Floristic Similarity Research Articles

Effect of vegetation matrix on diversity and distribution of epipetric bromeliads in a transitional region between Evergreen and Seasonal Forest

Bromeliaceae is frequently an important family in several distinct environments of the Brazilian Atlantic Forest, including rocky habitats. They are also one of the most common and diverse taxonomic groups in neotropical rocky outcrops. For the first time, diversity and distribution patterns of epipetric bromeliads immersed in forest matrix were evaluated in different forest physiognomies. We tested the precepts of the Theory of Island Biogeography to verify the isolation effect that rocky areas operate on Bromeliaceae. We hypothesize that epipetric bromeliads are represented by exclusively rupestrial species, but also by species commonly epiphytic, coming from the flora of the surrounding matrix. Furthermore, composition and diversity of Bromeliaceae are influenced by the forest type, area of the rocky surface, and the distance between these habitats. The study area comprises sandstone cliffs immersed in the fragmented Atlantic Forest on Southern Brazil. Twenty-four mostly vertical rocky outcrops were sampled, 12 in each forest physiognomy. We used diversity curves, analysis of variance, and indicator species analysis to evaluate how bromeliad communities vary among the two forest types. Generalized linear models and correlation tests were used to evaluate the relationship between species richness, cliff area, and distance. The relationship between species similarity and geographical distance of the cliffs was estimated by a Mantel test. We recorded 26 bromeliad species. The data showed floristic differentiation between bromeliad communities in Evergreen and Seasonal forests. Species richness was positively correlated to the cliff area. Our results showed that bromeliad diversity is not directly related to the degree of isolation of the cliffs. However, floristic similarity decreased with inter-cliff distance. In general, our results corroborated our hypotheses and the predictions of the Theory of Island Biogeography, reflecting additionally the possibility of environmental filters, and limitations in species dispersion.

FOREST EDGE EFFECTS ON THE PHYTOSOCIOLOGICAL COMPOSITION OF AN ARAUCARIA FOREST FRAGMENT IN SOUTHERN BRAZIL

The Araucaria forests of Southern Brazil have been drastically reduced as a result of anthropic intervention and are currently found at different stages of succession. The objective of our study was to understand the influence of forest fragmentation on the phytosociological composition of its tree component. The composition of floristic groups of the tree component and their correlation with the edaphic and environmental variables in a fragment of the Araucaria Forest in the municipality of Curitibanos, state of Santa Catarina, Brazil was analyzed. A hundred and ten permanent continuous plots (10 m²) with forest edges of different origins and formation times were established for sampling. Trees with diameter ≥ 5 cm at breast height (DBH) were measured and identified. Using TWINSPAN, data were analyzed for species importance values (including indicator species) in the formation of floristic groups. Floristic similarities resulted in separating groups conditioned by the forest succession. The presence of the invasive species Pinus taeda L. and pioneer species at the forest expansion border contributed to the formation of a spatially cohesive group. The other areas did not show influence of edge effects, being in an initial secondary succession stage, dominated by Jacaranda puberula Cham. Low edaphic variation among the classes of lithosols in a flat relief had no influence on the formation of floristic groups.

Caracterización de cuatro bosques de pino piñonero del estado de Zacatecas, México

Introduction: Communities dominated in the canopy by pinyon pines harbor species richness and have complex physiognomy because they form an ecotone between arid and temperate zones. Objectives: To describe the floristic attributes that distinguish four communities dominated by pinyon pines; define units based on floristic composition and structure; and determine the influence of edaphic factors. Materials and methods: The flora of four communities in the state of Zacatecas was recorded. The arboreal and shrub vegetation was analyzed quantitatively using the point-centered quarter technique. Semi-realistic physiognomic profiles were made for each site. The groups resulting from cluster analysis were ordered with edaphic factors through a canonical correspondence analysis. Results and discussion: Floristic richness was 244 species; each community contains between 60 and 80 species. Structurally, three physiognomic variants were recorded: forests dominated by Pinus cembroides Zucc.; association of P. cembroides - P. cembroides var. bicolor Little; and forest dominated by P. maximartinezii Rzed. The pH, electrical conductivity and soil texture have a great influence on the structure and plant composition of the communities. The P. cembroides - P. cembroides var. bicolor association and its accompanying species develop in nutrient-poor soils, while P. maximartinezii forests prefer shallow soils. Conclusion: The floristic similarity among communities was low. Each community must be managed differently, meeting the particular requirements of the species that develop there.

Effectiveness of corridors varies among phytosociological plant groups and dispersal syndromes.

