Effects of oil contamination on plant growth and development: a review.

Oil spills generate several environmental impacts and have become more common with the increase in petroleum extraction, refining, transportation, and trade. In soil, oil contamination increases water and nutrient availability and compaction, directly affecting plant growth and development. Different aspects of phytotoxicity can be observed and will vary according to the characteristics of soil and plants. Oil-contaminated soil also results in negative effects on biomass and changes in leaves and roots. Investigating the effects of oil contamination on plant growth and development can aid in the conservation of plant species and in the development of techniques such as bioremediation and biomonitoring. Thus, this review aims to discuss the main effects of oil contamination on plants, such as environmental stress and morphological, physiological, and anatomical changes, and the strategies developed by plants to survive contamination, as well as to identify plants with phytoremediation potential that can assist in removing oil from the environment.

Floristic patterns of alluvial forests in Atlantic Forest and Pampa: Climate and geographic insertion as determining factors.

The aims of this study were to identify floristic assemblages for alluvial forests in the Atlantic Forest and Pampa regions in Brazil, assess the level of floristic similarity between assemblages, and determine environmental gradients and indicator species for these assemblages. Surveys carried out in alluvial forests in the Atlantic Forest and Pampa regions were selected, based on which a presence/absence matrix was built for tree species. A cluster analysis was performed to verify the existence of species assemblages. Floristic similarity was determined by means of the Sorensen Distance measure, from which a dendrogram was developed. The floristic matrix was ordinated by means of NMDS. A PCA was performed with climatic data from areas to determine environmental gradients. An assessment of indicator species was carried out afterwards. Two groups of areas not related to the separation of the regions became visible from the dendrogram and were corroborated by NMDS. Temperature, rainfall and altitude gradients were synthesized by the PCA. Gymnanthes klotzschiana and Andira fraxinifolia were the most relevant species, respectively, in the Paraná-Uruguay and Atlantic assemblages. Alluvial forests were gradually separated in two floristic assemblages associated with river basins and migration routes, while especially influenced by tropicality and altitude gradients.

Vascular epiphyte biomass in a South Brazilian fragment of Atlantic Forest.

The present study aimed at sampling the biomass of vascular epiphytes within a protected area in South Brazilian Atlantic Forest. All tree specimens with diameter at breast height equal or greater than 4.8 cm were measured and divided into classes. In each class, 10% of tree specimens were randomly selected for epiphytic biomass measuring. Furthermore, we divided the phorophytes into five tree parts to analyze epiphytic biomass. We generated mathematical models to estimate epiphytic biomass in similar forest areas. We analyzed 55 phorophytes and found an estimated epiphytic biomass of 5.3 Mg/ha. Epiphytic biomass ranged from 0.02 to 135 kg and the lower values were found on small-sized phorophytes. Higher values of epiphytic biomass were found on phorophytes with diameter at breast height between 30 and 36.5 cm. The tree part with higher epiphytic biomass was the outer crown. The epiphytic biomass showed a high correlation with phorophyte diameter, according to the mathematical models. We selected two equations which presented the most similar values to the ones we measured. Our results corroborate that epiphytes play a very important role as to the biomass level within tropical forests.

Dispersion and aggregation patterns of tree species in Araucaria Forest, Southern Brazil.

Studies about dispersal syndromes and spatial distribution can provide information about species ecology. However, few studies analyze these ecological patterns in different vegetation layers. In this work, we verified the relationship between the dispersion syndromes and the spatial distribution in different layers in Araucaria Forest. We sampled 180 plots with size and inclusion criteria that changed according to the vegetative layer. We sampled 15,545 individuals in 103 tree species. We found significant differences between the number of species in the dispersion syndromes (χ2 = 11.52; P ≤ 0.05) and spatial distribution patterns (χ2 = 10.94; P ≤ 0.05), being zoochoric and tends to clustering the most predominant. We also found a significant interaction between the dispersion syndromes and spatial distribution patterns in the analyzed layers (F = 1,044; P < 0.0001), with anemochoric species characterized by random distribution, autochoric in the cluster distribution and zoochoric in the tends to clustering. The results demonstrate that the tree species of the different layers are related to the type of dispersion and the aggregation pattern.

Using worldwide edaphic data to model plant species niches: An assessment at a continental extent.

