Course Of Secondary Succession Research Articles

Hosszú távú kaszálás hatása a vegetációra és a biomassza összetételére a Nyugat-Cserhát pannon száraz gyepeiben

This study is focusing on the vegetation of seminatural dry grasslands. Those loess grasslands are valuable with large biodiversity; however their long-term preservation requires regular conservation management. The report demonstrates the results of mowing experiment, designed to suppress the spread of unpalatable grass species, Calamagrostis epigeios. The study site is located in mid-successional loss grasslands, in the Western-Cserhát, near Rád, northern Hungary.
 The study aims to the investigate the followings: Can the unpalatable Calamagrostis epigejos be suppressed by mowing? Are there possibilities to increase the diversity of sward by this? The study aims, to measure potential value-increasing effect of mowing, and to determine the carrying capacity in the aspect of grassland management.
 In 2001, Camagrostis epigeios was the species with the highest coverage rate according to the both treatment types, with an average cover value of 63%. However, as a result of mowing, a significant difference was detected in the amount of litter and legumes species as well. The number of species showed a slight increase in both types of treatment, from 15 to 37 in the mowed plots, but also from 18 to 27 in the control plots. We concluded that mowing twice a year was beneficial to modify botanical composition of a grassland. In a way it was suited well for agricultural usage, in particular grazing which can replace the expensive and time-consuming scythe. It is also a suitable management measure for controlling the native invader species as a Calamagrostis epigeios, and can significantly increase the proportion of species with higher forage values.
 Mowing has significantly increased the density of Calamagrostis epigeios, the species richness, and the diversity in the course of secondary succession. Therefore, mowing twice a year proved to be a successful management measure for controlling Calamagrostis epigeios, and for obtaining a sward composition. The treatment was effective in restoring grassland composition, although the achievement and maintenance of favourable conservation status for the grassland habitat require long-term management planning and regular treatment. According to the objectives, mowing not only promotes the control of the invasive species, but also the economic utilization of the area.

Avifauna Structure Of Boreal Zone Open Habitats (Ishim Plain, Western Siberia)

Abstract In 2014‒2016 field seasons, bird censuses were conducted on 34 flyways in seven different types of open habitats of the Russian part of the Ishim River region. Ninety-five species from 72 genera from 10 orders were registered. It is established that the taxonomic composition and ecological structure of avifauna of the habitats under investigation comply with their biotopical characteristics; diversity of taxons and ecological groups show positive correlation with habitats’ heterogeneity. In natural habitats, the maximum total abundance of birds, highest species diversity within the habitat (α-diversity) and species sustainability are characteristic of river meadows ornithocenoses, mainly due to low-numbered species and a higher evenness index. In disturbed habitats, the maximum total abundance, species diversity, Shannon diversity index, Pielou’s evenness index, minimal index of diversity and highest indices of elastic and general sustainability are characteristic of abandoned fields ornithocenoses, due to a more complex structure of vegetation communities and habitat resource capacity, which increased in the course of secondary succession. Due to natural and historical unity, middle and northern forest steppe’s avifaunae are most similar. The southern taiga open habitats’ ornithocenoses are most heterogeneous, due to an increased amount of dendrophilous birds along with forest habitats’ increased area and diversity.

Changes in soil microbial community structure during long‐term secondary succession

AbstractUnderstanding the changes in microbial community composition that occur during succession can help elucidate the mechanisms that drive successional dynamics. However, the mechanisms underlying community assemblages and promoting temporal succession are often overlooked in microbial ecology, and comparisons of the relative roles of bacteria and fungi during long‐term secondary succession are rare. Using both 16S and ITS rRNA gene sequencing, we studied shifts in bacterial and fungal communities in a well‐established secondary successional chronosequence that spanned approximately 160 years in an ecosystem. Our results showed that the abundance of both bacteria and fungi increased with succession in the early stages but then reached a relatively stable state in later successional stages. Diversity showed a fairly linear increase with succession, and there were inconsistent changes between the bacterial and fungal communities. During succession, soil bulk density, soluble carbon, total nitrogen and plant richness had large effects on the microbial community. The abundance of most phyla showed parabolic trends with succession; however, Verrucomicrobia and Basidiomycota showed linear increases with succession, and Cercozoa and Chytridiomycota showed linear decreases with succession. These microbial taxa may be considered collaborative development microbial biomarkers of secondary succession. The predicted microbial functions related to C and N cycle genes showed corresponding changes in succession, which need further study. Our findings suggest that the relationships between soil physicochemical properties and microbial communities mutually influence one another, leading to their ongoing relationship in the course of secondary succession.

