarily establish and disperse seed. Natural measurements and clipping experiments demonstrated that A. breviligulata competitively dominated S. sempervirens in undisturbed grasslands. Coastal dune blow‐outs reversed this dominance by temporarily burying A. breviligulata and increasing densities and above‐ground biomass of S. sempervirens. Examination of size/density distributions of S. sempervirens suggested that blow‐outs were seed sources but not regeneration sites. Regeneration was found primarily in neighboring transition and undisturbed grassland areas. Comparison of lateral growth by A. breviligulata on blow‐out margins suggested that disturbances were closed by lateral encroachment from gap edges. After blow‐out recovery, greater densities and skewed size distributions of S. sempervirens could still be detected for a number of years after blow‐out recovery.
Clonal growth inAilanthus altissimaon a natural site in West Virginia
Authors: Kowarik Ingo
Published: May 2006

Abstract.: The exotic treeAilanthus altissimais usually confined to open sites. As an exception,Ailanthusestablished in a densely closed forest in West Virginia, which was analyzed with the aim to elucidate possible pathways of persistence in forest succession of this light‐demanding pioneer species. Demographic analysis revealed a seedling mortality of 100 %. Instead, the understory is populated by clonal ramets, ranging from one to more than 19 yr of age, with a mean of 5 yr. Growth averages only 0.11 m/yr, and height is correlated with age. This clonal growth contrasts with the performance ofAilanthuson open sites. The possible ecological benefits of establishing a ramet bank in a resource‐poor habitat are considered in terms of space occupation of a pioneer species.
The vegetation of the Farasān Islands, Red Sea, Saudi Arabia
Authors: El‐Demerdash M.A.
Published: May 2006

Abstract. Classification of the vegetation of the Farasān Islands using TWINSPAN technique resulted in the recognition of seven community types associated with seven different habitat types: silty runnels, palm orchards, rocky plains, rocky plateau crevices, coastal sand dunes, sand plains, and mangroves. These communities were dominated or co‐dominated by 13 perennial species; 87 associate species were recorded in the study area with chamaephytes dominating the life‐form spectrum. Canonical Correspondence Analysis (CCA) indicated that organic carbon, soil moisture, silt, electrical conductivity and calcium carbonate were the major edaphic gradients controlling the distribution of the plant communities on the Farasān Islands.

Higher species richness was recorded in the plant communities inhabiting the palm orchards, the crevices of the rocky plateau, silty runnels, rocky plains and rocky plateau, while those of the mangrove and sand formations (dunes and plains) showed a lower species richness.

Soil texture and organic matter are the main factors promoting species diversity in the more diversified habitats, while high salinity and calcium carbonate are the main factors associated with lower species diversity in the less diversified habitats of the study area.
Variation in species richness on small grassland quadrats: niche structure or small‐scale plant mobility?
Authors: Van Der Maarel Eddy , Noest Vera , Palmer Michael W.
Published: May 2006

Abstract. In this study we make clear that the significance of deviations from an expected variance in species richness as demonstrated in alvar grassland, is a function of spatial pattern at the scale richness was measured, i.e. 10 cm2. If corrected for spatial dependence, more than half of the significant cases become nonsignificant. As regards cases of significant variance deficit, which has been interpreted as an indication of niche limitation, we suggest that there may be a simple physical limitation to the number of species on the scale of observation in the form of a low number of plant units which can find a place because of the modal plant size of the species involved. In most cases of significant variance deficit the modal size of the plant units involved was probably bigger than average.

Insofar as a significant variance deficit can be demonstrated, the resulting species richness distribution curve should be analyzed and we propose a skewness test, enabling us to differentiate between significantly left‐skewed curves (‘niche limitation’), significantly right‐skewed curves (‘niche facilitation’) and symmetrical curves. We present results obtained with the G‐test, a log‐likelihood ratio goodness of fit test. Only few cases of significantly left‐skewed curves and a majority of symmetrical curves were found.

Attempts to demonstrate guild proportionality in grasslands suffer from the heterogeneity of usually distinguished guilds, such as annuals vs. perennials or graminoids vs. dicotyledons.