In agricultural landscapes, semi-natural habitats are scarce and remaining habitat patches are largely isolated. However, linear landscape elements might facilitate dispersal of plant species through the agricultural landscape matrix. We investigated the following research questions: 1. are open linear landscape elements (LLE) effective corridors for dispersal of vascular plant species? 2. Which plant species, with respect to phytosociological group and dispersal-distance class, do use LLE as corridors? 3. To which extent is floristic similarity of communities influenced by dispersal through corridors? Field work was carried out in agricultural landscapes of Northwest Germany. We sampled 50 vegetation relevés on open linear landscape elements i.e. field margins (incl. road verges) and ditches, in eight 1-km2 study areas. Then, we calculated Jaccard similarities of all plot pairs within study areas using either all species or only species of certain phytosociological groups or dispersal-distance classes. We assessed the isolation of the plots from each other using both Euclidean distance and resistance distance along LLE. Resistance distance reflected the degree of connectivity of the LLE network between the plots. A stronger effect on Jaccard similarity of resistance distance compared to Euclidean distance would indicate corridor dispersal of plants through LLE. Relationships between Jaccard similarity and the two isolation measures were analysed with Generalised Linear Mixed Models. Resistance distance of LLE had a stronger negative effect on Jaccard similarity than Euclidean distance in field margins, but not in ditches. This was found for species of ‘meadows and pastures’ and short to medium dispersal distance. In plot pairs that were highly connected by LLE, the models suggested that roughly 20% of all species occurred in both plots due to dispersal through LLE. Other species groups did not respond more strongly to resistance distance than to Euclidean distance. We conclude that linear landscape elements in agricultural landscapes are effective corridors for dispersal of plant species that are confined to semi-natural habitats, such as traditional grasslands, and lack mechanisms of long-distance dispersal.

MUDANÇAS PÓS-FOGO NA FLORÍSTICA E ESTRUTURA DA VEGETAÇÃO ARBÓREO-ARBUSTIVA DE UM CERRADO SENTIDO RESTRITO EM PLANALTINA, DF

O monitoramento da vegetação arbóreo-arbustiva foi realizado em parcelas permanentes, em duas áreas de Cerrado sentido restrito em Planaltina (DF), em sete ocasiões de 1988 a 2012. Em uma área, Área 1, foram aplicadas queimadas bienais, em agosto de 1988, 1990 e 1992; a outra área, Área 2, foi protegida até julho de 1994, antes do fogo acidental que atingiu as duas áreas em agosto. As áreas foram protegidas da ação do fogo de 1995 a 2012. Antes das queimadas, foram medidas a circunferência, a 30 cm do solo, e a altura de todos os indivíduos arbóreo-arbustivos que atingiam um metro ou mais; em 1988, foi medida a altura apenas. A riqueza foi comparada entre as duas áreas. A diversidade de espécies foi analisada por meio dos perfis de diversidade e a similaridade florística, pelo método UPGMA. Foram avaliados os parâmetros de densidade, frequência, dominância e Índice de Valor de Importância. O fogo não influenciou a riqueza de espécies nas duas áreas, em todo o período. Foram registradas 82 espécies nas duas áreas durante todo o período de estudo, sendo, na Área 1, 74 espécies, em 35 famílias, e na Área 2, 73 espécies, em 34 famílias. De 1988 a 1994, as duas áreas apresentaram diferenças na diversidade e na similaridade florística. Após 18 anos de proteção, em 2012, as duas áreas mostraram similaridade florística, porém, diferenças na diversidade, com maior diversidade na Área 1. A comunidade arbóreo-arbustiva se mostrou resistente e resiliente ao fogo. As queimadas bienais reduziram a densidade e a área basal, mas, a exclusão do fogo favoreceu o aumento desses parâmetros nas duas áreas. As distribuições dos indivíduos em classes de altura e de diâmetro não diferiram significativamente, nas duas áreas, mas o fogo afetou, principalmente, os indivíduos nas menores classes de altura e de diâmetro.

