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Ksudach Volcano, southern Kamchatka Peninsula, erupted in 1907 and impacted over 2000 km2 of forests with air-fall pumice deposits. We identified three impact zones. In Zone I, deposits deeper than 100 cm destroyed all vegetation. Two early successional stages occur, a lichen-dominated desert and isolated patches of a pioneer herb stage. Zone II is defined by pumice deposits 30 to 100 cm deep. Deposits of 70 to 100 cm destroyed all vegetation, but left scattered snags. Here primary succession dominates recovery, but its rate varies. Isolated trees survived in deposits of 30 to 70 cm and primary and secondary successional stages form a complex mosaic termed an intermediate succession. In Zone II, the primary stages found in Zone I are joined by a dwarf shrub-herb stage and a secondary birch forest stage. Zone III occurs where thinner deposits permitted some vegetation to survive in all locations. Secondary succession dominates in deposits of 10 to 30 cm. Trees suffered damage, but survived deposits of 20 to 30 cm, while other vegetation layers were eliminated. Deposits of 10 to 20 cm eliminated mosses and lichens and but only reduced the number of dwarf shrubs and herbs. Deposits of less than 10 cm damaged herb, moss and lichen layers but did not eliminate any species. All sampled vegetation remains in a pre-climax state, having yet to recover fully from earlier eruptions. Reconstructed vegetation maps for before 1907 and for ca. 1925 are compared to the map of vegetation in 1994. Based on degree of soil formation, vegetation recovery and colonization rates at different pumice depths, and the current vegetation, we estimate that full recovery of the soil-vegetation system will take more than 2000 years.

In comparison to countries with a tradition of vegetation studies, a comprehensive, hierarchical classification of plant communities in the province of British Columbia has not yet been developed. Such a classification is needed for systematic ecological studies and coordinated conservation of vegetation. As the culmination of fifty years of detailed surveys, tabular and multivariate analyses of 3779 releves of natural, old-growth, submontane, montane and subalpine forest communities in coastal British Columbia were used to develop a hierarchy of vegetation units according to the Braun-Blanquet approach. At the highest level, we distinguished seven orders: Quercus garryana, Pseudotsuga menziesii-Mahonia nervosa, Tsuga heterophylla-Rhytidiadelphus loreus, Tsuga mertensiana, Thuja plicata-Tiarella trifoliata, Populus trichocarpa, and Pinus contorta-Sphagnum. Diagnostic table, ordination, and elimatic and edaphic regimes were used to show floristic affinities among the orders and to interpret their relationships to regional environmental gradients. Plant communities of each order were briefly characterized by their floristic composition, physiognomy, succession, and environment. The synopsis for all delineated vegetation units (order, suborder, alliance, and association) of coastal British Columbia is included.

The soil algal communities of forested and reforested, limed and unlimed plots were compared in the acid rain impacted Kru sne hory Mountains. The floristic composition of unlimed plots is similar to that found in acid forest soils with a naturally low pH and no effect of the acid rain on these communities can be detected. Chlorophyceae are the only group present in these soils. In limed areas with a higher soil pH, algal diversity is significantly increased while algal densities remain similar. Chlorophyceae, while still the dominant group, are accompanied in these soils by Bacillariophyceae, Xanthophyceae, Eustigmatophyceae and Cyanophyceae. Total vegetation cover and thus light hitting the soil surface seems to be most important in determining the algal biomass.

We investigated successional trends on windthrow mounds in two old-growth Tsuga heterophylla-Picea sitchensis forests in northern southeast Alaska to determine the influence of windthrow disturbance on the maintenance of plant diversity. We were particularly interested in assessing the value of mosses in detecting long-term effects of disturbance in temperate rainforests. Mosses established a dense carpet on windthrow mounds within the first few decades after the disturbance. No consistent changes were noted in total moss and vascular plant cover, moss biomass, or species diversity between young mounds (±50 yrs), intermediate mounds (±150 yrs) or old mounds (> 200 yrs), or between mounds and the undisturbed forest floor, despite consistent differences in soils development.

Three aspects of the paramo vegetation's response to fires were investigated: the measurement of fire temperatures, general observations of changes in plant communities following fires, and monitoring the fate of individual plants after burning. Fire temperatures were strongly influenced by the physiognomy of the vegetation, dominated by tussocks of Calamagrostis spp. Temperatures were highest amongst the upper leaves of the tussock (sometimes >500°C). The middle levels of the tussock experienced temperatures in excess of 400°C, but in the dense leaf bases temperatures were often below 65°C. On the ground between tussocks, temperatures were variable, whereas 2 cm below ground temperatures failed to reach 65°C. Plant survival depended on the intensity of the fire and the plant's position within the tussock structure. Survival was often the result of high temperature avoidance (with buds shielded by other plant parts or buried beneath the soil surface). Post-fire Calamagrostis tiller mortality rates were high and tussock regrowth was slow. Some other species appear to maintain their populations by exploiting this recovery phase for seedling establishment on tussocks. Between tussocks, changes of occupancy at the level of the individual plants were greater after fire than in control vegetation. Most transitions were random. Those which departed from random often involved gaps and were related to post-fire mortality, regrowth from below-ground parts, colonisation or, in the case of a clonal mat-forming species, to spatial rearrangement of rosettes. Recovery was slower at higher altitude. Recovery was much slower in burned plots when the upper 2 cm of soil was removed (along with buried plant parts) compared with burned plots. Qualitative observations suggest that recovery may consist of a cyclical process, mediated by the serial dominance of several species that are physiognomically important. The frequency of fires determines the amount of fuel accumulated within grass tussocks and some plants may be unable to survive repeated burning. Chance survival of species in unburned patches of vegetation and random colonisation of gaps may be important determinants of subsequent community structure.

