bluuebunny/crossref_metadata_2025 huggingface dataset:
Species turnover and diversity patterns along an evergreen broad‐leaved forest coenocline
Authors: Itow Syuzo
Published: May 2006

Direct gradient analysis was applied to the evergreen broad‐leaved forest coenocline in the Tatera Forest Reserve, Japan. 10 quadrats of 0.1 ‐0.05 ha were laid out from 140 m to 560 m above sea level at intervals of 25–70 m. Gradient analysis revealed that distributions of many species terminated or started at ca. 400 m. Community similarity, calculated in Percentage Similarity (PS) and Community Coefficient (CC), changed abruptly below and above the 400 m contour, suggesting a change of vegetation structure at this altitude, which was also clear from population distributions.

The spatial turnover rate of species along the altitudinal gradient was calculated in two ways: as the Average turnover rate along the whole range of the gradient, and as the Zone turnover rate at individual altitudes. The overall rates calculated for five categories of populations: DBH > 10 cm, DBH >3 cm, all woody species, herb‐layer, and total vegetation, were‐ 0.0011 to‐ 0.0021 for PS, and ‐ 0.0009 to‐ 0.0019 for CC. The calculated rates (PS basis) indicate that a 95% change in species composition is reached at 1120 to 620 m altitude. Similarly, the rates ‐0.0009 to ‐ 0.0019 (CC) correspond to 1410 ‐ 680 m. The altitudinal range expected here for a 95% change agrees with the actual elevation of forest zonation in northwestern Kyushu. The average rate of both PS and CC in the herb‐layer population was 1.56 times higher than the rate in the woody species population, showing a more rapid change in herb‐layer population than in the woody ones along the gradient.

The Zone turnover rates were higher at the 370–440 m belt than those below and above the belt. This coincided with the interchanging pattern in population distributions and the abrupt change in similarity at about 400 m above sea level. This may be due to the change in environmental conditions such as physiography and air humidity. In the diversity measurements, the species density per 100 m2 showed a gradual increase in the DBH >3 cm population but a constant level in the DBH >10 cm population along the whole range of the forest coenocline studied, while index values of S(100) and Shannon's H showed decreasing trends in the same gradient with a few exceptionally high and low values.
Succession of mycorrhizal fungi in stands of Pinus sylvestris in the Netherlands
Authors: Termorshuizen A. J.
Published: May 2006

The mycorrhizal mycoflora was investigated in 35 stands of Pinus sylvestris in three types of young (4‐13 yr) and three of old (50‐80 yr) stands in the Netherlands, differing in number of rotations and soil type. A plot of 1050 m2 (30 m x 35 m) within each stand was searched for carpophores during the autumns of 1986 and 1987. 10 soil samples per plot were taken in October 1987 in order to assess the mycorrhizal status of the tree roots. The composition of mycorrhizal mycoflora in the different plots was subjected to TWINSPAN cluster analysis and Detrended Correspondence Analysis.

Plot groupings generated by these analyses largely parallelled the stand types, indicating that each stand type has its own mycoflora. Differences in myco‐floristic composition between stand types were parallelled by differences in the composition of green vegetation. The young stand types had 3.5–27 x more carpophores and 1.4–6.8 x more species than two of the old stand types One old stand type was intermediate. Considerable differences in species composition between the young stand types were observed. It is concluded that the succession of mycorrhizal fungi is not primarily influenced by ageing of the trees, but rather by changes in the soil.

The results were compared with data on changes in the occurrence of fruiting species of mycorrhizal fungi in the Netherlands during this century. It appeared that species which have declined according to these data were more frequent in the young plots than in the old plots. However, these species are reported to be frequent in old stands of P. sylvestris in Estonia and Finland. It is argued that this difference is related to the high nitrogen deposition in the Netherlands.
The effect of salinity on the reproduction of coastal submerged macrophytes in experimental communities
Authors: Bonis Anne , Grillas Patrick , van Wijck Carla , Lepart Jacques
Published: May 2006

The effects of salinity on the reproduction of coastal submerged macrophyte species were studied on samples of communities from six seasonal marshes in two outdoor experiments performed in autumn and in spring. The submerged macrophyte communities were submitted to five different salinity levels (0, 1, 2, 4 and 6 g/1 Cl−1). In a companion paper (Grillas, van Wijck & Bonis 1993) three groups of species were distinguished on the basis of their biomass production over the salinity range 0 to 6 g/1 Cl−1: (1) glycophytes (non‐salt‐tolerant species), (2) salt‐tolerant species and (3) halo‐phytes. This part of the study describes the impact of salinity on the reproduction of the individual species during the two experiments.

The species differ in their capacity to reproduce in the autumn; only Zannichelliapedunculata and Tolypella hispánica were able to produce fruits in that season. For all species reproduction was greater in spring and strongly correlated with biomass, except for Chara canescens. Differences in reproductive effort over the salinity range amplified the halophytic nature of Ruppia marítima and Chara canescens and the intolerance of Callitriche truncata and Chara contraria. For the other species, reproductive effort did not differ significantly over the salinity range.