Angiospermas nativas documentadas en la literatura para el Estado de México, México

Antecedentes y Objetivos: En 1979 se publicó por primera vez la riqueza de plantas vasculares en el Estado de México. La información allí presentada ha perdido actualidad debido al incremento de aportaciones florísticas. El objetivo de este trabajo es contribuir al conocimiento de la flora del Estado de México, a partir de la literatura florística-taxonómica disponible.Métodos: Se integró una base de datos con la información proveniente de 351 documentos. Se elaboró un mapa que ilustra la ubicación geográfica de los inventarios florísticos y se determinó, mediante el índice de Sørensen, la similitud florística entre inventarios.Resultados clave: Se compiló una lista con 169 familias, 1103 géneros y 3924 especies de angiospermas. Asteraceae (153 géneros y 588 especies), Fabaceae (82 y 372), Poaceae (85 y 340) y Orchidaceae (70 y 231) son las familias mejor representadas. Muhlenbergia (54 especies), Salvia (53) e Ipomoea (51) presentaron el mayor número de especies. Las tesis fundamentan 80% de los taxa. El índice de similitud reveló que la mayoría de las especies están restringidas a una o dos compilaciones. La distribución de los sitios de exploración botánica no es uniforme, se han realizado más trabajos florísticos en las zonas sur y suroeste del estado. Las investigaciones se han llevado a cabo principalmente en sitios próximos a vías de comunicación e instituciones educativas de trascendencia y las regiones montañosas han sido pobremente recolectadas.Conclusiones: La información sobre la riqueza de angiospermas acumulada en la literatura resulta fundamental para determinar la distribución geográfica de las especies en los municipios del estado, adicionar información sobre endemismo, usos actuales y potenciales, así como establecer programas de conservación de los recursos naturales.

Spatial distribution of caatinga plants in the environment of a thermelectric

The vegetation of the Caatinga of the Brazilian semiarid of the xerophilous type is usually found between shallow and poorly permeable soils, which is constantly affected by irregular deforestation. In this context, the objective of this work was to identify the floristic species of a thermoelectric plant located in the semi - arid Paraibano region, in addition to diagnosing the ecological integrity of the arboreal remnants of this area. The Phytosociological Survey of this study was carried out in an area with 20.1ha, with sampling in six plots. The processing of phytosociological data was carried out using Mata Nativa 4.0 software. The identification of floristic species was evaluated through the basal area, density, frequency, dominance, cover value and importance value. For the analysis of the data, the similarity between the species was compared by the Jaccard index, the floristic similarity matrix was used for cluster analysis and dendrogram generation. The floristic species inventoried, totaled 280 individuals and the family that had the largest representative was the Euphorbiaceae. It was observed that the studied area is in process of ecological succession, due to the physical pressures of the residents of the surroundings, with exploitation of natural resources of uncontrolled form causing, deforestation, burnings, among others. It is verified that floristic inventories are of great importance to monitor biodiversity, as well as to draw up, goals of efficient environmental management and serve as a tool aimed at the conservation of the Caatinga species.

Floristic composition and similarity of 15 hectares in Central Amazon, Brazil

The Amazon region is one of the most diverse areas in the world. Research on high tropical forest diversity brings up relevant contributions to understand the mechanisms that result and support such diversity. In the present study we describe the species composition and diversity of 15 one-ha plots in the Amazonian terra firme dense forest in Brazil, and compare the floristic similarity of these plots with other nine one-ha plots. The 15 plots studied were randomly selected from permanent plots at the Embrapa Experimental site, Amazonas State in 2005. The diversity was analysed by using species richness and Shannon's index, and by applying the Sorensen's index for similarity and unweighted pair-group average (UPGMA) as clustering method. Mantel test was performed to study whether the differences in species composition between sites could be explained by the geographic distance between them. Overall, we identified 8 771 individuals, 264 species and 51 plant families. Most of the species were concentrated in few families and few had large number of individuals. Families presenting the highest species richness were Fabaceae (Faboideae: 22spp., Mimosoideae: 22spp.), Sapotaceae: 22spp., Lecythidaceae: 15 and Lauraceae: 13. Burseraceae had the largest number of individuals with 11.8% of the total. The ten most abundant species were: Protium hebetatum (1 037 individuals), Eschweilera coriacea (471), Licania oblongifolia (310), Pouteria minima (293), Ocotea cernua (258), Scleronema micranthum (197), Eschweilera collina (176), Licania apelata (172), Naucleopsis caloneura (170) and Psidium araca (152), which represented 36.5% of all individuals. Approximately 49% of species had up to ten individuals and 13% appeared only once in all sampled plots, showing a large occurrence of rare species. Our study area is on a forest presenting a high tree species diversity with Shannon's diversity index of 4.49. The dendrogram showed two groups of plots with low similarity between them (less than 0.25), and the closer the plots were one to another, more similar in species composition (Mantel R = 0.3627, p < 0.01). The 15 plots in our study area share more than 50% of their species composition and represent the group of plots that have the shortest distance between each other. Overall, our results highlight the high local and regional heterogeneity of environments in terra firme forests, and the high occurrence of rare species, which should be considered in management and conservation programs in the Amazon rainforest, in order to maintain its structure on the long run.