To evaluate alpha diversities, various variables such as density, cover, volume, and weight have been used. However, density is often a distinct variable from the remaining three. To clarify differences in diversity measured by those two kinds of variables, the data collected in fourteen 2×5 m permanently-marked plots on Mount Usu, Japan, which erupted during 1977 and 1978 in growing seasons from 1983 to 1989 was analyzed, using Shannon's species diversity (H′) that is represented as a result of combination of species richness and evenness (J′). H′ and J′ were evaluated by density (density H′ and J′) and cover (cover H′ and J′). Cover H′ and J′ were significantly lower than density H′ and J′, indicating that cover H′ has different characteristics from density H′. Those differences are due to differences in evenness, because species richness is the same. The rank orders of species density are different from those of cover. The predominance of a few perennial herbs greatly decreases cover evenness, while seedling establishment success influences density evenness. Therefore, I propose that, during the early stages of succession on harsh environments such as volcanoes, density diversity represents seedling establishment success rate while cover diversity expresses vegetative reproduction success rate.

Inland dunes in northwestern Europe support a number of dry vegetation types. These ecosystems are poor in nutrients and it has been suggested that accumulation of nutrients triggers succession in such systems.

This study examined the temporal patterns of establishment, suppression, and release of major tree species in two old-growth Ohio forest remnants as a means to determine the past disturbance history of these forests. Increment cores were taken from a total of 154 trees from two well-drained, upland plots and two poorly-drained, bottomland plots in each of the two forested areas. Acer saccharum and Fagus grandifolia exhibited multiple episodes of suppression and release prior to becoming canopy trees, and could tolerate suppressions as long as 84 years. In contrast, Quercus macrocarpa, Q. muehlenbergii, Prunus serotina, and Acer saccharinum rerely exhibited any tolerance to suppression and appeared to have entered the canopy after single disturbances had opened large areas of canopy. There was clear synchrony in the temporal pattern of establishment and final release from suppression among trees from bottomland plots scattered throughout the stands, indicating that relatively large disturbances were important in these poorly-drained areas. In contrast, there was little synchrony among trees from well-drained upland plots, except in a single instance where selective cutting of Quercus trees opened the canopy. Thus, the canopy of upland site was likely subjected only to small disturbances resulting from the death of one or a few trees. At the whole of forest level, there was evidence of episodic recruitment of canopy trees in both forests. Establishment of Fraxinus spp. and Quercus spp. were particularly episodic, and few Fraxinus or Quercus trees alive today established during the last century. These data suggest that large disturbances have affected canopy dynamics of both upland and bottomland areas prior to 1900 and in bottomland forests through this century. In contrast, disturbances in upland areas during this century have been restricted to small, treefall-generated canopy gaps.

To understand the human influence on the successional process of vegetation, structures of the pine forest as a dominant vegetation were compared between in Yanghwa-ri of rural Korea and Miwa-cho of rural Japan. The secondary pine forests are well developed around the villages in both regions. In rural Korea, pine forests are still used intensively for several traditional purposes. The pine forests in Yanghwa-ri of Korea, therefore, are stayed in the early stage of the succession. The floristic composition in pine forests of Yanghwa-ri was similar to that in the secondary grasslands. The fertilizer trees such as Robinia and Alnus contributed to develop the stratification of the forest. On the other hand, in Japan, almost all pine forests in rural regions had been abandoned due to the changing of traditional use because of the economic growth and the development of alternative energy sources since 1960s. In the case of pine forests of Miwa-cho, those in the early successional stage were few in number and small in patch size. Several woody plants covered under the pine canopy. The shade-tolerant shrub invaded into pine forest floor, because the undergrowth as a traditional energy source had no longer used. Pine forests were partly succeeded by deciduous oaks in Miwa-cho corresponding to the social changes. On the contrary in Yanghwa-ri, the vegetation replacement will not present because traditional management such as collecting fuels and making graveyards will be remained as a Korean ideology in the rural landscape.

A synchronic method was applied in order to investigate the growth process of the dominant woody plants in an undisturbed Mediterranean evergreen-sclerophyllous ecosystem in central Greece. Cover (%), biomass and leaf area data of Arbutus unedo, Erica arborea, Quercus coccifera and Phyllyrea latifolia over a period of 30 years are provided. The investigation of growth by means of the Richards function revealed two plant groups, following two different growth strategies: A ‘fast growth’ strategy, followed by A. unedo and E. arborea and a ‘slow growth’ strategy followed by Q. coccifera and P. latifolia. Furthermore, a succession pattern was described in which the fast growing initial dominants are being replaced by the slow growing plants. Two succession scenaria are proposed as alternative plant responses to grazing and fires, which are the major anthropogenic impacts in the mediterranean environment.

We studied the conditions that permit the shrub, Cordia multispicata, to establish in Amazon pastures and the potential role of this shrub as a ‘succession facilitator’ near the town of Paragominas, Para State, Brazil. Local disturbances that reduce cover such as grazing and burning helped C. multispicata establish in pastures in active use. Germination of C. multispicata was significantly improved on sites subjected to simulated grazing and seedling growth was hastened following pasture burning. We found that below-ground competition, evaluated using root ingrowth cores, was reduced by burning and grazing. Recently abandoned pastures are frequently composed of a mix of forbs and grasses but as succession proceeds a mosaic of more discrete vegetation patches appears. At our site, a five-year-old abandoned pasture, grass patches (primarily Panicum maximum) and shrub patches (mainly C. multispicata) were common. We compared physical and biotic characteristics of zones dominated by C. multispicata and P. maximum and found: (1) the rain of bat and bird dispersed seeds of woody species was much greater in the zones of C. multispicata (92 seeds/m2/year) than in the patches of grass (6 seeds/m2/year); (2) the density of woody seedlings was eight times greater in the C. multispicata patches (0.65/m2) than in the zones of P. maximum (0.08 woody individuals/m2); (3) soil nutrient availability and litter nutrient concentrations were greater in the shrub zones than in the grass zones; and (4) photosynthetic photon flux density at the soil surface was generally more favorable for rainforest tree seedling growth in C. multispicata patches (16% of full sunlight) as compared to the grass zones (7.7% of full sun). We conclude that the shrub, C. multispicata, acts as a magnet, attracting volant seed vectors, and as a nurse plant, facilitating the establishment of woody species in abandoned Amazon pastures.

