Early Stages Of Primary Succession Research Articles

Anti-seasonal flooding drives substantial alterations in riparian plant diversity and niche characteristics in a unique hydro-fluctuation zone.

Human-induced disturbances such as dam construction and regulation have led to widespread alterations in hydrological processes and thus substantially influence plant characteristics in the hydro-fluctuation zones (HFZs). To reveal utilization of limited resources and mechanisms of inter-specific competition and species co-existence of plant communities based on niche breadth and overlap under the different HFZs of the Three Gorges Reservoir (TGR) in China, we conducted a field investigation with 368 quadrats on the effects of hydrological alterations on plant diversity and niche characteristics. The results showed anti-seasonal flooding precipitated the gradual disappearance of the original diverse niches, resulting in the reduction of plant species richness and functional diversity and more obvious competition among plant species with similar resource requirements. Annuals, perennials and shrubs accounted for 71.23%, 27.39% and 1.37%, respectively, suggesting that annuals and flood-tolerant riparian herbs were favored under such novel flooding conditions. A consistent increase in species number, Shannon-Wiener diversity index and Simpson dominance index with altitude was inconsistent with hump-shaped diversity-disturbance relationship of the intermediate disturbance hypothesis, while the opposite trend was observed for the Pielou evenness index. This species distribution pattern might be caused by several synergetic attributes (e.g., the submergence depth, plant tolerant capacity to flooding, life form, dispersal mode and inter-specific competition). Vegetation types shifted from xerophytes to mesophytes and eventually to hygrophytes with the increasing flooding time in the HFZs. Hydrological alterations proved to be the paramount driver of vegetation distribution in the different HFZs. The niche analysis provided the first insights on the mechanisms of resource utilization and inter-specific competition, of which annuals could germinate quickly after soil drainage to achieve the greatest competitive advantages and occupy a larger niche space than other plants. Vegetation was still in the early stage of primary succession in the novel riparian forests. Therefore, vegetation restoration strategies should be biased towards herbaceous plants, due to annuals with better environmental adaptability, supplemented by shrubs and small trees. To establish a complete reference system for vegetation restoration, natural vegetation monitory plots in the different succession stages should be established in the different HFZs of the TGR, and their environmental conditions, community structures and inter-specific relationships further analyzed.

ECOLOGICAL STRATEGIES OF PLANTS IN THE PROCESS OF RESTORATION OF DISRUPTED NATURAL ECOSYSTEMS OF UKRAINIAN POLISSIA

Tasks related to the restoration of disturbed natural ecosystems are of theoretical and practical importance. Traditional approaches to remediation are often utilitarian. We often observe that the natural processes of ecosystem restoration occur faster and with better quality than those carried out by humans under similar conditions. The purpose of our work is to investigate the role of plants that have different ecological strategies during the process of restoration of disturbed ecosystems. The following tasks were outlined to achieve this goal: to identify groups of plants with different ecological strategies involved in the restoration of natural vegetation; develop models of vegetation restoration using plants with different ecological strategies. The materials of our research are standard geobotanical descriptions made on the territory of Ukrainian Polissia in the period from 2004 to 2023. We consider environmental strategies more broadly than R. Whittaker, L. H. Ramensky, J. Grim and E. Pianki in their classic works. The ecological strategies of plants differ in the way of spreading and reproduction, as well as in the signs of fixation on the soil; by methods of energy reservation; changing the environment around itself. The rate of restoration of natural ecosystems, as well as their characteristics, depend on the configuration of the disturbed area, the substrate of its surface, and the adaptive strategies of the plants that fall on it. The classification of adaptive strategies of species that affect the process of restoration of natural ecosystems is formed on the basis of the variety of methods of reproduction and distribution of fruits and seeds of autotrophs, as well as the peculiarities of their energy distribution in the reproduction process. The change in ecological strategies of species is because ecosystems are dynamic systems, therefore, during primary successions; disturbed ecotopes are most successfully populated by patient species, and during secondary ones by explerent species and violent species. Plants penetrate the primary substrate with the help of seeds, spores, or vegetative organs (most often rhizomes). In the early stages of primary succession, the seeds and spores of patient species are the most successful – those with low competitiveness and can achieve reproductive and vegetative success outside the communities. The balance of the amount of energy of Polissia pioneer patients is often shifted from supporting the vegetative part of the body to its seeds. Species that spread to pioneer substrates using rhizomes do not have such a limitation because they share a common distribution of matter and energy with the pioneer part of the community. Those species on the primary substrate, having no competitors, actively photosynthesize and share carbohydrates, while those on the formed substrate and have many competitors for solar energy share water and mineral nutrients. Global climate changes, which lead to xerophytization of Polissia and warm winters with little snow, are becoming an obstacle to the rapid natural restoration of pine forest ecosystems in large areas of disturbed areas.

