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Land abandonment is increasing in recent decades in Europe, usually accompanied by a decline in biodiversity. Whether livestock grazing and mowing can safeguard biodiversity across spatial scales in the long term is unclear.Using a 48-year experiment in a salt marsh, we compared land abandonment (without grazing and mowing) and seven management regimes including cattle grazing, early season mowing, late season mowing, both early and late season mowing, and grazing plus each of the mowing regimes on plant diversity at the local (i.e. plot) and landscape scales (i.e. across plots). Also, we compared their effects on community composition (both in identities and abundances) in time and space.Under land abandonment, plant diversity declined in the local communities and this decline became more apparent at the landscape scale, particularly for graminoids and halophytes. All management regimes, except the late season mowing, maintained plant diversity at these scales.Local plant communities under all treatments underwent different successional trajectories, in the end, diverged from their initial state except for that under grazing (a cyclic succession). Interannual composition change remained stable over time under land abandonment and grazing plus early season mowing. It increased over time under grazing and late season mowing, it increased in the second half of the experiment under other treatments. Vegetation homogenized in the landscape over time under land abandonment while vegetation was heterogeneous under all management regimes.Synthesis. Our experiment suggests that late season mowing may not be sustainable to conserve plant diversity in salt marshes. Other management regimes can maintain plant diversity across scales and vegetation heterogeneity in the landscape in the long term, but local community composition may change over time.

Small lakes and ponds occupy an enormous surface area of inland freshwater and represent an important terrestrial–water interface. Disturbances caused by extreme weather events can have substantial effects on these ecosystems. Here, we analysed the dynamics of nutrients and the entire plankton community in two flood events and afterwards, when quasi-stable conditions were established, to investigate the effect of such disturbances on a small forest pond. We show that floodings result in repeated washout of resident organisms and hundredfold increases in nutrient load. Despite this, the microbial community recovers to a predisturbance state within two weeks of flooding through four well-defined succession phases. Reassembly of phytoplankton and especially zooplankton takes up to two times longer and features repetitive and adaptive patterns. Release of dissolved nutrients from the pond is associated with inflow rates and community recovery, and returns to predisturbance levels before microbial compositions recover. Our findings shed light on the mechanisms underlying functional resilience of small waterbodies and are relevant to global change-induced increases in weather extremes. Resilience of freshwater microbial communities to flooding is revealed by high-resolution in situ sampling experiments in a forest pond during two extreme rain events.

The paper describes the analysis of long-term fluctuations of aquatic communities (phytoplankton, macrophytes, zooplankton, zoobenthos, fishes) influenced by abiotic factors (water level, salinity) in model lakes of the Onon-Torey plain in Russia. The cyclic succession series are elucidated. These series may provide a basis for monitoring and forecasting the state of the ecosystem for the researched lakes and for other similar lakes in Central Asia.

Highly abundant, small waterbodies contribute substantially to global freshwater shoreline and surface area. They are strongly interlinked with the terrestrial surrounding, thus controlling the flow of energy, nutrients and organisms through the landscape. Disturbance events can have severe consequences for these ecosystems and the entire downstream freshwater network and require more attention in the context of global change-induced increases in weather extremes. Here we show that extreme rain events (floods) cause cyclic successions in microbial communities and the planktonic food web of a small forest pond. We analyzed the dynamics of nutrients and the entire plankton community during two flood events and subsequent quasi-stable conditions. Floods induced a repeated washout of resident organisms and hundred-fold increases in nutrient load. However, within two weeks, the microbial community recovered to a pre-disturbance state through four well-defined succession phases. Reassembly of phyto- and especially zooplankton took considerably longer and displayed both repetitive and adaptive patterns. Release of dissolved nutrients from the pond was associated with inflow rates and state of community recovery, and it returned to pre-disturbance levels earlier than microbial composition. Our study exemplifies extraordinary compositional and functional resilience of small waterbodies and presents the detailed mechanism of the underlying processes.

Classical old‐field succession studies focused on vegetation changes after the abandonment of annual croplands or on succession after the elimination of cultivated crops. Perennial‐crop‐mediated succession, where fields are initially covered by perennial crops, reveals alternative aspects of old‐field succession theories. We tested the validity of classical theories of old‐field succession for perennial‐crop‐mediated succession. We formulated the following hypotheses: (1) functional diversity increases with increasing field age; (2) resource acquisition versus conservation trade‐off shifts toward conservation at community level during the succession; (3) the importance of spatial and temporal seed dispersal decreases during the succession; and (4) competitiveness and stress‐tolerance increases and ruderality decreases at community level during the succession. We studied functional diversity, trait distributions and plant strategies in differently aged old‐fields using chronosequence method. We found increasing functional richness and functional divergence, but also unchanged or decreasing functional evenness. We detected a shift from resource acquisition to resource conservation strategy of communities during the succession. The role of spatial and temporal seed dispersal was found to be important not only at the initial but also at latter successional stages. We found an increasing stress‐tolerance and a decreasing ruderality during succession, while the competitiveness remained unchanged at the community level. Despite the markedly different starting conditions, we found that classical and perennial‐crop‐mediated old‐field successions have some similarities regarding the changes of functional diversity, resource acquisition versus conservation trade‐off, and seed dispersal strategies. However, we revealed also the subsequent differences. The competitive character of communities remained stable during the succession; hence, the initial stages of perennial‐crop‐mediated succession can be similar to the middle stages of classical old‐field succession. Moreover, the occupied functional niche space and differentiation were larger in the older stages, but resources were not effectively utilized within this space, suggesting that the stabilization of the vegetation requires more time.