Disturbances play an important role in the establishment of vegetation at Inaccessible and Nightingale Islands in the South Atlantic Ocean. Type, altitude and age of disturbance all influenced the species richness, life-form and abundance of seedlings. A few indigenous species appear to be dependent on small disturbances, such as the clearings around albatross nests, for their perpetuation, e.g. Acaena sarmentosa and Gnaphalium thouarsii. Alien forbs and grasses, e.g. Conyza albida, Holcus lanatus, Pseudognaphalium luteo-album and Rumex obtusifolius, tended to dominate large recent disturbances such as soil-slips and depressions, and to colonize man-modified sites. Alien plants were less common on the plateau at Inaccessible Island than on the lowlands. Their success appears to be enhanced by large-scale disturbances. The highest density and diversity of seedlings occurred on large soil-slips where mineral soil was exposed and vegetation cover was minimal.

Dehesa ecosystems on granite and on slate clearly differ in soil characteristics. Our aim was to find out whether floristic composition differed too. we selected an equal number of plots, on both granite and slate, in different successional stages of development and at various ages after field abandonment (the youngest 15–20 years). Plots with rock-outcrops, which had never been cultivated, were also included in the study. The results showed that floristic differences between granite and slate communities were not detectable in the younger successional stages. However, they showed up with time and on stabilized grasslands became significant. But on plots with rock-outcrops the differences were not observable. This was undoubtedly influenced by the peculiar features of these plots, characterised by poor arid soils and surface parent material. In fact they did not show significant differences in the analysed soil parameters either. Species diversity and biomass showed a similar pattern of differences to floristic composition. The highest species diversity was found on plots with lower biomass (the youngest ones). The lowest biomass in conjunction with quite low species diversity was found on plots with rock-outcrops, which again is consistent with their peculiar features.

A distribution of the epiphytic bryophyte and lichen vegetation of deciduous forests from the centre and north of the supramediterranean belt from the Spanish Iberian Peninsula was established using numerical (PCA, CCA) and traditional floristic characteristics. Four groups have been established in relation to several syntaxa. Derived by numerical classification, possible successional trends between the groups with respect to changes in moisture, light and diameter of the trees are described. Nevertheless, patterns with succession in epiphytic communities are very complex to establish.

Four seventy-year-old broadleaved recent woods adjacent to three ancient woodland fragments, which all together covered an area of 27.5 ha, were investigated. Two of the recent woods were established naturally and two were planted. The ancient woodlands, including oak-hornbeam and oak-pine woods, were the only near source of diaspores of woodland species. The recent woods differed in area, location, soil richness and light conditions. On the basis of the data from 236 systematically located plots the similarities and differences in ground vegetation between the ancient and recent woods were studied by detrended correspondence analysis (DCA). Even after 70 yr of forest vegetation recovery in the recent woodlands differences were found in the vegetation of the woods examined. The direction of secondary succession was strongly determined by soil conditions. Mature woodlands showed higher beta-diversity. The causes of convergence and divergence in the composition of the communities were analyzed and discussed. The greatest similarity was found between recent and adjacent ancient woods growing on rich brown soils. The greatest divergence was observed in the recent woods growing on poor soils and more open to light, where the very great density of Carex brizoides inhibited the rate of succession. The results obtained indicate that with no isolation and only small distances from ancient woods the community composition in recent woods is to a greater degree dependent upon soil conditions, light and the influence of dominants than on the modes of species dispersal. The regeneration of ground vegetation of woodland communities is possible to a high degree, close to ancient woodlands, on rich brown soils.

I examine the process of plant community colonization through a chronosequence study of permanent plots spanning 45 years on a 70-year-old subalpine earthflow in south-western Colorado, USA. While local diversity and average density of vegetation remained stable throughout the study, the overall diversity increased through the early years of the study with little change over the past 20 years. A gradual shift in species composition occurred through time with species with good dispersal and stress tolerance abilities colonizing the site initially followed by more generalist species. After over 70 years the disturbed communities remained distinct from adjacent relatively undisturbed areas in diversity, density, and species composition. Soil translocation experiments suggest that it is the severe microclimate of the earthflow which is limiting further colonization of the site.

Eight grassland associations with ten phases and two riverine forest associations were identified on the floodplains of Chitwan National Park in lowland Nepal. TwoThemeda arundinacea associations were primarily stable edaphic associations on mollic soils, often with aquic moisture regimes.Themeda associations were floristically similar to adjacent sal forest. Four mixed tall-grass associations primarily ofNarenga porphyrocoma, Saccharum bengalense, andSaccharum spontaneum were identified. These andThemeda arundinacea types were characterized by a very weak component of woody species. Two grass-shrub associations ofSaccharum bengalense andNarenga porphyrocoma with a strong woody species component typical of riverine forest were described.Trewia nudiflora-Bombax ceiba riverine forest and mixed riverine forest types also were identified on the basis of understory composition. Mixed tall-grass and grass-shrub associations appeared to represent early and late phases of grassland succession to riverine forest. Trajectories of succession are controlled primarily by fire and wildlife grazing. The classification refines the general classifications applied to the central Terai of Nepal and India, and should provide insight for classification of other Terai riverine grasslands.