Regarding the effect of salinity on biomass and reproductive effort of individual species, there were large differences in the total weight of propagules produced at the community level and in the relative contribution of individual species. The resulting quantitative changes in the species composition of the seed bank could affect the structure of the communities by their effects on the establishment and survival of species populations.
Plant communities of the Stirling Range, Western Australia
Authors: Pignatti Erika , Pignatti Sandro , Lucchese Fernando
Published: May 2006

The Stirling Range is a mountain system of Proterozoic origin in the southern part of Western Australia, reaching an altitude of 1000 m; it consists of acid rocks and has a mediterranean climate with a rainfall of 500 ‐ 550 mm/yr. It is the only extensive mountain system of this portion of the continent and presents a rich endemic flora. The vegetation of the area was investigated from 1984 to 1992; 68 phytosoci‐ological releves, ecological observations and extensive floris‐tic collections were made. On the basis of multivariate analysis eight communities have been distinguished: Eucalyptus woodland, mallee, evergreen shrubland (plain, mountain and slope), and herbaceous communities of wet sands, springs and rocks. The Stirling Range is the only area in the south of Western Australia where vegetation belts can be recognised.
The hierarchical continuum concept
Authors: Collins Scott L. , Glenn Susan M. , Roberts David W.
Published: May 2006

Abstract. Two general models have been proposed to explain the structure of the plant community: the community‐unit model of Clements and the continuum model of Whittaker and Curtis, the latter based on Gleason's individualistic distribution of species. It is generally assumed that most ecologists now accept the continuum model. Empirical evidence suggests, however, that the continuum in its current form does not fully describe the observed patterns of vegetation along environmental gradients. In this paper, we introduce the hierarchical continuum as a general concept to represent dynamic community structure along regional spatial gradients. The hierarchical continuum is derived from a combination of the individualistic distribution of species, hierarchical assemblage structure, and the core‐satellite species hypothesis. The hierarchical continuum concept predicts that the distribution of species across sites in a region will be polymodal, which reflects hierarchical structure, and that the distribution and abundance of species within and between sites will be spatially and temporally dynamic. Regional distribution of plant species in North American tallgrass prairie, southeastern flood‐plain hardwood forests, northern upland hardwood forests, and boreal forests were either bimodal or polymodal as predicted by the hierarchical continuum concept. Species in tallgrass prairie were spatially and temporally dynamic with an average turnover of 8–9 species per 50 m2 yr1. In addition, the hierarchical continuum concept predicts the potential for fractal (self‐similar) patterns of community structure, and provides a framework for testable hypotheses concerning species distributions along environmental gradients.
Changes in chalk‐grassland structure and species richness resulting from selective nutrient additions
Authors: Willems J. H. , Peet R. K. , Bik L.
Published: May 2006

Abstract. A series of fertilization experiments was carried out over a 5‐yr period in a chalk grassland in Limburg (The Netherlands) as part of a study of the maintenance of species richness in species‐rich grasslands. Phosphorus and nitrogen were shown to be the most limiting nutrients. Addition of both elements doubled above‐ground production, and species richness dropped ca. 50 % in 0.01‐m2 subplots, relative to controls. However, neither the above‐ground production nor plant growth‐forms were sufficient to explain the observed changes in species richness. Small‐scale structural heterogeneity of the vegetation is probably critical for maintaining high levels of richness. Historically, high nitrogen, low phosphorus conditions were rarely encountered in the Dutch landscape and few species appear adapted to these conditions. Among the chalk grassland species, Brachypodiumpinnatum seems well adapted to these conditions, where it dominates and excludes most other species. A detailed understanding of the small‐scale processes responsible for maintenance of species richness is critically important in efforts to maintain the biodiversity of natural ecosystems.
Structure and regeneration patterns in a virgin Picea abies forest in northern Sweden
Authors: Hofgaard Annika
Published: May 2006

Abstract. A high‐altitude boreal Picea abies forest, with tree ages of up to 410 yr, was studied with respect to age structure, spatial regeneration patterns, and substrate. The results suggest that recruitment is primarily dependent on germination substrate but also negatively correlated with the density of the tree layer. 60 % of all spruces < 1.3 m high grew on substrates connected with tree‐fall; ca. 40 % were found on decomposing logs and stumps, covering only ca. 6 % of the forest floor. Individual logs remain important as a regeneration substrate for ca. 150 yr. Continuous presence of decomposing coarse wood is a condition for the maintenance of the population structure under the prevailing climatic conditions. Peaks in the age distribution (the 1870's and the 1940's ‐ 1950's) are probably climatically induced. The results challenge the previous assumptions that this kind of forest undergoes cyclic development. Long‐term structural stability with climatically induced minor variations may be an alternative model.
Importance of short‐lived components of a dry tropical forest for biomass production and nutrient cycling
Authors: Singh Lalji , Singh J. S.
Published: May 2006

