Forest Successional Stages Research Articles

Primary production in forests of the mangrove palm Nypa fruticans

We investigated the forest structure, leaf demography, leaf allometry and growth of the erect canopy of the mangrove palm Nypa fruticans in four river systems distributed over 10 degrees of latitude in the tropics of northeast Australia and Papua New Guinea to obtain estimates of aboveground biomass (AGB) and annual aboveground net primary production (ANPP). In the four river sites Nypa mean leaf and tree densities ranged from 6538 to 12,200 leaves ha−1, and 1526 to 3550 trees ha-1 and differed significantly among sites, with the lowest densities at the lowest latitude site. AGB ranged from 36.5 to 55.7 Mg ha−1 and also differed among sites with the lowest AGB at the lowest latitude site. The mean plastochron increased with increasing periods of cooler air temperatures. Mean litter production per tree (range, 6.0–16.2 kg year−1) was least in the low latitude site and mean total productivity per tree (range, 13.9–25.1 kg year−1) did not differ significantly across sites. ANPP was lowest in the low latitude site and ranged from 23.8 to 60.9 Mg ha−1 year−1. This placed Nypa forests in the mid to high range of global estimates of ANPP. Rates of litter production at three sites (range, 25.7–37.5 Mg ha−1 year−1) was much greater than for litterfall in any other mangrove forest. ANPP estimated using a combination of demographic data and leaf allometry compares well with previous estimates using a light interception method to predict productivity. The complex pattern of differences in forest structure, growth and ANPP across latitudes likely represent differences in catchment land use, successional stages of forests, river discharge and variation in the length of the dry season.

Recovery of a boreal ground‐beetle (Coleoptera: Carabidae) fauna 15 years after variable retention harvest

Abstract Retention harvests are preferred over traditional clear‐cuts for sustainable forest management because maintenance and re‐establishment of native forest biodiversity is a priority. However, few studies have examined long‐term responses of biotic assemblages to retention harvest at particular sites. We studied the effects of decreasing initial harvest intensities (clear‐cut, 10%, 20%, 50% and 75% dispersed green‐tree retention) on carabid beetle assemblages relative to assemblage changes in un‐harvested control stands in four successionally ordered cover‐types of boreal mixedwood forest. We also studied temporal effects by comparing assemblages over a 16‐year pre‐ and post‐harvest period, using data collected through monitoring of the EMEND (Ecosystem Management Emulating Natural Disturbance) experiment in NW Alberta, Canada. Retention harvests affected assemblages differently across cover‐types. Assemblages in compartments harvested in the earlier forest successional stages of ‘deciduous’ or ‘deciduous with spruce understorey’ converged towards the pre‐harvest structure of corresponding controls over time. In contrast, beetle assemblages in ‘mixed’ or ‘conifer’ compartments, that represent later successional forest, moved steadily away from their pre‐harvest structures during the first post‐harvest decade. These latter assemblages became strikingly more similar to those under deciduous canopies by 15‐year post‐harvest. Synthesis and applications. Variable retention harvests will promote and maintain biodiversity better than clear‐cutting. Higher retention levels promote faster recovery, but towards fauna typical of early successional forest in all cover‐types. Carabids associated with conifer habitats are less resistant to impact from harvesting than are those from broadleaf deciduous forest. Therefore, conifer‐dominated stands present the most significant management challenge and higher retention levels are required to promote rapid and effective faunal recovery in such late successional stands.