Regenerative potential of the soil seed bank along an elevation gradient of rupestrian grassland in southeastern Brazil

The objective of this study was to determine the species richness and abundance of the seed bank and the influence of soil attributes along an elevation gradient (800–1400 m a.s.l.). We examined the floristic similarity among areas and determined the regional diversity along this gradient in Serra do Cipó (Minas Gerais, Brazil). A total of 1975 individuals from 149 species were germinated. Richness and abundance were not linearly related to elevation, and exhibited a threshold at 1200 m. The low degree of similarity among the areas reflects environmental heterogeneity, resulting from a rich mosaic of habitats, distinguished by the substrate configuration, continuity of vegetation, floristic composition, and proportion of exposed rock. The diversity between plots of different areas (β2) contributed to regional diversity, and species turnover was the most important factor. The physical variables and base saturation, which had high spatial heterogeneity, may be the most important factors with which to determine species turnover and β diversity. The studied seed bank is strongly influenced by edaphic variables, with a gradient of increasing acidity and proportion of fine sand, and decreasing proportion of clay and organic matter, with elevation. In addition, species richness was influenced by cation exchange capacity, organic matter, and clay; and abundance was influenced by cation exchange capacity, H + Al, organic matter, and base saturation.

POTENCIAL REGENERATIVO DE UMA FLORESTA ECOTONAL NA REGIÃO DO ALTO URUGUAI EM SANTA CATARINA

Objetivou-se avaliar o potencial regenerativo do componente arbóreo em uma área ecotonal entre Floresta Ombrófila Mista e Estacional Decidual, na região do Alto Uruguai, Santa Catarina. Para isso, foi realizada a caracterização florístico-estrutural do componente arbóreo regenerante em diferentes classes de tamanho e verificada a similaridade florística entre as classes e o componente adulto. Foram consideradas três classes para o componente regenerante: Classe 1, plantas com altura entre 0,2 e 1 m, Classe 2, plantas maiores que 1 m e até 3 m, e Classe 3, plantas maiores que 3 m e com DAP &lt; 5,0 cm. Informações sobre o componente adulto para as mesmas unidades amostrais foram extraídas do banco de dados Laboratório de Dendrologia e Fitossociologia (LABDENDRO), da Universidade do Estado de Santa Catarina. Todas as espécies regenerantes foram classificadas em guildas de regeneração (pioneiras, climácicas exigentes em luz e climácicas tolerantes à sombra), a partir de revisão de literatura e observações de campo. Para todo o componente e para cada classe de tamanho, foram calculados os índices de diversidade de Shannon (H’), de equabilidade de Pielou (J) e os Índices de Regeneração Natural por Classe (RNC) e Total (RNT). As similaridades entre os componentes foram obtidas pelo Índice de Sorensen. Foi realizado um teste de qui-quadrado aplicado a uma tabela de contingência para verificar a existência de associação entre a distribuição dos indivíduos pertencentes a espécies de diferentes guildas de regeneração e a classe de tamanho. Foram amostrados 771 indivíduos regenerantes, distribuídos em 51 espécies, cujos valores de H’ e J foram, respectivamente, de 3,06 e 0,77. A espécie com maior RNT foi Nectandra megapotamica (Spreng.) Mez. A similaridade com o componente adulto variou entre 0,46 para a Classe 3 e 0,62 para a Classe 1. Em todas as classes de tamanho ocorreu a predominância de indivíduos de espécies classificadas como clímax exigentes em luz. Conclui-se que as espécies do componente adulto estão representadas, principalmente, na classe de menor tamanho, na qual se encontra a maior parte dos indivíduos amostrados.

Floristic affinities of the lowland savannahs of Belize and southern Mexico.

Environmental heterogeneity of Belize and southern Mexico savannahs as well as their geographical location suggest that these plant communities share floristic elements, making them conducive to a phytogeographical analysis. The aim of this study was to analyse the floristic affinities of nine savannahs of Belize and southern Mexico and to explain the similarities and differences amongst them.A binary data matrix containing 915 species was built based on the authors’ own collections and on nine floristic lists already published. A second data matrix, consisting of 113 species representing trees, was also used since most literature on neotropical savannahs has focused on this life form. In addition, the ten most species-rich families as well as the characteristic species present in more than five savannahs were analysed. Floristic similarities were calculated using the Jaccard index. Dendrograms obtained in both types of analysis showed clusters with low similarity values, corresponding to geographic locations formed by the savannahs of Belize-Tabasco and the Yucatan Peninsula.The floristic affinities of the savannahs may be explained in terms of heterogeneity in climate and physiography. The Yucatan Peninsula and Belize-Tabasco groups have differences in climate type and the amount of rainfall. In addition, the Yucatan Peninsula savannahs are established at the bottom of karstic valleys, while the Belize and Tabasco savannahs develop on extensive flatlands. The savannahs of Oaxaca have the same climate type and amount of rainfall as those of the Yucatan Peninsula but they are distributed along peaks and the slopes of shale hills. Fabaceae and Poaceae mainly dominated the local floras with 121 and 116 species each; remarkably, Melastomataceae was absent in the Yucatan Peninsula and Oaxaca. Nine species occurred in five to seven savannahs, confirming that they are widespread in both Belize and southern Mexico, and the Neotropics. Geographic location and floristic affinities of the nine savannahs support, to some extent, three different biogeographic provinces.