We observe that niche limitation may occur in alvar grassland, but indications for niche facilitation are stronger. Finally, we conclude that deviations in species richness variance are interesting indications of community structure, but only of spatial structure. Niche structure resulting from assembly rules should be investigated through experiments.
The migration of sessile organisms: a simulation model with measurable parameters
Authors: Collingham Yvonne C. , Hill Mark O. , Huntley Brian
Published: May 2006

Abstract. Palaeoecologists have shown that trees migrated at rates of 100–1000 m/yr in response to post‐glacial warming. In order to predict the impact of forecast anthropogenic climate changes upon forest ecosystems we need to simulate how trees may migrate in response to the changes predicted for the next 1–2 centuries. These predictions must take account of the impacts upon migration of human land‐use and habitat fragmentation. We have developed a spatially‐explicit mechanistic model (MIGRATE) able to simulate the migration of a single species across a realistically heterogeneous landscape. MIGRATE uses biological parameters that readily may be estimated from data in the literature or from field studies, and represents the landscape as a grid of cells, each with an associated carrying capacity. A one‐dimensional version of MIGRATE has been compared both with Skellam's (1951) diffusion model and with the more recent analytical models of van den Bosch et al. (1990, 1992); despite its fundamentally different approach, MIGRATE provides comparable estimates of migration rates, given equivalent input parameters. An example is described that demonstrates the ability of the two‐dimensional version of MIGRATE to simulate the likely pattern of spread of a species across a heterogeneous landscape. It is argued that MIGRATE, or models like it, will play a central role in a spatially‐hierarchic modelling strategy that must be developed if we are to achieve the goal of simulating the likely response of trees, and other organisms, to both global climate change and the increasing pressures of human land‐use.
Regeneration of monsoon rain forest in northern Australia: the sapling bank
Authors: Jeremy Russell‐Smith
Published: May 2006

Abstract. As part of a wider study examining regeneration pathways in monsoon rain forest vegetation in northern Australia, a one‐off, dry season census of saplings was undertaken along transects sampled at each of 33 relatively undisturbed sites broadly representative of the range of regional monsoon rain forest vegetation. Four floristic quadrat groups were derived through TWINSPAN classification. Subsequent analyses involved: (1) comparison of mean dry season stockings of juveniles occurring in different rain forest types, and their structural and environmental correlates; (2) comparison of the contributions of different life forms, and the influence of clonal reproduction in the sapling regeneration banks of different forest types; and (3) exploration of relationships between the distributions of saplings of common tree species with respect to seed bank, floristic, structural, and environmental variables. While data presented here require cautious interpretation given that processes of seedling/sapling recruitment and mortality are highly dynamic, sapling banks were found to be most dense on coarse‐textured, moist soils, and least dense on coarse‐textured, seasonally dry soils. Canopy cover and fire impact were shown to be highly influential on sapling distribution, especially for saplings of tree species and those growing on seasonally dry sites. Sapling densities were little influenced by proximity to rain forest margins, except for shrubs. The potential for clonal reproduction was significantly greater on dry sites, especially for trees. The majority of saplings sampled were derived from relatively few common, non‐clonal, canopy tree species. Sapling distributions of 20 out of 23 common tree species were clumped in the vicinity of conspecific adults; for most species the strength of this relationship was greater than that for any other variable. These data support observations in the literature concerning the distribution of sapling banks in moist and dry tropical forests.
Changes in landscape structure in the northwestern Alps over the last 7000 years: lessons from soil charcoal
Authors: Carcaillet Christopher , Brun Jean‐Jacques
Published: May 2006

Abstract. Current land‐use a bandonment and the current rise in temperature in the Alps both suggest that tree limits may change. When it is assumed that the climate of the early mid‐Holocene between 8000 and 5000 yr before present is analogous to that of the predicted climate of the late 21st century, palaeo‐ecological studies of the early Holocene may provide data for the prediction of the vegetation pattern in a century from now. It appears that mid‐Holocene charcoal assemblages can be used to reconstruct the spatial patterns of the vegetation before, or during, the practice of slash‐and‐burn.