The effects of different mowing regimes on diversity of grasses in lowland meadows

This study addresses the question of how changing the mowing regime influences the floristic composition and floristic diversity of grasses in an experimental lowland meadow. The study location is Bia?owie?a Forest, NE Poland. To achieve the aim we used phytosociological data from long-term studies in Bia?owie?a Forest on the course of secondary succession. The relationship between the biodiversity of grasses and type of mowing was determined using statistical analysis. Changes in the dominance and frequency of individual grass species have occurred during the last 28 years of observations. The analysis of floristic similarity demonstrated a turnover of species between the individual years of observation. Principal component analysis showed that the change in mowing method resulted in a change of the species composition, cover, and domination. However, differences in the intensity of disturbance level were rather small (one cut yearly by scythe, by sickle bar mower, and by trimmer), and changes in floristic composition were also moderate in most years. During the initial years (1984?1990), Dactylis glomerata, Agrostis gigantea, and Anthoxanthum odoratum dominated. After 1990, Arrhenatherum elatius and Holcus lanatus spread and took over, with Trisetum flavescens joining them later. Between 2008 and 2012 the cover of Dactylis glomerata increased more than two times. The reasons for the floristic transformations were changes in the management mode, e.g., the transition from mowing by scythe (medium disturbance) to mechanized mowing, first by sickle bar mower (strong disturbance) and then by trimmer (weak disturbance).

Rodent community responses to vegetation and landscape changes in early successional stages of tropical dry forest

The extent to which the array of land covers dominating anthropogenic landscapes impacts on biodiversity remains today an open question of great relevance. The characteristics of the animal communities inhabiting tropical forest early successional stages can determine, to a large extent, the course of secondary succession and natural regeneration. In this study, we evaluated the response of terrestrial rodents to variations in vegetation and landscape attributes, in early stages of tropical dry forest succession, at three integration levels: (1) communities, (2) populations, and (3) individuals. Our results reveal a rodent response to the variation in vegetation and landscape attributes, which indeed was largely modulated by seasonality, and determined by the focal spatial scale considered. In general, most of the species were favored by vegetation structure simplification and increase in understory density, probably due to the increase in refuge and trophic resources. Nevertheless, one species, Lyomis pictus, was sensitive to variation in vegetation composition and negatively affected by a reduction in vegetation structural complexity, which could be explained by the high number of tree seeds included in their diet. We found a higher diversity of rodents in sites surrounded by a high coverage and connectivity of dry and riparian forest, probably because large forest patches act as sources of species and the forest connectivity favors the colonization process toward sites under regeneration. Our results showed that preserving remnants of the original vegetation and implementing management actions at different spatial scales in anthropogenic landscapes is critical for preventing: (1) an increase in generalist populations, (2) rapid faunal homogenization, (3) defaunation, and (4) the loss of specialist species; with profound implications for the ecology of forest, ecosystem services and human health.

Effect of vegetation and its succession on water repellency in sandy soils

AbstractVegetation and its succession can change the parameters of soil water repellency (SWR) due to the change in amount and composition of soil organic matter. This hypothesis was tested in natural and agricultural environments in Germany, Hungary, and Slovakia. The parameters investigated were the extent (determined by the repellency indices RI, RIc, and RIm) and persistence (determined by the water drop penetration time and water repellency cessation time) of SWR, as well as the potential wettability index of organic matter in sandy soils. The SWR parameters and soil organic carbon (SOC) content increased in the course of primary succession at Mehlinger Heide, Germany, and Sekule, Slovakia. Dye tracer experiments undertaken at Sekule revealed contrasting flow patterns: (a) preferential flow in water‐repellent soil under biological soil crust and grass and (b) piston flow in wettable soil that consists almost of pure quartz sand. The effective flow cross section decreased, and the degree of preferential flow increased in the course of primary succession at Sekule. No consistent trend of the SWR parameters and SOC was observed in the course of secondary succession at Csólyospálos, Hungary. This is the first time that differences between trends in SWR parameters due to primary and secondary successions were observed and related to the composition of SOC and extracellular polymeric substances. It can be concluded that dynamics of soil organic matter composition during the succession controls SWR.