Recurrent wildfires drive rapid taxonomic homogenization of seasonally flooded Neotropical forests

SUMMARYRecent evidence has shown that most tropical species are declining as a result of global change. Under this scenario, the prevalence of tolerant species to disturbances has driven many biological communities towards biotic homogenization (BH). However, the mechanisms that drive communities towards BH are not yet thoroughly understood. We tested effects of recurring wildfires on woody species richness and composition in six seasonally flooded Amazonian forests and whether these fires reduce species composition (i.e., taxonomic homogenization) over short periods of time. Our results show that these forests are undergoing taxonomic homogenization in response to recurring fire events. Species richness decreased as a result of local extinctions and floristic similarity increased among forest communities. Fire was selecting tolerant (‘winner’) species and eliminating the more sensitive (‘loser’) species. BH leads to biodiversity erosion, which can deeply alter ecosystem processes such as productivity, nutrient cycling and decomposition, resulting in important consequences for conservation.

Temporary freshwater wetlands floristics in central Mexico highlands

Background: Mexico has a high diversity of aquatic and subaquatic plants that occur between 1,000 and 2,500 m of elevation, although a larger proportion of aquatic plants is concentrated at lower altitudes. Temporary wetlands harbor close to 73 % of the aquatic species in Mexico. These systems are under a strong anthropogenic pressure and suffer constant degradation.Questions: i) How many species grow in highland temporary wetlands? ii) Are they floristically similar? iii) Is there a latitudinal pattern of species richness?Studied groups: Charophyta, Pteridophyta, Angiosperms.Study site and years of study: Central Mexico (39 wetlands) from 2015 to 2016.Methods: We collected in 39 temporary wetlands for two years. We made a presence/absence list of species per locality, and calculated floristic similarities and correlations between wetlands. We include data characterizing life form, plant use, and conservation status.Results: We found 126 species belonging to 80 genera and 38 families. The richest families were Cyperaceae, Asteraceae, and Poaceae. As to genera, Eleocharis , Cyperus , and Juncus had more species. Species with the widest distributions were Persicaria mexicana , Marsilea mollis , Luziola fluitans , Heteranthera peduncularis , and Nymphoides fallax . We found five different life forms – all herbaceous, including 27 threatened species, 24 species with economic use, 48 endemic species, and 19 cosmopolitan species. In addition, we found 20 species recorded for the first time in some states included in our study, and two species of Eleocharis that might represent undescribed species. The richest wetland harbors 40 species, the poorest has only five. Wetlands were comparable to each other in species composition, and species richness increases towards the south.Conclusions: Temporary wetlands harbor a high floristic diversity and are similar to each other. Lower latitudes host higher numbers of species.

Vegetation response to restoration management of a blanket bog damaged by drainage and afforestation

AbstractQuestionsDoes restoration management of a formerly afforested blanket bog lead to the vegetation, and the environmental conditions it indicates, becoming similar to intact bog?LocationA 147‐ha blanket bog in Scotland's Flow Country, afforested in the 1980s but undergoing restoration since 1998.MethodsVegetation in the restoration area was surveyed in nine, 1.6–6.4‐ha plots, in 1998, 2003 and 2011. Each plot was matched to nearby plots that were either intact bog or remained afforested. Principal Response Curves were used to highlight the main axes of vegetation variation and test whether plant community trajectories in the restoration area differed from intact bog. The following restoration outcomes were assessed: floristic similarity to bog vegetation; and moisture, fertility and acidity, as inferred from vegetation using Ellenberg indicator values.ResultsIn the 6 years after restoration began, vegetation developed towards bog‐like conditions. In the subsequent 8 years, overall vegetation change stalled, and spatial variability increased, reflecting diverging trajectories in wetter and drier parts of the site. Ellenberg's F‐values implied significant re‐wetting in the restoration area, reaching moisture levels similar to intact bog. Other restoration outcomes progressed in wetter microsites and areas (furrows and flat ground), but stalled in drier locations (plough‐ridges and steeper slopes).ConclusionsOverall moisture conditions, as indicated by plants, have recovered. However, restoration progress has stalled in drier areas, where additional management may be needed. Long‐term vegetation monitoring has helped clarify barriers to recovery and the management needed to overcome them. The value of such monitoring schemes in guiding restoration should be reflected in their wider implementation, within an adaptive management framework.