Abstract. Short‐lived components in a dry tropical forest ecosystem in India ‐ tree foliage, fine roots and herbaceous plants ‐ are shown to be important for biomass production and nutrient cycling. With 62 % they contribute much more to the dry matter production than the long‐lived components‐ tree boles, branches and coarse roots ‐ which make up only 38 %. The contribution of short‐lived components to the total uptake of different nutrients was also high: 18 ‐ 30 % for tree foliage, 26 ‐ 34 % for fine roots and 6–19 % for herbs; their share in the total nutrient storage is less: 6–19 % for tree foliage, 4–8 % for fine roots and 0.6–1.3 % for herbs. The transfer of nutrients by the short‐lived components was also substantial: 31 ‐ 46 % for foliage, 7–24% for herbs and 33–45% for fine roots. The results indicate that the short‐lived components play a significant role in the functioning of a dry tropical forest.
BOOK REVIEWS
Authors: Hunt E. Raymond
Published: May 2006

Book reviewed in this issue.

Solomon, A. M. & Shugart, H. H. (eds.) 1993. Vegetation Dynamics & Global Change. xii+338 pp. Chapman & Hall, New York, London. (cloth) ISBN 0–412–03671–1. Price: USD 65.‐. (paper) ISBN 0–412–03681–9. Price: USD 29.95.
Simulated dynamics of succession in a North American subtropical Prosopis savanna
Authors: Scanlan J. C. , Archer Steve
Published: May 2006

Abstract. A transition matrix model was used to explore the dynamics, rate and potential extent of changes in landscape vegetation patterns on a southern Texas Prosopis savanna. Transitions between seven vegetation classes were determined for the periods 1941–1960 and 1960–1983 on aerial photographs of three sites. During these periods, the sites were heavily grazed by cattle and were fire‐free. Vegetation states assessed in grids of 20 m x 20 m cells superimposed on photographs ranged from grass‐dominated to woody plant‐dominated. The 1941–1960 period (denoted DRY) was characterized by prolonged drought, whereas annual rainfall during the 1960–1983 period (denoted WET) was typically normal to above‐normal. The 1941 landscape consisted of herbaceous zones (6% of cells), woodland (50% of cells) and savanna parkland (44% of cells with grass/woody plant mixtures). The woodland state was the most stable, with probabilities of no change being 0.970 and 0.873 in WET and DRY periods, respectively. The herbaceous state was least stable, with corresponding values of 0.074 and 0.353.

Past and future landscape structure was modelled by randomly selecting DRY or WET transitions at 20 year time steps. The model was run under a series of rainfall scenarios where the probability of selecting the WET transition matrix (P[WET]) ranged from 0 (DRY always chosen) to 1 (WET always chosen). Historical records indicate P[WET] has approximated 0.3 to 0.4 in the region. The rate of succession to states of greater woody cover increased as P[WET] increased. Forward simulations based on P[WET] > 0.2 suggest the present landscape is unstable and will develop into a closed‐canopy woodland within the next 180 years, assuming the processes operating between 1941 and 1983 continue (e.g. grazing by cattle and lack of fire). Reverse simulations concur with historical observations and projections derived from woody plant growth rates in other studies and suggest that 200 to 300 yr BP these landscapes contained a substantially greater proportion of cells dominated by grassland or grassland with scattered woody plants (43 to 74%) than was present in 1983 (19%). Based upon elapsed time between predicted past and future steady states, succession from open savanna to closed‐canopy woodland may occur in ca. 400 to 500 yr for P(WET) ≥ 0.33. Arresting or reversing the projected trend may require changes in climate and/or changes in livestock grazing and land management practices.

The approaches employed in this study illustrate how time series maps, aerial photographs and satellite imagery can be analyzed and used to interpret, project and reconstruct local and regional changes in ecosystem structure. Difficulties and limitations associated with the use of Markov chains to model succession are identified and discussed.
High species richness in an Estonian wooded meadow
Authors: Kull Kalevi , Zobel Martin
Published: May 2006

Abstract. A wooded meadow at Laelatu in western Estonia was found to be very rich in vascular plants. The maximum number of species found was 25 in a 10 cm x 10 cm plot, 42 in a 20 cm x 20 cm plot and 63 in a 1 m2 plot.

Species richness is related to the management history of the site. The highest richness was found in sites with the most regular long‐term mowing. Species density was lower in the case of fertilization or temporary cessation of mowing.