Convergence of community composition during secondary succession on Zokor rodent mounds on the Tibetan Plateau

The community succession theory is much debated in ecology. We studied succession on Zokor rodent mounds on the Tibetan Plateau to address several fundamental questions, among them: (i) During secondary succession, does the community composition converge towards one community state or multiple states depending on the initial colonization? (ii) Do mound communities located in different background communities exhibit different assembly trajectories? In a sub-alpine meadow, we investigated a total of 80 mound communities at several successional stages in three different background communities resulting from different management histories and compared their changes in species composition. The distribution of plant communities over time was analyzed with quantitative classification and ordination methods. The co-occurrence patterns of species were evaluated at each successional stage, and the degree of convergence/divergence among communities was obtained by calculating two beta-diversity indices. During secondary succession, species richness of mound communities changed over time, and this change was dependent on the background community. Five life-form groups exhibited different dynamic patterns in species richness and plant cover. Community composition and the degree of species co-occurrence between communities increased over time since disturbance. There was much variation in species composition at earlier stages of succession, but communities on older mounds became more similar to each other and to their surrounding vegetation over the course of secondary succession. Post-disturbance succession of Zokor mound communities transitioned from ‘multiple alternative states’ to ‘background-based deterministic community assembly’ over time. Tradeoffs between competition and colonization, as well as the characteristics of different life-forms and mass effects within a limited species pool are the mechanisms responsible for convergence of mound communities.

Multiscale analysis of factors influencing herpetofaunal assemblages in early successional stages of a tropical dry forest in western Mexico

The Tropical Dry Forest (TDF) is one of the most highly transformed and threatened neotropical systems in the world and much of its original area has been replaced by secondary forests. Therefore, it is important to understand the process of ecological succession underlying the natural regeneration of TDF, especially the role of early successional stages as drivers of the course of secondary succession. In this study, we investigated the response of herpetofaunal assemblages to vegetation and landscape attributes in areas dominated by early successional stages of TDF. Such response was evaluated in terms of assemblage's composition, richness, taxonomic diversity and functional diversity. We found a high variation in composition, richness and diversity of herpetofaunal assemblages at the initial stages of TDF succession. According to our hypothesis, in general we found the richest herpetofaunal assemblages in sites embedded in the most conserved matrix with higher levels of vegetation cover. Additionally, patch density of forest was also associated to the variation in assemblages' richness. We found high specificity on the response of frogs, lizards and snakes to the surveyed local and landscape attributes. This response involved both taxonomic and functional diversity. This study shows that composition and quality of the surrounding matrix can actually drive the maintenance of herpetofauna species in early successional stages. Considering that these stages greatly influence the course of secondary succession, the natural regeneration of the herpetofauna communities of TDF will depend not only on the local vegetation attributes but also on the initial status of the surrounding matrix. Thus, in order to preserve the resilience of the herpetofaunal assemblages it is important an adequate management of the system, maintaining high levels of the original vegetation in anthropogenic landscapes.

Simulating Changes in Fires and Ecology of the 21st Century Eurasian Boreal Forests of Siberia

Wildfires release the greatest amount of carbon into the atmosphere compared to other forest disturbances. To understand how current and potential future fire regimes may affect the role of the Eurasian boreal forest in the global carbon cycle, we employed a new, spatially-explicit fire module DISTURB-F (DISTURBance-Fire) in tandem with a spatially-explicit, individually-based gap dynamics model SIBBORK (SIBerian BOReal forest simulator calibrated to Krasnoyarsk Region). DISTURB-F simulates the effect of forest fire on the boreal ecosystem, namely the mortality of all or only the susceptible trees (loss of biomass, i.e., carbon) within the forested landscape. The fire module captures some important feedbacks between climate, fire and vegetation structure. We investigated the potential climate-driven changes in the fire regime and vegetation in middle and south taiga in central Siberia, a region with extensive boreal forest and rapidly changing climate. The output from this coupled simulation can be used to estimate carbon losses from the ecosystem as a result of fires of different sizes and intensities over the course of secondary succession (decades to centuries). Furthermore, it may be used to assess the post-fire carbon storage capacity of potential future forests, the structure and composition of which may differ significantly from current Eurasian boreal forests due to regeneration under a different climate.

Microbial Community and Greenhouse Gas Fluxes from Abandoned Rice Paddies with Different Vegetation.