Plot 82 is one of a hundred permanent plots that have been set up in Croatia for the purpose of long-term and continual investigations of ecosystems and their successions. It is located in the area of Karleusine Plase within the Plitvice Lakes National Park. Vegetation on the plot belongs to association Bromo-Plantaginetum mediae. The association develops in mountainous regions of continental Croatia within a wide altitude range, from 180–1300 m a.s.l. on shallow soil over pervious carbonate rocks. The floristic composition and phytocoenological characteristics of the association have been analyzed using the common methods of the phytocoenological school Zurich-Montpellier, on the basis of 17 phytocoenological records. In addition to floristic composition, some site characteristics have been analysed: soil moisture, calcium carbonate, phosphates, pH value, humus, cation exchange capacity and nitrogen mineralization on the site and in the laboratory. The results obtained are comparable with the data presented in the available phytocoenological and ecological literature.

The vegetation dynamics in two former braided channels of the Rhone River was studied at two time scales in order to test the following hypothesis: fluctuations would occur within seasons (flood disturbances, hydrological fluctuations, phenology) while successions would occur between years. The vegetation was surveyed in 1983, 1988 and 1989 during summer for the interannual investigation, and in spring 1989, summer 1989, winter 1989 and spring 1990 for the seasonal investigation. Terrestrialization, which was observed within the same period in other braided former channels of that river, did not happen here despite the 1989 drought. However, a vegetation zone situated in the upstream part one channel seems to represent some successional trend, resulting in the establishment of Nasturtium officinale and the increasing abundance of Chara vulgaris. In disagreement with the tested hypothesis, only fluctuations are observed at the two temporal scales in the other vegetation zones. The amplitude of cyclic trajectories observed in the seasonal study depends of the degree of hydraulic disturbances (floods, drought) that affects each vegetation zone. The channel that is closer to the river is maintained at a steady state by the periodical inputs of kinetic energy during river overflows and fast floods; the disturbances wash away fine deposits and rejuvenate the vegetation mosaic. In the other former channel that is less disturbed by floods and is characterized by a thick layer of fine sediments, the groundwater inputs from numerous limnocrene springs carry away organic matter and slow down ecological successions.

Critical review of explanations for patterns of natural succession suggests a strong, common basis for theoretical understanding, but also suggests that several well known models are incomplete as explanations of succession. A universal, general cause for succession is unlikely, since numerous aspects of historical and environmental circumstances will impinge on the process in a unique manner. However, after disturbance, occupation of a site by any species causes changes in the conditions at the site. Sorting of species may result, since different species are adapted to different regions of environmental gradients. Such sorting can generate several patterns of species abundance in time, but commonly results in sequential replacements of species adapted to the varying conditions. This may be due to constraints on species' strategies, or life history traits, placed by the limited resources available to the organism. These constraints often result in inverse correlation between traits which confer success during early and late stages of succession. Facilitatory or inhibitory effects of species on each other are best understood in terms of these life history interactions, perhaps as restrictions on, or as moderation of, these processes. Strong support for the importance of correlations in life history traits stems from comparisons of simulated succession with and without these correlations. These simulations are reviewed in some detail, and followed by brief reviews of other prominent models for succession. Several aspects of the confusion and controversies in the successional literature are then discussed, with a view to a more optimistic synthesis and direction for successional ecology.

We evaluated effects of soil texture and disturbance size on the successional dynamics of a semiarid grassland dominated by the perennial bunchgrass, Bouteloua gracilis (H.B.K.) Lag. ex Griffiths. A spatially-explicit gap dynamics simulation model was used to evaluate recovery patterns. The model simulates establishment, growth, and mortality of individual plants on an array of small plots through time at an annual time step. Each simulated disturbance consisted of a grid of plots of the same soil texture interconnected by processes associated with dispersal of B. gracilis seeds. Soil texture was incorporated into the model as effects on seed germination, seedling establishment, and subsequent growth of B. gracilis. Five soil texture classes and five disturbance sizes were simulated. Soil texture was more important to recovery of B. gracilis than either size of a disturbance or location of plots within a disturbance. Constraints on recruitment of seedlings had a greater effect on recovery than constraints associated with plant growth. Fastest recovery occurred on soils with the largest silt content, the variable that affects seedling establishment. Disturbances with slowest recovery were on soils with low silt contents, and either high or low water-holding capacity, the variable that affects plant growth. Biomass and recovery decreased as disturbance size increased, and as distance from a disturbed plot to the edge of the disturbance increased. In most cases, important interactions between soil texture and disturbance size on recovery were not found.

Knowledge of the structure and dynamics of Central European virgin forests is very restricted and in many respects hypothetical. Analysis of the development of forest stands influenced by natural disturb ances (storm; snow avalanche) is considered to lead to new information about the natural processes involved in virgin (near-nature) forests within a relatively (!) short time span (which, in forests, still counts for decades). National Parks offer areas big enough for such studies, and they guarantee a study period of several decades (or more). This paper presents the first results of vegetation development following natural destruction of the tree layer

The effects of foliar- and root-feeding insects on the dynamics of an early successional plant community, representing the first four years of colonisation, were examined. Subterranean insect herbivores were found to increase in density with increasing successional age of the plant community. In early succession, chewing insects mainly Coleoptera (Scarabaeidae) and Diptera (Tipulidae) were dominant. This was in direct contrast to the foliar-feeding insects, which were dominated by sap-feeders (mainly Auchenorrhynchan Hemiptera).