Successional processes in agricultural mosaics in the eastern Amazon

Most tropical landscapes are mainly composed of dynamic mosaics involving multiple land uses. Different histories of land use management can lead to different successional paths. The aim of this study was to determine if there is a successional floristic gradient related to land use types and how these gradients change across three rural mosaics in Eastern Amazon. We also investigated what are the indicator species across mosaics and land use types and how they change through succession. Five sampling points were established in nine family farms at each mosaic. A detrended correspondence analysis was used to reveal the successional gradient. A multivariate regression tree was used to analyze differences in floristic composition between mosaics and land uses. Floristic similarity between land uses formed successional gradient at the mosaics, in which agricultural land uses represent the early stages of secondary succession and forests represent more advanced stages. Total number of species and total number of shade-tolerant species were correlated with advanced successional stages in all mosaics, but pioneer trees were also correlated with advanced stages in fragmented mosaics. Each mosaic had a distinct successional series due to different management approaches. Where the matrix was mainly composed of forest fragments and the human intervention period was shorter, land use types were more similar to one another as they were grouped into fewer successional stages. Thus, the floristic similarity between land use types appears as an indicator of successional advancement across the mosaics and help determine the regenerative capacity of those areas.

Floristic and Phytosociology of Weeds in Upland Rice in the Humid Tropics

ABSTRACT: Knowledge of the floristic composition and vegetation structure are essential conditions for development of more efficient and economic weed management strategies in crops in the humid tropics. The objective of the research was to carry on floristic and phytosociological surveys to know the main weeds in upland rice fields in the humid tropics of the Brazilian State of Maranhão. Weed samples were done by means of an open metal rectangle of 0.15 m2 thrown at random in the vegetative and reproductive stages of rice crop in 2009/10 and 2010/2011 harvest. A total of 65 species from 23 families was identified 35 (53.85%) from the eudicotyledons botanical group, 29 (44.06%) from the monocotyledonous and one (1.53%) belonged to the pteridophytes. The most representative families were from the monocotyledonous botanical group including Poaceae and Cyperaceae, followed by Amaranthaceae and Malvaceae, both from the eudicotyledons group. The weed species with higher importance values in the upland rice crop vegetative stage were Urochloasp., Panicumsp., C. flavus, C. benghalensis and C. argutus whereas in the reproductive stage the higher importance values were recorded for S. latifolia, C. argutus, L. octovalvis, A.tenella and P.maximum. The most important weeds in the crop vegetative phase were mainly from the monocotyledonous group, while in reproductive one they were the eudicotyledons. Weed diversity was high and the floristic similarity was lower in the vegetative one compared to the reproductive stage of upland rice cultivation in the humid tropics.

Peculiarities of spatial structure, floristic similarity and phytocoenic activity of herbaceous plant species in afforestations and natural steppe groups of Southern Kryvyi Rih area

The spatial structure, phytocoenic activity, frequency of occurrence and floristic similarity of herbaceous and shrub tiers have been studied in different-aged (30–50 years) afforestations of five species (Gleditsia triacanthos L., Quercus robur L., Robinia pseudoacacia L., Pinus pallasiana D. Don, P. sylvestris L.) and steppe communities of Southern Kryvyi Rih area. It was shown that the spatial structure, floristic similarity in the number of species and phytomass in these afforestations depends on the composition of tree species, their age and the type of light structure. During studying the spatial and storey structure of tree plantations it has been found that multi-storeyness is characteristic for the different ages oakeries. The second storey consists of an artificially planted undergrowth. In the stands of Gleditsia triacanthos, the second storey is not developed, and, in artificial pine forests at the sand arenas, the undergrowth is practically absent. The spatial structure of the national-significant nature monument "Natural Landmark Stepok" depends on the mesophytization and ruderalization of the communities, which are the result of a long and complete reservation. It leads to the increase of the areas of Bromopsideta inermis, Poeta angustifoliae formations and the community with domination of Galium aparine L. During the studying steppe phytocoenoses, it has been found that similarity of their floristic compositions depends on the pasture degeneration (slope steppes), and similarity of their phytomasses depends on the dominant species in phytocoenoses. In forest plantations and steppe communities, the largest number of species has a low occurrence rate (up to 20%) and phytocoenic activity by projective coverage up to 1%. In forest and steppe communities, only dominant species have constant phytocoenotic activity of species by phytomass over the years. In general, the species composition of forest stands, their age and light structure affect in different ways the spatial structure, phytocoenic activity by the projective cover and phytomass of species that spontaneously emerge in the stands.