The area of rice paddy fields has declined continuously in East Asian countries due to abandonment of agriculture and concurrent socioeconomic changes. When they are abandoned, rice paddy fields generally transform into wetlands by natural succession. While previous studies have mainly focused on vegetation shifts in abandoned rice paddies, little information is available about how these changes may affect their contribution to wetland functions. As newly abandoned fields proceed through succession, their hydrology and plant communities often change. Moreover, the relationships between these changes, soil microbial characteristics, and emissions of greenhouse gasses are poorly understood. In this study, we examined changes over the course of secondary succession of abandoned rice paddies to wetlands and investigated their ecological functions through changes in greenhouse gas fluxes and microbial characteristics. We collected gas and soil samples in summer and winter from areas dominated by Cyperaceae, Phragmites, and Sphagnum in each site. We found that CO2 emissions in summer were significantly higher than those in winter, but CH4 and N2O emission fluxes were consistently at very low levels and were similar among seasons and locations, due to their low nutrient conditions. These results suggest that microbial activity and abundance increased in summer. Greenhouse gas flux, soil properties, and microbial abundance were not affected by plant species, although the microbial community composition was changed by plant species. This information adds to our basic understanding of the contribution of wetlands that are transformed from abandoned rice paddy systems.

Soil–vegetation interactions in abandoned farmland within the temperate region of Europe

Forests are becoming increasingly dominant in the landscape of north-eastern Europe as a result of a decline in agriculture, land abandonment and the related trend of afforestation. This is also the case in Latvia, where former agricultural land is either artificially afforested or taken over by the natural process of secondary succession. A large spatial and temporal variety of succession and compositional diversity of tree species colonizing fields is observed in the central part of Latvia. Understanding of the possible scenarios in the development of plant communities after land abandonment is important for deciding on viable management solutions, e.g. restoration of semi-natural grasslands or forest regeneration. The aim of the research was to determine the factors affecting the course of secondary succession at its initial stage and the composition of tree species that are colonizing abandoned fields. Ten abandoned fields were surveyed, recording species composition and vegetation structure, determining soil properties and analysing correlations between these factors. The research results help to explain the mechanisms of how soil properties affect the course of succession. On fertile soils a dense herbaceous layer developed, which in abandoned fields resulted in accumulation of a thick cover of litter. Such conditions hinder establishment of typical pioneer species, e.g. grey alder Alnus incana, aspen Populus tremula and birch Betula pendula, whereas Norway spruce Picea abies is able to compete with grass species and thus can more easily establish in abandoned fields, creating favourable conditions for invasion by other tree species.

Secondary successional trajectories of structural and catabolic bacterial communities in oil-polluted soil planted with hybrid poplar.

Poplars have widely been used for rhizoremediation of a broad range of organic contaminants for the past two decades. Still, there is a knowledge gap regarding the rhizosphere-associated bacterial communities of poplars and their dynamics during the remediation process. It is envisaged that a detailed understanding of rhizosphere-associated microbial populations will greatly contribute to a better design and implementation of rhizoremediation. To investigate the long-term succession of structural and catabolic bacterial communities in oil-polluted soil planted with hybrid poplar, we carried out a 2-year field study. Hybrid aspen (Populus tremula × Populus tremuloides) seedlings were planted in polluted soil excavated from an accidental oil-spill site. Vegetated and un-vegetated soil samples were collected for microbial community analyses at seven different time points during the course of 2 years and sampling time points were chosen to cover the seasonal variation in the boreal climate zone. Bacterial community structure was accessed by means of 16S rRNA gene amplicon pyrosequencing, whereas catabolic diversity was monitored by pyrosequencing of alkane hydroxylase and extradiol dioxygenase genes. We observed a clear succession of bacterial communities on both structural and functional levels from early to late-phase communities. Sphingomonas type extradiol dioxygenases and alkane hydroxylase homologs of Rhodococcus clearly dominated the early-phase communities. The high-dominance/low-diversity functional gene communities underwent a transition to low-dominance/high-diversity communities in the late phase. These results pointed towards increased catabolic capacities and a change from specialist to generalist strategy of bacterial communities during the course of secondary succession.

