Successional Class Research Articles

The Inhibitory Tendency of Calamagrostis epigejos and Solidago spp. Depends on the Successional Stage in Postindustrial Vegetation

ABSTRACTIn spontaneously vegetated postindustrial areas, we have limited knowledge of whether the known inhibitory tendencies of herbaceous species—Calamagrostis epigejos and Solidago spp.—vary across successional stages. Our study fills this knowledge gap to assess the inhibitory role of the invasive alien and expansive native species with known behavior from the literature. Specifically, we hypothesized: (i) there will be an inhibitory effect of these species on diversity across successional classes; (ii) the effect of a species will depend on the successional class due to abiotic requirements of plant communities in each successional class. We recorded vascular plant species and their abundance across 400 plots on post‐coal mine heaps in Upper Silesia, Poland. We classified spoil heaps into three successional classes (early‐stage; mid‐stage; late‐stage). We calculated plant community taxonomic, functional, and phylogenetic diversity and, using generalized linear mixed‐effects models, we estimated predictors of diversity indices across successional classes. While we found no limiting effects of these species on diversity indices across successional classes, the effects of a species depended on the successional stage. We found the impacts of Calamagrostis and Solidago cover on diversity indices in the mid‐successional stage. This implies that the early‐successional stage is controlled by the lottery (random) model of community assembly. However, in the mid‐successional stage, the competitive exploitation mechanism is evident, resulting in declines in diversity indices. Thus, the impacts of Calamagrostis and Solidago on diversity indices are evident in the mid‐successional stage.

Pioneer Arabidopsis thaliana spans the succession gradient revealing a diverse root-associated microbiome

BackgroundSoil microbiomes are increasingly acknowledged to affect plant functioning. Research in molecular model species Arabidopsis thaliana has given detailed insights of such plant-microbiome interactions. However, the circumstances under which natural A. thaliana plants have been studied so far might represent only a subset of A. thaliana’s full ecological context and potential biotic diversity of its root-associated microbiome.ResultsWe collected A. thaliana root-associated soils from a secondary succession gradient covering 40 years of land abandonment. All field sites were situated on the same parent soil material and in the same climatic region. By sequencing the bacterial and fungal communities and soil abiotic analysis we discovered differences in both the biotic and abiotic composition of the root-associated soil of A. thaliana and these differences are in accordance with the successional class of the field sites. As the studied sites all have been under (former) agricultural use, and a climatic cline is absent, we were able to reveal a more complete variety of ecological contexts A. thaliana can appear and sustain in.ConclusionsOur findings lead to the conclusion that although A. thaliana is considered a pioneer plant species and previously almost exclusively studied in early succession and disturbed sites, plants can successfully establish in soils which have experienced years of ecological development. Thereby, A. thaliana can be exposed to a much wider variation in soil ecological context than is currently presumed. This knowledge opens up new opportunities to enhance our understanding of causal plant-microbiome interactions as A. thaliana cannot only grow in contrasting soil biotic and abiotic conditions along a latitudinal gradient, but also when those conditions vary along a secondary succession gradient. Future research could give insights in important plant factors to grow in more ecologically complex later-secondary succession soils, which is an impending direction of our current agricultural systems.

Impact of Fire on Secondary Forest Succession in a Sub-Tropical Landscape

In Hong Kong, as in many tropical areas, grasslands are maintained by fire on disturbed and abandoned land. However, Hong Kong’s native forests are regenerating in many areas, alongside frequent burning of the hillsides, and are in different stages of structural succession to closed canopy forest patches. Understanding the major determinants of secondary succession is a vital input to forest management policies. Given the importance of forests for biodiversity conservation, watershed protection and carbon cycling. This study examines the relationship between burning regimes and structural forest succession over 42 years from 1973 to 2015, using an archive of satellite images, aerial photographs and field plot data. Overlay of a fire frequency map with maps of forest structural classes at different dates indicates the number of fires undergone by each successional class as well as the time taken to progress from one class to another under different fire regimes. Results indicate that the native sub-tropical evergreen forests, which are naturally fire intolerant, can regenerate alongside moderate burning, and once the shrub stage is reached, succession to closed forest is relatively rapid and can occur within 13 years. More than one burn, however, is more destructive, and twice-burnt areas were seen to have only one-third of the woody biomass of once-burnt plots. The most frequent fires occurred in areas where mono-cultural plantations had been destroyed by disease in the 1960s and were subsequently invaded by grasslands. These former plantation areas remained in early successional stages of grass and open shrubland by 2015. Other plantations from the 1970s and 1980s remain as plantations today and have acted as a barrier to natural forest succession, attesting to the greater effectiveness of fire control over re-afforestation measures.