Successional Variation in the Soil Microbial Community in Odaesan National Park, Korea

Succession is defined as variation in ecological communities caused by environmental changes. Environmental succession can be caused by rapid environmental changes, but in many cases, it is slowly caused by climate change or constant low-intensity disturbances. Odaesan National Park is a well-preserved forest located in the Taebaek mountain range in South Korea. The forest in this national park is progressing from a mixed-wood forest to a broad-leaved forest. In this study, microbial community composition was investigated using 454 sequencing of soil samples collected from 13 different locations in Odaesan National Park. We assessed whether microbial communities are affected by changes in environmental factors such as water content (WC), nutrient availability (total carbon (TC) and total nitrogen (TN)) and pH caused by forest succession. WC, TC, TN and pH significantly differed between the successional stages of the forest. The WC, TC and TN of the forest soils tended to increase as succession progressed, while pH tended to decrease. In both successional stages, the bacterial genus Pseudolabrys was the most abundant, followed by Afipia and Bradyrhizobium. In addition, the fungal genus Saitozyma showed the highest abundance in the forest soils. Microbial community composition changed according to forest successional stage and soil properties (WC, TC, TN, and pH). Furthermore, network analysis of both bacterial and fungal taxa revealed strong relationships of the microbial community depending on the soil properties affected by forest succession.

Impact of vegetation succession on leaf-litter-soil C:N:P stoichiometry and their intrinsic relationship in the Ziwuling Area of China\u2019s Loess Plateau

Long-term natural vegetation succession plays a substantial role in the accumulation and distribution of plant and soil C:N:P stoichiometry. However, how plant and soil C:N:P relationships or ratios change along with successional stages over a century in the severely eroded areas remain unclear. These were measured over a 100-year natural succession in five successional stages from annual grasses to climax forests. The results show that natural succession had significant effects on carbon (C), nitrogen (N) and phosphorous (P) concentrations in leaf-litter-soil and their ratios in severely eroded areas. Nitrogen concentrations and N:P ratios in leaf and litter increased from annual grasses to the shrub stage and then decreased in the late successional forest stages. Leaf P levels decreased from annual grasses to shrub stages and did not significantly change during late successional stages. Litter P concentration decreased in the early successional stages and increased during late successional stages, with no overall significant change. Soil C and N concentrations and C:N, C:P and N:P ratios increased with successional stages. Soil C and N concentrations decreased with the increasing soil depth. Both were significantly different between any successional stages and controls (cropland) in the upper 10 cm and 10–20 cm soil layers. Leaf N:P ratios may be used to indicate nutrient limitations and this study suggests that plant growth during the grass stages was limited by N, during the shrub stage, by P, and during the forest stages, by both of N and P. In addition, there were close correlations between litter and leaf C:N:P ratios, soil and litter C and N levels, and C:P and N:P ratios. These results show that long-term natural vegetation succession is effective in restoring degraded soil properties and improving soil fertility, and provide insights into C:N:P relationships of leaf, litter and soil influenced by vegetation succession stage.

Wild bee distribution near forested landscapes is dependent on successional state

BackgroundForested landscapes are valuable sources of ecosystem services especially in areas dedicated to intense agricultural activities. Distance from forest margin is known to influence the wild bee community in the landscape surrounding forested patches. Yet little is known regarding how bee communities distribute themselves in landscapes that exhibit different forest successional states.MethodsWe examined how land use type and distance from the forest edge affect the abundance and richness of the wild bee community across four forest successional states. Bees were collected in sites representing four stages of forest succession and analyzed using generalized linear mixed models with negative binomial distributions.ResultsWild bee diversity is reduced in forested environments that maintain dense stands of trees and high canopy cover. Additionally, distance from the forest edge was an important factor determining wild bee distribution in successional stages adjacent to forest edges. Furthermore, we found that bees maintain high specificity for distinct successional states and distances.ConclusionsOur results demonstrate how different successional stages can harbor different bee species and highlight the ability of microhabitats to act as reservoirs of bee diversity in and around forest margins. Furthermore, we found that maximizing successional patchiness across forested landscapes increases the amount of available habitat that can support a diverse suite of bees with different nesting biologies and behaviors.