Changing importance of environmental factors driving secondary succession on molehills

Question: Species composition during secondary succession is influenced by a number of factors, such as soil moisture, disturbance timing and surrounding vegetation. How does the importance of these factors change over the course of succession? Methods: We set up a full-factorial block design using molehills differing in (a) disturbance timing, (b) soil moisture and (c) composition of surrounding vegetation, and recorded the cover of all species present on the molehills over 3 years. M1ultiple regression analyses on the dissimilarity matrices of community composition and of environmental factors were applied for each of five age classes of molehills to estimate the effect of the single factors at different stages of succession. Results: The timing of disturbance did not significantly affect community composition at any stage of succession. In contrast, the effects of soil moisture and surrounding vegetation changed significantly over time, with moisture being more important at earlier stages of succession and surrounding vegetation at later stages. Conclusion: The importance of environmental factors for species composition change significantly over the course of secondary succession. Instead of aggregating the effects of environmental factors over time, future studies should consider underlying dynamics of recolonization more comprehensively.

Woody debris stocks and fluxes during succession in a dry tropical forest

In Southern Mexico, shifting cultivation is creating a mosaic of agricultural lands, secondary forests, and disturbed mature forests (montañas). Increased land-use change, due to population and market pressures has changed the structure and function of these forests. This study investigates the stocks and fluxes of woody debris during the course of secondary succession. We inventoried fine (≥1.8 cm to ≤10 cm diameter) and coarse woody debris (≥10 cm diameter) stocks in 28 stands. In a subset of montañas and secondary forest fallows, we monitored inputs and decomposition over a 2-year period. Total woody debris stocks were largest in montañas (37.46 Mg/ha) and in the first year after clearing (milpa, 51.62 Mg/ha). Woody debris was 22% of the total aboveground biomass in montañas and 88% in milpas. Although stocks were highly variable in secondary forest, coarse woody debris stocks were roughly three times larger than fine woody debris stocks. Coarse woody debris stocks decreased following cultivation for 10–15 years, until inputs exceeded losses to decomposition. Inputs were higher in montaña (0.91 Mg ha −1 year −1) than in secondary forest (0.11 Mg ha −1 year −1). Coarse woody debris inputs were higher during the dry season, while fine woody debris inputs tended to be higher during the wet season. Decomposition varied significantly among tree species, with decomposition rate constants from 0.124 to 0.643 year −1 for coarse woody debris and 0.368–0.857 year −1 for fine woody debris. In young forests, when woody debris stocks are largest, cultivation history is the most important factor in predicting stocks of woody debris. As forest age increases woody debris processes, both inputs and decomposition, become increasingly important factors in regulating woody debris stocks, and therefore age is a better predictor of woody debris stocks in older forests.

Competitive dominance in a secondary successional rain-forest community in Borneo

Competitive interactions among pioneer species may have a significant impact on the course of secondary succession in tropical rain forests. We predicted that the outcome of competitive interactions in early succession would vary with soil nutrient availability. To test this hypothesis we grew seven pioneer tree species alone and in dense competitive mixtures, with four nutrient treatments: no nutrient addition, and N, P, and N plus P addition. Performance of plants grown alone and in mixtures was strongly nutrient limited. However, contrary to expectation, the competitive hierarchy among the seven species was almost identical among the four nutrient treatments. The dominant species, Melastoma malabathricum, accounted for > 70% of total stand biomass in all nutrient treatments. Seedlings of this species had higher rates of gas exchange and initial growth, and lower root allocation than the other species. Profiles of light availability within the competitive stands indicated that light levels at ground level were well above levels at which pioneer species can successfully survive and grow, yet seedlings of species other than Melastoma remained stunted. Leaf N concentrations in all stands were 25–55% reduced by competitive interactions, and N addition increased relative competitive performance in only Melastoma suggesting that Melastoma was particularly effective at N acquisition, limiting nutrient uptake by the other species. Toward the end of the experiment individuals of Melastoma began to reproduce, suggesting that the competitive hierarchy would have changed in a longer-duration experiment.

Changing course of secondary succession in abandoned sandy fields

The vegetation of abandoned arable fields on dry sandy soils was investigated in 1986 and again in 2000. Comparison of the two data sets by ordination, calibration based on indicator values, and statistical modelling revealed that the vegetation in 2000 differed significantly from the vegetation in 1986. Part of this difference could be explained by field age, but significant difference remained after correction for age. The analysis showed that species indicating nutrient-rich and acidic conditions were more abundant in the 2000 samples than expected from the age of the fields. Possible causes for the observed differences are discussed, and the role of airborne nitrogen deposition and landscape changes is emphasised. Changing course of successional processes may place serious constraints on future habitat restoration.