A Comparison of Methods for Determining Forest Composition from High-Spatial-Resolution Remotely Sensed Imagery

Remotely sensed imagery has been used to support forest ecology and management for decades. In modern times, the propagation of high-spatial-resolution image analysis techniques and automated workflows have further strengthened this synergy, leading to the inquiry into more complex, local-scale, ecosystem characteristics. To appropriately inform decisions in forestry ecology and management, the most reliable and efficient methods should be adopted. For this reason, our research compares visual interpretation to digital (automated) processing for forest plot composition and individual tree identification. During this investigation, we qualitatively and quantitatively evaluated the process of classifying species groups within complex, mixed-species forests in New England. This analysis included a comparison of three high-resolution remotely sensed imagery sources: Google Earth, National Agriculture Imagery Program (NAIP) imagery, and unmanned aerial system (UAS) imagery. We discovered that, although the level of detail afforded by the UAS imagery spatial resolution (3.02 cm average pixel size) improved the visual interpretation results (7.87–9.59%), the highest thematic accuracy was still only 54.44% for the generalized composition groups. Our qualitative analysis of the uncertainty for visually interpreting different composition classes revealed the persistence of mislabeled hardwood compositions (including an early successional class) and an inability to consistently differentiate between ‘pure’ and ‘mixed’ stands. The results of digitally classifying the same forest compositions produced a higher level of accuracy for both detecting individual trees (93.9%) and labeling them (59.62–70.48%) using machine learning algorithms including classification and regression trees, random forest, and support vector machines. These results indicate that digital, automated, classification produced an increase in overall accuracy of 16.04% over visual interpretation for generalized forest composition classes. Other studies, which incorporate multitemporal, multispectral, or data fusion approaches provide evidence for further widening this gap. Further refinement of the methods for individual tree detection, delineation, and classification should be developed for structurally and compositionally complex forests to supplement the critical deficiency in local-scale forest information around the world.

Drivers of Restoration Trajectory of a Community of Regenerant Plants: Natural Regeneration or Tree Seedling?

Tree plantation is the most used technique for ecological restoration, although passive restoration requires a lower investment of resources. This research aimed to compare the composition and structure of the community of regenerant plants in areas under restoration through Assisted Natural Regeneration and mixed native Tree Planting, in the same area. We randomly placed 12 plots of 100 m2 each and sampled all the regenerating individuals found within them. We compared both restoration methods regarding growth pattern, dispersal syndromes, and successional groups. In both methodologies, trees and shrubs were the most abundant growth forms. The pioneer successional class was the most abundant in number of individuals for both treatments. We concluded that the two restoration methods allowed the regeneration of native species. We propose that Assisted Natural Regeneration is a viable restoration strategy, capable of boosting the initial processes of the community, especially in a matrix surrounded by remaining forests.

Chuva de sementes como indicador ambiental de áreas em processo de restauração ecológica do Mato Grosso do Sul

A chuva de sementes (CS) é caracterizada pela chegada de propágulos ao solo, advindos por mecanismos de dispersão e é essencial para a dinâmica da regeneração natural de florestas. O objetivo deste trabalho foi avaliar a CS como indicador de três áreas em processo de restauração do Mato Grosso do Sul, Ivinhema 12 anos (IV-12), Jateí 13 anos (JA-13) e Caarapó 16 anos de plantio (CA-16). Foram instalados aleatoriamente 15 coletores de 0,64 m² em cada uma das áreas e o material coletado mensalmente de maio/2015 a janeiro/2016. Foram calculados os índices de Shannon (H’) e Equabilidade de Pielou (J’) e as sementes classificadas quanto à síndrome de dispersão, hábito e classe sucessional das sementes de espécies arbóreas. Foi identificado o total de 47.124 propágulos nas três áreas. Para CA-16 foram amostradas 27.033 sementes, 29 famílias, 39 gêneros e 41 espécies. JA-13 obteve 8.056 sementes, 22 famílias, 32 gêneros e 33 espécies. A área IV-12 resultou em 12.035 sementes, 13 famílias, 21 gêneros e 22 espécies. Das 61 espécies encontradas para as três áreas, 88,5% são de hábito arbóreo. Referente à síndrome de dispersão, a maioria são zoocóricas, com destaque para IV-12 com 93,7%, sendo que 40,9% são alóctones. Quanto à classificação sucessional, as pioneiras foram destaque, principalmente para IV-12 (91,7%). A CS pode ser considerada um bom indicador para a avaliação da integridade ambiental de áreas em restauração por fornecer subsídios para compreensão da manutenção dos processos ecológicos, visto que nas áreas avaliadas, a maioria das sementes foi de espécies zoocóricas, com expressiva contribuição de espécies alóctones, demonstrando a existência de uma fauna dispersora facilitadora da sucessão florestal.