Root suckering promotes recruitment in two temperate rainforest trees with contrasting shade tolerance

The regeneration niche differentiation helps to explain plant coexistence and thus biodiversity. The study of the regeneration niche has been traditionally based on sexual recruitment, while overlooking clonal growth. Root suckering offers a successful alternative for local dispersal under suboptimal conditions for sexual reproduction. For light-limited forests, we hypothesized that: 1) root suckering would increase the regeneration niche towards high-light conditions in shade-tolerant trees and towards dark conditions in light-demanding species; 2) contrasting responses of survival and growth to light availability would explain niche differentiation of both suckers and saplings; and 3) distinct responsiveness to light among species and recruit-types would reflect differences in functional traits. We tested these hypotheses with two evergreen tree species that coexist in the temperate rainforest of southern South America: Embothrium coccineum (light-demanding) and Eucryphia cordifolia (shade-tolerant). We measured the light availability in two study plots above each recruit and along transects established in the understory. Niche selection, niche differentiation and changes in survival probability with light were inferred from the analysis of the light frequency distributions. We evaluated the effect of light on the relative volumetric change in stems over a 1-year period. Functional traits of leaves, stems, and crowns were measured in suckers and saplings growing under similar light conditions; these traits were then compared among size classes, recruit-types and species. Root suckering was the prevalent reproduction mode of both studied species, extending the light niche towards open microenvironments only during the earliest ontogenetic stages. The poor structural strength of the leaves and wood of small Eucryphia saplings explains its underuse of open microsites. Neither photosynthetic assimilation nor carbon subsidy can sustain Embothrium suckers at the shadiest microsites. Suckering proved to increase the persistence of Embothrium until advanced stages of forest succession, facilitating its coexistence with the late-successional Eucryphia. Our study emphasizes that clonal growth is essential to understand the dynamics of temperate rainforests.

Alternate reproductive strategies of Populus nigra influence diversity, structure and successional processes within riparian woodlands along the Allier River, France

The European black poplar (Populus nigra L.) is a riparian tree that dominates the early successional stages of alluvial floodplain forests throughout Continental Europe. River management and hybrid poplar plantations have contributed to the loss of this foundational species, and measures to conserve and restore the ecologically rich and diverse natural woodlands must sustain poplar reproduction. P. nigra is able to reproduce through either generative (sexual) or vegetative (asexual or clonal) processes and this enhances its chances for preservation in future forests. This research was undertaken to quantify the dominant reproductive strategy of natural black poplar stands, and to determine how this influenced woodland structure and successional processes within the floodplains along the lower Allier River. Two approaches were integrated: (1) analyses of the degree of clonality of stands based on DNA genotyping, sapling excavations, and the uniformity of poplar height and spatial distributions; and (2) retrospective analyses of successional processes to investigate spatiotemporal correspondences with the reproductive strategies. Structural stand patterns indicated the dominant reproductive strategy, with vertical heterogenity indicating clonality, while generative stands were more uniform. One half (50.2%, or 164 ha) of the floodplain study area supported woodlands with P. nigra stands or individuals. Of this area, 42% had apparently reproduced generatively with limited clonality; 43% had dominantly vegetative regeneration with high clonality; and 15% included generatively established, solitary old trees. The generatively and vegetatively reproduced stands displayed generally similar establishment rates but differed in their spatial patterns, with generative seedling bands or patches largely limited to barren streamside sites, while vegetative stands were more diversely distributed. The reproductive types also differed in successional dynamics, with generative stands providing more persistent successional phases with longer residence times. Thus, sexual reproduction enables woodland colonization and introduces genetic diversity, while clonal reproduction expands the population and structural diversity. Both reproductive strategies should be encouraged to provide healthy, diverse and resilient riparian woodlands.

Rare species, functional groups, and evolutionary lineages drive successional trajectories in disturbed forests.