The cyclic succession of brown coals in the Latrobe Valley, Gippsland Basin, Australia, records an exceptional floral and charcoal record from the Late Oligocene to Middle Miocene. New palynological, geological and charcoal data are consistent with existing colourimetry, carbon isotope, and organic geochemical and palaeobotanical data, indicating that the repeated lithotype cycles represent relative drying (terrestrialization). Based on this detailed palynological study, the vegetation succession within the Latrobe Valley peatlands is interpreted to have begun with a fire-prone emergent marsh of bulrushes (Typhaceae), which grades landward into a fire-prone meadow marsh of rushes (Restionaceae), heaths (Ericaceae) and coral-ferns (Gleicheniaceae). This marsh environment then developed into a forested bog, with gymnosperms (e.g. the Podocarpaceae Dacrycarpus and Dacrydium ) as the dominant trees, until an ombrogenous forest bog developed, predominantly consisting of angiosperms (e.g. Nothofagus , Quintinia ). The similarity between vegetation successions in New Zealand and the lightening-upwards cycles from the Latrobe Valley coals suggests that New Zealand's modern vegetation communities represent a floral analogue for the successions preserved in the Latrobe Valley coals. High abundances of micro and macro charcoal recorded in the darker lithotypes, within the lithotype cycles of the M1B and M2A seams, suggest that the Latrobe Valley peatlands were subject to repeated fires during the Late Oligocene to Early Miocene.

Advanced knowledge of forest disturbance regimes (the temporal and spatial patterns of periodic disturbances) has key relevance to implementation of effective managements for forest communities. For many forest ecosystems such knowledge is inadequate or is lacking. Spatially explicit simulations, testing effects of alternative disturbance regimes on fine-scale spatial genetic structure (FSGS) may provide information on key components of forest disturbance regimes. Here, we compare FSGSs assessed using 18 microsatellite markers with spatially explicit simulations, to characterise a natural disturbance regime in a European temperate swamp forest dominated by Alnus glutinosa. Individual-based population genetic simulations were carried out for three previously introduced models of disturbance regime, to determine which best fits the FSGS assessed by the kinship coefficient in a natural old-growth forest. We hypothesised a low proportion of trees removed (the gap dynamic model) accentuates high-relatedness among individuals over short distances (i.e. it accentuates FSGS), while a high proportion of trees eliminated by a disturbance (the cyclic succession model and the stand-replacing dynamic model) leads either to random FSGS (i.e. a point pattern of genotypes that cannot be differentiated from a complete spatial randomness) or a high spatial clustering of genotypes. Spatial genetic analyses found significant positive autocorrelations of genotypes at

Secondary succession on arable fields is a popular system for studying processes influencing community assembly of plants. During early succession, the arrival and establishment of those propagules that can pass the environmental filters operating at a given site should be among the dominant processes leading to an initial increase in species richness. With ongoing succession, environmental filtering should decrease in relative importance compared to competitive interactions, which then should decrease species richness. Thereby, the phylogenetic structure of communities should change from random or clustered patterns during early succession to overdispersion. Disturbance is supposed to act as an additional filter, causing communities to be phylogenetically clustered. By analysing the species richness and phylogenetic structure of secondary succession in two different regions in Germany with three different disturbance levels each, we tested this general model. Although in one of the regions (Gimritz) we found the expected trajectory of species richness, phylogenetic structure did not follow the expected trend from random or clustered towards overdispersed communities. In the other region (Bayreuth), species richness did not follow the expected trajectory and phylogenetic structure remained clustered over the course of succession. A preliminary analysis of autecological characteristics of the species involved (Ellenberg indicator values) nevertheless showed clear contrasting trends. The idiosyncrasies of successional trajectories across sites might be due to the environmental context, the regional species pool as well as the legacy of former land use reflected in the seed bank.

Ecological theory suggests that coexistence of many species within communities requires negative frequency-dependent feedbacks to prevent exclusion of the least fit species. For plant communities, empirical evidence of negative frequency dependence driving species coexistence and diversity patterns is rapidly accumulating, but connecting these findings to theory has been difficult as corresponding theoretical frameworks only consider small numbers of species. Here, we show how frequency-dependent feedback constrains community coexistence, regardless of the number of species and inherent fitness inequalities between them. Any interaction network can be characterized by a single community interaction coefficient, IC, which determines whether community-level feedback is positive or negative. Negative feedback is a necessary (but not sufficient) condition for persistence of the entire community. Even in cases where the coexistence equilibrium state cannot recover from perturbations, IC

Movile Cave harbors a completely isolated groundwater ecosystem. Although it lacks any input of photoautotrophically based food, it is inhabited by a rich invertebrate community. Chemoautotrophic microbial mats float at the surface of the thermomineral cave water, which is rich in sulfide and methane. The mats are mainly inhabited by dense populations of five bacterivorous nematode species and one predacious copepod species. As extensive investigations of these mats are hampered by the fragility and isolation of this ecosystem, we developed a model system allowing long-term studies of their meiofaunal communities. Using the original cave water (same aquifer), we carried out experiments in a laboratory basin that allowed us to simulate the labile oxic and sulfidic conditions of Movile Cave. A few weeks after the start of the experiment, floating microbial mats developed within hypoxic enclosures and were quickly colonized by highly adapted organisms, including a meiofaunal community dominated by five nematode species (Poikilolaimus sp., Monhystrella sp., Panagrolaimus c.f. thienemanni, Udonchus tenuicaudatus, and Chronogaster troglodytes). The faunal composition of samples from the original mat material was identical. In the laboratory, peak densities of 193.2 nematodes cm−2 were reached after three months. By monitoring the nematode community structure over one year, we observed a sequential shift in the relative importance of the nematode taxa, in which those that were fast growing and r-selected (P. c.f. thienemanni, Poikilolaimus sp.) were gradually displaced by more K-selected species (C. troglodytes, U. tenuicaudatus). Similar oscillations were determined in samples of native mat material, apparently reflecting a cyclic succession characterized by decreasing microbial food availability.