Correspondence analysis (CA) of charcoal assemblages shows that an important ecological gradient is determined by elevation. However CA also shows that charcoal assemblages in profiles between 1700 and 2100 m a.s.l. are roughly stratified: the more recent assemblages from the topmost centimetres of soil are intermediate between the lowermost assemblages and assemblages from higher elevations. This suggests that the woody communities at the highest elevation were located at lower elevations at a later date. The taxonomic diversity of the soil charcoal assemblages has been compared to that of present‐day phytosociological relevés after transformation to charcoal‐equivalent data. This comparison revealed that the vegetation pattern along the altitudinal gradient in the mid‐Holocene was different from that at present. The assemblages indicate that some communities disappeared, that Picea is a late‐Holocene invading species, and that there is no strict modern analogue for the vegetation structure prior to that of 3000 yr ago. The past structure of the woody vegetation was also different from that of today. Although past vegetation is not a good analogue for predicting future vegetation patterns, it still has potential as an indicator for the potential presence of tree species where there is none today. If we assume a temperature rise, and take into account current trends of landscape use abandonment, then we can expect strong vegetation dynamics at the upper tree line in the future: Abies alba may expand to occupy elevations of ca. 1800–2000 m in mixed communities with Picea abies, Pinus sylvestris and hardwood species, and Pinus cembra may expand up to 2500–2700 m a.s.l.
International Code of Phytosociological Nomenclature. 3rd edition
Authors: Weber H.E. , Moravec J. , Theurillat J.‐P.
Published: May 2006

Abstract. This is the 3rd edition of the Code of phytosociological nomenclature, prepared by the Nomenclature Commission of the International Association for Vegetation Science (IAVS) and the Fédération Internationale de Phytosociologie (FIP) on the basis of the 2nd edition. The Code consists of a series of definitions, principles, rules and recommendations which will facilitate the proper use of syntaxonomical names for the denomination of syntaxonomical units.
Slow‐motion population dynamics in Mojave Desert perennial plants
Authors: Cody Martin L.
Published: May 2006

Abstract. To investigate survivorship and regeneration in desert perennial plants, individual shrubs were mapped, measured and tagged on a nearly level 360 m2 plot of diverse Mojave Desert vegetation in 1981, they were re‐mapped and measured 15 years later, in 1996. A large majority of the shrubs persisted between censuses. Modest birth (establishment) and death rates indicate that plants are replaced approximately every century, while the median longevity of several species is much longer. A 15‐yr intercensus interval, appropriate for most species (i.e. birth and death rates were measurable), is too short for several larger shrubs (including Larrea divaricata, Ephedra nevadensis, Yucca schidigera and the larger Opuntia spp.) in which virtually no births or deaths occurred and in which longevity must be extremely high.

While individuals of most species grew over the 15‐yr interval, others did not, and some individuals shrank in size. In a number of species, individual growth rates were significantly reduced according to the number of neighbouring plants rooted 0.5–2.0 m distant. Even Larrea tridentata, one of the largest species, showed significant effects of growth rate reduction where crowded by allospecific plants, despite the generally much smaller sizes of these neighbours.
Acidification and eutrophication of deciduous forests in northwestern Germany demonstrated by indicator species analysis
Authors: Diekmann Martin , Dupré Cecilia
Published: May 2006

Abstract.A new method of indicator species analysis is suggested that can be used to demonstrate changes in the species composition of forests resulting from atmospheric deposition of acidifying substances and nitrogen. The method is not dependent on an exact re‐localization of sites. 2162 published relevés ofFagus sylvaticaandQuercus robur‐Carpinus betulusforests from two study areas in Germany (S Niedersachsen and Nordrhein‐Westfalen) were compiled and divided into relevés from before 1975 and more recent relevés. Weighted averages of Ellenberg indicator values for light (L), moisture (M), reaction (R), and nitrogen (N) were calculated and for each of the four data sets ‐ mesic and dry sites in two areas ‐ N was regressed on R to give a predicted value (Npred) for any given R. The differences between observed values Nobsand Npredwere calculated separately for old and new relevés (Ndev‐old and Ndev‐new). The same analysis was applied to model data including 16 different scenarios of acidification and/or eutrophication.