Regeneração natural em área de reflorestamento misto com espécies nativas no município de Laranjeiras, SE

Mixed reforestation with native species can establish a process of ecological succession in disturbed or degraded areas, with natural regeneration as one of the most important indicators of progression of ecological succession. In this sense, this work was carried out with the objective of evaluating the composition and phytosociological structure of the natural regeneration in a mixed reforestation area with native species in the municipality of Laranjeiras, SE. In a reforested area of 46 ha, 30 plots of 1 x 1 m were sampled, all individuals with a base height circumference &lt; 15 cm and in the following height classes were sampled: 0,30 m ≤ H ≤ 1,0 m; 1,1 m ≤ H ≤ 2; 2,1 m ≤ H ≤ 3 m. The species were classified according to the ecological group to which they belong and their dispersion syndromes. The parameters of the vertical and horizontal structure, the indexes of diversity and equability and the floristic similarity between the planted species and the natural regeneration were analyzed. The species G. americana and S. terebinthifolia are indicated as facilitating species for the restoration of degraded areas in the Atlantic Forest in the State of Sergipe, as they occurred in the three height classes. A predominance of pioneer species, low diversity in natural regeneration was verified, caused by grazing of horses in the area. There was little floristic similarity between the regenerants and the planted tree species, since the planted adult individuals did not reach reproductive age yet.

Riqueza y afinidades geográficas de la flora de un bosque de Abies religiosa de la Faja Volcánica Transmexicana

Los bosques de oyamel (Abies religiosa) del centro de México han estado sometidos a fuertes presiones humanas y la información sobre su riqueza y la afinidad geográfica de su flora en algunas regiones ha sido poco estudiada. Mediante recorridos de campo y colectas de ejemplares botánicos, se determinó la composición florística y los patrones de distribución geográfica actual de las familias, géneros y especies de un bosque de oyamel localizado en la Faja Volcánica Transmexicana. Se obtuvo una lista de 94 especies agrupadas en 74 géneros y 42 familias. El 67 % de la flora se concentra en 13 familias de las que Asteraceae destaca por contener el mayor número de especies (24,5 %) y géneros (22 %). La similitud florística entre la zona de estudio y bosques vecinos se incrementa con la cercanía geográfica. El 60 % de las familias son de amplia distribución y cerca del 50 % de los géneros son americanos distribuidos principalmente de México a Centroamérica. El 95,8 % de las especies son exclusivas de América, de las cuales el 44,2 % se encuentran solo en los límites de México y 36,8 % se distribuyen de México a Centroamérica. Entre las especies arbóreas predominan los elementos distribuidos de México a Centroamérica (61,4 %), mientras que entre los arbustos y hierbas sobresalen las especies endémicas de México (60 % y 43,6 %, respectivamente). La alta proporción de especies endémicas de la zona analizada demandan monitoreo continuo que garantice la generación de nuevas alternativas para su conservación.