Ecological niche modeling (ENM) is a broadly used tool in different fields of plant ecology. Despite the importance of edaphic conditions in determining the niche of terrestrial plant species, edaphic data have rarely been included in ENMs of plant species perhaps because such data are not available for many regions. Recently, edaphic data has been made available at a global scale allowing its potential inclusion and evaluation on ENM performance for plant species. Here, we take advantage of such data and address the following main questions: What is the influence of distinct predictor variables (e.g. climatic vs edaphic) on different ENM algorithms? and what is the relationship between the performance of different predictors and geographic characteristics of species? We used 125 plant species distributed over the Neotropical region to explore the effect on ENMs of using edaphic data available from the SoilGrids database and its combination with climatic data from the CHELSA database. In addition, we related these different predictor variables to geographic characteristics of the target species and different ENM algorithms. The use of different predictors (climatic, edaphic, and both) significantly affected model performance and spatial complexity of the predictions. We showed that the use of global edaphic plus climatic variables generates ENMs with similar or better accuracy compared to those constructed only with climate variables. Moreover, the performance of models considering these different predictors, separately or jointly, was related to geographic properties of species records, such as number and distribution range. The large geographic extent, the variability of environments and the different species' geographical characteristics considered here allowed us to demonstrate that global edaphic data adds useful information for plant ENMs. This is particularly valuable for studies of species that are distributed in regions where more detailed information on soil properties is poor or does not even exist.

Floristic evolution in an agroforestry system cultivation in Southern Brazil.

Bracatinga (Mimosa scabrella Bentham) is an important pioneer tree species in Ombrophylous Mixed Forest of Brazil and is widely used as an energy source. In traditional agroforestry systems, regeneration is induced by fire, then pure and dense stands known as bracatinga stands (bracatingais) are formed. In the first year, annual crops are intercalated with the seedlings. At that time the seedlings are thinned, then the stands remain at a fallow period and cut at seven years old. The species is very important mainly for small landowners. We studied the understory species that occur naturally during the succession over several years in order to manage them rationally in the future and maintain the natural vegetation over time. Three to 20 year-old Bracatinga stands were sampled between 1998 and 2011. All tree species with diameter at breast height (DBH) ≥ 5 cm were measured.The floristic evolution was assessed with respect to Sociability Index, the Shannon Diversity Index and the Pielou Evenness Index. Graphs of rank/abundance over different age groups were evaluated using the Kolmogorov-Smirnov test. We identified 153 species dispersed throughout the understory and tend to become aggregated over time.

Gradiente ambiental em comunidades arbóreas no baixo rio Jacuí / Environmental gradient analysis in arboreal communities in the lower Jacuí river

A região da Depressão Central do Rio Grande do Sul estende-se por planícies e relevos suaves ondulados, com predomínio de florestas de galeria. Este estudo teve o objetivo de investigar a estrutura e a diversidade dos remanescentes de Floresta Estacional Decidual em diferentes posições na paisagem de pequenos tributários ao longo de uma microbacia em Pantano Grande, RS. Os levantamentos foram realizados em 40 pontos amostrais com 500 m2. Foi constatada a existência de três grupos ecológicos, espacialmente correlacionados à posição no relevo, tendo diferentes estágios de conservação, diversidade, estrutura e florística. O grupo 1, formação submontana (FS), destacou-se pela maior densidade de indivíduos nas maiores classes de diâmetro e pela maior altura, com alta dominância ecológica, determinada por uma particular espécie tolerante à sombra, Actinostemon concolor. O grupo 2, FA/FS, revelou-se com maior diversidade que os demais grupos, apresentando menor dominância ecológica. O grupo 3, formação aluvial (FA), foi caracterizado por indivíduos arbóreos menores e pela presença dominante deSebastiania commersoniana.

Central Depression region in the state of Rio Grande do Sul extends across plains and gentle undulated reliefs, with a predominance of gallery forests. This study aimed to analyze remaining tree communities of the seasonal deciduous forest in different positions of the landscape in small tributaries of a watershed in Pantano Grande, RS, Brazil. Surveys were conducted at 40 sampling points equaling 500 m2. The analysis pointed to the existence of three ecological groups, spatially correlated with their positions in the landscape, at different stages of preservation, diversity, structure and floristic development. The community groups were named sub-montane (upper plains) and alluvial formations, and the domain area of both formations (FA/FS). TheFA/FS proved to be more diverse than the others, with lower ecological dominance in narrow fragments. Submontane stood out with higher density of individuals in the largest diameter and height classes, with high ecological dominance, determined by a particular species tolerant to shade,Actinostemon concolor. Alluvial formation (FA) was characterized by smaller individual trees and the dominant presence of Sebastiania commersonianain narrow corridors.

Seasonal changes in dominant bacterial taxa from acidic peatlands of the Atlantic Rain Forest.