Following natural disturbances, additional anthropogenic disturbance may alter community recovery by affecting the occurrences of species, functional groups, and evolutionary lineages. However, our understanding of whether rare, common, or dominant species, functional groups, or evolutionary lineages are most strongly affected by an additional disturbance, particularly across multiple taxa, is limited. Here, we used a generalized diversity concept based on Hill numbers to quantify the community differences of vascular plants, bryophytes, lichens, wood-inhabiting fungi, saproxylic beetles, and birds in a storm-disturbed, experimentally salvage logged forest. Communities of all investigated species groups showed dissimilarities between logged and unlogged plots. Most species groups showed no significant changes in dissimilarities between logged and unlogged plots over the first seven years of succession, indicating a lack of community recovery. In general, the dissimilarities of communities were mainly driven by rare species. Convergence of dissimilarities occurred more often than divergence during the early stages of succession for rare species, indicating a major role in driving decreasing taxonomic dissimilarities between logged and unlogged plots over time. Trends in species dissimilarities only partially match the trends in dissimilarities of functional groups and evolutionary lineages, with little significant changes in successional trajectories. Nevertheless, common and dominant species contributed to a convergence of dissimilarities over time in the case of the functional dissimilarities of wood-inhabiting fungi. Our study shows that salvage logging following disturbances can alter successional trajectories in early stages of forest succession following natural disturbances. However, community changes over time may differ remarkably in different taxonomic groups and are best detected based on taxonomic, rather than functional or phylogenetic dissimilarities.

Quantifying the effect of shading and watering on seed germination in translocated forest topsoil at a subtropical karst of China

Soil translocation is recognized as a promising method to recover degraded ecosystems and save regionally threatened species, however, the diversity and density of woody species, and the similarity of germinated seedlings between translocated site and donor forest are always low, and few studies have paid attention to the manageable environmental factors for seed germination when forest topsoil exposed to strong light condition. In this study, we tested how shading treatment (ST) and watering treatments (WT) affect the germination of species in translocated forest topsoil and whether different life forms respond differently to different ST and WT following soil translocation. We found that the richness of shrub species had a positive linear relationship with WT, and increased by 0.8 species when additional 10 L m−2 water was added. The richness of trees species was positively linearly correlated with ST and increased by 0.5 species when 10 units of shade degrees was increased. The effect of ST on richness was greatest for total species, followed by herb and tree species, while the effect of WT affected these in the order total > herb > shrub species. The densities of shrub and tree species had a positive linear relationship with ST and increased by 1.0 and 1.2 seedlings m−2 when 10 units of shade degrees were increased respectively. Whereas, the densities of total species, herb species, and liana species had a parabolic relation with ST, reaching maximum densities of 79.8, 39.8, and 5.3 seedlings m−2 at shade degrees of 70%, 45%, and 27.5%, respectively. Moreover, the similarity between germinated communities and donor forest had positive linear relationship with ST and WT, except for herb species. Therefore, in theory, ST and WT significantly improved the diversity, density, and similarity of woody seedlings in translocated forest soil, but the density of herb and liana species decreased respectively when shade degrees exceeded 45% and 27.5% respectively. In practice, putting soil under moderate or heavy shade (shade degrees range from 45% to 70%) is a promising method to duplicate a diverse and similar forest if translocation process coincides with the rainy season. This finding can be incorporated into the practice and management of natural forest restoration and accelerate the early stage of forest restoration and succession.

Epiphyll specialization for leaf and forest successional stages in a tropical lowland rainforest