Aim: We studied the legacy effects of shrubs during the downgrade phase of high–cover patches. Specifically, are woody species able to modify environmental attributes at patch level to such an extent as to alter the colonization once they have vacated their original position? Methods: We monitored five environmental variables along an experimental four-stage downgrading gradient of high–cover patches during two years in cold- and warm-seasons, individual plant growth during three years, as well as the floristic composition of patches along the same gradient after 13 years. Results: The downgrade of high–cover patches reduces the aboveground protection due to the increase in wind speed (400–500%) and evaporation rate (43–160%) associated with shrub death and senescence. In addition, high–cover patches increase the total soil nitrogen (400–600%) and reduce the infiltration rate (44–73%) on the top layer. Leaf length and flower culms of grass tussocks were lower in bare soil patches (7.5 cm and 3) compared to whatever degradation stage of high–cover patches (9–10 cm and 18–32). Floristic composition after 13 years reveals that grass species occupied the patch stages differentially, with a disjunctive pattern among species within the Poa and Pappostipa genus. Conclusions: Legacy effects prompted by shrubs through changes in soil properties at the horizontal plane can conditioned the patch dynamics. The ability of different plant species to cope with the spatial heterogeneity at the horizontal plane should be included as a new criterion to define plant strategies from arid ecosystems according to the gap–phase dynamics and mosaic maintenance. Fil: Cipriotti, Pablo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; Argentina Fil: Aguiar, Martin Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Ecología; Argentina

Eugene Odum’s 1969 paper, The Strategy of Ecosystem Development, marks a watershed moment in approaches to the study of succession, ecosystem change caused by discrete disturbances. He argued that succession is unique from other kinds of change with regard to mechanisms (modification of the physical environment by the community), trajectory (orderly, directional and predictable), and endpoint (a stable climax ecosystem in which “maximum biomass and symbiotic function between organisms are maintained per unit energy flow”). Odum also argued that understanding successional change was central to the management of a great variety of environmental challenges. Given the important role of disturbance in these ecosystems, this is particularly true for management aimed at restoration and conservation of forests. Although there was considerable debate among ecologists regarding successional mechanisms, trajectories and endpoints in the decades preceding his exegesis, the views outlined by Odum generally prevailed. These significantly influenced answers to three central restoration and conservation questions during that era. (1) What should we restore and conserve? Climax ecosystems. (2) How should boundaries be set for restoration and conservation areas? This was not an important matter. (3) How should restoration and conservation be accomplished? Because succession would inexorably lead to the ultimate climax goal, forest ecosystems should be protected from disturbance. Over the past five decades, virtually every aspect of succession theory as presented by Odum (1969) has come into question. We now understand that there is no single unique or unifying mechanism for successional change, that successional trajectories are highly varied and rarely deterministic, and that succession has no specific endpoint. Answers to the three restoration and conservation questions have changed accordingly. (1) Restoration and conservation goals should include the full range of variation in species diversity and composition associated with disturbance and the succession that proceeds from it. (2) Pattern, scale and context influence patterns of both disturbance and succession, and preserve design really does matter. (3) Restoration and conservation practice must be tailored to the unique mechanisms and post-disturbance ecological legacies that determine the trajectory and tempo of successional change in each particular ecosystem. The search for a grand unified theory of succession apart from other kinds of ecosystem change is futile. Nevertheless, the change caused by discrete disturbances remains an important matter for concern for restoration and conservation practitioners.

Questions What are the interactive effects of succession time, disturbance and productivity on the fine-scale species richness of beach vegetation? How do these effects differ between functional groups that are known to represent different adaptive strategies? Location Boreal beach and dune systems (ca. 60°–65° N) of the Baltic Sea coast in Finland, characterized by steep environmental gradients, post-glacial land uplift and resulting primary succession. Methods The analysis was based on an extensive and systematic survey of vascular plant, bryophyte and lichen species and environmental factors. Total species richness and the species richness of seven functional groups were modelled as functions of succession time, disturbance, productivity and their statistical interactions. The effects of the local environmental variability were taken into account by applying generalized linear mixed models (GLMM). Results All three environmental factors and their statistical interactions, including the three-way interaction, were highly significant in explaining total species richness. The effect of disturbance on total species richness changed from negative to positive along succession time and productivity gradients. The response of beach specialist richness to succession time and disturbance was unimodal, while the responses of the generalist functional groups were monotonic. Beach specialist richness showed a strong positive response to productivity, whereas the richness of the generalist groups was not related to changes in productivity. Conclusions The patterns of species richness on uplifting beaches are determined by the interplay of primary succession, disturbance and productivity. When both succession time and productivity increase, competitive exclusion starts to limit total species richness. In these circumstances, disturbance favours diversity by creating gaps in the vegetation. A combination of long succession time, low disturbance and low productivity result in maximum species richness. The richness of functional groups, particularly the opportunistic and disturbance-tolerant beach specialist group and the competitive but disturbance-sensitive groups, reach their peak in divergent environmental conditions. Consequently, the complex richness patterns observed on uplifting beaches are created not only by strongly interacting environmental drivers but also by differences in species' adaptive strategies.