The acidic peatlands of southern Brazil are essential for maintenance of the Atlantic Rain Forest, one of the 25 hot-spots of biodiversity in the world. While these ecosystems are closely linked to conservation issues, their microbial community ecology and composition remain unknown. In this work, histosol samples were collected from three acidic peatland regions during dry and rainy seasons and their chemical and microbial characteristics were evaluated. Culturing and culture-independent approaches based on SSU rRNA gene pyrosequencing were used to survey the bacterial community and to identify environmental factors affecting the biodiversity and microbial metabolic potential of the Brazilian peatlands. All acidic peatlands were dominated by the Acidobacteria phylum (56-22%) followed by Proteobacteria (28-12%). The OTU richness of these phyla and the abundance of their Gp1, Gp2, Gp3, Gp13, Rhodospirillales and Caulobacteriales members varied according to the period of collection and significantly correlated with the rainy season. However, despite changes in acidobacterial and proteobacterial communities, rainfall did not affect the microbial metabolic potential of the southern Brazilian Atlantic Rain Forest peatlands, as judged by the metabolic capabilities of the microbial community.

Composição florística e distribuição altitudinal de epífitas vasculares da Floresta Ombrófila Densa na Serra da Prata, Morretes, Paraná, Brasil / Floristic composition and altitudinal distribution of vascular epiphytes in the Ombrophilous Dense Forest of the Prata Mountain Range, Morretes, Paraná State, Brazil

O levantamento de epífitas vasculares foi realizado na porção norte da Serra da Prata (48º 41' 59,39" O e 25º 36' 46,39" S), município de Morretes, abrangendo 6,3 ha de encosta situada entre 400 e 1.100 m s.n.m., coberta por Floresta Ombrófila Densa Submontana e Montana. Os objetivos do trabalho foram: 1) caracterizar a flora epifítica vascular; 2) discutir sua distribuição altitudinal e nas categorias ecológicas; 3) avaliar a similaridade florística com outras áreas do sul e sudeste do Brasil. O levantamento foi efetivado entre 2005 e 2010. Cento e vinte forófitos, distribuídos por quatro altitudes (400, 600, 800 e 1.000 m), foram escalados e detalhadamente vasculhados. Foram registradas 278 espécies, 109 gêneros e 30 famílias de epífitas vasculares. Pteridófitas englobaram 74 espécies, 30 gêneros e 10 famílias. Angiospermas totalizaram 204 espécies, 79 gêneros e 20 famílias. A riqueza de epífitas vasculares foi a maior já registrada em estudos de Floresta Ombrófila Densa no sul do Brasil. Sete espécies tiveram seu primeiro registro para o Paraná e seis enquadraram-se como ameaçadas em nível estadual. Orchidaceae foi a mais rica, com 103 (37,2%) espécies e 43 (39,1%) gêneros, seguida de Bromeliaceae (38), Polypodiaceae (28), Hymenophyllaceae (15), Araceae (14) e Piperaceae (14). As holoepífitas características constituíram o grupo dominante, perfazendo 83% do total. Apenas 54 (19,5%) espécies foram registradas em todas as faixas altitudinais, sendo que 131 (47,3%) foram registradas somente abaixo dos 700 m e 54 (19,5%) encontradas somente acima dos 800 m. Detectou-se reduzida similaridade florística entre as extremidades da encosta estudada, o que destaca a importância da altitude na distribuição das espécies. A flora epifítica da Serra da Prata apresentou reduzida similaridade com outras comunidades de Floresta Ombrófila Densa do PR e SP.

The floristic survey of vascular epiphytes was done in the northern part of the Prata Mountain Range (48º 41' 59.39" W and 25º 36' 46.39" S), Morretes municipality, comprising 6.3 ha of a slope between 400 and 1,100 m a.s.l., covered by submontane and montane Atlantic Rainforest. The aims of this study were: 1) characterize the vascular epiphytic flora; 2) discuss the species distribution along the slope and in ecological categories; 3) evaluate the floristic similarity among the study area and other forests of South and Southeastern Brazil. The present survey was carried out between 2005 and 2010. One hundred twenty phorophytes were climbed and closely examined. Two hundred seventy-eight species, 109 genus and 30 families of vascular epiphytes were recorded. Pteridophytes comprised 74 species, 30 genus and 10 families. Angiosperms comprised 204 species, 79 genus and 20 families. The vascular epiphytic richness was the highest registered in studies of Atlantic Rainforest in South Brazil. Seven species were the first records for the Paraná State and six are threatened considering the Paraná state official list of endangered species. Orchidaceae was de richest family, with 103 (37.2%) species and 43 (39.1%) genus, followed by Bromeliaceae (38), Polypodiaceae (28), Hymenophyllaceae (15), Araceae (14) and Piperaceae (14). The holoepiphytes were the dominant group, comprising 83% of the total. Only 54 (19.5%) species were recorded in all altitudinal belts. Other 131 (47.3%) species were recorded only under the 700 m a.s.l. and 54 (19.5%) were found just above the 800 m a.s.l. The floristic similarity between the two extremities of the studied slope was low, showing the importance of the altitude for the species distribution. The epiphytic flora of the Prata Mountain Range presented low similarity with others Atlantic Rainforest communities of Paraná and São Paulo states.