We studied the seed dispersal spectra of 46 Iberian plant communities of five types: potential woodland, forest fringe, substitutional scrubland, nitrophile communities and montane communities. There were no significant differences between the spectra of communities of the same type from Mediterranean and Eurosiberian regions. Biotic dispersal is most common at mature stages of succession, and abiotic dispersal at immature stages.

(1) The influence of sheep grazing of moderate grazing (MG), heavy grazing (HG), inordinate grazing (IG), over grazing (OG), and extinct grazing (EG) on vegetation succession was studied in the Stipa baicalensis steppe during 1984–1986. (2) The relationships between the relative sum of dominance ratio (RSDR) and the degree of succession (DS) at all stages of grazing succession in the Stipa baicalensis steppe were revealed in terms of the method of mathematical analysis under five grazing intensities mentioned above. (3) The dynamic models of grazing succession that are based on accurate grazing intensities in relation to succession courses were constructed using RSDR5, and DS. The models may explain the rules of grazing succession in the Stipa baicalensis steppe.

This study documents the stem size and age-structure in forests dominated by different species of Nothofagus in Torres del Paine National Park (51° S), in the Chilean Patagonian region. We also explored the relationship between the various types of Nothofagus forest and postglacial succession. Pioneer stands on moraine fields 1–2 km of the glacier front are dominated by Nothofagus betuloides and Nothofagus antarctica. Moraines appear to be first colonized by the evergreen N. betuloides, followed within 5–7 years by deciduous N. antarctica. Nothofagus antarctica may replace the former species and develop monospecific stands on glacial valleys. Most trees in the N. antarctica stand studied were older than 40 years and floods may cause a significant mortality of young trees. Recruitment from seed seems to be infrequent. Old-growth stands dominated by deciduous Nothofagus pumilio occupy more stable substrates, and probably represent the last stage of postglacial succession. This long-lived tree species had recorded ages over 200 years. The canopy of N. pumilio forests appears to be a mosaic of even-aged, old-growth patches. We propose that regeneration episodes follow the blowdown of a large portion of the canopy, with long intervals with little or no regeneration. Windstorms may be an important force influencing the regeneration of N. pumilio. Exogenous disturbances, such as floods and windstorms, are an integral part of the forest cycle in the Patagonian region.

A series of coal mine spoils (5, 10, 12, 16 and 20-yr old) in a dry tropical environment was sampled to assess the changes with time in spoil characteristics, species composition and plant biomass. Coarse fragments (>2 mm) decreased with age of mine spoil while the proportion of 0.2–0.1 mm particles increased. Total soil N, mineral N, NaHCO3-extractable Pi, and exchangeable K increased with age of mine spoil and these parameters were lower in mine spoils than native forest soil even after 20 years of succession. Exchangeable Na decreased with age of mine spoil and in 20-yr old spoil it was higher than native forest soil. Plant community composition changed with age. Only a few species participated in community formation. Species richness increased with age, while evenness and species diversity declined from 5-yr old to 16-yr old community with an increase in the 20-yr old community. A reverse trend occurred for concentration of dominance. Area-weighted shoot and root biomass of other species increased with the age of the mine spoil while that of Xanthium strumarium patches declined with age. Data collected on spoil features, microbial C, N and P, and shoot and root biomass when subjected to Discriminant Analysis indicated a continued profound effect of age. 10 and 12-yr old mine spoils were closer to each other, and 5 and 20-yr old spoils were farthest apart.

Rangeland vegetation in the Great Basin of the United States is found in several seral stages depending upon gradients related to distance from water and grazing differences across fencelines. Detailed documentation of vegetation changes was attempted on a representative vegetation type in northern Nevada using a chronosequence approach. Frequency of occurrence appeared to be the vegetation attribute most clearly expressing an axis of change or differences across the site. Soil profile descriptions and soil analyses helped relate plant community changes to abiotic variation. Species, microtopography and soil surface characteristics varied with seral stage. Pattern analysis proved useful for relating vegetation changes to successional stages. Computer-based classification (TWINSPAN) and ordination (DECORANA) techniques defined a successional gradient that differed from a theoretical or assumed successional classification.

A synchronous study was carried out of plant succession in land abandoned after cultivation in the Camargue (southern France) in relation to the main biotic and abiotic environmental factors. Correlations between environmental factors and species abundance were established using Canonical correspondence analysis. The most strongly correlated variables were those of the water regime. Abandonment of cultivation does not always imply abandonment of management, but a change in land use. Water level management (flooding in winter, or in summer, irrigation) creates and maintains communities suitable for grazing. In the absence of water level management, the soils become saline and stable plant communities similar to those present under natural conditions quickly develop. The salt generally limits the installation of woody plants; only Phillyrea angustifolia can develop and then only when the water stable is quite deep. It appears that the forest stage can only be reached in the proximity of riverine gallery forest and irrigation canals where Populus alba is dominant.

Effects of spatial processes on temperate deciduous forest structure and dynamics were investigated with a spatial simulator derived from a forest gap model. The multi-species neighborhood model accounted for competitive interactions and endogenous disturbance in the form of small canopy gaps. Simulated and actual spatial pattern of old-growth stands were compared. The 400 yr simulations produced a pattern scale (0.07–0.2 ha patches) similar to that of an actual stand; simulated pattern intensity was greater than actual intensity, however. Distances to nearest neighbor were somewhat similar for trees in the simulated and actual stands; yet the frequency distributions of distance to nearest neighbor values differed substantially. The simulated stand patterns were generally less random than the actual patterns. Spatial pattern changed markedly during the course of simulated succession. Pattern approached a random dispersion in early succession. Intensity peaked at mid-succession (ca. 150 yr) with a hyperdispersed overstory and a strongly clumped understory. Pattern intensity diminished in late succession as a mixed size structure developed. Old-growth patch size was greater than the neighborhood (or gap) size, suggesting the gap-sized areas do not behave independently.