The richest community had an LAI of 2.8 and an above‐ground dry biomass of 175 g/m2. With increasing height of the herb layer the number of species decreases. Small disturbances cause a remarkable decrease in species density.
A survey of plant associations and alliances from Svalbard
Authors: Elvebakk Arve
Published: May 2006

Abstract. Most vegetation classification studies on Svalbard have followed the phytosociological tradition. Exposed ridges and accumulation sea shores are the habitats investigated best, whereas the open vegetation of screes, active sedimentation plains, erosion plains, young moraines, polar desert and saxicolous vegetation range from almost unknown to poorly known. All published associations and non‐ranked plant communities based on relevé data are reviewed and discussed in an ecological framework with 19 major habitat types. Most of them are arranged in a system of 17 alliances. Most of the alliances are expected to occur elsewhere in the Arctic, but this remains to be documented. The majority of the Svalbard studies are local and have obvious shortcomings. Nevertheless, vegetation types are probably better known on Svalbard than elsewhere in the northern parts of the Arctic.
The importance of bryophytes in the classification of human‐disturbed high arctic vegetation
Authors: Forbes Bruce C.
Published: May 2006

Abstract. Evidence is presented from a variety of tundra cover types under human disturbance at three sites in the Canadian High Arctic to indicate that higher plants may be insufficient to differentiate among the apparently distinct geobotanical signatures of discrete surface disturbances. Unlike in the Low Arctic, woody growth forms are often minimal or lacking on heavily disturbed ground and several prominent species of ruderal herbs and especially graminoids occur on a wide variety of substrates. Therefore, cryptogams, particularly bryophytes, are important indicator taxa. Presence‐absence data on bryophytes from minerotrophic and oligotrophic soils, combined with vascular cover‐abundance data, enhanced detection of patch‐level floristic gradients within and among disjunct coastal lowlands. However, the pool of ruderal bryophytes is limited, and ultimately factors such as frequency and abundance should be considered.
Plant communities on anthropogenically disturbed sites on the Chukotka Peninsula, Russia
Authors: Sumina Olga I.
Published: May 2006

Abstract. The vegetation of anthropogenically disturbed sites on the Chukotka Peninsula was investigated in 1986 and 1990. 102 sites had been bulldozed free of vegetation and soil between 2 and 20 yr ago and revegetated. Anthropogenic vegetation differs considerably from natural tundra. The total plant cover decreases, lichens are absent, moss composition changes, and graminoids predominate. A floristic classification was developed in order to describe the diversity of anthropogenic communities formed on these sites. Four associations were distinguished, all belonging to the alliance Poion glaucomalacanthae. An additional alliance characterized by Alopecurus alpinus is suggested for colder sites, but it has not yet been described. There is a correspondence of associations to substrate types. The association Phippsietum algidae was found only on loam substrate. The Artemisietum glomeratae and Saxifragetum punctatae are connected with rubble or gravel. The graminoid association Arctagrostietum arundinaceae is generally widespread in disturbed habitats and occurs on a variety of substrate types.
Establishment of pasture species on cattle dung: the role of endozoochorous seeds
Authors: Malo J.E. , Suárez F.
Published: May 2006

Abstract. The process of colonization of cattle dung patches and its relation to endozoochorous dispersal is analysed in a Mediterranean pasture. Dung pats dropped in spring and winter were marked, and the vegetation developing on them during the first two years of colonization was followed. The influence of endozoochorous seeds on dung colonization is assessed through the study of: (1) the vegetation on spring and winter dung pats and the seed contents of both, which is abundant in the former and negligible in the latter; and (2) the vegetation on spring dung pats compared with that of the surrounding pasture. The origin of plants growing on dung (either seeds in the manure or in the soil seed bank) was traced by studying dung colonization under controlled conditions in pots with manure put on seed‐free sand, and on pasture turf. The results indicate that endozoochorous seeds germinate in manure; they are the main source of recovery in gaps generated by dung pats. The micro‐succession involved is independent of the type of pasture. A small‐scale spatial pattern results in which gaps of old dung are dominated by endozoochorous species. Thus, dung patches enhance the similarity between grazed communities, and the variation within communities.
Community and species‐performance patterns along an alpine poor‐rich mire gradient
Authors: Gerdol Renato
Published: May 2006

Abstract. Vegetation, water table depth and water chemistry of 16 peatlands in the southern Alps, Italy, were analysed in 115 sample plots. A poor‐rich gradient could be detected along the first axis of a partial Detrended Canonical Correspondence Analysis. Both vegetation and hydrochemistry vary gradually along the gradient. Vascular plants have much broader niches along the gradient than bryophytes. Mosses (except Sphangnum) and hepatics have narrower niches than Sphagnum. The various species of Sphagnum segregate more clearly from each other along the moisture gradient than along the poor‐rich one. The positions of species optima along the latter gradient largely reflect the ecological preferences of mire plants in peatlands with respect to nutrient status.
Influence of trees on above‐ground production dynamics of grasses in a humid savanna
Authors: Mordelet Patrick , Menaut Jean‐Claude
Published: May 2006

Abstract. Above‐ground grass biomass, necromass and tree litter were measured monthly over a vegetation cycle under tree clumps and in the open, in a humid savanna in Côte d'Ivoire. Grass production was calculated using several methods to better discriminate the contribution of the different grass compartments. Above‐ground grass biomass is higher in the open than under canopies during the second part of the growing season, but there is no difference in grass necromass dynamics. Physical protection of grass necromass by tree litter against decaying under tree canopies was assumed to explain this discrepancy. Grass production, calculated as the sum of positive increments of biomass and necromass, equals 1073 g m‐2 yr‐1 in the open, against 74 % underneath trees. However, basal ground cover is only 50 % of that in the open. Comparison with other savanna studies as a whole does not show any significant effect of rainfall on the relationship between under‐canopy and outside‐canopy grass production. However, in arid conditions, grass production tends to increase under light‐canopied trees (mostly Acacia legumes) which hardly affect grass photosynthesis, but add high quality litter to the soil surface.
Modelling potential impacts of climate change on the spatial distribution of zonal forest communities in Switzerland
Authors: Brzeziecki B. , Kienast F. , Wildi O.
Published: May 2006