AbstractQuestionsThe importance of tropical rainforest gap dynamics in biodiversity maintenance is not fully understood, in particular for taxa other than trees and lianas. We used epiphylls on rainforest leaves to study the importance of leaf‐ and forest‐scale succession in determining biodiversity patterns by characterizing community change with leaf age in gaps and closed‐forest habitats. We asked: (1) Do epiphylls show specialization for leaf and forest successional stages? (2) Can early‐ and late‐successional epiphyllous species be recognized at these two scales? (3) How do epiphyll presence, species richness, and cover change with leaf and forest successional stages?LocationBarro Colorado Island, Panama.MethodData were collected from 420 leaves, in three age groups and at two heights on shrubs in gaps and closed forest. We calculated turnover and nestedness components of dissimilarity to evaluate the importance of species replacement or accumulation during leaf and forest succession. Using generalized linear mixed models we determined what factors explain epiphyll species occurrence, richness and cover.ResultsClosed forest contained more liverwort and lichen specialist species than gaps. Specialist species were identified for older leaves only. Dissimilarity between leaves within age groups was dominated by turnover within and between forest successional stages. Dissimilarity between leaf age groups, at the site level, was dominated by nestedness, i.e., species accumulation. Both in forest and gaps, epiphyll presence and cover increased with leaf age for all taxa except fungi, while species richness increased only for lichens.ConclusionEarly and late forest successional stages both contribute to epiphyll species richness by harboring specialized species. Among leaf successional stages, young leaves contain a mere subset of the species found on older leaves. Epiphyll communities do not follow classic succession, in the sense of changes being driven by species replacement, but are characterized by species accumulation through time.

Fire regime characteristics in relation to physiography at local and landscape scales in Lake States pine forests

Examining fire regime characteristics across temporal and spatial scales is critical to understanding relationships between fire and landscape physiography. In the Lake States (Wisconsin, Michigan, Minnesota) we have often relied on either broad extrapolation from local studies, and/or interpretations of coarse-scale Euro settlement era records tied to landscape-scale physiography to understand complex fire regimes. In this study, we used detailed fire frequency and origin-to-first-scar (OFS, patterns of fire-scar formation) intervals to evaluate fire characteristics in relation to physiography at local and landscape scales. We found frequent fires (mean fire return intervals, MFRI = 8 years) and widespread fire years were common among our sites. OFS intervals were also less than half as long (µ = 18.3) as intervals often deemed necessary for seedlings to survive fires (ca. 50 years). We found no differences in either MFRI or OFS intervals nor physiographic effects (topography and water features) at broad ecological landscape scales. Most variability in OFS was accounted for at a site scale with increased water features and topographical ruggedness both resulting in shorter OFS intervals (trees surviving and recording fires at a younger age). We found few differences in MFRI’s among sites, which ranged from 4 to 13 years. Relationships between fire resistance and stand level physiography, which was highly variable, may have a greater role than recognized in forest successional stages and stand dynamics.

A System Dynamics Model Examining Alternative Wildfire Response Policies

In this paper, we develop a systems dynamics model of a coupled human and natural fire-prone system to evaluate changes in wildfire response policy. A primary motivation is exploring the implications of expanding the pace and scale of using wildfires as a forest restoration tool. We implement a model of a forested system composed of multiple successional classes, each with different structural characteristics and propensities for burning at high severity. We then simulate a range of alternative wildfire response policies, which are defined as the combination of a target burn rate (or inversely, the mean fire return interval) and a predefined transition period to reach the target return interval. We quantify time paths of forest successional stage distributions, burn severity, and ecological departure, and use departure thresholds to calculate how long it would take various policies to restore forest conditions. Furthermore, we explore policy resistance where excessive rates of high burn severity in the policy transition period lead to a reversion to fire exclusion policies. Establishing higher burn rate targets shifted vegetation structural and successional classes towards reference conditions and suggests that it may be possible to expand the application of wildfires as a restoration tool. The results also suggest that managers may be best served by adopting strategies that define aggressive burn rate targets but by implementing policy changes slowly over time.

¿Refleja Formicidae el impacto de la degradación de los bosques ribereños en la Amazonía Oriental?