Stem and leaf functional traits allow successional classification in six pioneer and non-pioneer tree species in Tropical Moist Broadleaved Forests

More than half of the tropical forests are secondary forests that are undergoing a highly dynamic interplay of forest succession of uncertain outcome. Vegetation models can help predict forest trajectory but require simplifying the high biodiversity of these forests into a few distinct classes of functional or successional groups. The classification of tree species by successional groups has traditionally relied on qualitative criteria such as life span, or on parameters that are difficult to measure on mature trees in the field, like photosynthetic activity, in particular in tropical forests. Hence, quantitative traits that can be easily measured in a number of species may provide more accurate classification thresholds. The present study identifies quantitative anatomical and biochemical traits of leaf and stem of six species that are useful for classification of successional groups in the Tropical Moist Broadleaved Forest (TMBF) of south-eastern Brazil. Consistent with assumed fast growth and high light requirements of pioneers the investigated pioneer species presented higher stem glucose content (600%), larger vessel elements (162%), greater stomatal density (72%) and higher chloroplastic pigments concentrations (90%) than non-pioneer species. By contrast, non-pioneers were characterized by larger mesophyll cells (70%) and higher cell wall polymers concentrations (65–100%) in leaf and stem. The biggest differences between pioneer and non-pioneer species were observed in leaf blade thickness, followed by vessel lumen diameter, and stem lignin. We provide research laboratories a variety of different tools that they can use as a guideline to accurately assess the successional class of tree species in the TMBF of south-eastern Brazil.

Bee pollinator functional responses and functional effects in restored tropical forests.

Wild pollinators are necessary for ensuring plant reproduction, not only among crop fields but also remnant and restored ecosystems. Restoration activities should, therefore, lead to wild pollinator recovery, and thus be monitored to evaluate effects on pollinator diversity and functionality. We assessed bee pollinator functional responses in restoration plantings by creating functional groups (traits: body size, nesting location, sociality, and foraging strategy), comparing their abundance and diversity to that of other habitats (i.e., conserved and degraded primary forest fragments, anthropogenic wetlands, and sugarcane fields), and testing for an effect of source habitat (i.e., primary forest fragments) isolation. We analyzed functional effects on pollen transportation by identifying the pollen grains attached on the bodies of bees; creating plant functional groups with the identified species (traits: habit, successional class, geographic origin, and pollination mode); comparing their frequency, diversity, and interaction network structure among habitats; and searching for key interactions in network modules. In general, the abundance and diversity of bee communities and the frequency and diversity of the interacting plant species in restoration plantings were lower than those in primary forest fragments but higher than those in anthropogenic wetlands and sugarcane fields, suggesting that restoration plantings better enhance bee community recovery and functionality than other disturbed habitats. The interacting bees and plants were also negatively affected by habitat isolation, demonstrating the importance of primary forest fragments to supply bee populations to restored sites. The structure of interaction networks was little affected by habitat change and isolation, but the composition and diversity of functional groups varied significantly. There were more effects on larger bee species with more restricted nesting and floral requirements, and the woody species with which they interact most frequently. We identified key functional groups of bee pollinators that deserve priority for conservation because they play an important role in the pollen transportation of some the most relevant species in remnant forests and restoration plantings and also respond more negatively to habitat disturbances. Restoration efforts should include provisioning of nesting resources and management and conservation of primary forest remnant fragments that represent source habitats for them.

