bluuebunny/crossref_metadata_2025 huggingface dataset:
Topographic position and water chemistry of fens in a Dutch river plain
Authors: Wassen Martin J. , Barendregt Aat
Published: May 2006

Abstract. On the Vecht river plain (western Netherlands), small fens, remnants of a large mesotrophic wetland bordering a moraine, of 1 to 5 ha are found in a man‐made matrix of lakes and pastures. The regional position of the fens, local position of sampling sites, composition of the vegetation and local hydrological variables were measured.

Polders in the river plain produce a complex hydrology obscuring the regional zonation between moraine and river. Water supply and species composition are determined more by a site's regional than local position. High‐productivity reedlands are abundant close to the river. Carex paniculata reedlands receive large amounts of river water, which gives their fen water a high K+ concentration. Low‐productivity C. diandra fens and litter fens have their optimum closer to the moraine. C. diandra fens are fed mainly by inflowing nutrient‐poor ground‐ or surface water; litter fens receive primarily rainwater.

Nutrients in fen water and in peat are lowest in C. diandra and C. lasiocarpa fens, but do not differ significantly between the communities. In both, iron seems to be more important than calcium in reducing phosphate solubility. Iron richness in the C. diandra fens is caused by present inflows of ground‐ or surface water, while in C. lasiocarpa fens, which succeed the former, iron richness is the result of historical inflows.
Air temperature, tree growth, and the northern and southern range limits to Picea mariana
Authors: Bonan Gordon B. , Sirois Luc
Published: May 2006

Abstract. Many models that simulate the long‐term response of forests to climatic change use the assumption that northern and southern range limits are caused by the deleterious effects of cold and hot air temperatures, respectively, on individual tree growth and that growth declines symmetrically with air temperatures above and below some optimal value in between these extremes. To test the validity of this assumption, we combined physiological data for black spruce, Picea mariana, growing near the treeline in subarctic Quebec with a model of the biophysical and biochemical effects of temperature on photosynthesis. The physiological conditions allow black spruce to grow over a wider range of air temperatures than is reflected in its geographic distribution. In particular, the physiological data suggest that the northern range limit of black spruce is not caused by the direct effects of cold growing‐season air temperatures on tree growth and that growth is optimal, with respect to temperature, at the southern range limit. While pollen data indicate large geographic changes in spruce abundance with past climatic changes, the current analyses suggest that the direct effect of air temperature on individual tree growth has not caused these changes. Until we better understand the effects of air temperature on ecological processes, the efficacy of climatic change analyses must be evaluated in terms of model assumptions.
Climatic responses of plant species on Tenerife, The Canary Islands
Authors: Fernández‐Palacios José María
Published: May 2006

Abstract. The distribution of 44 common vascular plant species on Tenerife, The Canary Islands, has been related to the variation in temperature and precipitation. Frequency values for these speceis were obtained using a stratified sampling system with 200 10 m x 10 m plots distributed all over the island. A model is proposed relating variation in vegetation to altitude according to two main climatic gradients occurring between the 3718 m summit and the coastline of Tenerife. The vascular plants have been classified into guilds according to their presumed tolerance to cold and drought; one remainder group includes species which are randomly distributed without any relation to climatic variation. Differences between the guild structure suggested here and common knowledge of plant species occurrence in the well‐known vegetation belts of Tenerife are explained by assuming disturbance and local ground‐water availability as additional decisive factors.
Effects of high temperatures, ash and seed position in the inflorescence on the germination of three Spanish grasses
Authors: González‐Rabanal F. , Casal M. , Trabaud L.
Published: May 2006

Abstract. Seed germination of three perennial grasses, Agrostis curtisii, Avenula marginata and Pseudarrhenatherum longifolium was studied in relation to the position (basal, intermediate, apical) in the panicle and two factors typically associated with fire, high temperatures and ash.

Two similar germination responses were observed in A. curtisii and A. marginata: (1) germination rates were lower for seeds from higher positions in the inflorescence; and (2) watering with a plant‐ash solution improved the ability of apical seeds to germinate, but had the opposite effect on basal seeds. In A. curtisii, the latter response was also dependent on whether or not the seed was exposed to high temperatures. In P. longifoliium the exposure to high temperatures and the position of the seeds in the inflorescence influenced the effect of ash. This could be due to the different degrees of development of the seeds.
Comparison of old‐field and forest revegetation dynamics in Provence
Authors: Tatoni Thierry , Roche Philip
Published: May 2006

Abstract. This paper describes vegetation changes on cultivation terraces after abandonment, considered as secondary succession, and vegetation responses after clear‐cutting, considered as regeneration. Species were grouped in life form and dynamic categories in order to infer dynamic patterns. By applying the Shannon diversity index to these characteristics, an index of functional diversity is obtained. Regenerative succession is considered here as a particular case of secondary succession, characterized by a fast vegetative regeneration of the dominant woody species, which controls the succession of the understorey species. Post‐agricultural succession and forest regeneration succession show a similar relation between the diversity index and a forest index, indicating the relative amount of forest species. It appeared that the old‐field dynamics resemble the deciduous oak‐forest regeneration after the woody species have established. The species diversity at the end of the post‐agricultural succession and in the forest is controlled by the nature of the dominant tree species.
Vegetation of European springs: High‐rank syntaxa of the Montio‐Cardaminetea
Authors: Zechmeister Harald , Mucina Ladislav
Published: May 2006