The model runs resulted in six different types of regression plots for Ndev and R. All models had in common that the regression lines for Ndev‐new lay, completely or largely, above the zero line ofno change and above the lines for Ndev‐old. Also, in the four data sets, Ndev‐newwas generally larger than Ndev‐old, and particularly so in Nordrhein‐Westfalen. The values of Ldev‐oldand Ldev‐newindicate that the differences in Ndevare unlikely to be caused by altered forest management, but must result from atmospheric pollution.
Chlorophyll fluorescence, stress and survival in populations of Mediterranean grassland species
Authors: Figueroa M.E. , Fernández‐Baco L. , Luque T. , Davy A.J.
Published: May 2006

Abstract. Photosynthetic stress in response to a natural episode of frost and seasonal drought was assessed in a ‘dehesa’ grassland of SW Spain with a portable fluorimeter. Chlorophyll fluorescence characteristics of dark‐adapted leaves of 11 abundant species of Mediterranean grassland were measured over the course of a growing season from November 1992 to July 1993. Concomitant changes in population size were estimated from censuses of permanent quadrats. There was a general decline in the photochemical efficiency (Fv/Fm) during the growing season and this was particularly evident late in the growing season (spring and early summer) when ambient temperatures were increasing rapidly and rainfall was low; it coincided with the period of most intense mortality for most species. A frost in early March (‐ 5 °C), when photosynthetically active radiation was relatively high, resulted in a small decrease in Fv/Fm that was consistent across many species. The mechanisms of protection in species of Mediterranean grassland appear to be sufficiently effective to avoid damage to PSII for most of the year. For most species there was little evidence of photosystem II damage, as initial fluorescence (F0) usually did not increase. Many of the effects observed were due to a reduction in Fm and thus were consistent with non‐photochemical quenching. This could be adaptive in protecting PSII from damage in species that show little evidence of stress. The sharp increase in stress toward the end of the life cycle coincided with the fall in net population size.
Competition between Quercus petraea and Carpinus betulus in an ancient wood in England: seedling survivorship
Authors: Le Due M.G. , Havill D.C.
Published: May 2006

Abstract. Age structures of populations of canopy trees in Wormley Wood are consistent with reports that successional change is occurring, with Carpinus betulus replacing Quercus petraea as the dominant species. TWINSPAN analysis of data from a vegetation survey identifies three communities (described in earlier work), the ‘Bracken’, ‘Bramble’, and‘Bareground’ societies, characterized by increasing prominence of C. betulus and loss of species diversity.

An experiment was set up in which C. betulus, Q. petraea and Betula pendula seedlings were explanted into each of the communities. Survival of seedlings was monitored over 860 days and differences investigated. Cohort survivorship differed between species and sites. C. betulus seedlings survived longer than Q. petraea in Bracken and Bramble communities.

Species‐ and site‐specific variation in the types and effects of herbivory were found. Herbivory did not appear to be a critical factor in the survival of Q. petraea seedlings. The photosynthetic light response of the seedling species was measured in the field. The light compensation point for Q. petraea seedlings (77 μmol photon m‐2 s‐1) is higher than the maximum available light under the main tree canopies in the wood. In contrast, seedlings of C. betulus have a lower light compensation point (15 μmol photon m2 s‐1) and the mature tree casts a deeper shade than Q. petraea. It is suggested that the invasion of the canopy by C. betulus, following the cessation of coppicing, is creating light levels too low for Q. petraea seedling banks to persist.
BOOK REVIEWS
Authors: Meijer Willem
Published: May 2006

Book Reviewed in this article:

Anhuf, Dieter. 1997. Satellitenbildgestützte Vegetationklassifikation der Côte d'Ivoire. Mannheimer Geographische Arbeiten 45. ix + 190 pp. ISBN Price:

Anhuf, Dieter (ed.). Forschungen im französischsprachigen Ausland. Mannheimer Geographische Arbeiten 43. 179 pp. ISBN Price:
Ecological requirements of Abies alba in the French Alps derived from dendro‐ecological analysis
Authors: Rolland C. , Michalet R. , Desplanque C. , Petetin A. , Aimé S.
Published: May 2006

Abstract. We used dendro‐ecological techniques to investigate fundamental relationships between climate and growth of Abies alba (silver fir) in eastern France. Seven Abies forests in the Trièves region of the French Alps were chosen to represent a wide range of ecological conditions based on the results of previous forest vegetation surveys. In each forest, four trees were sampled in each of five different stands with two cores per tree. These 280 cores were studied using two separate dendro‐ecological methods: the pointer years method (based on extreme growth events), and correlation functions between tree ring‐widths and monthly climatic data. Data from 11 meteorological stations were combined to provide a regional analysis of precipitation and minimum and maximum temperatures. The two dendro‐ecological methods appear to be complementary, as the first technique emphasizes common and low intensity linear correlations between ring‐widths and climatic variations, and the second method emphasizes extreme and unusual climatic events such as exceptionally cold or dry years.