Question Can the co-existence of the cactus and the shrub in the community be driven by a cyclic succession mechanism? Location Mapimi Biosphere Reserve (southern Chihuahuan Desert). The vegetation is scrub, dominated by Larrea tridentata. Methods Interspecific spatial association between adult L. tridentata and differently sized Cylindropuntia leptocaulis plants was analysed using Ripley′s K function, exploring the hypothesis that facilitation causes differential recruitment of cactus below the shrub and a subsequent interspecific association, the intensity of which declines with the cactus size due to competitive elimination of the shrub. Competition for water among adult plants was investigated by irrigating solitary and associated plants of both species. The proportion of vigorous (measured by the percentage of dead branches) and dead L. tridentata plants associated with adult cacti was compared to that of solitary L. tridentata plants, testing the hypothesis that competition among associated adults reduces the vigour and increases the proportion of dead shrubs, relative to that of solitary plants. Results In 14 out of 16 spatial analyses (four cactus sizes in four plots), C. leptocaulis was found to clump around the L. tridentata adults. Larrea tridentata suffered the effects of interspecific competition for water, but these diminished with increased water provision. In contrast, C. leptocaulis was unaffected by interspecific competition for water. The proportion of vigorous shrubs was higher in solitary than in associated individuals; however, the proportion of dead shrubs was lower in associated than in solitary individuals. Conclusion The irrigation experiment and the proportion of dead branches suggest interspecific competition. However, spatial association of the shrubs with every cactus size and the proportion of dead shrubs associated with the cacti both suggest that replacement of the shrub by the cactus is an infrequent event. Cyclic succession therefore appears to be the exception rather than the rule, and does not account for the co-existence of the species in the community. The possible scenarios in which cyclic succession may occur are discussed.

The influence of animal-mediated processes on the purported cyclical succession model of vegetation dynamics in arid subtropical thicket of southern South Africa was examined. We used spatially explicit sampling methods to evaluate the influence of dispersal and decomposition on plant community structure. The harvester ant Messor capensis was the only ant species recorded harvesting Portulacaria afra fruit and the elaiosome bearing seed of the tree Gymnosporia polyacantha from experimental piles. Propagules were dispersed to nest mounds positioned beneath woody shrubs. Vertebrates dispersed fleshy-fruited tree species to regeneration sites beneath P. afra clumps. The minute seeds of succulent shrubs were secondarily dispersed from beneath shrubs to ant nest sites located in the open. The results from two experiments indicate that soil nutrients and decomposition activity are spatially localised. The rate of below-ground decomposition, and the incidence of an invertebrate detritivore assemblage, was high beneath P. afra clumps compared with exposed nutrient-enriched and grassy sites. Animal dispersal vectors are integral to the regeneration of major plant groups in arid subtropical thicket by moving seeds from competitively harsh environments to safe sites beneath nurse plants. Decomposition and nutrient release are localised beneath P. afra clumps due to the unique conditions that support a suite of detritivore taxa recorded nowhere else at the study site.

The studies on populations in the course of forest succession in abandoned meadows (15 ha) were conducted for 15 years (1974-1988). It was found that the population size of species which took part in the successional process either changed directionally, i.e. developmental phases of populations conformed to the succession stages, or fluctuated, when no direct relationship between both was determined. Three types of population dynamics were distinguished: 1) developmental cycle (increase, decrease and equilibrium in population size) lasted as long as forest comeback; 2) developmental cycle accompanied one successional phase; 3) species appeared in cycles, as a series of populations in the course of long-term succession. Following species groups were distinguished regarding their role in the vegetation transformation in unmown meadows: 1) long-term promotors, present throughout succession and affecting both, changes in meadow vegetation, and initiation of tall-herb and brushwood communities; 2) short-term promotors, present in the first successional phases, especially at the stage of transformation of meadow phytocoenoses; 3) stenoecious promotors, confined to various depressions, periodically or permanently overlogged. All succession promotors were characterized by: high fecundity, ability to form polycormones and clones, strong and long-lived underground organs, modification of lifecycles, dual reproductive mode.

Geometric patterning in vegetation is often the result of cyclic succession, although circular forms sometimes result from the clonal growth of individual plants. We investigated whether cyclic succession or clonal growth created patterns in Poa subalpine grassland with rush (Empodisma minus) circles on the Central Plateau of Tasmania, Australia. We mapped change in the number, size and reflectance of the rush circles from 1953 to 2011 using aerial photographs, tested whether the circles occurred in distinct microenvironments, and whether the circles were likely to be individuals and determined whether the smallest circles were associated with disturbance. The number and area of circles increased with time. As circles became larger they became more reflective, evenly across their extent. The circles were associated with flatter patches in the plain. Surface soil characteristics did not differ between an exemplar circle and adjacent grassland. The Empodisma foliage in each circle tended to have colour consistently distinct from that of other circles in its vicinity, indicating that the circular form was a product of vegetative expansion of a single individual at a much more rapid velocity than the expansion of woody plant rings. The smaller circles were sometimes associated with frost-damaged Astelia alpina mounds, although far from confined to them. We did not find any instances of Empodisma circles

Succession is one of the most studied processes in ecology and succession theory provides strong predictability. However, few attempts have been made to influence the course of succession thereby testing the hypothesis that the passage of one stage is essential to enter a next one. At each stage of succession ecosystem processes may be affected by the diversity of species present, but there is little empirical evidence showing that plant species diversity may affect succession. The main objective in the present study is to test if there is any effect of plant species diversity on the functioning of artificially-created grassland communities. We were mostly interested in how successful is the sowing of meadow species into newly abandoned land and how long do the effect of initial sowing persist, how is affected the set of natural colonizers, which includes both the weed species and also the later successional species arriving naturally into the zone. One of the main questions concerning succession is to which extent the trajectory may be predictable or not. What will be the consequence of the different succession pathways for ecosystem processes, such as productivity and resource utilization, as well as species composition of both above and belowground communities? What will be the subsequent effects of feed back to vegetation development through initial manipulation of vegetation after land abandonment? And, finally, how general may results be when obtained in specific conditions? Our hypothesis is that an increase in the initial plant species diversity at the start of secondary succession enhances the amount of biomass produced and consequently stimulates the soil microbial biomass and the abundance of soil invertebrates. It has been suggested that changes in plant species diversity affect several ecosystem processes, such as primary productivity, nutrient retention and vegetation dynamics. A positive impact of species diversity on plant productivity has been explained by the complementarity of resource use among plant species or their functional groups.