Invasão de palmeira australiana no sub-bosque de uma floresta plantada, Viçosa, MG

O objetivo desse trabalho foi avaliar a regeneração natural e a abundância de espécies exóticas no sub-bosque de um plantio experimental de Araucaria angustifolia, em Viçosa, MG. A amostra correspondeu a 40 parcelas de 2 m x 2 m, onde mediu-se o diâmetro ao nível do solo (DNS) de todos os indivíduos arbustivo-arbóreos com diâmetro ≤ a 5,0 cm e altura ≥ a 0,5 m. Foram calculados os parâmetros fitossociológicos e os índices de diversidade e equabilidade. As espécies foram classificadas quanto à forma de vida, classe sucessional e síndrome de dispersão. Foram amostrados 980 indivíduos, sendo observada maior proporção de espécies arbustivas, típicas de sub-bosque e zoocóricas. A espécie exótica Archontophoenix cunninghamiana, conhecida como palmeira australiana, obteve o terceiro maior valor de importância, a maior dominância e 19,25% da área basal total, valor consideravelmente maior que o das demais espécies. A. cunninghamiana foi caracterizada como uma espécie exótica invasora que domina o estrato de regeneração natural. A inibição da sucessão natural pela presença de espécies exóticas, como A. cunninghamiana, precisa ser monitorada, visando eliminar as espécies-problema, para garantir a continuidade do processo de sucessão.

Banco de sementes de áreas em restauração florestal em Aimorés, MG

With the objective to evaluate the soil seed bank of four distinct areas undergoing restoration activities of different intensities 30 samples of topsoil from 30 x 25 x 7.0 cm in deep were collected in each area and transported to greenhouse at 25 °C and relative humidity around 70%. The emerging seedlings were counted every two weeks for one year. Shannon diversity and Pielou evenness were calculate. The species were classified according to dispersal syndrome, life form and successional class. Considering the four areas, 323 individuals m-², emerged on average, belonging to 26 families and 69 species. Approximately 31% of the sampled individuals were Setaria vulpiseta, and it was present in all four areas. Areas 1 and 2 have low diversity and low ecological dominance. Areas 3 and 4 present mean diversity and low ecological dominance. Herbaceous form and anemochoric syndrome were the most outstanding. The seed bank of areas 1 and 2 have a low potential for auxiliary the forest restoration. In areas, 3 and 4 the seed bank showed a good potential for forest resilience.

Estrato de regeneração natural de um trecho de floresta estacional semidecidual, Viçosa, MG

Este estudo foi realizado na Mata da Praça de Esportes, situada no Campus da UFV, em Viçosa, MG, com 10,65 ha em regeneração há 75 anos. Foram estabelecidos quatro transectos paralelos de 3 x 50 m, espaçados por 3 m e subdivididos em 10 parcelas de 3 x 5 m cada. A amostragem do estrato de regeneração natural incluiu todos os indivíduos com altura ≥ 0,3 m e com DAP < 5 cm. Calcularam-se os parâmetros fitossociológicos, e realizou-se a classificação quanto à classe sucessional e à síndrome de dispersão. Comparou-se a composição florística entre a área estudada e diversos levantamentos florísticos de regeneração na região de Viçosa, MG, por meio de análise de agrupamento. Foram obtidas 30 famílias e 84 espécies. As espécies mais importantes foram Coffea arabica, Siparuna guianensis, Psychotria sessilis e Erythroxylum pelleterianum. Houve predomínio da classe sucessional secundária tardia (49,3% dos indivíduos) e da síndrome de dispersão zoocórica (91,6% dos indivíduos). Não houve similaridade florística entre o trecho de floresta estudada e os demais fragmentos florestais da região. A predominância da síndrome de dispersão zoocórica no estrato de regeneração natural é fator importante para a continuidade da manutenção de animais frugívoros na área. A riqueza florística e a abundância de espécies secundárias tardias são fortes indicativos de que o ambiente estudado está oferecendo condições ecológicas adequadas ao desenvolvimento dessas espécies, permitindo, assim, o avanço da sucessão secundária.

Relações ecológicas entre estratos de uma área restaurada, com 40 anos, Viçosa, MG

The objective of this study was to evaluate the ecological relationships between different layers of a restored area in Vicosa, State of Minas Gerais. A floristic survey of the tree layer, natural regeneration and soil seed bank was carried out. The floristic composition between layers of the restored area (tree layer, regeneration and seed bank) was compared, and this composition was also compared to various forest fragments in the area; the comparisons were made through cluster analysis. The successional class and dispersion syndrome between layers of the restored area were compared by analysis of variance (ANOVA). The dendrogram obtained distinguished the seed bank of the other layers. There was no similarity between the area studied and the forest fragments in Vicosa. In the distribution by successional class and dispersal syndrome, there was significant difference between the seed bank and other layers of the restored area. Results evinced the discrepancy of the seed bank floristic compared to other layers of the forest, proving that the forest area is in a headmost stage of succession.