Abstract. A survey of high‐rank syntaxa of vegetation of European springs (class Montio‐Cardaminetea) is presented. It shows the complexity of the class and the relations between the units. More than 1200 relevés were arranged into six phytosociological tables, each representing an alliance. A synoptic table comprising all alliances is presented. Bryo‐phytes are the most important group in most of the communities, both regarding biomass and cover. The Adiantetea and the Montio‐Cardaminetea are combined into one class. As to floristics and ecology, there are no obvious reasons to distinguish more than one order in this class. The vegetation of European springs is divided into six alliances: (1) Adiantion, split into two new suballiances, Adiantenion and Lycopodo‐Cratoneurenion; (2) Cratoneurion commutati; (3) Cardamino‐Montion ‐ incl. three new suballiances: Mniobryo‐Epilobienion hornemannii, Swertio‐Anisothecienion and Cardamino‐Montenion; (4) Dermatocarpion; (5) Epilobio nutantis‐Montion; (6) Caricion remotae ‐ incl. two new suballiances: Caricenion remotae and Cratoneuro filicini‐Calthenion laetae. The alliances are floristically and ecologically characterized and their distributions in Europe shown on maps.
Interaction between the cactus Neobuxbaumia tetetzo and the nurse shrub Mimosa luisana
Authors: Valiente‐Banuet Alfonso , Vite Fernando , Zavala‐Hurtado J. Alejandro
Published: May 2006

Abstract. Pattern analysis and association analysis showed that recruitment of the giant columnar cactus Neobuxbaumia tetetzo in the semi‐arid valley of Zapotitlán is largely limited to areas beneath the canopies of perennial shrubs, acting as nurse plants. Chi‐square and Haberman tests revealed that young cacti were more frequently found beneath canopies of leguminous shrubs, especially Mimosa luisana, than were older cacti. Segregation analysis indicated a positive association (= negative segregation) of young cacti and M. luisana canopies, but older cacti were randomly distributed with respect to M. luisana. This, and the height class distributions of cacti associated withM luisana or not, suggested the replacement of M. luisana by N. tetetzo. Mimosa luisana plants in association withiV. tetetzo had greater amounts of dead basal area thanM luisana lacking associated N tetetzo. This suggested competition from JV. tetetzo promotes the replacement process.

The roots of N tetetzo are ≤ 30 cm deep. Interception of soil water before penetration to deeper roots of M luisana may be the mode of competition between the two species.
Seedling development of the miombo woodland tree Julbernardia globiflora
Authors: Chidumayo E. N.
Published: May 2006

Abstract. The development of seedlings of the miombo tree (Julbernardia globiflora) was studied for 28 months (December 1987 ‐ April 1990) at a Zambian grassland site from which fire has been excluded for many years. Germination occurred 10–25 days after seed planting and germination rates under laboratory and field conditions did not differ significantly.

Seed germinability after one year of storage declined to 38 %. Leaf production occurred between December and April with peaks in January each year. Leaf fall occurred steadily throughout the dry season but leafless seedlings were first observed in August of each year. All seedlings had shed all their leaves by the end of November during the first year while 10% of the seedlings remained leafy throughout the second year. Annual seedling mortality was about 60 % during the first year and declined to 3 6 % during the second year. Survivorship appeared to stabilise at 3 8 % when seedlings were 5 5 ‐ 5 9 weeks old. Every seedling experienced shoot die‐back during the first hot dry season (September ‐ November) when open‐pan evaporation rates averaged 5–10 mm / day. However, shoot mortality did not necessarily result in plant mortality. Because of recurrent shoot die‐back there was little increase in shoot biomass and height at the end of the second and third growing seasons. Seedlings that survived shoot die‐back sprouted from roots which showed a steady annual accumulation of biomass.

Early shoot die‐back in seedlings of Julbernardia globiflora as documented in this study was not causedby fire but most probably by drought and / or nutritional stress.
BOOK REVIEWS
Authors: Snoeijs Pauli
Published: May 2006

Book reviewed in this issue.

Margulis, L., Corliss, J. O., Melkonian, M. & Chapman, D. J. (eds.) 1990. Handbook of Protoctista. The structure, cultivation, habitats and life histories of the eukaryotic micro‐organisms and their descendants exclusive of animals, plants and fungi, xii + 914 pp. Jones and Bartlett Publishers, Boston. ISBN 0–86720–052–9. Price: GBP 195.‐.
Fire regimes and phytomass growth dynamics in a Quercus coccifera garrigue
Authors: Trabaud Louis
Published: May 2006

An experiment was set up in a Quercus coccifera garrigue in southern France to analyze the effect of burning frequency and season on phytomass production. Fire regimes consisted of late spring or early autumn burns, every 6 yr, every 3 yr, or every 2 yr. The experiment started in 1969 and lasted for 19 yr. In May 1981 and May 1987, 10 samples, each 1 m2, were harvested per treatment. Fire frequency had an effect on the quantity of phytomass which was produced: above‐ground phytomass decreased with increasing fire frequency. This was mainly due to the lower biomass of woody plants.