Deposition is a phosphorus source for Fallopia japonica during early-stage primary succession

Phosphorus is a key plant nutrient linked to plant growth during the early stages of primary succession in volcanic soils. Available phosphorus is thought to include soil and atmospheric phosphorus, but it is not well understood. Here, we focused on deposition as a potential phosphorus source. We evaluated the contribution of deposition to phosphorus uptake and growth in Fallopia japonica, a key pioneer species of primary succession. When we experimented with growing F. japonica under field conditions, F. japonica not covered by a roof absorbed more phosphorus than that covered by the roof, suggesting the influence of total (dry + wet) deposition. Furthermore, we tested the effects of deposition by treating F. japonica seedlings with wet deposition or distilled water in six volcanic soils. Plants that received the wet deposition treatment exhibited higher phosphorus contents and growth rates than those treated with distilled water. The phosphorus from wet deposition and the phosphorus from soil contributed nearly equally to F. japonica development. Our findings suggest that F. japonica grows during primary succession and builds up the phosphorus cycle by absorbing a trace amount of phosphorus from deposition and volcanic soils.

Dynamic trophic shifts in bacterial and eukaryotic communities during the first 30 years of microbial succession following retreat of an Antarctic glacier.

We examined microbial succession along a glacier forefront in the Antarctic Peninsula representing ∼30 years of deglaciation to contrast bacterial and eukaryotic successional dynamics and abiotic drivers of community assembly using sequencing and soil properties. Microbial communities changed most rapidly early along the chronosequence, and co-occurrence network analysis showed the most complex topology at the earliest stage. Initial microbial communities were dominated by microorganisms derived from the glacial environment, whereas later stages hosted a mixed community of taxa associated with soils. Eukaryotes became increasingly dominated by Cercozoa, particularly Vampyrellidae, indicating a previously unappreciated role for cercozoan predators during early stages of primary succession. Chlorophytes and Charophytes (rather than cyanobacteria) were the dominant primary producers and there was a spatio-temporal sequence in which major groups became abundant succeeding from simple ice Chlorophytes to Ochrophytes and Bryophytes. Time since deglaciation and pH were the main abiotic drivers structuring both bacterial and eukaryotic communities. Determinism was the dominant assembly mechanism for Bacteria, while the balance between stochastic/deterministic processes in eukaryotes varied along the distance from the glacier front. This study provides new insights into the unexpected dynamic changes and interactions across multiple trophic groups during primary succession in a rapidly changing polar ecosystem.

Stoichiometric flexibility and soil bacterial communities respond to nitrogen fertilization and neighbor competition at the early stage of primary succession