To determine whether soil disturbance by digging and burrowing mammals altered community structure and the rate of succession in a midsuccessional abandoned pasture, species richness, composition and relative abundance were monitored over a two year period both on and off artificially created earth mounds (100, 900, 8100 cm2). Mean species richness increased by up to two species per small mound (100 cm2) and by up to four species per large mound (8100 cm2). However, increased species richness was evident for less than two years. Initially, up to sixteen of the twenty species present occurred more often on earth mounds than off mounds, with two of these species found only on large mounds (8100 cm2). After two years, there was little or no significant difference in species composition and relative frequency on and off earth mounds. Experimental soil disturbance temporarily altered community structure simply by increasing space available for colonization since light, nutrient and water supply did not increase significantly on mounds. Soil disturbance can increase species richness and change species' relative frequency in disturbances as small as 100 cm2 but such changes were likely too small and short lived to alter permanently the structure and rate of succession in the abandoned pasture studied here.

In the low-lying parts of The Netherlands peat-cutting in the past resulted in many large and small lakes. The larger ones were often reclaimed and turned into arable land. In smaller ones a process of secondary succession led to the establishment of reed and sedge fens. Due to changes in the management many of the still existing fens have been left over to natural developments over the last decades. Here succession rapidly led to woodland communities. These woodlands are initially often dominated by Salix species, soon followed by Alnus glutinosa and Betula pubescens. In species composition these young woodlands are closely related to the Carici elongatae-Alnetum glutinosae. There are, however, considerable differences in species composition. This woodland type as found in the western parts of The Netherlands was also recognized in releves from Belgium, western Germany and Norfolk in the UK. As it also differs in ecological conditions from the brooks and rivulets accompanying forms of the Alnion glutinosae elsewhere in western Europe, it is here proposed to treat these communities as a separate community-type within the Alnion glutinosae.

A vegetation survey was carried out in the Ujung Kulon nature reserve (West Java, Indonesia). Particular attention was paid to the altitudinal zoning of the vegetation, to succession and to the applicability of the phytosociological approach in forests of the humid tropics. The altitudinal zoning provides a clear example of the telescope effect: low, isolated mountain complexes surrounded by sea reflect the vegetation zoning of higher mountains in a condensed, ‘telescoped’ way. The pattern of primary forests, secondary forests and rattan-dominated shrublands can be explained by the former shifting cultivation practice and the impact of ash rains following the notorious eruption of the nearby volcano Krakatau in 1883. The arguments against the phytosociological approach in the humid tropics are found to be invalid. The minimal area concept does not cause great problems if used in a practical sense and if plants of all age classes and all terrestrial growth forms are included in the releve.

The rich deciduous woodland at Loi, Luster, Inner Sogn, 61° 20′ N., was traditionally used for fodder production from both tree and field layer. After more than nearly 40 years of disuse and secondary forest succession, experimental efforts were made to restore the traditional agricultural ‘meadow woodland’. Following a detailed preliminary registration of the vegetation the following measures were taken: 1. The understory tree layer, mainly Alnus incana was removed. 2. The old Ulmus glabra pollards were pruned back to traditional shape, as were some tall shurbs of Corylus avellana. 3. The field layer was mown once or twice yearly.

Oak (Quercus petraea Liebl.) and larch (Larix decidua Mill.) forest plantations of the study area ‘Mlodzawy’ in Poland were analysed. Changes in the syntaxonomic composition and of Ellenberg's indices (light, continentality, moisture, reaction and nitrogen index) were determinated. The results obtained mostly conform to the assumption that the herb layer of both plantations becomes, gradually with tree growth, more similar to each other and to that of mature oak-hornbeam forests. Such statement is justified by: an increase in the share of species common to both plantation types, a significant increase in the number and cover of the Querco-Fagetea character-species, accompanied by a decrease in the number and cover of other character-species, a general decrease in the share of species with extreme climatic and edaphic requirements, accompanied by a gradual increase in the share of number and cover of species with average demands. From the studies it may be concluded that the developmental mechanisms w which determine the direction and trends of changes in the herb layer are mainly common to both plantation types, whereas tree stand species, in spite of different habit, ecological demands, and effect on soil properties, have only slight modification influence.

A.K. Cajander's forest site type classification system is based on definition of plant communities typical to certain climatical and edaphical site conditions, but the structure and composition of the tree stands in Finland are considered sensitive to random variation and are therefore not used as primary classification criteria. The system has often received criticism, usually that the effects of the tree stand and successional stage of the stand have been underestimated. Most of the present-day forest stands in Finland represent young successional stages and are subjected to intensive management. This should result in an additional difficulty in the application of the forest site types in the field.

Quercus ilex L. (holm oak) coppices, widespread around the Mediterranean basin, are probably the result of 5 000 years of prolonged human disturbance of the original Quercus pubescens Willd. (downy oak) forests. Since disturbance has almost ceased in recent years, a question arises as to the development of these coppices: will the Q. pubescens forests return, or will Q. ilex remain the dominant species? To investigate the phenomenon, we analyzed the first stages, i.e. germination of the two species in holm oak coppices. Our experiments show that both species germinated better in coppices than in clearings or clear-cuts. Moreover, Q. pubescens appears to be slightly favored above Q. ilex and it is suggested auto-allelopathy is involved, at least partially inhibiting the germination of Q. ilex.