In all burning treatments the phytomass of herbs was higher than in the unburned vegetation. Within each burning frequency, the total phytomass of the spring‐burned vegetation was always higher than that of the autumn‐burned community. Generally, the herb phytomass produced was higher in the autumn‐burned plots. There were two fairly distinct phases in the period following fire, each with a different level of annual phytomass production. For the first six years it was about 300 g m−2 yr−1, falling thereafter to about 50 g m−2 yr−1. This and other studies on Q. coccifera garrigue indicate that this community is very resilient with respect to fire, but possesses a low productive capacity and does not show any sign of degeneration up to 30 yr old.
Abundance of trees and grasses in a woodland savanna in relation to environmental factors
Authors: Ben‐Shahar R.
Published: May 2006

The relationships of plant species associations and underlying environmental factors in a woodland savanna in South Africa were investigated. 40 plots were included with 25 tree and 17 grass species dominating the arboreal and ground cover. Correspondence Analysis described the relationships between soil moisture retention, soil nutrients and the abundance of trees and grasses. Dry matter indices represented the accumulated effects of rainfall, fire and grazing of the herbaceous layer. Variations in the abundance of plants corresponded to well‐defined gradients of soil nutrients. The distribution of grass and tree species along the ordination axes indicated that soils with high water retention capacity and high nutrient contents provided a suitable substrate for many of the tree species sampled. However, grass species abundance was high in plots with porous soils and poor nutrient availability.
Nested spatial patterns in seed bank and vegetation of Mediterranean old‐fields
Authors: Lavorel S. , Lebreton J. D. , Debussche M. , Lepart J.
Published: May 2006

A nested sampling design was used to describe the spatial patterns for the species richness and composition in the seed bank and vegetation of three Mediterranean old‐fields (1, 7, and 15 yr after the last ploughing). Three scales were examined hierarchically: sampling units within plots of 0.25 m2 for the vegetation and of 0.05 m2 for the seed bank, 100 m2 plots within fields, and fields of 1000 m2. In spite of the strong spatial variation among sampling units, species richness and composition of both seed bank and vegetation showed hierarchically structured patterns of heterogeneity, while each old‐field was a homogeneous entity. These spatial patterns tended to be partially masked when the data were aggregated at the scale of the plot. Such results stress the use of a nested sampling design for studying variation in species richness and taxonomic composition in both vegetation and seed bank. This design, in combination with CCA, also showed that the vegetation showed a coarser grain than the seed bank, probably in relation to seed clumping.
Effects of woodlot isolation on the dispersion of plants with fleshy fruits
Authors: van Ruremonde R. H. A. C. , Kalkhoven J. T. R.
Published: May 2006

By relating species presence, number and density to the perimeter and isolation of small (0.1–2.75 ha) homogeneous woodlots (n = 43), indications were obtained that some fleshy‐fruited species are negatively affected by woodlot isolation. The number of fruit‐bearing herbaceous perennial species increased with woodlot area, probably because of the increasing heterogeneity of the herb layer. The density of individuals of the investigated species were negatively correlated to woodlot area. There were also some indications thatthe presence/absence of species was related to the length of the forest edge (e.g. Hederá helix). Because woodlot area and shape index were strongly correlated, the effects of increased forest area and forest edge were hard to separate.

The probability of occurrence of Lonicera periclymenum and the density oí Ilex aquifolium decreased with an increasing degree of isolation of present forest islands. The chance of occurrence of L. periclymenum decreased also with the degree of isolation in the past, measured from topographical maps of about 60 yr ago.

The total area of broad‐leaved forest within a radius of 500 m, as well as the distance to the nearest connecting landscape element, seem to be good indicators of woodlot isolation.
A remnant New Zealand carr
Authors: Sykes Martin T. , Wilson J. Bastow , Lee William G. , Allen Ralph B.
Published: May 2006

Carr vegetation was once extensive in New Zealand. It can be divided into Cordyline australis I Carex secta carr, comprising an open wood with scattered large herbs and an abundance of Carex species, and podocarp carr, dominated by tall conifers. Both have been almost eliminated by agricultural development. We studied a remnant of Cordyline australis I Carex secta carr in South Island, which graded at one end into salt marsh. Eight communities were recognized, including one pure salt marsh and two more with saline influence. Near the stream that provided moisture and alluvium for the area were herbaceous communities. In the poorly‐drained area away from the stream were communities dominated by shrubs and small trees. The soil environment is similar to that of many European carrs, though generally less organic. A number of the exotic species are also found in European carrs.
Vegetation zonation in dune slacks on the Leba Bar, Polish Baltic Sea coast
Authors: Zoladeski Christopher A.
Published: May 2006

Vegetation zones in dune slacks on the Leba Bar on the Polish Baltic Sea coast are described. Plant colonization starts on moist sand in eastern ends of slacks, in the wake of receding mobile dunes. Communities on deflation ribs, dominated by psammophytic grasses, sedges and lichens, are structurally simple. Communities in troughs, dominated by species of fresh habitats, become structurally more complex in a western direction and they culminate with thePinus silvestrisforest. The main lines of vegetation variation correlate with groundwa‐ter depth, micro topography, soil profile build‐up and substrate acidification.
Demographic structure of California chaparral in the long‐term absence of fire
Authors: Keeley Jon E.
Published: May 2006