Questions Do long-term observations in permanent plots confirm the conceptual model of Metrosideros polymorpha cohort dynamics as postulated in 1987? Do regeneration patterns occur independently of substrate age, i.e. of direct volcanic disturbance impact? Location The windward mountain slopes of the younger Mauna Loa and the older Mauna Kea volcanoes (island of Hawaii, USA). Methods After widespread forest decline (dieback), permanent plots were established in 1976 in 13 dieback and 13 non-dieback patches to monitor the population structure of M. polymorpha at ca. 5-yr intervals. Within each plot of 20 × 20 m, all trees with DBH >2.5 cm were individually tagged, measured and tree vigour assessed; regeneration was quantified in 16 systematically placed subplots of 3 × 5 m. Data collected in the subplots included the total number of M. polymorpha seedlings and saplings (five stem height classes). Here we analyse monitoring data from six time steps from 1976 to 2003 using repeated measures ANOVA to test specific predictions derived from the 1987 conceptual model. Results Regeneration was significantly different between dieback and non-dieback plots. In dieback plots, the collapse in the 1970s was followed by a ‘sapling wave’ that by 2003 led to new cohort stands of M. polymorpha. In non-dieback stands, seedling emergence did not result in sapling waves over the same period. Instead, a ‘sapling gap’ (i.e. very few or no M. polymorpha saplings) prevailed as typical for mature stands. Canopy dieback in 1976, degree of recovery by 2003 and the number of living trees in 2003 were unrelated to substrate age. Conclusions Population development of M. polymorpha supports the cohort dynamics model, which predicts rebuilding of the forest with the same canopy species after dieback. The lack of association with substrate age suggests that the long-term maintenance of cohort structure in M. polymorpha does not depend on volcanic disturbance but may be related to other environmental mechanisms, such as climate anomalies.

Current theories about vegetation succession and food web assembly are poorly compatible, as food webs are generally viewed to be static, and succession is usually analyzed without the inclusion of higher trophic levels. In this study we present results from a detailed analysis of ecosystem assembly rules over a chronosequence of 100 years of salt marsh succession. First, using 13 yearlong observations on vegetation and soil parameters in different successional stages, we show that the space-for-time substitution is valid for this chronosequence. We then quantify biomass changes for all dominant invertebrate and vertebrate species across all main trophic groups of plants and animals. All invertebrate and vertebrate species were assigned to a trophic group according to feeding preference, and changes in trophic group abundance were quantified for seven different successional stages of the ecosystem. We found changes from a marine-fueled, decomposer-based (brown) food web in early stages to a more terrestrial, plant-based, herbivore-driven (green) food web in intermediate succession stages, and finally to a decomposer-based, terrestrial-driven food web in the latest stages. These changes were accompanied not only by an increase in live plant biomass and a leveling toward late succession but also by a constant increase in the amount of dead plant biomass over succession. Our results show that the structure and dynamics of salt marsh food webs cannot be understood except in light of vegetation succession, and vice versa. © 2012 by the Ecological Society of America.

Deterministic and stochastic processes jointly determine the community dynamics of forest succession. However, it has been widely held in previous studies that deterministic processes dominate forest succession. Furthermore, inference of mechanisms for community assembly may be misleading if based on a single axis of diversity alone. In this study, we evaluated the relative roles of deterministic and stochastic processes along a disturbance gradient by integrating species, functional, and phylogenetic beta diversity in a subtropical forest chronosequence in Southeastern China. We found a general pattern of increasing species turnover, but little-to-no change in phylogenetic and functional turnover over succession at two spatial scales. Meanwhile, the phylogenetic and functional beta diversity were not significantly different from random expectation. This result suggested a dominance of stochastic assembly, contrary to the general expectation that deterministic processes dominate forest succession. On the other hand, we found significant interactions of environment and disturbance and limited evidence for significant deviations of phylogenetic or functional turnover from random expectations for different size classes. This result provided weak evidence of deterministic processes over succession. Stochastic assembly of forest succession suggests that post-disturbance restoration may be largely unpredictable and difficult to control in subtropical forests.

The determination of past successional stages, as well as the factors triggering succession, is crucial for the understanding of forest dynamics and the design of current and future management and conservation strategies. Shifts between successional stages can take decades or even centuries to occur because of tree longevity; therefore palaeoecological studies are important tools for their study. The present research involved the palaeoreconstruction of a transitional forest dominated by Pinus-Carpinus-Quercus in west-central Mexico over the last ~1230 years. The proxies employed include fossil pollen, microscopic fossil charcoal, magnetic susceptibility and organic matter content evaluated by multivariate techniques. The findings reveal that an initial cloud forest stage developed from 1230 to 1050 cal. yr BP. This stage was then interrupted for ~400 years (1050–690 cal. yr BP) when a regional climate change event decreased the number of cloud forest taxa and increased herbaceous taxa including Asteraceae, Poaceae, Plantago and Zea. The cloud forest stage recovered at 690 cal. yr BP and the community has persisted to the present time, yet this stage is dominated by human-induced taxa such as Pinus and Acacia. Whilst the dynamics of individual taxa were related to forest fires and soil erosion, changes between community types were related to an interval of regional climate change (greater aridity) that occurred between 1050 and 690 cal. yr BP. Results from this study indicate that, in order to preserve the cloud forest stage, human disturbances such as logging and agriculture should be excluded; a conservation strategy established in the transitional forest in recent years.