In the temperate forests of southwestern Japan, the population density of woody plants in the community increases in the early stage of secondary succession, reaches a peak in the old oak-chestnut forest, and decreases towards the climax beech forest. The species richness and diversity of woody plants also show a trend similar to that of the population density. The canopy-tree population decreases in the course of the succession while the basal area increases, showing a self-thinning process. The species richness, diversity and population density of herbaceous plants are much influenced by the dominance of the bamboo, Sasa palmata. The life-history traits of trees, lower trees and shrubs are discussed in relation to their shoot system, reproductive pattern and successional processes.

Within a few years of field abandonment on the coastal dunes, a considerable number of species of trees and woody lianes of the climax evergreen forest enter the succession. At a relatively large-scale of analysis (a 100 m2 plot), there is no evidence of soil development during the early succession, with no accumulation of soil organic matter nor nutrients being detected. At this scale there is, therefore, little support for the facilitation model of succession. However, when smaller scales of analysis are employed (e.g. a plot equivalent to the canopy area of a sapling) a very different picture emerges; most recruitment of forest woody species occurs beneath saplings found in early succession. Nutrient concentrations were higher in soils under sapling canopies than in soils beyond sapling canopies. With increasing sapling size, an increasing number of seedlings of forest woody species were found and there is progressive soil amelioration. Thus, during the early succession, there is considerable small-scale patterning in soil development and recruitment. This pattern is largely established through bird dispersal, with the intensity of recruitment being dependent on the distance to seed sources.

Pinus taiwanensis is a widely distributed species in the southeastern China (Zhejiang, Anhui, Hubei, Human, Jiangxi, Fujian, Taiwan provinces) at an elevation of 700–2000 m. This pine is a pioneer in forest succession and is often used as a species for afforestation in this region at an elevation above 700 m. This study was carried out at Guanshanyuan, Zhejiang province, at a latitude of N 28° 18′, a longitude of E 119° 16′ and an altitude of 800–1502 m above sea level. On the basis of a census of all individuals of Pinus taiwanensis at different successional stages and various habitats, age structure, spatial pattern, density, biomass of population and their dynamics were described. Considering the population dynamics throughout the successional process, three phases could be recognized. Until about 9–10 years after Pinus taiwanensis invaded the stands, the density of population was increased by the recruitments along with increase of the mean tree weight and population biomass (phase I). Thereafter, the population was in full density state, the biomass of population and the mean tree weight increased exponentially, while the density was decreased drastically by the self-thinning and the invasion of other broad-leaved trees (phase II). The −3/2 power law of natural thinning was applicable to the populations in this phase. When the broad-leaved trees reached the canopy, although the mean tree weight increased slowly, the density and biomass of Pinus taiwanensis population decreased gradually (phase III) until the population senesced and retreated from the successional series completely. The population dynamics of Pinus taiwanensis during the successional process was in common with pioneer species in forest succession. At some special habitats such as rocky steep slopes and ridges, however, Pinus taiwanensis population could form such an edaphic climax community that the population density, biomass and the mean tree weight in phase III could be in a stable state for very long period.

The vertical growth ofLarix gmelini in the north of the Greater Khingan Mts., north-eastern China is very fast during the first 50 yr. ThoughPinus sylvestris var.mongolica shows a higher growth rate, it will be replaced by the larch population.Picea jezoensis is the most tolerant tree species and will replace all other trees.

The relationship between secondary succession, soil disturbance, and soil biological activity were studied on a sagebrush community (Artemisia tridentata) in the Piceance Basin of northwestern Colorado, U.S.A. Four levels of disturbance were imposed. I: the vegetation was mechanically removed and as much topsoil as possible was left; 2: the vegetation was mechanically removed and the topsoil scarified to a depth of 30 cm; 3: topsoil and subsoil were removed to a depth of 1 m, mixed and replaced; 4: topsoil and subsoil were removed to a depth of 2 m and replaced in a reverse order. Plant species composition, dehydrogenase and phosphatase enzymatic activity, mycorrhizae infection potentials, and percent organic matter were the variables measured. Treatment 4 drastically altered the pattern of vegetation succession. Treatments 2, 3, and 4 started with Salsola iberica as the dominant species but six years later, 3 and to lesser extent 2 changed in the direction of the species composition of 1, dominated by perennial grasses and perennial forbs. Treatment 4 developed a shrub dominated community. The rate of succession was not decreased by the increased levels of disturbance. Both dehydrogenase enzyme activity and mycorrhizae infection potential (MIP) increased with the change from Salsola iberica to a vegetation dominated by either perennial grasses and forbs or shrubs. The intensity of disturbance in 2, 3, and 4 reduced drastically dehydrogenase activity and MIP, but in six years they recovered to levels comparable to 1. Phosphatase enzyme activity and organic matter were unrelated to species composition but related to treatment and time elapsed. In both cases a significant decrease was observed throughout the six-year period.

The vegetation dynamics of heathlands in Brittany have been followed for three years in areas subject to fire in August 1976. The pre-fire vegetation had been analysed and mapped before its destruction. The structure of the community and the processes taking place in it (in terms of biomass, primary productivity, phenology, mineral nutrition and food value) had been examined. The redevelopment of the canopy was studied by the point-contact method along permanent line transects. This semi-quantitative study permits calculation of the relative frequency of each species and, from this, its cover. The growth form of each species and the stratification of the community are also indicated by this method. Permanent plots were also used to record changes in the vegetation, by means of a census of individuals and records of the development and growth strategy of each species. The plots were located in homogeneous areas, or on bare soil around seed parents in order to examine seed dispersal and seedling establishment. These two methods yielded detailed information on the nature of the secondary successions following fire in the heathlands of Brittany.