Abstract. Demographic structure of 12 chaparral sites unburned for 56 to 120 years was investigated. All sites were dominated by vigorous shrub populations and, although there was colonization by seedlings of woodland tree species in several stands, successional replacement of chaparral was not imminent. Although successional changes in community composition were evident, there was no indication of a decline in species diversity. Non‐sprouting species of Ceanothus suffered the greatest mortality at most, but not all, sites. Sprouting shrubs, such as Quercus and Heteromeles had very little mortality, even in stands more than a century old. All postfire resprouting species had multiple stems of different ages indicating these shrubs were capable of continuously regenerating their canopy from basal sprouts. Ceanothus populations were highly clumped and there was a significant correlation across all sites between variance/mean ratio and percentage mortality. As Ceanothus populations thinned, they became less clumped. In mixed chaparral stands, Quercus and Heteromeles were significantly taller than associated Ceanothus shrubs and overtopped the Ceanothus; at two sites, the density of live Quercus per plot was correlated with the density of dead Ceanothus. Thus, mortality of Ceanothus stems is likely related to both intra and interspecific interations.

Seedling recruitment was observed for most shrub species that regenerate after fire by resprouting; seedling and sapling densities ranging from 1000–36 500 ha‐1 were recorded for Quercus dumosa, Rhamnus crocea, Prunus ilicifolia, Heteromeles arbutifolia and Cercocarpus betuloides. For all but the last species, seedlings and saplings were most abundant beneath the canopy cover and not in gaps. Across all sites, recruitment was significantly correlated with depth and bio‐mass of the litter layer. Cercocarpus betuloides was present in several stands, but seedling establishment was found only in one very open, disturbed stand. Regardless of stand age, taxa such as Adenostoma, Arctostaphylos and Ceanothus, which recruit seedlings after fire, had no significant seedling production.
The relationship between the seed bank and species composition of plant communities in two British salt marshes
Authors: Ungar Irwin A. , Woodell S. R. J.
Published: May 2006

The composition of the seed bank was compared with that of the above‐ground vegetation in two British salt marshes. Vegetation and seed banks were sampled in autumn and spring. There was a relatively low correlation between seed bank and vegetation in most perennial‐dominated zones. Percentage annual plant cover was significantly positively correlated to percentage similarity value between vegetation and seed bank. Cluster analysis indicated that the zones dominated by annuals and by Suaeda vera on the ungrazed Nod Marsh in Norfolk formed groups between seed bank and vegetation, whereas on the Llanrhidian Marsh in Wales the seed bank of four of the six zones formed a group.
Microhabitat differentiation among serotinous plants in the Namib Desert
Authors: Günster Antje
Published: May 2006

Abstract. Four coexisting serotinous desert plants in the central Namib were investigated with respect to microhabitat preferences. The annual Blepharis grossa preferred the microhabitat on the plains, while the perennial Petalidium setosum dominated in channels. The remaining two species, the common Geigeria alata and the rare Geigeria ornativa, were evenly distributed in all microhabitats. Interspecific competition, seed dispersal mode and ecophysiological niches might be responsible for this pattern.
Ecology of a paramo cushion mire
Authors: Bosnian A.F. , van der Molen P.C. , Young R. , Cleef A.M.
Published: May 2006

Abstract. The vegetation ecology of a paramo cushion mire was studied along four transects. Six local vegetation types were distinguished. Two types are called cushion bogs; one is dominated by Oreobolus cleefii and the other by Plantago rigida. Types 3 and 4 are mire vegetation dominated by bryophytes; one is characterised by Sphagnum sparsum, Breutelia sp. and Campylopus cucullatifolius, the other one is dominated by Lophozia subinflata with Cortaderia sericantha. Vegetation type 5 is dominated by submerged Sphagnum cyclophyllum; type 6 refers to aquatic vegetation with only Equisetum bogotense and algae.

The relation between the first four vegetation types and edaphical and hydrological gradients is analysed by means of Canonical Correspondence Analysis (CCA). From the results of CCA it can be concluded that the occurrence of the Oreobolus cleefii type is restricted to areas with a thinner peat layer, a wider distance surface‐anaerobic zone and water table‐anaerobic zone, a higher NO2 concentration and a lower pH. The occurrence of the Plantago rigida type is restricted to a situation with a lower electrical conductivity of the ground water, a lower NO3 and PO4 concentration, and a higher Fe concentration. The occurrence of the Sphagnum type is restricted to places with a higher conductivity of the ground water, a higher NO3 and PO4 concentration, and a lower Fe concentration. The occurrence of the Lophozia subinflata with Cortaderia sericantha type is restricted to a situation with a lower K and Al concentration.
BOOK REVIEWS
Authors: Thompson Philip A.
Published: May 2006

Book reviewed in this issue.