At the early stage of primary succession, there are deficient nutrient resources as well as competition stress among neighboring plants. Our aims were to elucidate the flexibility of tree seedlings’ stoichiometric relationships and their effects on soil microbial communities, and to determine the driving forces of species turnover during primary succession through the evaluation of carbon (C) : nitrogen (N) : phosphorus (P) stoichiometric relationships. We conducted an experiment testing N addition effect on two species from the early stage of primary succession, under intra- and interspecific competition conditions. Our results showed that higher values of δ15N-NO3− and δ13C were observed in Populus purdomii individuals than in Salix rehderiana after N application, which indicated a more efficient N uptake and water-use efficiency in P. purdomii plants. Furthermore, under N addition, the intraspecific competition of P. purdomii presented a higher urease activity, microbial biomass C (MBC), microbial N:P ratio (MBN:MBP), and phylogenetic diversity compared to the intraspecific competition of S. rehderiana. The results showed that P. purdomii seedlings influenced soil properties in a way that led to a positive feedback on their performance with an increasing N availability. In contrast, S. rehderiana seedlings influenced soil properties in a way that caused a negative feedback on their performance with increasing N. Such events can promote species turnover from Salix to Populus during succession. Additionally, DNA sequencing of soil bacterial communities showed differences in the composition of microbial communities in response to N fertilization and different competition patterns. Altogether, our results showed that plant, soil, and microbial community responses to N fertilization in a subalpine glacier forefield differed among tree species and competition patterns. This study brings new insight into mechanisms that drive species replacement and biogeochemical cycling during primary succession.

Dynamics of apomictic and sexual reproduction during primary succession on a glacier forefield in the Swiss Alps

Apomixis, the asexual reproduction through seeds, is thought to provide reproductive assurance when ploidy is not even and/or when population density is low. Therefore, apomicts are expected to be more abundant, and the frequency of apomictic offspring higher, at early stages of primary succession when mates are rare. To test this hypothesis, we sampled facultative apomictic Hieracium pilosella L. along the successional gradient on a glacier forefield and determined their ploidy, the level of apomixis in their offspring, and the genetic diversity of the entire meta-population and within subpopulations. We found that apomixis is more common in odd- and aneuploid cytotypes, which are more frequent at early stages of primary succession. However, apomixis was uncommon at all successional stages and sexual hexaploids were dominating throughout. Reproductive assurance was reflected in the higher fertility of all odd-ploid apomictic plants (3×, 5×) by avoiding meiosis, illustrating that apomixis provides an escape from sterility, as proposed by Darlington. Odd-ploid plants are supposedly better colonizers (Baker’s law), which is supported by their higher occurrence close to the glacier snout. Independent of succession, we found gene flow between apomicts and sexuals, which allows for the continuous creation of new apomictic and sexual genotypes. We conclude that apomixis in H. pilosella does indeed provide an escape from sterility, and therefore reproductive assurance, in aneuploid cytotypes. We further propose that apomixis preserves beneficial combinations of unlinked alleles in every generation for as long as apomictic genotypes persist in the population.

Effects of pioneer N2-fixing plants on the resource status and establishment of neighboring non-N2-fixing plants in a newly formed glacier floodplain, eastern Tibetan Plateau

The ecological roles of dinitrogen-fixing plants (N2-fixers) in the early stage of primary succession remain unclear. We aimed to examine the effects of pioneer N2-fixers on the resource status and establishment of neighboring non-N2-fixing plants (non-fixers) in a newly formed glacier floodplain, eastern Tibetan Plateau. We set up three plots in the floodplain and assessed the abundance, height, and coverage of two N2-fixing and three non-fixing species. We also collected plant and soil samples for the analyses of nutrient status and stable isotope signatures. The two N2-fixing species acquired > 80% of the nitrogen (N) from N2 fixation. The cushion-forming N2-fixer Astragalus mahoshanicus increased the soil nutrient availability compared with the non-fixers and improved the microclimate beneath the cushions. Natural 15N abundance indicated significant transfer of N from A. mahoshanicus to its neighboring non-fixers. Consequently, the neighboring non-fixers were significantly higher in N concentration, above-ground to below-ground biomass ratio and height and density than the non-fixers growing alone, but more deficient in some rock-derived nutrients. The other N2-fixer Hippophae rhamnoides (in seedling stage) generally did not increase the resource availability, and its neighboring non-fixers were similar in height and lower in density than the non-fixers growing alone. The effects of pioneer N2-fixers on the resource status and establishment of neighboring non-fixers in the subalpine floodplain were species dependent and were related to the life history traits of the N2-fixers. A. mahoshanicus has the potential to be used in the restoration of newly exposed land in subalpine regions.