Across all sites, drought in the previous year was consistently correlated with a low growth rate; however, other climatic variables varied substantially among sites. For example, drought in the current year reduced growth more in the low elevation sites than in the high elevation sites and severe winter frost reduced growth the most in the high altitude sites and the driest site. Moreover, certain growth responses are better correlated with the age of the stands, the canopy closure and the floristic composition of the community than the abiotic factors, emphasizing the value of dendro‐ecological sampling based on phytosociological units.
How do species dominating in succession differ from others?
Authors: Prach Karel , Pyšek Petr
Published: May 2006

Abstract.Data on succession were collected from 15 seres starting on bare ground in man‐made habitats (i.e. sites disturbed by various mining activities, bulldozed sites, ruderal urban sites, the exposed bottom of a destroyed water reservoir, and abandoned fields), all in the western part of the Czech Republic, Central Europe. The period for which the data on succession were available ranged from 12 to 60 yr. 56 species reaching dominance in some period of succession were selected (the criterion being: at least 25 % cover in at least one year in any sere); they were compared for biological and ecological traits with other species participating in the seres (167 species with at least 1 % cover in at least one year in any sere), and with the Central European flora as a whole. Significant differences between the species dominating in succession and others were found for the following traits: life form, life strategy, pollination mode, and ability of lateral spread. Dominant species differed from the regional flora in distribution of life strategies, pollination mode and immigration status. The results suggest that an ‘ideal successional dominant’ is a tall, wind‐pollinated plant, often a geophyte capable of intensive lateral spread, requiring high nutrient supply and sufficient site moisture. The set of traits contributing to achieving dominance by a species in human‐made habitats includes both features occurring independently of phylogenies (life strategy, pollination mode, plant height, moisture demands) and those which dominant species probably share due to their common ancestors (nutrient demands, capability of extensive lateral spread).
Phenology, growth and ecophysiological characteristics of Fallopia sachalinensis
Authors: Marigo Gérard , Pautou Guy
Published: May 2006

Abstract. Fallopia (Polygonum) sachalinensis (Polygonaceae) is native to the Far East from where it was introduced into Europe and Northern America. It has only recently appeared on the large alluvial plains of alpine rivers, while it has formed monospecific stands in many habitats. In this study, we investigated some of the biological characteristics of this species in order to predict its invasiveness under the specific environmental conditions of alpine alluvia. When compared to other plants which tend to monopolize space, F. sachalinensis appears to have a life cycle characterized by an early seasonal development. It exhibits a high growth rate – ca. 4 to 5 cm/day, and its productivity is associated with intrinsic characteristics of the species: abundant leaf cover, the appearance of branches when the leaves reach an optimal size on the main stem, and favourable leaf orientation to capture high light intensity. Another morphological characteristic is the presence of a large medullary air cell containing a liquid rich in mineral salts which can be used by the plant when the demand for evaporation increases. Clonal spread associated with an extraordinarily high rate of proliferation of below‐ground organs, and mechanisms for adaptation to adverse conditions are biological traits rendering F. sachalinensis an invader in alluvial plains along alpine rivers. There is a risk that such species experience a demographic explosion in the geographical region under study.
Effects of soil texture and precipitation on above‐ground net primary productivity and vegetation structure across the Central Grassland region of the United States
Authors: Lane Diana R. , Coffin Debra P. , Lauenroth William K.
Published: May 2006

Abstract. A potentially important organizing principle in arid and semi‐arid systems is the inverse‐texture hypothesis which predicts that plant communities on coarse‐textured soils should have higher above‐ground net primary productivity (ANPP) than communities on fine‐textured soils; the reverse is predicted to occur in humid regions. Our objectives were: (1) to test predictions from the inverse‐texture hypothesis across a regional precipitation gradient, and (2) to evaluate changes in community composition and basal cover on coarse‐ and fine‐textured soils across this gradient to determine how these structural parameters may affect ANPP. Sites were located along a precipitation gradient through the Central Grassland region of the United States: mean annual precipitation ranges from 311 mm/y to 711 mm/y, whereas mean annual temperature ranges from 9 °C to 11 °C.