Dafni, A. 1992. Pollination Ecology: A Practical Approach. xiv + 250 pp. Oxford University Press, Oxford, U.K. Cloth: ISBN 0–19–963299–5. Price: USD 56.95. Paper: ISBN 0–19–963298–7. Price: USD 39.95.
Variation in competition in eucalypt forests: the importance of standardization in pattern analysis
Authors: Wilson Scott D.
Published: May 2006

Abstract. Contrasting views have been put forward that competition intensity should either increase with community standing crop or remain constant. Testing these hypotheses with long‐lived plants in natural communities is possible using pattern analysis, involving statistical summaries of the relationships between the total size and distance of nearest neighbors. This approach, however, may produce a spurious negative correlation between competition intensity and standing crop in cases where individual size increases with standing crop. A method for overcoming this problem using data standardization is illustrated using data from 15 stands in a variety of forest types (subalpine woodland, dry forest, warm wet forest, cool wet forest, and near‐rainforest) in southeastern Australia. Standing crop, estimated from stand volume, and water availability, estimated from evapotranspiration, varied significantly among forest types. Total size and nearest neighbor distance was measured for 50 pairs of trees in three stands of each forest type. The sum of nearest neighbor sizes increased significantly with interneighbor distance in all forest types, indicating that competition contributed to pattern at all levels of standing crop. The slopes of the regression equations describing these relationships varied significantly among forest types and with evapotranspiration, suggesting that competition intensity varied. This result, however, was shown to be the product of a significant positive correlation between individual size and standing crop. Once this correlation was removed by using standardized measures of tree size, there was no evidence for variation in competition intensity among forest types or with evapotranspiration.
BOOK REVIEWS
Authors: Denslow Julie S.
Published: May 2006

Book reviewed in this issue.

Holm‐Nielsen, L. B., Nielsen, I. S. & Balslev, H. (eds.) 1989. Tropical Forests: Botanical Dynamics, Speciation and Diversity, xv + 380 pp. Academic Press, London. ISBN 0–12–323550–6. Price: USD 49.50.
Vegetation classification in Greenland
Authors: Daniëls Fred J.A.
Published: May 2006

Abstract.An account of the description and classification of the vegetation of Greenland is presented. Four periods are recognized: the Physiognomic period, the Extension period, the Floristics‐Dominance period, and the Syntaxonomic period. The approaches used in vegetation classification pertaining to Greenland are discussed. A first survey is presented of the higher syntaxa known from suboceanic‐oceanic, subarcticlow arctic Greenland. 14 classes are dealt with. The syntaxa are floristically defined and their concept is discussed. TheJuncetalia trifidi, Caricetea curvulae, are described for the first time.
Floristic classification and ecology of tundra vegetation of the Taymyr Peninsula, northern Siberia
Authors: Matveyeva Nadezhda V.
Published: May 2006

Abstract. A first systematic description is presented of tundra plant communities of the Taymyr Peninsula, northern Siberia, using the floristic approach of the Braun‐Blanquet School. Five associations are described: 1. Carici arctisibiricae‐Hylocomietum alaskanii, the main‘zonal’association, widely spread on ‘plakor’, i.e. flat or slightly sloping well‐drained sites in the tundra zone, but absent in the polar desert zone. 2. Meesio triquetris‐Caricetum stantis, typical for mire depressions throughout the tundra zone. 3. Poo arcticae‐Dupontietum fisheri, found in the northern part of the typical tundra subzone on western Taymyr. 4. Gymnomitrio‐Phippsietum concinnae and 5. Deschampsio‐Cerastietum regelii, which occur on snowbeds with various snow duration. Within several of these associations vicariants are described.

These syntaxa are only the first to be described for the Taymyr area. A complete description is still under way.
Ecology of a steppe‐tundra gradient in interior Alaska
Authors: Lloyd Andrea H. , Armbruster W. Scott , Edwards Mary E.
Published: May 2006

Abstract. Subarctic steppe is currently restricted in interior Alaska and the Yukon Territory to steep, south‐facing river bluffs. Paleoecological and biogeographic evidence suggests that some steppe taxa may have been more widespread during the Full‐Glacial. We examined factors controlling the distribution of steppe taxa on an elevation gradient across a steppetundra ecotone; such analyses may help define potential Full‐Glacial distributions of these taxa. Multivariate analyses suggest that species can be divided into four spatially distinct groups, but individualistic species distributions create considerable overlap among these groups. The steppe‐tundra ecotone comprises a broad zone of mixing between steppe taxa and drought‐tolerant alpine tundra taxa, followed by an abrupt shift to alpine shrub tundra. The transition from low steppe to tundra vegetation is primarily associated with a gradient of decreasing soil temperature. The more abrupt transition from mixed steppe‐tundra to alpine shrub tundra vegetation is primarily associated with changes in soil depth and soil moisture. Variation in vegetation within steppe is associated with gradients in soil phosphorus and moisture. Greenhouse experiments on drought tolerance of two steppe and two tundra taxa suggest that the individualistic distribution of species along the ecotone is partly a function of physiological differences among species. Our analyses of vegetation‐environment relationships support the hypothesis that some components of the steppe community could have been more widespread during the colder Full‐Glacial.
Restoration of natural vegetation in degraded Imperata cylindrica grassland: understorey development in forest plantations
Authors: Kuusipalo Jussi , Ådjers Göran , Jafarsidik Yusuf , Otsamo Antti , Tuomela Kari , Vuokko Risto
Published: May 2006