Whether plant communities in a given region converge towards a particular stable state during succession has long been debated, but rarely tested at a sufficiently long time scale. By analysing a 50-year continuous study of post-agricultural secondary succession in New Jersey, USA, we show that the extent of community convergence varies with the spatial scale and species abundance classes. At the larger field scale, abundance-based dissimilarities among communities decreased over time, indicating convergence of dominant species, whereas incidence-based dissimilarities showed little temporal tend, indicating no sign of convergence. In contrast, plots within each field diverged in both species composition and abundance. Abundance-based successional rates decreased over time, whereas rare species and herbaceous plants showed little change in temporal turnover rates. Initial abandonment conditions only influenced community structure early in succession. Overall, our findings provide strong evidence for scale and abundance dependence of stochastic and deterministic processes over old-field succession.

The development of a community through time, or succession, is generally described as the orderly replacement of species until a deterministic, stable endpoint is reached. However, stochastic factors, coupled with intrinsic biotic factors, such as herbivory or predation, can cause communities within the same habitat to become highly dissimilar in composition. Much research on the succession of terrestrial systems has been conducted, but factors influencing the succession of a terrestrial system may not apply to aquatic systems. To determine whether succession in an aquatic system is deterministic or dominated by contingency of stochastic factors, and the role that higher trophic level interactions and resources have in shaping successional patterns, I followed community development and dynamics of the intermediate and bottom trophic level (protozoans and bacteria) in the model Sarracenia purpurea pitcher plant system throughout an entire growing season. By comparing these dynamics across pitcher plant leaves within the same bog, I was able to determine whether there is a predictable pattern for community assembly in this aquatic community. The results from this study suggest that rather than a sequential replacement of early colonizers with more competitive species through time, competitively superior species establish in newly formed communities simultaneously with less competitive species, which coexist throughout the growing season. Community assembly in this system can also be altered by stochastic events. Resources and predators had a variable effect on the patterns of community change observed during succession. Patterns of community assembly were also dependent on the trophic level examined but, for the bottom trophic level, not on the sampling method used.

Background: Twelve distinct explanations have been proposed for the co-existence of species in ecological communities. Types of mechanism: The mechanisms can be divided into those that are stabilizing, i.e. with an increase-when-rare mechanism, and those that are equalizing, the latter on their own only delaying the exclusion of species. However, by evening out fitness, equalizing mechanisms can facilitate the operation of stabilizing mechanisms. Importance: It is suggested that circular interference networks, co-evolution of similar interference ability, cyclic succession, equal chance (neutrality) and initial patch composition are likely to be unimportant, or perhaps not even occur. Equal chance is an equalizing mechanism. Allogenic disturbance, alpha-niche differentiation, environmental fluctuation (relative non-linearity and/or the storage effect) and pest pressure are probably important. All four are stabilizing. More evidence is needed on aggregation, interference/dispersal trade-offs and the spatial mass effect. Aggregation and the spatial mass effect are equalizing. Suggestions are made of the evidence needed to make informed judgements on which contribute the most to co-existence in plant communities.

It is generally hypothesized that forest dieback is a characteristic of alder swamp forests (alder carrs, Alnion glutinosae alliance). Different internal and external factors may trigger this process, including human disturbance, changes in river discharge, unusually severe and prolonged flooding, terminal age of an even-aged alder forest (ca. 100&ndash, 150 years) and others. Although forest dieback in this type of forest may cause major changes in environmental conditions, the influence of this change on the floristic composition has not been well recognized. The study aimed to detect any possible changes in floristic variation in alder swamp forest following forest dieback. Vegetation plots in alder swamp forests affected by forest dieback were resurveyed 20 years after a previous study. PERMANOVA was used to test the significance of the compositional change and nonmetric multidimensional scaling (NMDS) with passively fitted means of the Ellenberg&rsquo, s Indicator Values were used to interpret its ecological meaning. In addition, different structural and diversity indices were compared, including species richness, percentage cover of vegetation layers, Shannon and Simpson diversity and evenness. Finally, we analyzed changes in the frequency of vascular plant species using Chi square tests. We recorded clear and significant compositional changes following alder swamp forest dieback. This change was most related to the gradient of moisture, followed by the gradients of light and temperature. The analysis of the individual species showed that the species of hummocks declined, while the species of hollows increased. Moreover, the current communities are dominated by some hydrophytes that were not recorded 20 years ago. Forest dieback resulted in profound changes in the hydrological regime. The observed changes are consistent with a model of cyclic succession as proposed for alder swamps. In addition, we conclude that the natural forest dynamics have to be taken into consideration while interpreting the results of re-survey studies.

1. We investigated the characteristics and causes of striped patterning in minerotrophic Sphagnum cristatum mires on the western Central Plateau in Tasmania by surveying the mire vegetation, surface and subsurface topography, analysing their topographic exposure to the prevailing strong winds relative to non-striped mires, stratigraphic analysis, measurements of wind speed and direction across and along ridges and swales in typical synoptic conditions, and measurement of growth rates and asymmetry of shrubs. 2. The stripes were orientated south-west–north-east, independent of the aspect of the general slope. The shrub Richea scoparia was dominant on the north-west-facing slopes of the low ridges that formed the stripes. Sphagnum cristatum was dominant on the south-east-facing ridge slopes and the restiad, Baloskion australe was dominant in the swales. The stripes were independent of the topography of the underlying block stream. Striped mires were more exposed to both north-westerly and south-westerly winds than non-striped mires. 3. Strong north-westerly winds formed rotors behind each ridge, with wind speed being highest on the north-west-facing ridge slope and lowest on the south-east-facing ridge slope. The annual growth of R. scoparia inversely reflected this variation in wind speed. South-westerly winds were stronger in the swales than on the ridges and stronger on the south-west extremity of the ridges than further to the north-east. Asymmetry in R. scoparia on the ridges reflected this variation in wind speed. 4. We infer that the ridges slowly migrate in a cyclic successional pattern as the result of differential growth rates of R. scoparia in response to variation in the speed of drying north-westerly winds. The stripes appear to result from training of shrubs by strong, cold south-westerly winds, which also inhibit the growth of R. scoparia in the swales. 5. Synthesis. There are no other documented cases of wind-controlled patterning and cyclic succession in mires, and no case of exposure to two distinct wind directions being responsible for patterning in any vegetation type. The distinctiveness of the process and the form merit recognition of these striped mires as outstanding in their universal value under the world heritage area criteria.