A methodology for assessing departure of current plant communities from historical conditions over large landscapes

Fire frequency and severity, and vegetation composition and structure have been altered across much of North America during the past century because of fire exclusion and other land management practices. The cumulative results are now recognized to be partly responsible for dramatic increases in wildland fire severity and declines in ecosystem health. In response, the Departments of Agriculture and Interior are developing a strategy for reducing fire hazard and restoring forest health. A key component of this strategy is the assessment of the departure of current plant communities from historical conditions. Assessing departure is difficult because of limited spatial coverage of data on successional class distribution prior to European settlement (historical) conditions. This article discusses a two-step approach to the problem that first generates data on historical vegetation composition and structure by simulating succession and disturbance processes under historical conditions, and then measures departure by comparing these simulated data to an observation on current conditions. The data are observations on high-dimensional multinomial categorical variables, and pose several problems that limit the usefulness of conventional statistical methods. We propose a method that constructs a linear approximation of the current observation vector from the simulated historic data, and measures the departure of the current observation vector by the length of the residual error vector. A simulation study indicates that this departure measure is substantially more sensitive than conventional outlier detection methods. Our methodology is demonstrated using a pilot region encompassing lands in Utah.

Life history diversity among six species of canopy lianas in an old-growth forest of the eastern Brazilian Amazon

Lianas are woody vines that rely on external support for height growth. Although variations among species of lianas in traits ranging from climbing mechanism to stem anatomy have been described, little attention has been paid to interspecific differences in life history traits. The objective of this study was to assess the diversity in life history strategies among lianas in an old-growth forest of the eastern Brazilian Amazon. Population size class structure, microsite light environment affinity, forest successional phase affinity, and regeneration mode were assessed and growth and mortality rates were measured over 3 years for six species of lianas: Acacia multipinnata, Bauhinia cupreonitans, Bauhinia guianensis, Croton ascendens, Memora schomburgkii, and Serjania caracasana. Each of the study species had a free-standing seedling phase prior to the initiation of climbing, but the density of free-standing saplings (≥50 cm tall) ranged widely among species from 408 stems ha −1 for B. guianensis to 2 stems ha −1 for A. multipinnata. Species also differed in their propensity for vegetative reiteration of rooted stems; the mean number of climbing ramets per genet ranged from 1.1 for B. guianensis to 7.4 for S. caracasana. Four of the study species ( M. schomburgkii, S. caracasana, and both species of Bauhinia) had the majority of climbing ramets in small diameter classes. However, for two of these species ( M. schomburgkii and S. caracasana) the size class distributions of the largest stems per genet were flat and unimodal, respectively. A. multipinnata and C. ascends had flat size class distributions of both ramets and largest stems per genet. Among the six species there were three apparent patterns of changing association with light environment and forest successional phase over size classes. Two species ( M. schomburgkii and B. guianensis) are late successional species. These species were found in all forest phases at relatively low median levels of illumination as seedlings and free-standing saplings, more frequently associated with gaps as small diameter climbing stems, and in late building and mature phase forest as larger (≥1.5 cm diameter) climbing stems. Three species ( B. cupreonitans, S. caracasana, and A. multipinnata) are early successional species. These species were distinguished from late successional species by occurring in better illuminated and more gap-associated microsites as free-standing saplings and by remaining strongly associated with early building phase forest as large diameter stems. Only C. ascendens, is like a pioneer species in being found exclusively in high light microsites in its free-standing stages and associated with gaps or early building phase forest as climbing stems. Median stem diameter growth rates were correlated with successional class ranging from the lowest in late successional species to the highest in the pioneer species. Annual ramet mortality rates differed among species with the lowest rates for the late successional species (1.3 and 4.3% for M. schomburgkii and B. guianensis, respectively). Annual genet mortality rates were lower than ramet mortality rates and ranged from 0.2% for M. schomburgkii to 5.5% for C. ascendens. The results suggest that, while lianas exhibit a diversity of life history strategies, some patterns in liana life history traits, for example a positive correlation between stem diameter growth rate and mortality rate, may parallel patterns found for trees.