Abstract. Reclamation of former, degraded forest lands occupied by Imperata cylindrica is one of the crucial environmental and forestry issues in the humid tropics, notably Southeast Asia. We suggest that it is possible to gradually restore the original natural forest cover with the help of a sacrifice fallow crop of fast‐growing exotic tree species. Recently, a set of suitable fast‐growing plantation tree species has been identified and stand establishment methods developed for this purpose. We assessed the regeneration of natural vegetation in stands of different plantation tree species and evaluated the ecological impact of species composition in the plantation understorey. PCA ordination, regression analysis and analysis of covariance were applied at different stages of the study. We found a marked vegetational resemblance between stands dominated by Acacia mangium: they had the highest number of indigenous trees in their understorey, whereas stands of other plantation trees supported more diverse grass and herb vegetation. A high proportion of evergreen woody vegetation reduces the risk of fire and grass competition and enhances secondary succession towards natural forest.
Primary succession of Hawaiian montane rain forest on a chronosequence of eight lava flows
Authors: Kitayama Kanehiro , Mueller‐Dombois Dieter , Vitousek Peter M.
Published: May 2006

Abstract. The primary‐successional sere of a Hawaiian montane rain forest was inferred from an age sequence of eight closely located ‘a’ ā flows (clinker type lava); 8, 50, 140, ca. 300, ca. 400, ca. 1400, ca. 3000 and ca. 9000 yr, on a windward slope of Mauna Loa, Hawaii.

All study sites (0.2 ha each) were at 1120 — 1250 m a.s.l. with 4000 mm mean annual rainfall. The 400‐yr, 1400‐yr, and 9000‐yr flows had younger volcanic ash deposits, while the others were pure lava. Comparisons of tree size and foliar nutrients suggested that ash increased the availability of nitrogen, and subsequently standing biomass. An Unweighted Pair Group Cluster Analysis on the samples (flows) using quantitative vascular species composition revealed that clusters were correlated with age regardless of the substrate types (pure lava vs. ash), and an indirect ordination on the samples suggested that the sequence of sample scores along axis 1 was perfectly correlated with the age sequence. Although ash deposits increased biomass, they did not affect the sequence of the successional sere. Both pubescent and glabrous varieties of Metrosideros polymorpha (Myrtaceae) dominated upper canopy layers on all flows ≥ 50 yr and ≤ 1400 yr, but the pubescent variety was replaced by the glabrous on the flows ≥ 3000 yr. Lower layers were dominated initially by a matted fern, Dicranopteris linearis, up to 300 yr, and subsequently by tree ferns, Cibotium spp., to 9000 yr. The cover of Cibotium declined slightly after 3000 yr, while other native herb and shrub species increased. A ‘climax’ stage in the conventional sense was apparently not reached on the observed age gradient, because the sere changed continuously in biomass and species; this divergent successional phenomenon may be unique to Hawaii where the flora is naturally impoverished and disharmonic due to its geographic isolation in contrast to more diverse and harmonic floras in continents.
Establishment processes and regeneration patterns of montane virgin coniferous forest in northeastern China
Authors: Okitsu Susumu , Ito Koji , Li Chong‐hao
Published: May 2006

Abstract. The co‐occurrence of Larix olgensis var. changpaiensis, Picea jezoensis and Abies nephrolepis in the coniferous forest of Mount Changbai, northeastern China, is discussed, and the regeneration pattern of these taxa compared on the basis of the analysis of the age structure and the age‐height relationship of the three conifers. The presence of tall individuals (ca. 30 m in height) of Larix olgensis var. changpaiensis, which does not show any regeneration, was related to the large eruption of Mount Changbai up to ca. 400 yr ago. Picea jezoensis compensates its small recruitment by a large stem size and long life span together with a continuous height growth. Abies nephrolepis recruits well, but its small stem size and short life span do not result in its dominance in the forest.
Dynamics of Vaccinium myrtillus patches in mountain spruce forest
Authors: Maubon Michel , Ponge Jean‐François , André Jean
Published: May 2006

Abstract. The dynamics of Vaccinium myrtillus (bilberry) patches were studied in spruce (Picea abies) forest at the higher montane and lower subalpine level in the Tarentaise valley (Savoy, France). Although aerial parts of the shrub may give some indication of age and density of the patches, the annual growth and death of rhizomes are better indicators of patch dynamics. In some cases, dead and young rhizomes may occur simultaneously in the same patch, indicating that growth and death proceed continuously on the inside of dense patches. At mountain sites, slope position of plants significantly influences rhizome growth. A theoretical model of growth of bilberry patches is proposed which takes into account the anisotropic influenceof slope and the postulated independence of different rhizome units belonging to the same individual.
Responses to recent climatewarming of Pinus sylvestris and Pinus cembra within their montane transition zone in the Swiss Alps
Authors: Hättenschwiler Stephan , Körner Christian
Published: May 2006