Abstract. A spatially explicit, climate‐sensitive vegetation model is presented to simulate both present and future distribution of potential natural vegetation types in Switzerland at the level of zonal forest communities. The model has two versions: (1) a ‘basic’ version using geographical region, aspect, bedrock (represented by soil pH), and elevation, and (2) a ‘climate‐sensitive’ version obtained by replacing elevation (complex environmental gradient) with temperature (climatic factor). Version 2 is used to predict vegetation response under different (today's and projected) climatic conditions.

Two regional climate scenarios are applied: (1) assuming an annual mean temperature increase of 1.1 — 1.4 °C, and (2) assuming an increase of 2.2 — 2.75 °C. Both scenarios result in significant changes of the spatial vegetation patterns as compared with today's climatic conditions. In scenario 1, ca. 33 % of the sample points remain unchanged in terms of the simulated zonal forest community; in scenario 2, virtually all sample points change. The most noticeable changes occur on the Swiss Plateau with Carpinion forests (zonal vegetation of present colline belt) expanding to areas that are occupied today by submontane and low‐montane Fagus forests.

To estimate the reliability of the simulation, quantitative (comparison with field mapping) and qualitative (comparison with climate types in the Alpine region) tests are performed and the main limitations of the approach are evaluated.
Comparison of different methods for diversity ordering
Authors: Tóthmérész Béla
Published: May 2006

Abstract. The measurement of diversity, one of the most important concepts in present‐day ecology, can be improved by methods of diversity ordering which have recently been developed. This ordering is achieved by a D(α) diversity index family. Indices of this family show varying sensitivities to the rare and abundant species as the scale parameter, α, changes. The aim of this paper is to review and assess 12 methods of diversity ordering and discuss their relationships in detail. Two of the methods are new to the ecological literature.

The diversity ordering methods are compared as to their effectiveness in graphically displaying the differences of community structure and demonstrating the (non‐)comparability of communities. Small, medium and large data sets were used to evaluate the methods. A small artificial data set (five to seven species) and a large semi‐artificial data set (31 — 141 species) are used in this paper.

The results suggest that Rényi's diversity index family and Logarithmic dominance ordering are the most useful methods for diversity ordering of communities of all sizes. Right‐tailsum diversity ordering performs well for small communities.
Variation in net primary productivity and biomass of forests in the high mountains of Central Himalaya
Authors: Garkoti S.C. , Singh S.P.
Published: May 2006

Abstract. This study describes the biomass and net primary productivity of the forests of Central Himalaya occurring in areas where vegetation ranges from close‐canopy broad‐leaved forest to stunted open‐canopy timberline vegetation. The forests studied were Acer cappadocicum forest at 2750 m, Betula utilis forest at 3150 m, and Rhododendron campanulatum forest at 3300 m altitude in Central Himalaya. With the rise in altitude the forest biomass decreased from 308.3 ton/ha in Acer forest to 40.5 ton/ha in Rhododendron forest. The decrease in net primary productivity was less steep, from 19.6 ton/ha/yr in Acer forest to 10.0 ton/ha/yr in Rhododendron forest. The production efficiency of leaves (net production per unit leaf weight) in these forests is higher than in low altitude broad‐leaved forests of Central Himalaya, i.e. from 2.89 in Acer forest to 3.41 g net production/g leaf biomass/yr, against 0.81‐1.55 at lower altitudes.
Major plant communities of warm North American deserts
Authors: Peinado M. , Alcaraz F. , Aguirre J.L. , Delgadillo J.
Published: May 2006

Abstract. A syntaxonomic study of the major plant communities in neotropical North American deserts (Sonoran, Mojave and Baja California Deserts) is presented. The field method of the Braun‐Blanquet approach was combined with a numerical syntaxonomical analysis (cluster analysis and principal coordinate ordination). 21 associations are described for the first time: Ambrosio chenopodifoliae‐Larreetum tridentatae, Acamptopappo sphaerocephali‐Larreetum tridentatae, Hymenocleo monogyrae‐Baccharidetum glutinosae, Bergerocacto emoryi‐Agavetum shawii, Burseretum hindsianomicrophyllae, Cercidio microphylli‐Carnegieetum giganteae, Bursero microphyllae‐Cyrtocarpetum edulis, Hymenocleo salsolae‐Daleetum spinosae, Echinocereo engelmannii‐Agavetum deserti, Euphorbio californicae‐Fouquierietum diguetii, Fouquierio splendentis‐Larreetum tridentatae, Agavo cerulatae‐Idrietum columnaris, Mascagnio macropterae‐Lysilometum candidae, Maytenetum phyllanthoidis, Opuntio basilaris‐Larreetum tridentatae, Prosopidetum torreyanae, Roso minutifoliae‐Aesculetum parryi, Opuntio taponae‐Agavetum subcerulatae, Tidestromio oblongifoliae‐Atriplicetum hymenelytrae, Eurotio lanatae‐Larreetum tridentatae and Yucco validae‐Fouquierietum diguetii. Some associations include subassociations. Ecological, biogeographical and floristic bioclimatic data are given for each association.
Plant functional types and climate at the global scale
Authors: Box Elgene O.
Published: May 2006