For both coarse‐ and fine‐textured sites in 1993 and 1994, August ‐ July precipitation in the year of the study explained greater than 92% of the variability in ANPP. Soil texture did not explain a significant proportion of the variability in ANPP. However, soil texture did affect the proportion of ANPP contributed by different functional types. Forbs and shrubs made up a larger proportion of total ANPP on coarse‐ compared to fine‐textured sites. Shrubs contributed more to ANPP at the drier end of the gradient. Basal cover of live vegetation was not significantly related to precipitation and was similar for both soil textures. Our results revealed that across a regional precipitation gradient, soil texture may play a larger role in determining community composition than in determining total ANPP.
Shrub facilitation of Quercus humilis regeneration in succession on calcareous grasslands
Authors: Rousset Olivier , Lepart Jacques
Published: May 2006

Abstract. In southern France, the natural invasion by Quercus humilis of calcareous grassland takes place in a mosaic of herbaceous and scrubby patches. We hypothesized that the presence of the shrubs Buxus sempervirens and Juniperus communis alter the rate and the pathway of the succession by facilitating the regeneration of Q. humilis. To infer the process of facilitation at a large scale, the spatial distribution of Q. humilis was studied in relation to acorn sources and the type of plant cover in grazed and ungrazed sites.

Abundant recruitment up to 80 m from the wood margins and from isolated oak trees in grassland shows that acorns are dispersed effectively. At the three study sites, the density of Q. humilis individuals was higher under shrubs than in grassland, suggesting that facilitation may occur. This density difference was much higher in the grazed sites than in the ungrazed site. Moreover, before grazing by livestock, the distribution of first‐year seedlings is independent of vegetation cover. Thus, shrubs improve Q. humilis regeneration by protecting individuals from grazing. The high density of individuals at the northern edge of shrubs suggests that a second facilitation mechanism may exist, probably related to improved germination conditions. Facilitation by shrubs appears to be very important for Q. humilis dynamics.
The alien flora of Europe: a taxonomic and biogeographic review
Authors: Weber Ewald F.
Published: May 2006

Abstract. A geographic and taxonomic overview of the non‐indigenous plant species of Europe, based on the ‘Flora Europaea’ is given. The flora of Europe includes 1568 species which have either expanded their ranges within Europe under human influence (naturalized European species) or are of non‐European origin (exotic species). The latter group consists of 580 species (37%) which form a diverse group in terms of their taxonomic composition and geographic origin. The exotics are represented by 113 families, of which the Compositae, Rosaceae and Gramineae are most important. The ratio of species to families is low. Most exotic species in Europe originate from the Americas and Asia. Countries of southern Europe have a higher relative number of exotics in their non‐native flora than northern ones. The species‐range size distribution differs between naturalized European and exotic species; the latter are on average more widespread than the naturalized.
Fine‐scale distribution of the epiphytic lichenUsnea longissimaon two even‐aged neighbouringPicea abiestrees
Authors: Gauslaa Y. , Ohlson M. , Rolstad J.
Published: May 2006

Abstract.Two neighbouring even‐aged 130‐yr oldPicea abiestrees in a homogeneous stand can differ substantially with respect to their epiphytic vegetation. Sampled branches from the canopy of one tree harboured 781 specimens of the old forest lichenUsnea longissimaof which only 50 could be seen from the ground, whereas noU. longissimawere found on its nearest neighbour.Usnea longissimawas most abundant on branch tips in lower parts of the canopy on branch segments having the highest biomass of other alectorioid species. Trees with and withoutU. longissimashowed a different pattern in their mineral composition, suggesting that a tree‐specific difference in nutritional status might contribute to explain the patchy distribution of this lichen within seemingly homogeneous stands.
Establishment of Fagus sylvatica and Fraxinus excelsior in an old‐growth beech forest
Authors: Peltier Aline , Touzet Marie‐Claire , Armengaud Claude , Ponge Jean‐François
Published: May 2006

Abstract. Distribution of tree seedlings, forest architecture, light conditions, ground vegetation and humus conditions were studied in a 45 m × 100 m area including multiple gaps in an old‐growth beech forest. Gaps were created after some beech trees had been felled in severe storms in February 1990. A group of adult ash trees is found near the study site. The data were analyzed by Correspondence Analysis. Young seedlings (< 4 yr), of both Fraxinus (a sun species) and Fagus (a shade species), were most abundant under the crown of beech trees in semi‐shade conditions, and where beech litter did not accumulate.