Abstract. Altitudinal and latitudinal distribution limits of trees are mainly controlled by temperature. Therefore climate warming is expected to induce upslope or poleward migrations. In the Swiss Central Alps, summers in the period 1982‐1991 were on average 0.8 °C warmer than those of the period 30 yr before. We investigated whether populations of conifers at the montane Pinus sylvestris‐Pinus cembra ecocline exhibit demographic trends in response to that warming. We found no evidence for this. Young seedlings of Pinus sylvestris, the species which is expected to expand its range upward in a warmer climate, were virtually absent from all sites, whereas large fractions of Pinus cembra populations were observed in the seedling and juvenile categories even below the present lower distribution limit of adult trees. This suggests that there are no major altitudinal shifts in response to the recent sequence of warmer summers. Germination and seedling survival trials with Pinus sylvestris suggest that temperature per se would not exclude this species even from establishing at the current treeline in the Swiss Central Alps. Similar results were found at the polar treeline. Phytotron tests of seedling survival showed much less drought resistance in Pinus sylvestris than in Pinus cembra which is in contrast to their phytogeographic distributions. Thus, the montane pine ecocline in the Swiss Central Alps seems to be stabilized by species interactions and may not be directly responsive to moderate climatic change, which needs to be taken into account in predictive attempts.
Vicinism and mass effect
Authors: Zonneveld Isaak S.
Published: May 2006

Abstract. The term vicinism (neighbourship), first published in a phytosociological context by Nordhagen, refers to the occurrence of plant species in a less favourable environment ‐outside their sociological (ecological) amplitude — as a result of the continuous supply of propagules from neighbouring areas. In recent studies on this subject the term mass effect has been used for what seems to be the same phenomenon. This is unfortunate since this term was introduced much earlier to indicate the ability of plants which are able to grow in dense stands in order to change the local environment to the benefit of themselves — physically, chemically or mechanically‐ by developing a dense vegetation cover. Examples of this mass effect are mainly found in extreme environments such as salt marshes and lake shores. The occurrence of both vicinism and mass effect indicates that competition is not the only biological factor important in selection. Vicinism also contributes to connectivity, a major topic in landscape ecology. Both vicinism and connectivity as synecological concepts in their original meaning deserve more attention from ecologists.
Litter fall and decomposition in a Pinus halepensis forest on Mallorca
Authors: García‐Plé C. , Vanrell P. , Morey M.
Published: May 2006

Abstract. Litter fall and decomposition in a Pinus halepensis forest was studied in order to help understand nutrient cycles in this ecosystem, threatened as it is by fire and tourism. The study was done over two years in an experimental forest stand at Cap des Pinar on Mallorca, Spain. The woodland area has not been disturbed for about 40 yr. Total litter fall amounted to 3.44 ton ha‐1 yr‐1 and 2.52 ton ha‐1 yr‐1 in the first and second year, and leaf fall to 2.00 ton ha‐1 yr‐1 and 1.93 ton ha‐1 yr‐1 respectively with a maximum in July. As to litter fall, there was a summer maximum for brown needles and kernels, a spring maximum for inflorescences and bud scales, and an autumn maximum for bark. Erratic maxima occurred for fall of green needles, cones and branches, linked to strong winds in winter. The total amount of litter mass on the forest soil reached 12.68 ton/ha: 5.75 ton/ha in the L organic horizon, 3.46 ton/ha needles, and 6.93 ton/ha in the F organic horizon. Weight loss from annual decomposition, measured using litter bags, was 18.1 % in year 1 and 26.8% in year 2. Over 365 days, an Olson (1963) decomposition rate of 0.045 %/day was found in year 1 and of 0.084 %/day for year 2. Decomposition half‐time was 1529 for year 1 and 827 days for year 2.
Use of paired plots and multivariate analysis for the determination of goat grazing preference
Authors: Lepš Jan , Michálek Jaroslav , Kulíšek Petr , Uhlík Petr
Published: May 2006

Abstract. Goat grazing is examined as a possible tool for grassland management. In this paper, goat grazing preferences are described. The proportion of biomass of particular species eaten by a goat was estimated on the basis of comparison of paired quadrats. The control quadrats were clipped before grazing and their biomass was compared with the biomass in grazed quadrats. Estimates of the proportion consumed were calculated for frequent species; they were significantly different among species; the most preferred species was Polygonum bistorta, a species with broad, soft, nutritious leaves. The least grazed species were Agrostis tenuis and Galium harcynicum. Various indices of food selectivity (e.g. forage ratio, electivity index) were calculated and their behaviour was compared. Canonical Correspondence Analysis and Redundancy Analysis with appropriate covariates reflecting the block design of the experiment were used to evaluate overall changes in species composition and yielded results similar to those from the direct estimation of the proportion consumed.
Parallel Analysis: a method for determining significant principal components
Authors: Franklin Scott B. , Gibson David J. , Robertson Philip A. , Pohlmann John T. , Fralish James S.
Published: May 2006

Abstract. Numerous ecological studies use Principal Components Analysis (PCA) for exploratory analysis and data reduction. Determination of the number of components to retain is the most crucial problem confronting the researcher when using PCA. An incorrect choice may lead to the underextraction of components, but commonly results in overextraction. Of several methods proposed to determine the significance of principal components, Parallel Analysis (PA) has proven consistently accurate in determining the threshold for significant components, variable loadings, and analytical statistics when decomposing a correlation matrix. In this procedure, eigenvalues from a data set prior to rotation are compared with those from a matrix of random values of the same dimensionality (p variables and n samples). PCA eigenvalues from the data greater than PA eigenvalues from the corresponding random data can be retained. All components with eigenvalues below this threshold value should be considered spurious. We illustrate Parallel Analysis on an environmental data set.