Increasing soil age drives shifts in plant-plant interactions from positive to negative and affects primary succession dynamics in a subalpine glacier forefield

The stress gradient hypothesis predicts that plant-plant interactions switch between facilitation (positive) and competition (negative) along environmental gradients, with facilitation being more common under high abiotic stress conditions relative to more moderate abiotic stress conditions. Our aim was to reveal, whether the interactions between Populus purdomii Rehder and Salix rehderiana Schneider switch from positive to negative during the early stages of primary succession in the Gongga Mountain glacier retreat region. We also investigated, whether soil age is a major driving factor for the transformation of interactions between neighboring plants. We analyzed differences between intraspecific interactions and interspecific interactions of Populus and Salix under 20- and 40-year-old soil conditions, including plant biomass accumulation and allocation, nutrient absorption and utilization, relative competition intensity, non-structural carbohydrates, foliar carbon and nitrogen isotope composition, mesophyll cell ultrastructure, soil microbial biomass and community structure, extracellular enzyme activities, and soil organic carbon (SOC), soil total nitrogen (TN), soil ammonium (NH4+-N), and soil nitrate (NO3−-N) contents. We found that P. purdomii and S. rehderiana growing under interspecific interactions had greater contents of aboveground dry matter, belowground dry matter and total dry matter compared to intraspecific interactions in 20-year-old soil. Furthermore, in 40-year-old soil conditions, the phospholipid fatty acid (PLFA) analysis showed that Populus and Salix exposed to interspecific interactions exhibited lower amounts of gram-positive bacteria, fungi (18,1 ω9c) and actinomycetes, and lower levels of total PLFAs than those growing under intraspecific interactions. The redundancy analysis (RDA) results demonstrated that soil N was the most important parameter contributing to the composition of microbial communities. In addition, the 15N stable isotope labeling method showed that Populus and Salix growing under interspecific interactions had higher foliage δ15N derived from NO3− (δ15N-NO3−) than those growing under intraspecific interactions in 20-year-old soil. In summary, our results demonstrated that Populus-Salix interactions exhibited positive effects on survival in 20-year-old soil. Conversely, under 40-year-old soil conditions, Populus-Salix interactions presented negative effects in relation to nutrients and elimination by neighboring plants. Moreover, soil age is a major driving factor for plant-plant interactions that shift from positive to negative with an increasing soil age in the Gongga Mountain glacier forefield. In all, our results support the stress gradient hypothesis. Our findings improve understanding of plant-plant interactions and plant-soil feedbacks during the early stages of soil development, and of the construction of vegetation communities.

When and where does dispersal limitation matter in primary succession?

AbstractPrimary succession encompasses the earliest and most fundamental stages of community assembly. The relative contributions of plant dispersal and ecosystem development, the main drivers that control the rate of primary succession, remain largely unknown, in spite of their central roles in community organization in general. Understanding the contribution of dispersal is especially critical because it casts light on our ability to manage succession resulting from climate change or anthropogenic disturbance.Here, we review the literature in order to understand when and where dispersal limits primary succession. Studies from many systems (tropical, temperate, boreal, arctic, alpine, floodplain forest, desert, mines, volcanic eruption and glacier forelands) show that dispersal limitation occurs consistently in the early stages of primary succession, suggesting that this is a general pattern. On the other hand, we found strong biases in study sites towards the Northern Hemisphere, temperate regions, volcanic eruptions and glacier forelands, which suggests that there are risks in drawing general conclusions about the importance of dispersal for primary succession for other biomes.Little is known about the contribution of dispersal to the later stages of primary succession. We present a recently developed method, multiscale chronosequence comparison that compares rates of succession in similar systems at relatively small and large spatial scales. Rapid succession at small scales compared to large scales suggests that seed dispersal influences succession over time periods of centuries and also limits the development of ecosystem functions such as vegetation cover and soil carbon accumulation.Synthesis: Dispersal limitation likely matters not only in the early stages but also in the late stages of primary succession by controlling the rate at which new species arrive. Both the accumulation of comparable case studies and novel approaches, such as multiscale chronosequence comparisons and factorial experiments, in contrasting biomes, are necessary to clarify the generality or context dependency of the role of dispersal in future primary successions undergoing changing climate.