Abstract. Globally applicable sets of terrestrial plant functional types (PFTs) have been identified as a major need in the development of dynamic global vegetation models for use with global atmospheric models. Global sets of PFTs should represent the world's most important plant types; characterize them through their functional behavior; and provide complete, geographically representative coverage of the world's land areas. Three main schools of thought on PFTs have emerged: (1) a physiological focus on internal function, especially at the level of basic metabolism; (2) an ecological focus on function in relation to plant form and environmental conditions; and (3) a geophysical focus on how plant functions affect the adjacent atmosphere. A structural approach based on pheno‐physiognomy permits ready identification of relatively familiar, recognizable plant types. Many of the criteria cited by other approaches also are intimately related to structure and its seasonal changes. An earlier global system of structural‐functional PFTs and their climatic relations has been improved, including addition of less well‐known plant types, and is briefly described. A more strictly ‘functional’ approach is proposed, in which major aspects of plant function, initially metabolism and water balance, are used to classify functional types and suggest how these are constrained by climate. Such functional considerations, however, are closely linked to structural manifestations ‐ but also require other functional criteria for more completely functional classifications. A recent global model of potential natural vegetation types suggested ca. 15 major plant types as necessary to cover the world's main terrestrial vegetation patterns. These essential types correspond well with a first‐cut set of structural types implied by metabolic considerations.
Implementation of a hierarchical global vegetation classification in ecosystem function models
Authors: Nemani Ramakrishna , Running Steven W.
Published: May 2006

Abstract. We propose an alternative approach for the currently used biogeographic global vegetation classifications. A hierarchical vegetation classification system is proposed for consistent and routine monitoring of global vegetation. Global vegetation is first defined into six classes based on plant canopy structure and dynamics observable by remote sensing from satellites. Additional biome variability is then represented through a remote sensing derived leaf area index map, and direct climate data sets driving an ecosystem model to compute and map net primary production and evapotranspiration. Simulation results from an ecosystem function model suggest that the six canopy structure‐based classes are sufficient to represent global variability in these parameters, provided the spatio‐temporal variations in Leaf Area Index and climate are characterized accurately.

If a bioclimatically based classification is needed for other purposes, our six class approach can be expanded to a possible 21 classes using archived climatic zones. For example, tropical, subtropical, temperate and boreal labels are defined by absolute minimum temperature. Further separation in each class is possible through changes in water availability defined by precipitation and/or soils. The resulting vegetation classes correspond to many of the existing, conventional global vegetation schemes, yet retain the measure of actual vegetation possible because remote sensing first defines the six biome classes in our classification.

Vegetation classifications are no longer an end product but a source of initializing data for global ecosystem function models. Remote sensing with biosphere models directly calculates the ecological functions previously inferred from vegetation classifications, but with higher spatial and temporal accuracy.
Ecosystem responses to changes in plant functional type composition: An example from the Patagonian steppe
Authors: Aguiar Martín R. , Paruelo José M. , Sala Osvaldo E. , Lauenroth William K.
Published: May 2006

Abstract. Grass cover along a grazing intensity gradient in Patagonia decreases, whereas bare soil and shrub cover increases. Our objective was to study the effect of a change in the dominant plant functional type on soil water balance, primary production, herbivore biomass, roughness, and albedo. Using a soil water balance model, we found increases in evaporation and deep drainage, and a decrease in total transpiration along the grazing intensity gradient. Above‐ground primary production, estimated from transpiration, decreased along the grazing intensity gradient because shrubs did not fully compensate for the decrease in grass production. Using a statistical model, we calculated herbivore biomass from estimates of above‐ground primary production. Estimated herbivore biomass was lowest in the shrub‐dominated extreme of the grazing gradient. Roughness increased from the grass‐dominated to the shrub‐dominated community. Albedo had a maximum at an intermediate position along the gradient.