The increasing anthropogenic pressure on the Eastern Amazon makes the diagnostic of forest degradation imperative, particularly, the effect on key communities within the riparian ecosystems. Formicidae is commonly used in diagnostic and monitoring studies in areas under restoration. This study aimed to determine the impact of riparian forest successional stages (open areas, and, early, intermediate, and advanced succession) on the richness, frequency, and composition of Formicidae. Sampling was performed during both dry and wet seasons, with the TSBF (Tropical Soil Biological and Fertility) method. Collected organisms were identified to species and morphospecies level and the analysis of collector curves determined the method efficiency to represent the ant sub-community. Ant richness and frequency were submitted to generalized linear mixed models to evaluate the effects of season, local, and successional stage. We used linear regressions model to investigate the relationship between richness and frequency of ants with canopy cover and vegetation height. Species composition was represented by the Jaccard similarity index. In total, we observed 1940 individuals grouped into 86 (morpho)species. Analysis of sampling effort suggested that we obtained more than 80% of the probable species richness. Frequency and richness significantly increased following the advanced succession in comparison with the open areas during the dry season. Canopy cover and vegetation height seemed to moderately affect both richness and frequency of Formicidae during the dry season. Intermediate and advanced succession areas presented similar composition with 50 shared species, followed by the areas of early succession with 43, and, anthropic use with 34 shared species. We conclude that the elimination of riparian forests results in a substantial effect on the richness and frequency of Formicidae, with minimum values in open areas during the dry season. Forest areas transformed to agricultural systems suffered losses of 41% and 56% of richness and frequency respectively. Succession restores forest structure and functions thus, favoring re-colonization of ant species. Formicidae reflects forests degradation, and is a key group in monitoring programs for the conservation/restoration of local riparian forests. Agroforestry and silvopastoral systems should be promoted as low impact practices for adjacent lands to riparian forests.

Mapping forest successional stages in the Brazilian Amazon using forest heights derived from TanDEM-X SAR interferometry

Knowledge of the spatial patterns of successional stages (i.e., primary and secondary forest) in tropical forests allows to monitor forest preservation, mortality and regeneration in relation to natural and anthropogenic disturbances. Different successional stages have also different capabilities of re-establishing carbon stocks. Therefore, a successful discrimination of successional stages over wide areas can lead to an improved quantification of above ground biomass and carbon stocks. The reduction of the mapping uncertainties is especially a challenge due to high heterogeneity of the tropical vegetation. In this framework, the development of innovative remote sensing approaches is required. Forests (top) height (and its spatial distribution) are an important structural parameter that can be used to differentiate between different successional stages, and can be provided by Interferometric Synthetic Aperture Radar (InSAR) acquisitions. In this context, this paper investigates the potential of forest heights estimated from TanDEM-X InSAR data and a LiDAR digital terrain model (DTM) for separating successional stages (primary or old growth and secondary forest at different stages of succession) by means of a maximum likelihood classification. The study was carried out in the region of the Tapajós National Forest (Pará, Brazil) in the Amazon biome. The forest heights for three years (2012, 2013 and 2016) were estimated from a single-polarization in bistatic mode using InSAR model-based inversion techniques aided by the LiDAR digital terrain model. The validation of the TanDEM-X forest heights with independent LiDAR H100 datasets was carried out in the location of seven field inventory plots (measuring 50 × 50 m, equivalent to 0.25 ha), also allowing for the validation of the LiDAR datasets against the field data. The validation of the estimated heights showed a high correlation (r = 0.93) and a low uncertainty (RMSE = 3 m). The information about the successional stages and forest heights from field datasets was used to select training samples in the LiDAR and TanDEM-X forest heights to classify successional stages with a maximum likelihood classifier. The identification of different stages of forest succession based on TanDEM-X forest heights was possible with an overall accuracy of about 80%.