Aphid herbivory as a potential driver of primary succession in coastal dunes

Herbivory is a major factor affecting both the performance and the fitness of the species composing a plant community and, ultimately, conditioning its temporal and spatial dynamics. Coastal dunes are a typical example of primary succession where different biotic and abiotic factors determine plant species occurrence; however, the effect of insect herbivory herein has remained little explored. To address this matter, we combined an observational study along a successional gradient with a green-house experiment to determine the occurrence and the impact of plant–aphid interactions. We focused on the species Schizaphis rufula, a widespread and abundant aphid associated with dune grasses in early stages of primary succession in Europe. Firstly, we studied aphid infestation rates on the dune grass Ammophila arenaria along a succession gradient in three locations of the North Sea coast to address the relationship between plant community composition and aphid occurrence; secondly, we tested the effect of aphid herbivory on a set of dune species typical for the different stages of succession. We found that the degree of aphid infestation was inversely correlated with the degree of dune fixation. The results of the experiment showed that aphid multiplication was significantly higher and its effect more pronounced on two early successional grass species, i.e. A. arenaria and Leymus arenarius. Here aphid multiplication resulted in a severe decrease in plant biomass; in late successional grass species, there was limited multiplication and no effect on biomass. The results of the field survey and the green-house experiment indicate that aphids show a clear preference for plants from early successional stages and, moreover, they have a greater impact on these plant species. All this supports the hypothesis of aphid herbivory as a driving factor of primary succession in coastal dunes.

A simple method for determining limiting nutrients for photosynthetic crusts

Background: Photosynthetic crust communities are important to the functioning of many desert and early successional ecosystems. Little is known about the factors that limit the growth of these communities, especially during early stages of primary succession or following disturbance. Aims: Our main goal was to develop a method to study nutrient limitations of crust growth in laboratory microcosms. We used the new method to test the hypothesis that phosphorus limits the growth of crusts in newly deglaciated soils of the high Andes. Methods: We modified the point–intercept method used in plant ecology to quantify the spread of cyanobacteria, algae and mosses on the soil surface in response to additions of nitrogen and phosphorus. Results: Fertilization with phosphorus significantly increased the growth rate and final percentage cover, and decreased the lag time for growth of cyanobacterial and algal communities in recently deglaciated soils. By contrast, nitrogen additions had no significant effect on the growth of microbial phototrophs, and all nutrient additions suppressed the growth of early successional mosses. Conclusions: We propose that the method described here offers a valuable tool for assessing the nature of nutrient limitation of photosynthetic organisms in early successional and desert ecosystems. The information provided by using this approach can increase our understanding of the earliest stages of ecosystem development and may help inform strategies for the reclamation of disturbed arid ecosystems by identifying potential limiting nutrients.

Bacterial community structure and function change in association with colonizer plants during early primary succession in a glacier forefield

Plants directly interact with the soil microbial community through litter inputs and root exudates, and these interactions may be particularly important in nutrient poor soils that typically characterize early ecosystem development. However, little is known regarding how plant–microbe interactions may actually drive ecosystem processes in early succession, a perspective this study helps to define. We investigated how soil microbial communities develop and interact with the establishment of the first plants in the recently exposed soils of the Mendenhall Glacier forefield near Juneau, AK, USA. We sampled soils from under two different plant species (alder, Alnus sinuata and spruce, Picea sitchensis) and from unvegetated areas; all samples were collected along a single soil transect that had been exposed for 6 years. The presence or absence of vegetation as well as the type of plant (i.e., alder vs. spruce) structured the soil microbial community. Furthermore, asymbiotic nitrogen (N) fixation rates, which were greater in vegetated soils, correlated with differences in bacterial community composition. Although soil microbial community composition varied with vegetation type, soil nutrient and carbon (C) pools did not correlate with bacterial community composition. Moreover, pH did not significantly vary by vegetation type, yet it was the only soil parameter that correlated with bacterial community composition. Vegetation type explained more of the variation in bacterial community composition than pH, suggesting that plant acidification of soils only partly explains the observed shifts in bacterial communities. Plant specific differences in bacterial community structure may also relate to the chemical composition of litter and root exudates. Our research reveals differences in the bacterial community composition of vegetated soils, and how such differences may promote shifts in fundamental biogeochemical processes, such as rates of asymbiotic N fixation, in early stages of primary succession where low N availability may limit bacterial and plant growth and thus constrain ecosystem development. As such, this suggests that plant–soil microbe interactions in themselves may drive processes that shape the trajectory of primary succession.