We reviewed all articles utilizing PCA or Factor Analysis (FA) from 1987 to 1993 from Ecology, Ecological Monographs, Journal of Vegetation Science and Journal of Ecology. Analyses were first separated into those PCA which decomposed a correlation matrix and those PCA which decomposed a covariance matrix. Parallel Analysis (PA) was applied for each PCA/FA found in the literature. Of 39 analy ses (in 22 articles), 29 (74.4 %) considered no threshold rule, presumably retaining interpretable components. According to the PA results, 26 (66.7 %) overextracted components. This overextraction may have resulted in potentially misleading interpretation of spurious components. It is suggested that the routine use of PA in multivariate ordination will increase confidence in the results and reduce the subjective interpretation of supposedly objective methods.
Seed survival and persistence on a calcareous land surface after a 32‐year burial
Authors: Hendry G.A.F. , Thompson K. , Band S.R.
Published: May 2006

Abstract. Of 34 species of vascular plants recorded in an unimproved calcareous grassland community in 1960 and subsequently buried for 32 yr, just six spp. were recovered as viable seeds from the original land surface, following excavation of an experimental earthwork. Five of the six are known or suspected to form persistent seed banks; the status of Carex flacca as a persistent seed is now established. The exceptionally low density of viable seeds at 35 seeds/m2 and the paucity of other plant remains confirm that these calcareous soils have supported rapid decomposition. The complete absence of viable seeds known to be short‐lived indicated that the macrofauna has played no significant role in the introduction of viable seeds from the modern‐day surface down to depths in excess of 1.6 m, at least not in recent years. Because of the precise dates of burial and excavation, the results offer a rare opportunity to confirm laboratory and other indirect observations of long‐term seed persistence following burial in temperate climate calcareous soils.
Functional classifications of coastal barrier island vegetation
Authors: Guofan Shao , Shugart Herman H. , Hayden Bruce P.
Published: May 2006

Abstract. Due to the complexity of coastal barrier vegetation, it is useful to apply a functional‐type approach to assess the response of barrier island vegetation to climate change. In this paper, a simple clustering analysis is applied to a group of 19 plant associations, based on six plant attributes and six environmental constraints. This analysis results in the suggestion that the main division of the vegetation types at Virginia Coast Reserve is between herbaceous and woody types, which differs from the existing classification which recognizes three groups: xeric‐mesic herbaceous, woody and hydric‐halophytic herbaceous. Considerations about grouping plant functional types are also addressed in this paper. At a global scale, inclusion of barrier plant functional types may not be so important for the climate‐change response of vegetation, but it may be necessary to consider these important systems for spatially explicit modelling of landscape responses.
Plant functional types and climate in a southern African savanna
Authors: Skarpe Christina
Published: May 2006

Abstract. A system of easily defined plant functional types for a dry savanna is presented and related to climate data. To predict possible changes of vegetation in response to climate change, a system of functional attributes is developed. The attributes are based on both structural and functional characteristics and are chosen to be related to climatic conditions. plant functional types are defined as assemblages of plant species having similar combinations of plant functional attributes. Direct and indirect gradient analyses of a test data set show that the plant functional types as well as the vegetation described from them are strongly associated with total annual precipitation, precipitation of the wettest month and a moisture index (all related to soil moisture) and with temperature of the coldest month.
Colonization in an abandoned East‐Mediterranean vineyard
Authors: Ne'eman Gidi , Izhaki Ido
Published: May 2006

Abstract. Previous studies on secondary succession in abandoned agricultural land in the Mediterranean area were carried out by the chronosequence method, including data from different sites. A unique opportunity to study secondary succession arose from a situation in which different parts of one homogeneous East‐Mediterranean vineyard were abandoned for 5, 8, 15 and 35 yr, and did not suffer from any disturbance subsequently. Most of the perennial species that colonized the abandoned vineyard were fleshy fruited species, which apparently were dispersed by birds from the surrounding maquis into the vineyard. These bird‐dispersed species were the first to be established, and were the dominant plant group according to dispersal modes. The abandoned vine plants and their supporting columns provided the birds with perching and feeding sites, enhancing the arrival of bird‐dispersed species regardless of their life forms. Under these conditions the most important attribute that affected vegetation dynamics was seed dispersal mode. Trees were among the first to colonize in the vineyard, implying that no facilitation was needed for their establishment. Annual plant species were the only species to disappear during succession. Almost all perennial species which had arrived persisted in the vineyard, and no replacement of perennial species was found. The rate of succession was rapid, as expressed by the short time (8–15 yr) needed for the stabilization of species composition, for growth to average height of late succession trees, and for reaching high cover of the invading perennial species in the abandoned vineyard. The secondary succession described above differs from that in the western Mediterranean by the absence of perennial species replacement and its rapid rate. The possible causes are discussed.