Differences in the dissemination of Fraxinus and Fagus explained differences in the establishment of the two species. In contrast, older seedlings of beech established before the storms were more numerous in the gaps, suggesting a change in the ecological requirements of beech seedlings in the course of time.
The role of anthropogenic influences in a mixed‐conifer forest mortality episode
Authors: Savage Melissa
Published: May 2006

Abstract. Anthropogenic influences on recent tree mortality in mid‐montane mixed conifer forests of southern California, USA, and northern Baja California, Mexico, were investigated. The Pinus jeffreyi‐Abies concolor phase of the mixed‐conifer montane community was sampled at three sites, characterized by: (1) low levels of air pollution and long‐term fire suppression (Holcomb Valley in the San Bernardino Mountains, California); (2) chronic, severe air pollution and long‐term fire suppression (Barton Flats in the San Bernardino Mountains, California); and (3) little air pollution and no fire suppression (La Corona Arriba in the Sierra San Pedro Martir in Baja California, Mexico). Similar percentages of dead standing trees, around 14 %, were found at both San Bernardino sites, but a comparatively low level, 4 %, was found in the Mexican forest. Anthropogenic effects, in particular fire suppression, may play an important role in enhancing the impact of natural stresses on the dynamics of mixed conifer forests.
Distribution patterns of tree species in a Malaysian tropical rain forest
Authors: Fangliang He , Legendre Pierre , LaFrankie James V.
Published: May 2006

Abstract. Spatial patterns of tree species were studied in a 50‐ha tropical rain forest plot in the Pasoh forest, Malaysia. This forest is characterized by a high diversity and very high number of rare species. Out of the 745 species occurring with > five individuals, 80.4 % had an aggregated distribution, 19.5% were randomly distributed and one species had a regular distribution. The spatial patterns of rare vs. common species, juvenile vs. adult trees, and coarse vs. fine scales were compared. Rare species are generally less aggregated than common ones and most of the randomly distributed species are rare. Spatial patterns shift from high clumping to looser intensity or random distribution when moving from juveniles to adults for the same species. No adult tree species display a regular pattern, however. Regular distributions were rarely found; this is probably due to intraspecific competition at a local scale. There is a negative correlation between per capita death rate and population density.

This study suggests that the Pasoh forest and its high diversity are subjected to multiple controlling factors, e.g., topography, spacing effect, density‐dependent processes and species rarity. The importance of any factor changes across spatial and temporal scales.
Effects of overstory and understory vegetation on the understory light environment in mixed boreal forests
Authors: Messier Christian , Parent Sylvain , Bergeron Yves
Published: May 2006

Abstract. The percentage of above‐canopy Photosynthetic Photon Flux Density (%PPFD) was measured at 0, 50 and 100 cm above the forest floor and above the main understory vegetation in stands of (1) pure Betula papyrifera (White birch), (2) pure Populus tremuloides (Trembling aspen), (3) mixed broad‐leaf‐conifer, (4) shade‐tolerant conifer and (5) pure Pinus banksiana (Jack pine) occurring on both clay and till soil types. %PPFD was measured instantaneously under overcast sky conditions (nine locations within each of 29 stands) and continuously for a full day under clear sky conditions (five locations within each of eight stands). The percentage cover of the understory layer was estimated at the same locations as light measurements.