Nutrient limitation during long-term ecosystem development inferred from a mat-forming moss

Extant models of long-term ecosystem nutrient status, largely formulated using data from mid- and low-latitude settings dominated by vascular vegetation, predict nitrogen (N) limitation in the early stages of primary succession and phosphorus (P) limitation in the latter stages. The aims of this study were a) to examine the use of mosses to establish ecosystem nutrient status; b) to test an existing model of nutrient limitation during long-term primary succession and c) to assess the connection between nutrient dynamics and the emergence of spatially structured vegetation in a high-latitude, moss-dominated community. Spatiotemporal changes in nutrient availability were inferred using tissue nutrient concentrations in a moss sampled from a long (850-year) chronosequence of lava flows in Iceland. This is the first use of bryophyte nutrient concentrations, even though they should be a good indicator of nutrient status in high-latitude habitats. Samples of the moss, Racomitrium lanuginosum, from different topographic positions were collected from seven lava flows of different ages (26-848 years) and analyzed to establish concentrations of N, P and major mineral nutrients. Concentrations of N were low on all sites and evidence of progressive N accumulation is lacking; increasing concentrations of phosphorus indicated increasing N limitation with terrain age. This pattern contrasts with other studies of long-term nutrient limitation, where N limitation reduces and P limitation increases with increasing terrain age. Concentrations of mineral nutrients did not vary significantly with terrain age. Nutrient concentrations were only weakly related to spatial patterning in the vegetation. It is likely that element concentrations were strongly influenced by inputs of allochthonous sediment. These findings suggest that mat-forming, pleurocarpous mosses may be used to infer long-term changes in N & P limitation during primary succession and that existing models of nutrient limitation may not be robust over century - millennial timescales in low productivity, high-latitude habitats.

Production of biological soil crusts in the early stage of primary succession on a High Arctic glacier foreland

*We examined the photosynthetic characteristics and net primary production of biological soil crusts to evaluate their contribution to the carbon cycle in the High Arctic glacier foreland. *Biological soil crust samples were collected from a deglaciated area in Ny-Alesund, Svalbard, Norway. Net photosynthetic rates (Pn) and dark respiration rates (R) of biological soil crusts were determined using CO(2) gas exchange rates. We examined the effects of moisture conditions, temperature and photon flux density on Pn and R, and estimated the net primary production by a model based on the relationships between abiotic factors and Pn and R. *The maximum Pn value occurred at 50% of the maximum water-holding capacity. Pn decreased with increasing temperature and dropped below zero at high temperatures (c. > 13 degrees C). The estimated net primary production of the biological soil crust was greater than the net primary production of other vegetation when based on ground surface area, during the early stage of primary succession. Model simulation showed that the net primary production of the biological soil crust decreased with increasing temperature. *These results suggest that biological soil crust productivity plays an important role in the carbon cycle during the early stage of succession of the High Arctic glacier foreland, and is susceptible to temperature increases from global warming.