Our results suggest that changes in plant functional type composition, independent of changes in biomass, affect ecosystem functioning and the exchange of energy and material with the atmosphere. Grasses and shrubs proved to be appropriate plant functional types to link structure and function of ecosystems.
A periodic table for ecology? A chemist's view of plant functional types
Authors: Steffen William L.
Published: May 2006

Abstract. A functional type approach, in which the complexity found in nature is reduced by grouping organisms that are functionally similar into a single classification, is being promoted in global change research. This paper examines a proposed analogy between this functional type approach in global change ecology and the periodic table of the elements in chemistry. When applied to a ‘bottom‐up’ approach for defining functional types in ecology, in which large numbers of organisms are classified into smaller groups based on similarity of certain functions, the analogy fails. Ecological functions are not simple attributes of a biological entity, as electronic structure is for a chemical element, but are themselves complex chemical and physical systems that often interact strongly with the environment. The analogy to the periodic table may be of some use as an organizing tool in a ‘top‐down’ approach in which a modelling context is used to define the number of ‘elements’ and their properties. This will be elaborated for plant functional types. Each PFT is assigned characteristics that allow its response to the driving forces of change, e.g. temperature, precipitation, soil nutrients, disturbance, to be predicted. ‘Rules of combination’ determine how the mix of PFTs in a particular ecosystem changes to form different ecosystems, which would correspond in the analogy to chemical compounds. However, these requirements present significant challenges to the usefulness of the analogy, even as an organizing tool in the ‘top‐down’ approach.
Impact of grazing and atmospheric nitrogen deposition on the vegetation of dry coastal dune grasslands
Authors: ten Harkel Matthijs J. , van der Meulen Frank
Published: May 2006

Abstract. A five‐year experimental study was carried out to examine the combined effects of grazing and atmospheric nitrogen deposition on the vegetation of three dry dune grasslands: one short species‐rich, one short species‐poor, and one predominated by tall graminoids.

Additional fertilization with nitrogen had no significant effect, neither in grazed nor in non‐grazed plots. Exclusion of grazing by rabbits resulted in an increase in the frequency of perennial graminoids and a decrease in the frequency of annual graminoids and herbs. Nevertheless, species diversity remained the same in the species‐rich grassland. During the experiment, the above‐ground biomass increased in all nongrazed plots and the amount of bare soil and mosses decreased.

The vegetation changes occurred mainly within one year after the exclusion of grazing. An exception is the grass‐dominated site where the amount of Calamagrostis epigejos increased gradually from ca. 20 % in the first two years to about 50 % in the fourth and fifth year.

Grazing by rabbits seems essential to prevent graminoids to become predominant in the dry dunes. If graminoids are dominant, grazing by horses can be an appropriate method to restore the original grassland vegetation. After six months of grazing by horses the grass‐dominated site showed a decrease of the frequency of perennial graminoids, from 95 % to 80 %, and an increase of the frequency of perennial herbs, from 2.5 % to between 13 and 20 %.
Vegetation establishment on chalk marl spoil: the role of nurse grass species and fertiliser application
Authors: Mitchley J. , Buckley G.P. , Helliwell D.R.
Published: May 2006

Abstract. The Channel Tunnel workings on the UK side have yielded nearly 4 million m3 of chalk‐marl spoil which now forms a 36 ha landscaped reclamation platform. To establish vegetation of amenity and conservation interest on the spoil, seed mixtures of native wild flowers and grasses were sown with Lolium perenne (perennial rye grass) as a nurse species. Potentially, L. perenne is a suitable nurse species for grassland creation on infertile substrates as it provides rapid initial cover and stability, but it is non‐persistent and declines in vigour with time, allowing wild flower species sown alongside to expand their cover and spread in the longer term. On very low fertility substrates like chalk marl, an initial application of fertilizer is needed to encourage plant growth. Results are reported of a fertilizer experiment on Channel Tunnel spoil to determine appropriate levels of fertilizer for establishment of species‐rich grassland vegetation. An area hydroseeded with L. perenne and wild flowers in autumn 1992 was subjected to factorial treatment of four levels each of N and P in spring 1993. The results the following summer showed significant positive effects of nitrogen and phosphorus on L. perenne biomass and a negative impact of nitrogen on densities of wild flower species, especially legumes, establishing in the L. perenne sward. In general, low fertilizer applications encouraged low productivity and maximal species richness in the vegetation. Conversely high applications encouraged high productivity and competitive exclusion of sown wild flower species. Fertilizer applications must therefore balance encouragement of the stabilising nurse grass sward, while preventing competitive exclusion of wild flowers by the nurse grass.
Perennial nitrophilous vegetation of the northern Iberian Peninsula
Authors: Loidi J. , Berastegi A. , Biurrun I. , García‐Mijangos I. , Herrera M.
Published: May 2006

Abstract. The syntaxonomy of the perennial nitrophilous vegetation assigned to the Artemisietea vulgaris of the northern part of the Iberian Peninsula (Basque Country and surrounding areas) was revised. The study area is of biogeographic importance due to its transitional character ‐ here, the ruderal vegetation of the Mediterranean and that of temperate Europe meet. Numerical ordination of the communities was performed in order to reveal systematic relations between the syntaxa. Two subclasses, Artemisienea vulgaris and Onopordenea, encompassing five orders, Convolvuletalia, Galio‐Alliarietalia, Artemisietalia, Onopordetalia, Carthametalia lanati, and seven alliances with 12 associations and two rankless communities were distinguished.
Seed bank classification and its importance for the restoration of species‐rich flood‐meadows
Authors: McDonald A.W. , Bakker J.P. , Vegelin K.
Published: May 2006