The Schoenus phytocoenoses of South and South-eastern Sweden have been sampled by 189 releves of standard areas (4 m2) and divided into clusters using the TABORD program on two homotoneity levels. Two Schoenus associations and five potential nuclei of associations, mainly Schoenus nigricans phytocoena, have been distinguished. The species have been divided into twelve groups on the basis of similarities in distribution amongst phytocoena and assumed environmental preferences. Acidophilous or indifferent species together with common mire species are characteristics of the Oxycoccus-Schoenus ferrugineus association, while basiphilous and wet-meadow species are typical of the Primula-Schoenus ferrugineus association and the Fissidens-Schoenus nigricans phytocoenon. The Primula-Schoenus ferrugineus association is characterized by species associated with Tofieldietalia and Eriophorion latifolii, while in the Oxycoccus-Schoenus ferrugineus association also Scheuchzerio-Caricetalia and Oxycocco-Sphagnetalia species play an important role. Another difference between the two associations is that hemicryptophytes and helomorphes dominate in the Primula-Schoenus ferrugineus association, while in the Oxycoccus-Schoenus ferrugineus association dwarf shrubs, hydrophytes and hydromorphes are rather common. The properties of the homotoneity and diversity indices used are compared and their compatibility is discussed.

This study is based on a phytosociological table and a matrix of species and morphological characters. The releves were taken along a transect in a Myrica faya-Erica arborea formation on Tenerife (Canary Islands). The analysis of the phytosociological table reveals a vegetational succession and a corresponding ecological gradient. The study of correlations between morphological and ecological data leads to the creation of groups of species with different combinations of characters, and to a discussion of the adaptive values of each character combination. The species of each group occupy similar niches.

During the last decades chalk grasslands lost their agricultural importance in the greater part of their distribution area in W Europe. Due to their botanical richness a number of chalk grassland sites were established as Nature Reserve. As a consequence of the semi-natural character of these grasslands an appropriate management is necessary to maintain or to re-create this vegetation including a great number of rare and endangered species.

The paper reports results of a long-term (1964–1974) investigation on permanent study sites in natural forest ecosystems of the Tilio-Carpinetum and the Pino-Quercetum in the Bialowieza Forest. The influence of decaying logs and root craters was investigated. It was found that the main causes of uprooting were the spring and autumn winds. Wind direction and the position of logs lying on the ground are correlated. Picea is most susceptible to uprooting by winds. Almost one half of the trees of this species are alive at the moment of uprooting. By mapping changes in the distribution of uprooted trees on a permanent area in time, a balance of the change over in a 10-year period was determined. It appeared that the decomposition is slower than accumulation. From this, it was concluded that the stand is in a phase of natural thinning. In the study site, compartments were disinguished with various degrees of change in the number of uprooted trees, and the consequences of differentiation and constant transformation of the biotope and biocenosis by the occurrence of uprooted trees and by their decay are described.

Canopy gap area/age distributions and growth mechanisms were examined in a virgin subalpine forest in the White Mountains, New Hampshire, USA. The gap area distribution was negative exponential in form. Whithin gap tree ages varied widely in response to stepwise gap expansion caused by windthrow of peripheral trees or death of standing mature Picea rubens at gap edges. As a consequence, the density of small gaps may have been underestimated and the density of large gaps overestimated. The estimates of canopy turnover time, 303 yr, and of patch birth rate on an area basis, 3.3×10-3 ha new patches/ha land area/yr, were not affected by the gap expansion phenomenon. However, any estimate of patch birth rate as numbers of new patches formed per year would have been too low. Because of increasingly widespread Picea death, the patch area/age distribution of this forest may not currently be in steady-state.

Masson Pine (Pinus massoniana Lamb.) is a pioneer in forest succession in the subtropics of East Asia. However, the species persits, though with decreasing abundance, throughout the various successional phases. Agestructure, spatial pattern, density, population biomass, and their dynamics are described for a population in Sichuan, China, on the basis of a census of all individuals in the population while substituting space with time. In the course of succession, the population density increases and its rate of growth decreases until self-thinning starts; during the phase of self-thinning density decrease and continues to decrease even afterwards, but the rate of growth increase markedly after self-thinning has stopped. The development of population biomass (Bp) during the early succession from shrub-grassland to the early stages of mixed pine and broad-leaved forest can be described by a logistic equation. Later, Bp decrease rapidly. These changes are governed partly by inherent biological features of P. massoniana and partly by the invasion, establishment and development of shade-tolerant evergreen broad-leaved trees. Both self- and alien-thinning occur. Soil conditions affect the rates of these processes.

Dispersal of ornithochorous seeds from isolated forests in the phosphate mining region of central Florida, U.S.A., were studied for two seasons (July to November) to determine patterns of dispersal. Three separate studies included (1) dispersal directly from forest edges to early successional herbs; (2) standardized perches (2 m high post with a crossbeam); and (3) snags (dead trees, 11.3±2.8 m high, 21.4±23.3 stem branches). Perch availability was more important than distance in predicting seed types and quantities of bird-dispersed seeds. The greatest concentration of bird-dispersed seeds were found under standard perches (255±249 seeds/m2/fall) followed by snags (147±85 seeds/m2/fall) and early successional vegetation (3.0±4.1 seeds/m2/fall). Seed quantities dispersed to snags were positively correlated with the number of stem branches on snags. Seeds beneath standard perches were significantly lighter and less diverse than those found beneath snags. This difference is attributed to the larger percentage of forest or later successional species found beneath snags (73%) as compared to the standard perches (15%). Perches and vegetative structural development should facilitate ecological succession by increasing the quantity, quality and diversity of seed deposition.