In this study I document the growth rate and age of trees in an old-growth montane Hawaiian wet forest and use these results to evaluate the cyclic succession model for forest dynamics. I used two methods to estimate the age of trees – the crown-class model and radiocarbon dating. Over 6000 trees belonging to eight species were tagged and measured over 7 y on Hawaii Island. Growth rates for the dominant tree (Metrosideros polymorpha) were relatively low (mean = 1.3 mm y−1) and varied with tree size and crown class. 14C-based age estimates for 27 M. polymorpha trees loosely corroborated estimates based on the crown-class method. The oldest tree dated by 14C had a median age of 647 y BP, placing it among the oldest documented angiosperm trees in the northern hemisphere. 14C dating revealed that the upper canopy may be comprised of three distinct age groups of M. polymorpha trees of similar size, with the median age of each group separated by 200–250 y. The high density of large, very old trees in multiple groups is unusual for a tropical forest and indicates that forest development may occur through gap-phase regeneration at a fine scale and stand-level mortality at a coarser scale.

Succession is a key concept in ecology and its study has generated well known and highly debated theories on mechanisms by which communities are assembled, including the relative role of deterministic and stochastic pathways. The contribution of stream ecosystems to general successional theory, particularly primary succession, has been extremely limited due to the lack of long-term studies on stream channels at a large enough spatial scale. We suggest that the study of succession in streams in Glacier Bay, southeast Alaska where rapid ice recession has occurred may offer one of the few examples of the tolerance model as a major mechanism of macroinvertebrate community assembly; the majority of macroinvertebrate taxa, with the exception of the cold-tolerant first colonizers, have persisted within the community following colonization. Relative abundance has however changed markedly over time. In contrast, a meiofaunal component of the invertebrate community exhibited poor persistence with numerous extinctions. Stream successional processes may be unique in being closely linked to, and markedly influenced by, processes in other ecosystems, particularly the terrestrial environment. Stream succession in Glacier Bay also demonstrates differences from terrestrial succession in the number of reset mechanisms that can cause communities to significantly shift to an earlier successional stage or at least allow the persistence of early colonizers, including the loss of flow buffering lakes, floods and redd construction by spawning salmon. We suggest in these streams community assembly initially follows deterministic pathways due to the overriding influence of water temperature but as temperatures exceed 7°C then stochastic mechanisms influence succession and community assembly. Copyright © 2009 John Wiley & Sons, Ltd.

Question: What is the best way to model savanna dynamics? Specifically, under what conditions is a traditional succession model, i.e., a model of ordered, uni-directional change in the plant community, better than a state-and-transition model? Location: Central Texas savannas. Methods: We describe three examples of successional processes in central Texas savannas: (a) woody plant encroachment, (b) invasion by a non-native grass, and (c) establishment of different grass species in highly disturbed sites. Results and Conclusions: Savanna dynamics are now commonly conceptualized with state-and-transition models. However, in some situations a traditional succession model may be more appropriate or more useful. Succession models may better fit current ecological reality, as found in central Texas. Succession models emphasize transient dynamics rather than an (often unknown) endpoint, and direct us towards relevant literature from non-savanna ecosystems. Succession models may be particularly useful for land management and restoration, and where woody plant encroachment and/or invasions by non-native species control vegetation dynamics.

The formation of many arctic wetlands is associated with the occurrence of polygonpatterned permafrost. Existing scenarios to describe and explain surface landforms in arctic wetlands (low-center and high-center polygons and polygon ponds) invoke competing hypotheses: a cyclic succession (the thaw-lake hypothesis) or a linear succession (terrestrialization). Both hypotheses infer the predictable development of polygon-patterned wetlands over millennia. However, very few studies have applied paleoecological techniques to reconstruct long-term succession in tundra wetlands and thereby test the validity of existing hypotheses. This paper uses the paleoecological record of diatoms to investigate long-term development of individual polygons in a High Arctic wetland. Two landform processes were examined: (1) the millennial-scale development of a polygon-pond, and (2) the transition from lowcenter to erosive high-center polygons. Diatom assemblages were quantified from habitats associated with contrasting landforms in the present-day landscape, and used as an analog to reconstruct past transitions between polygon types. On the basis of this evidence, the paleoecological record does not support either of the existing models describing the predictable succession of polygon landforms in an arctic wetland. Our results indicate a need for greater paleoecological understanding, in combination with in situ observations in present-day geomorphology, in order to identify patterns of polygon wetland development and elucidate the long-term drivers of these landform transitions.

A detailed layer-by-layer description of the most complete section of the Upper Maastrichtian Rocks at the Tankovoe Settlement in the Bel’bek River valley in the Sevastopol’ District of the Southwest Crimea is presented along with microscopic description of the rocks and an analysis of ichnofossils. Late Maastrichtian paleogeographic and paleoclimatologic issues of the northern margin of the Tethys Ocean are discussed. A sedimentation model explaining the origin of the cyclic succession is suggested.

While ecological dogma holds that rates of community change decrease over the course of succession, this idea has yet to be tested systematically across a wide variety of successional sequences. Here, I review and define several measures of community change rates for species presence-absence data and test for temporal patterns therein using data acquired from 16 studies comprising 62 successional sequences. Community types include plant secondary and primary succession as well as succession of arthropods on defaunated mangrove islands and carcasses. Rates of species gain generally decline through time, whereas rates of species loss display no systematic temporal trends. As a result, percent community turnover generally declines while species richness increases--both in a decelerating manner. Although communities with relatively minor abiotic and dispersal limitations (e.g., plant secondary successional communities) exhibit rapidly declining rates of change, limitations arising from harsh abiotic conditions or spatial isolation of the community appear to substantially alter temporal patterns in rates of successional change.