Development and activity of Glomus intraradices as affected by co-existence with Glomus claroideum in one root system

The co-existence of two arbuscular mycorrhizal fungal (AMF) species, Glomus intraradices and Glomus claroideum, in the root systems of plants was investigated in a greenhouse experiment aimed at reconstructing interactions during an early stage of primary succession on a coal-mine spoil bank in Central Europe. Two plant species, Tripleurospermum inodorum and Calamagrostis epigejos, were inoculated either with one or both AMF species. Fungal development, determined by trypan blue and alkaline phosphatase staining as well as by PCR amplification of rRNA genes with species-specific primers, and the expression of five genes with different metabolic functions in the intraradical structures of G. intraradices were followed after 6 and 9 weeks of cultivation. The two AMF closely co-existed in the root systems of both plants possibly through similar colonisation rates and competitivity. Inoculation with the two fungi, however, did not bring any additional benefit to the host plants in comparison with single inoculation; moreover, plant growth depression observed after inoculation with G. claroideum persisted also in mixed inoculation. The expression of all the assayed G. intraradices genes was affected either by host plant or by co-inoculation with G. claroideum. The effects of both factors depended on the time of sampling, which underlines the importance of addressing this topic in time-course studies.

Destruction and Recovery of Vegetation Caused by the 2000-Year Eruption on Miyake-Jima Island, Japan

The active Mt. Oyama volcano on Miyake-jima Island in the Izu Islands, Japan, erupted in 2000 followed by large amounts of volcanic gas containing high concentrations of SO2has been emitted. The island ecosystem has been heavily damaged by the volcanic ash and gas. We detail the destruction and recovery of vegetation found in a 7-year study of 11 permanent plots from 2001 to 2007. Damage to vegetation by ash was worst near the crater in 2001. Trees began dying in 2001, apparently due to direct and/or indirect effects of volcanic gas emission. In contrast to the tree decline, two grass species,Miscanthus condensatusandCarex oshimensis, increased notably following the eruption, suggesting their high SO2and acidic soil tolerance.Miscanthus condensatusandC. oshimensiswere not dominant species in early stage of primary succession before the 2000-year eruption. In the vegetation recovery after the eruption, the tolerances to SO2and acidic soils are necessary for plant species to colonize on devastated sites.

Exploring spatiotemporal patterns in early stages of primary succession on former lignite mining sites

AbstractQuestions: 1. Does random colonization predominate in early stages of primary succession? 2. Do pioneer species facilitate the establishment of later arriving species? 3. Does an initially random distribution change to an aggregated pattern with ongoing succession?Location: Lignite mining region of Lower Lusatia, eastern Germany.Methods: Individual plants were mapped along a 2 m × 28 m transect during three successive years and classified into two groups (1) the pioneer Corynephorus canescens and (2)‘all other species’. Using the pair‐correlation function, univariate point pattern analysis was carried out by applying a heterogeneous Poisson process as null model. Bivariate analysis and a toroidal shift null model were applied to test for independence between the spatial patterns of the two groups separately for each year, as well by exploring spatiotemporal patterns from different years.Results: In the first year Corynephorus and ‘all other species’ showed an aggregated pattern on a spatial scale > 40 cm and in the second and third years a significant attraction for distances between 4 and 12 cm, with an increasing radius in the third year. The analyses of interspecific spatiotemporal dynamics revealed a change from independence to attraction between distances of 4 cm and 16 cm when using Corynephorus as focal species. However, applying ‘all other species’ as focal points results in a significant attraction at distances up to 60 cm in the first year and a diminishing attraction in the second and third years with distances ≤ 6 cm.Conclusions: Facilitative species‐species interactions are present in early stages of primary succession, resulting mainly from pioneer species acting as physical barriers and their ability to capture diaspores being drifted by secondary dispersal along the substrate surface. However, due to gradual establishment of perennial species and their ability of lateral extension by vegetative dispersal, facilitation may influence spatial pattern formation predominantly on short temporal and fine spatial scales.