Secondary succession of scuttle fly communities (Diptera: Phoridae) in moist pine forest in Białowieża Forest

The aim of the research was to define changes taking place in scuttle fly communities in the course of secondary succession of moist pine forest, and to determine which variant of secondary succession was being realized by this community. For this purpose the following were analysed: data on the number and abundance of species, on the species diversity of their communities and on the frequency distributions of the species which determined the structural relations within the taxon.

The effects of foraging by the superb lyrebird (Menura novae‐hollandiae) in Eucalyptus regnans forests at Beenak, Victoria

Abstract In an early spar‐stage stand of Eucalyptus regnans at Beenak, Victoria, foraging by lyrebirds in bare floor areas on steep slopes results in a complex microtopography of excavations, accumulations and terracettes. About 200 t ha−1 of litter and top soil may be displaced an average of 70 cm downhill per year. Magnetic ferruginous pisolite was used as a marker to monitor progressive soil movement over 3 years. Very little disturbance occurred in areas of dense ground fern, but in bare areas the whole forest floor may be turned over every 20 months. In the site studied, foraging activity by lyrebirds varied seasonally and topographically. Disturbance by other biotic agents was minimal. The mean depth of soil cultivation was about 10 cm and litter was frequently buried or mixed intimately with soil. Since buried leaf litter decays more quickly than that on the surface, lyrebird foraging is likely to increase the rate of nutrient cycling. The small, steep clifflets left at the uphill limits of each scratch microsite provide litter‐free niches for the establishment of tree fern prothalli and shade‐tolerant herbs. All stages in the growth of the rough tree fern, Cyathea australis, were present in bare floor areas, but in dense ground fern patches, young stages were confined to rotten logs and upturned root balls. Since dense tree fern development tends to diminish the cover of dense ground fern, lyrebird foraging activity may maintain an accessible food resource which would otherwise diminish with increased ground fern cover in these forests in the course of secondary succession after fire.

Regeneration in a Pole-Stage Forest of Eucalyptus regnans Subjected to Different Fire Intensities in 1982

In 1982, fire burnt stands of Eucalyptus regnans F.Muell. in a relatively dry site in Victoria. In one area, the fire killed both canopy and understorey; in an adjacent area, only understorey was destroyed. Regeneration in the two areas was similar over the following year, but diverged thereafter to produce understoreys with different species dominance. In both stands, a poor supply of mature E. regnans seed in the crowns at the time of the fire resulted in relatively low initial density of seedlings: in the firekilled stand, this meant that closure of the canopy of the stratum was delayed for 5 or 6 years; however, in the understorey-killed stand, none of the E. regnans seedlings survived for 2 years. The soil seed bank was reduced more severely in the fire-killed than in the understorey-killed stand, although not all seed germinated in the first year. Vegetative regeneration of herbs and shrubs occurred from shallower layers of soil in the understorey-killed than in the fire-killed stand. An increase in soil fertility after the fire, as measured by seedling bioassay, was apparent only in the first season after the fire and was correlated with higher levels of available P. In the understorey-killed stand, fertility in the topsoil was greater than that in the fire-killed stand, and growth in diameter at breast height of dominant trees was significantly greater than in adjacent unburnt stands in the first few years after the fire. By comparison, when fire burnt through a site of higher rainfall after the maturation of the current crop of canopy-stored seed, regeneration was initially denser and growth considerably greater than that in the drier site. The study demonstrated that the course of secondary succession depends on site quality, timing of the fire in relation to seed production, soil seed germination, vegetative growth from protected organs, the severity of the fire, the presence or absence of browsing, and, in the long term, the frequency of recurrent fire.

Element interactions in forest ecosystems: succession, allometry and input-output budgets

Element interactions within forests differ from those in other major ecosystems for three major reasons: — a greater allocation of carbon to structural material; — a greater element storage within biomass; and — the diversity of carbon- and nutrient-containing metabolites produced. The most important of these differences is structural material, which can lead to C: element ratios in biomass (as a whole) 100 × greater than those in unicellular organisms. Stand allometry causes the amount of carbon stored and C:element ratios in biomass to change in predictable ways in the course of secondary succession. Such changes affect microbial dynamics and C: element interactions within soils. Bicarbonate, organic acids, nitrate, phosphate, and sulfate are major anions within forest soils: they control leaching of both anions and cations. Biotic interactions of C, N, P, and S during both uptake and mineralization control the potential for production of these anions within forests, and geochemical interactions regulate their mobility and loss.