The succession of species-rich wetland vegetation in dune valleys into species-poor dwarf shrub vegetation was followed by means of permanent vegetation plots, in which the cover of vascular plant, moss and lichen species were recorded over a period of up to 33 years. Low density cattle grazing is an effective substitute for rabbits in stalling this succession, thus preserving the local plant species diversity. The influence of direct rabbit grazing pressure on the vegetation was studied in exclosures. The differences were significant, but not long-lasting after the exclosures had been opened again to the rabbits. Cladina lichen-rich Empetrum-heathland in the dunes is a stage in a probably cyclic succession that might be triggered by grazing. The total vascular plant, moss and lichen diversity of the dune ecosystem can be maintained by a combination of extensive cattle grazing and a regular but limited re-creation of pioneer situations.

Although mathematical models and laboratory experiments have shown that species interactions can generate chaos, field evidence of chaos in natural ecosystems is rare. We report on a pristine rocky intertidal community located in one of the world’s oldest marine reserves that has displayed a complex cyclic succession for more than 20 y. Bare rock was colonized by barnacles and crustose algae, they were overgrown by mussels, and the subsequent detachment of the mussels returned bare rock again. These processes generated irregular species fluctuations, such that the species coexisted over many generations without ever approaching a stable equilibrium state. Analysis of the species fluctuations revealed a dominant periodicity of about 2 y, a global Lyapunov exponent statistically indistinguishable from zero, and local Lyapunov exponents that alternated systematically between negative and positive values. This pattern indicates that the community moved back and forth between stabilizing and chaotic dynamics during the cyclic succession. The results are supported by a patch-occupancy model predicting similar patterns when the species interactions were exposed to seasonal variation. Our findings show that natural ecosystems can sustain continued changes in species abundances and that seasonal forcing may push these nonequilibrium dynamics to the edge of chaos.

Community structure varies not only in space but also in time. We stand in one position which located at Sinhung-ri, Sacheon-ci and observe the flora of area as time passes. This area begins after disturbance on sites where organisms are already present like secondary succession. In 2001, there are invaded by Trapa japonica, Salvinia natans, and Potamogon cristatus. Four or five years later, this abandoned areas support of clover, pine, and oak, resulting in a shifting pattern of species dominance and diversity through time. Patterns of community structure such as species composition and ecological diversity have shown through seasons and five years, that is the topic of this study. The values of turnover (TO) were changes through time intervals at three regions. The gradual and seemingly directional change in the structure of the community through time from aquatic like to field. Thus, we can observe the process of secondary succession at Sinhung-ri in the very short time.

Vegetation pattern and dynamics were characterized across a mid-Texas, USA coastal marsh ecotone subjected to snow goose herbivory, drought, and salt-water pulses. For eight years following snow goose feeding, species cover was evaluated in heavy and light goose-use patches at increasing distances from tidal influence. Just prior to and for two years after the feeding event, drought, and several salt-water pulses associated with tropical storms typified the hydrologic dynamics of the marsh. Herbivory history was more important than distance from tidal influence, salinity, or flooding in explaining spatial and temporal vegetation pattern for three years. Precipitation variation influenced vegetation dynamics in areas heavily used by geese. Recovery to pre-herbivory composition and abundance required six years without further snow goose feeding. Extremes of annual precipitation, salinities, and water levels impacted cover of Spartina patents dominated patches little unless feeding snow geese uprooted vegetation. Schoenoplectus americanus was more impacted by extremes of environmental dynamics than S. patens but even more impacted by synergistic effects of uprooting and environmental extremes. During this period, the ecotone could be characterized as patchy, with a gulfward waxing and waning of S. americanus.

Without humans, large areas of central Europe would be covered by forests dominated by beech (Fagus silvatica). The spatiotemporal dynamics of natural beech forests are hence a subject of interest for both forest management and conservation. However, since in most regions there are no longer any natural beech forests, their structure and dynamics cannot routinely be analysed and compared to managed forests. The forest model BEech FOREst (BEFORE) is therefore, designed to reconstruct the spatiotemporal dynamics of natural beech forests. BEFORE is a grid-based and partly individual-based model which divides beeches into four different height classes. Changes to the forest structure due to growth, mortality and storm disturbances are entirely described by empirical ‘if-then’ rules. BEFORE is capable of reproducing two patterns which have been observed in remnants of natural beech forests: beech forests consist of a mosaic pattern of small areas (on average 0.3 ha) which are at different developmental stages; at the scale of these small areas, a cyclic succession of three developmental stages occurs, which are characterised by different vertical structures. One typical feature of natural beech forests is hence their very high structural diversity. Gaps in the canopy induce a local pulse of vitality and growth for younger beech trees. These pulses are spread into the vicinity by two mechanisms. Firstly, windfalls affect not only the site of the tree knocked over itself but also neighbouring sites due to the damage caused by the tree falling over. Moreover, since the light is diffuse and oblique, canopy gaps affect also vitality and growth in the neighbourhood of a gap. The results obtained with BEFORE show that natural beech forests achieve quasi-stationary dynamics, demonstrating considerable fluctuations in the forest structure. For example, the percentage of forest area at the optimal stage, which is characterised by a closed canopy and almost no understorey, varies between 10 and 40%, and after extreme storm events even between 0 and 60%. Beech forests with an inner area larger than 40 ha (corresponding to a total area of 70 ha) develop spatiotemporal dynamics which do not differ qualitatively or quantitatively from larger forests, but even very small natural beech forests would exhibit very high temporal and structural diversity. Thus, even small ‘islands’ of unmanaged stands within larger, managed forests would contribute significantly to providing structures typical of natural beech forests.