The Role of Frugivorous Bats in Tropical Forest Succession

Discussion of successional change has traditionally focused on plants. The role of animals in producing and responding to successional change has received far less attention. Dispersal of plant propagules by animals is a fundamental part of successional change in the tropics. Here we review the role played by frugivorous bats in successional change in tropical forests. We explore the similarities and differences of this ecological service provided by New and Old World seed-dispersing bats and conclude with a discussion of their current economic and conservation implications. Our review suggests that frugivorous New World phyllostomid bats play a more important role in early plant succession than their Old World pteropodid counterparts. We propose that phyllostomid bats have shared a long evolutionary history with small-seeded early successional shrubs and treelets while pteropodid bats are principally dispersers of the seeds of later successional canopy fruits. When species of figs (Ficus) are involved in the early stages of primary succession (e.g. in the river meander system in Amazonia and on Krakatau, Indonesia), both groups of bats are important contributors of propagules. Because they disperse and sometimes pollinate canopy trees, pteropodid bats have a considerable impact on the economic value of Old World tropical forests; phyllostomid bats appear to make a more modest direct contribution to the economic value of New World tropical forests. Nonetheless, because they critically influence forest regeneration, phyllostomid bats make an important indirect contribution to the economic value of these forests. Overall, fruit-eating bats play important roles in forest regeneration throughout the tropics, making their conservation highly desirable.

Abundance of narG , nirS , nirK , and nosZ Genes of Denitrifying Bacteria during Primary Successions of a Glacier Foreland

Quantitative PCR of denitrification genes encoding the nitrate, nitrite, and nitrous oxide reductases was used to study denitrifiers across a glacier foreland. Environmental samples collected at different distances from a receding glacier contained amounts of 16S rRNA target molecules ranging from 4.9 x 10(5) to 8.9 x 10(5) copies per nanogram of DNA but smaller amounts of narG, nirK, and nosZ target molecules. Thus, numbers of narG, nirK, nirS, and nosZ copies per nanogram of DNA ranged from 2.1 x 10(3) to 2.6 x 10(4), 7.4 x 10(2) to 1.4 x 10(3), 2.5 x 10(2) to 6.4 x 10(3), and 1.2 x 10(3) to 5.5 x 10(3), respectively. The densities of 16S rRNA genes per gram of soil increased with progressing soil development. The densities as well as relative abundances of different denitrification genes provide evidence that different denitrifier communities develop under primary succession: higher percentages of narG and nirS versus 16S rRNA genes were observed in the early stage of primary succession, while the percentages of nirK and nosZ genes showed no significant increase or decrease with soil age. Statistical analyses revealed that the amount of organic substances was the most important factor in the abundance of eubacteria as well as of nirK and nosZ communities, and copy numbers of these two genes were the most important drivers changing the denitrifying community along the chronosequence. This study yields an initial insight into the ecology of bacteria carrying genes for the denitrification pathway in a newly developing alpine environment.

Effects of arbuscular mycorrhizal fungi and soil developmental stages on herbaceous plants growing in the early stage of primary succession on Mount Fuji

AbstractA pot culture experiment was conducted to examine the effects of arbuscular mycorrhizal (AM) fungi and soil developmental stages on the growth and nutrient absorption of pioneer plants growing in the early stage of primary succession on Mt. Fuji. Four herbaceous plants, Polygonum cuspidatum (Polygonaceae), Miscanthus oligostachyus (Gramineae), Aster ageratoides var. ovatus (Compositae), and Hedysarum vicioides (Leguminosae), were grown from seed in soils collected from two different successional stages, bare ground and an herbaceous plant community. Spores of indigenous AM fungi collected from the herbaceous plant community were used as inoculum. The initial colonizer P. cuspidatum showed very low levels of AM colonization (<0.4%), whereas the average AM colonization levels of M. oligostachyus, A. ageratoides var. ovatus, and H. vicioides were within the range of 13–49%. AM fungi had positive effects on the growth and N acquisition of the leguminous species (H. vicioides) irrespective of soil developmental stages. In contrast, AM colonization did not increase the plant dry weight and N content of the non‐leguminous species (P. cuspidatum, M. oligostachyus, and A. ageratoides var. ovatus) in both soil developmental stages. A positive effect of AM colonization on P content was observed in M. oligostachyus, A. ageratoides var. ovatus, and H. vicioides only in soil collected from the herbaceous plant community. P. cuspidatum showed no or a negative response to AM colonization in all cases. These results suggest that the effect of AM fungi on plant growth depends more on the plant species than soil developmental stages in the early stage of primary succession in this volcanic area.