Estrutura e regeneração de <i>Bertholletia excelsa</i> Bonpl. em castanhais nativos da Amazônia

O trabalho foi desenvolvido com o objetivo de comparar a estrutura diamétrica e os indicadores de regeneração natural em castanhais nativos e correlacioná-los a fase de desenvolvimento da floresta, a intensidade de coleta de sementes e a exploração madeireira. Os dados foram coletados em 54 hectares nos municípios de Caracaraí (RR) e Itaúba (MT). As distribuições de freqüência diamétricas foram comparadas por medidas de tendência central, variabilidade, forma e aderência por Kolmogorov-Smirnov. A regeneração natural foi correlacionada às variáveis ecológicas, intensidade de coleta e a atividade da fauna pelo Coeficiente de Correlação de Spearman e pelo teste de Kolmogorov-Smirnov. Não foi observada correlação entre a taxa de coleta e os indicadores de regeneração e, apesar da alta intensidade de coleta de sementes, observou-se um número satisfatório de indivíduos jovens, indicando que a abertura de clareiras pela exploração florestal pode ter sido o fator de maior impacto no estabelecimento da regeneração natural e no rejuvenescimento dos castanhais

Functional attributes of two Croton species in different successional stages of tropical dry forest: effects on herbivory and fluctuating asymmetry patterns

Tropical dry forests are among the most threatened ecosystems in the world. After habitat perturbation occurs, the habitat recovers naturally through ecological succession. This succession can modify functional attributes of plants, which in turn, can affect herbivorous insects’ performance. We analyzed morphological, functional, and chemical traits associated with herbivory patterns in Croton roxanae and C. suberosus, that occur in mature and secondary forests in the tropical dry forest of Chamela, Jalisco. Leaf area and leaf thickness were higher in secondary forest, while leaf density and fresh leaf mass were higher in mature forest. Dry leaf mass, specific leaf area, chlorophyll content, and water content showed variation between species in both forest conditions. The concentration of secondary metabolites showed variation between species and forest conditions. Croton roxanae showed higher herbivory in mature forest, and C. suberosus did not show differences between the two conditions. Leaves in secondary forest were slightly longer and broader than leaves in mature forest. Croton species showed higher fluctuating asymmetry in secondary forest. Herbivory was not associated with levels of fluctuating asymmetry levels in both Croton species. Our results suggest that plant attributes are influenced by forest condition, which in turn, indirectly affect the attack of herbivores.

BIRD FAUNA IN SECONDARY FOREST STAGES: A STUDY IN A SOUTHERN BRAZILIAN PROTECTED AREA

Environmental changes resulting from forest succession process may lead to changes in the abundance and composition of species. In each successional stage, faunal composition will depend on the structure of the habitats and the ecological requirements of each species. The effects seem to be more evident in small isolated forest fragments. In this study we recorded bird species composition and richness at different stages of secondary forest in a protected area located in a highly-fragmented region in southern Brazil. We predicted that bird species composition and richness will change according to the secondary forest stage, and will be affected by the ecological requirements of species. The study was carried out in the Mata do Rio Uruguai Teixeira Soares Municipal Park (TSP), in the northern part of the state of Rio Grande do Sul, Brazil. The park is the largest protected area in the region, with 423 ha. Representative areas of the three successional stages of secondary forest within TSP were selected, and the bird species in each area were recorded using the counting point sampling method. A total of 145 bird species were recorded in the three areas. There were differences in species composition between the areas, indicating that the structure of the bird community is directly linked to successional stages. This relationship is improved by differences in the number of birds with certain ecological traits between the areas. The size, connectivity of the forest fragments and the availability of habitats may be affecting the distribution of the avifauna in the park. Changes in the landscape may promote a restructuring of avifaunal communities, where species with certain ecological traits can be favored or excluded. The TSP, although relatively small , is important for the maintenance of bird species because it is a rare, well-preserved fragmented of the deciduous seasonal forest in the region.