Abstract. This paper focuses on the persistence of seeds in the seed bank of a formerly fertilized flood‐meadow into which seeds from an original Alopecurus pratensis‐Sanguisorba officinalis community have been introduced. The longevity of seeds in the seed bank of the original community is also estimated. The established vegetation was compared with the seed bank, as divided into two layers (0 ‐ 5 cm and 5–10 cm); this allowed a classification of species into three groups, with (1) transient, (2) short‐term persistent and (3) long‐term persistent seed bank. The majority of the species of the unfertilized flood‐meadow community have a transient or short‐term persistent seed bank with seeds showing a large variance in shape i.e. flattened or elongate. Because of this, the characteristic flood‐meadow species will disappear soon after the beginning of fertilizer application and will not re‐establish from the seed bank, once the fertilizer application is ceased. The formerly fertilized flood‐meadow contains many ruderal and arable weed species, the seeds of which tend to be compact or round. Significantly more seeds were found in the seed bank of the formerly fertilized flood‐meadow under cattle‐grazing than under sheep‐grazing and no grazing.
The significance of the asymmetric effect of crowding for coexistence in a mixed temperate forest
Authors: Nakashizuka Tohru , Kohyama Takashi
Published: May 2006

Abstract. The coexistence of coniferous (mostly Abies homolepis) and broad‐leaved tree species (mostly Fagus crenata) in a mixed temperate old‐growth forest in Japan was simulated by a size‐structure dynamics model incorporating the asymmetrical (one‐sided) effect of shading between these two life‐form guilds. The model assumes that the crowding effect due to one‐sided competition for light on a tree of a given size regulates the rate of size growth and recruitment. The cumulative basal area of trees larger than a given tree in the forest is employed to express the intensity of one‐sided competition on that tree. Cumulative basal areas of both guilds negatively affected the growth rate of any tree. The shading effect by conifers on the growth rate of either guild was stronger than that by broad‐leaved species. Two types of model were tested for recruitment; an additive and a reciprocal model. A reciprocal model, where basal area density of conifers and broad‐leaved species has a negative effect on the recruitment of its own guild but has a positive effect on that of the other guild, fit the observed data better than an additive model where total basal area of the two guilds suppresses recruitment rates. Simulations using these models showed that, within a particular range of the set of recruitment rates, the two guilds could coexist. The tendency for reciprocal replacement, incorporated in the reciprocal model, substantially widened the range of coexistence and shortened the time required for convergence.
Longevity, recruitment and mortality of desert plants in Grand Canyon, Arizona, USA
Authors: Bowers Janice E. , Webb Robert H. , Rondeau Renée J.
Published: May 2006

Abstract. The demography of woody desert plants along the Colorado River in Grand Canyon, Arizona, USA, was analyzed using 355 pairs of replicated photographs taken as long ago as 1872. Longevity, recruitment, and mortality were determined for 38 species characteristic of ungrazed desert scrub. Individual plants that survived 100 yr or more included Acacia greggii, Ambrosia dumosa, Atriplex canescens, A. confertifolia, Echinocactus polycephalus, Ephedra spp., Fouquieria splendens, Larrea tridentata, Lycium andersonii, Opuntia acanthocarpa, O. basilaris, O. erinacea, Pleuraphis rigida, and Yucca angustissima. This is the first evidence of long lifespan for most of these species, particularly the succulents. Most of the long‐lived species registered overall increases in population during the past century. Only four species with lifespans ≥ 100 yr had a net loss of individuals between 1889 and the present, and only two decreased between 1923 and the present. It seems likely that climatic fluctuations over the past century are largely responsible for these recruitment and mortality patterns; however, nurse plants, predation refuges and other biotic factors may also play a role.
Small‐scale species dynamics in semi‐arid steppe vegetation in Inner Mongolia
Authors: Wei Zhang , Skarpe Christina
Published: May 2006

Abstract. Small‐scale species dynamics in semi‐arid steppe vegetation under grazing and recovering from long‐term grazing were followed during five years. Most species successively increased their frequency during the study period, whereas some early successional species decreased in frequency. Perennial Artemisia spp. dominated the vegetation and showed low mobility, whereas small annual or short‐lived perennial species had a lower frequency and higher mobility. Significant associations between species were few.
Relationships between vegetation zonation and altitude in a salt‐marsh system in northwest Spain
Authors: Sánchez J.M. , Izco J. , Medrano M.
Published: May 2006

Abstract. Vegetation zonation in salt marshes has traditionally been attributed largely to altitudinal differences, since altitude determines the temporal pattern of tidal flooding and is thus closely related to proximate determinants of the distribution of species and plant communities. We investigated the distribution of vascular plants and plant communities along a series of altitudinal transects in two salt marshes in the northwestern Iberian Peninsula. Our results indicate that altitudinal range varies significantly both among species and among communities, and confirm that salt‐marsh vegetation characteristics (species cover and composition) can be predicted on the basis of altitude, particularly at the lower levels of the profile.