Синантропные сообщества с Dactylis glomerata L. в Курской области

The results of the studies of synanthropic vegetation in Kursk Region (area is 29 800 sq. km), that is located between 50°54′–52°26′ N and 34°05′–38°31′ E, are given. Zonal vegetation is represented by broad-leaved forests on dark-gray forest soils and meadow steppes on chernozems. Synanthropic vegetation was being studied since 2003. 58 relevés were performed in the city of Kursk and few district centers of Kursk Region. The data were treated by IBIS 7.2 software package (Zverev, 2007). Classification is carried out according to Braun-Blanquet approach, the names of the higher syntaxa follow to «Vegetation of Europe…» (Mucina et al., 2016). Ecological conditions, such as soil moisture, richness in mineral nitrogen, light were assessed with the use of average values by H. Ellenberg et al. (1992) ecological scales while hemero­biality with use of average values of N. G. Ilminskikh (1993) ecological scale and processed by IBIS software (Zverev, 2007). As a result, 2 new associations of synanthropic ve­getation were described. Their communities are widely distributed in anthropogenic habitats within the study area. Ass. Arrhenathero elatioris–Dactylidetum glomeratae (Arepieva 2015) ass. nov. et stat. nov. hoc loco (Table 2, relevés 1–35; nomenclature type (holo­typus) is relevé 19 in the paper by L. A. Arepieva (2015: 102, Table 34), it corresponds to relevé 4 ­(author’s number — 37) in Table 2 in this article) refers to the alliance Convolvulo arvensis–Agropyrion repentis Görs 1967, order Agropyretalia intermedio–repentis T. Müller et Görs 1969, class Artemisietea vulgaris Lohmeyer et al. in Tx. ex von Rochow 1951. Diagnostic species are Arrhenatherum elatius and Dactylis glomerata. Two variants are distinguished within the association. Communities of var. typica (Table 2, rele­vés 1–19; Fig. 1) are described on sunny sites. Communities of var. Glechoma hederacea (Table 2, relevés 20–35; Fig. 2) are often formed in partially shaded habitats under strong anthropogenic impact, that’s why species of the order Arctio lappae–Artemisietalia­ ­vulgaris Dengler 2002 and the class Sisymbrietea Gutte et Hilbig 1975 are more common there. Previously (Arepieva, 2015) we considered this association decribed in the Kursk city as subass. Convolvulo arvensis–Elytrigietum repentis Felföldy 1943 dactylidetosum glomeratae Arepieva 2015. Presently, its rank is rised up to the аssociation for the following reasons: this syntaxon has a wide area of distribution, as the studied communities are common throughout the region, and it good enough differs of the other syntaxa of the alliance Convolvulo arvensis–Agropyrion repentis that are known in our region. Synoptic table (Table 3), value ranges of ecological factors for аssociations (Fig. 3) and DCA-ordination diagram (Fig. 4) demonstrate the differentiation of the syntaxa. The differences of this аssociation of those close to it in composition known in other regions (ass. Convolvulo arvensis–Elytrigietum repentis in Czech Republic, ass. Agropyro repentis–Dactylidetum glomeratae Ubaldi 1976 em. Ubaldi, Puppi et Speranza 1983 in Italy, ass. Geranio tuberosae–Dactylidetum Korzh. et Kljukin 1990 in Ukraine) are discussed. Among syntaxa of the meadow vegetation the most similar in species composition to it is subass. Arrhenatheretum elatioris dactylidetosum glomeratae Nowiński 1967 (alliance Arrhenatherion elatioris Luquet 1926, order Arrhenatheretalia elatioris Tx. 1931, class Molinio-Arrhenatheretea Tx. 1937) in Poland. The syntaxon differentiations are shown in Table 4. In Kursk Region close to the described association is ass. Anthoxantho–Agrostietum tenuis Sillinger 1933 (alliance Cynosurion cristati Tx. 1947, order Arrhenatheretalia elatioris Tx. 1931, class Molinio-Arrhenatheretea Tx. 1937). Ass. Glechomo hederaceae–Dactylidetum glomeratae ass. nov. hoc loco (Table 2, relevés 36–58; nomenclature type (holotypus hoc loco) — relevé 41 (author’s number — 650); Fig. 5) belongs to the alliance Arction lappae Tx. 1937, order Arctio lappae–Artemisietalia vulgaris Dengler 2002, class Epilobietea angustifolii Tx. et Preising ex von Rochow 1951. Diagnostic species are Carex contigua, Dactylis glomerata, Elsholtzia ciliata, Glechoma hederacea, Xantho­xalis stricta. Its communities, that occur in parks and gardens, were described in shaded habitats. The differences between this association and those of synanthropic vegetation close to it in the species composition are shown: ass. Leonuro–Arctietum tomentosi Lohmeyer in Tx. 1950 in Kursk Region and ass. Arctio tomentosi–Rumicetum obtusifolii Passarge 1959 in Slovakia (Table 5; Fig. 6, 7). Identified syntaxa, described within different orders and classes, have high floristic similarity because their communities are directed series with gradually changing conditions (the DCA-ordination diagram on Fig. 8). There is a change of impact of some ecological factors (light, moisture, reaction and richness in mineral nitrogen of soils and substrates) along axis 1. On this axis the communities of var. Glechoma hederacea of the ass. Arrhenathero elatioris–Dactylidetum glomeratae occupy an intermediate position and species, that have high constancy in ass. Glechomo hederaceae–Dactylidetum glomeratae, also occur in these. In all likelihood, the axis 2 is a change in degree of anthropogenic impact, which does not significantly influence on the syntaxon differentiation. The results of DCA-ordination are confirmed by the value ranges of ecological factors (Fig. 9).