Mean %PPFD varied from 2% at the forest floor under Populus forests to 15% above the understory vegetation cover under Betula forests. Percent PPFD above the understory vegetation cover was significantly higher under shade intolerant tree species such as Populus, Betula and Pinus than under shade tolerant conifers. No significant differences were found in %PPFD above the understory vegetation cover under similar tree species between clay and till soil types. The coefficient of variation in %PPFD measured in the nine locations within each stand was significantly lower under deciduous dominated forests (mean of 19%) than under coniferous dominated forests (mean of 40%). %PPFD measured at the forest floor was positively correlated with %PPFD measured above the understory vegetation and negatively correlated with cumulative total percent cover of the understory vegetation (R2 = 0.852). The proportion of sunflecks above 250 and 500 mmol m–2 s–1 was much lower and %PPFD in shade much higher under Populus and Betula forests than under the other forests. Differences in the mean, variability and nature of the light environment found among forest and soil types are discussed in relation to their possible influences on tree succession.
Types of rarity of plant communities
Authors: Izco Jesús
Published: May 2006

Abstract. The concept of rarity has been used in an ambiguous and confused way in vegetation science. Some authors have defined rarity of plant communities in terms of frequency of occurrence, while others have used the term with reference to the abundance of participating species. Association rarity can be defined in three dimensions: geographical extent of occurrence, absolute frequency of occurrence within the geographical range, and characteristic size of individual stands of the association. Here, each dimension is considered as a binary variable, and seven types of rarity are defined and discussed with examples.
BOOK REVIEWS
Authors: Lechowicz Martin
Published: May 2006

Book reviewed in this article:

Lieth, H. & Schwartz, M.D. (eds.) 1997. Phenology in seasonal climates I. Progress in Biometeorology, Vol. 12. 143 pp. Backhuys Publishers, Leiden. ISBN 90–73348–79‐X. Price: USD 42.25.
Species diversity, susceptibility to disturbance and tree population dynamics in tropical rain forest
Authors: Burslem David F.R.P. , Whitmore Timothy C.
Published: May 2006

Abstract. In 1964 a census of all trees > 9.7 cm diameter at breast height (DBH) was conducted on 22 plots totalling 13.2 ha in lowland tropical evergreen rain forest on Kolombangara, Solomon Islands. Over the following 30 yr (1964–1994), populations of all individuals > 4.85 cm DBH of the 12 most common tree species and amounts of disturbance have been monitored on a declining number of these plots (in 1994, nine plots totalling 5.4 ha were still being recorded). Between November 1967 and April 1970, Kolombangara was struck by four cyclones, although only two of these caused substantial amounts of damage to the canopy structure. Multivariate analysis has identified six forest types on Kolombangara (Greig‐Smith et al. 1967). The species richness and diversity of trees in the 1964 census, turnover rates of the populations monitored over 1964–1975, and the amount of disturbance sustained during a cyclone in 1970, were all positively correlated across five of the forest types. The sixth forest type was a consistent outlier in these analyses and is believed to have been seriously disturbed by humans about a century ago. The floristics, turnover and disturbance data support Connell's intermediate disturbance hypothesis. The most species‐rich forest types contained a higher proportion of fast‐growing individuals and species that are early‐successional and which have low density timber. Properties of these species rendered them more susceptible to damage when struck by the 1970 cyclone. They showed higher turnover rates because disturbance‐dependent species are also characterised by higher mortality and recruitment rates. Thus, periodic cyclones appear to favour the maintenance of differences in species diversity and composition between forest types.
Fine‐scale spatio‐temporal patterns in a mountain grassland: do species replace each other in a regular fashion?
Authors: Herben Tomáš , Krahulec František , Hadincová Věra , Pecháčková Sylvie , Kováčiová Marcela
Published: May 2006

Abstract. Long‐term ‘high spatial resolution’ permanent plot data were used to determine whether fine‐scale species replacements in space occur more often than expected on the basis of random processes, and to test whether these replacements are species‐specific. Monte Carlo tests were used. There was no indication of significance in associated positive change (species A increased when B increased); the overall number of significant results was not higher than expected on a random basis. For associated negative change, or replacements (species A increased when B decreased) the overall number of significant results was significantly higher than expected. Significant reciprocal replacements between Deschampsia flexuosa, Festuca rubra and Nardus stricta were frequent; changes in Anthoxanthum alpinum and Polygonum bistorta were uncorrelated with changes of the former three. The first three species thus use the ‘same’ space. Both the latter species often reproduce by seeds and their turnover is much higher. The prevalence of negative correlations of changes (i.e. correlation of increase with decrease) supports the concept of an internal structuring within the grassland community.