Eco-hydrological Functions in Forested Catchments of Southern Chile

Ecosystem functions in forests can vary significantly after disturbance, depending on changes in vegetation structure during succession and soil biophysical characteristics. We examined streamflow regulation, water storage and soil protection functions in small catchments covered by evergreen temperate rain forests, developed over volcanic ash soils, in southern South America. Our aims were to understand the differences in ecosystem functioning among catchments representing different forest stages following human disturbance, from scrubland to old-growth forest condition. In these catchments (n = 3 per condition), we assessed and compared eco-hydrological functions over 21 months. In old-growth (OG) forest catchments, streamflow for the entire study period averaged 2102 ± 110 mm, followed by secondary forest (SF) catchments with an average of 1770 ± 284 mm and finally scrub catchments (CH) with 1684 ± 267 mm. Evapotranspiration showed higher values in SF catchments (643 mm), followed by CH catchments (612 mm) and OG catchments (346 mm). OG and CH catchments had the lowest sediment export in streamflow, without statistical difference between them, while SF catchments had the highest sediment concentrations in all seasons of the year. Principal component analysis revealed that soil physical properties, vegetation structure and catchment morphometry were all relevant to explain the differences among the three forest successional stages compared. We validate the hypotheses that streamflow regulation and soil water storage capacity are greatly enhanced in old-growth forests, while the soil protection function is maximized in both early (bamboo-dominated) and advanced forest stages.

Rhizosphere effects on soil microbial community structure and enzyme activity in a successional subtropical forest

Forest succession is a central ecological topic due to the importance of its dynamic process for terrestrial ecosystems. However, we have limited knowledge of the relationship between forest succession and belowground microbiota, particularly regarding interactions in the rhizosphere. Here, we determined microbial community structure and biomass using phospholipid fatty acid (PLFA) biomarkers and microbial activity using extracellular enzyme activity in bulk and rhizosphere soils from three successional stages of subtropical forests in eastern China. Principal component analysis of PLFAs indicated distinct soil microbial communities among different successional stages and habitat locations. Specifically for the topsoil, we found the total microbial biomass, bacterial biomass and enzyme activities showed higher levels in the late than early stage, with a significant succession-induced accentuated rhizosphere effect. The increase in total microbial biomass and activity coincided with a net growth in bacterial rather than fungal biomass, indicating a model in which microbial biomass carrying capacity and activity could be affected by the creation or expansion of niches for certain functional group rather than by a rebalancing of competitive interactions among these groups. Furthermore, we demonstrated that forest succession significantly influenced enzyme activity via the changes in microbial biomass, as driven by edaphic factors. Overall, our study deepens the mechanistic understanding of forest recovery by linking soil microbial community and activity along successional chronosequences.

DIVERSITY OF ARBUSCULAR MYCORRHIZAL FUNGI IN FOREST ECOSYSTEMS OF BRAZIL: A REVIEW

Plants can stablish symbiosis with arburcular mycorrhiza fungi (AMF), in which the fungus uses carbohydrates synthesized by plant photosynthesis in exchange for soil nutrients. AMF symbiosis may benefit plants by increasing the rates of nutrient uptake, tolerance to abiotic stresses, protection against pathogens and, by promoting resilience of forest species to adverse conditions. Knowledge about the diversity of mycorrhizas may help stablish relationships of species selection, AMF production and inoculation. Therefore, the objective of this review is to compile information to identify existing patterns in AMF diversity in Brazilian forest ecosystems. Compilation was based in 74 articles (in English, Portuguese and Spanish languages) searched in the Web of Knowledge and selected for having the keywords “forest”, “diversity”, “mycorrhizal” and “Brazil”, and that identified AMF species by spore morphology. Compilation resulted in a list of 164 AMF species and indicated that AMF species are not plant host specific but they are selected by environmental conditions where the host grows. Some AMF species were ubiquitous and some were rare in forest ecosystems. Rare AMF species may be an artefact of AMF identification because, in comparison to molecular tools, spore morphology may underestimate AMF diversity. Four AMF species, Acaulospora scrobiculata, Acaulospora foveata, Clareoideglomus etunicatum and Glomus macrocarpum, were ubiquitous to several biomes, existed in different stage of forest succession and seemed to be adapted to different forest managements. Therefore, A. scrobiculata, A. foveata, A. mellea, C. etunicatum and G. macrocarpum could have potential to be used as AMF inoculant in forest species.