Vegetation Composition Related to Environmental Factors along the International Highway-West Alexandria, Egypt

The present study aimed to characterize the ecological features of the vegetation along the international coastal road from El-Ajami to Ras El-Hekma, West Alexandria, Egypt. The cluster analysis of 60 stands was performed using the Community Analysis Package program and Detrended Correspondence Analysis (DCA). Canonical Correspondence Analysis (CCA) was used to identify the ecological relationships between the vegetation and the environment along the roadside. The total number of the recorded plant species surveyed in the present study was 84 species belonging to 74 genera and related to 25 families. Asteraceae, Poaceae, Fabaceae, and Chenopodiaceae were the largest families (53.57% of the total species, collectively). Therophytes is the most abundant life forms. Mediterranean chorotype (58.32%) was the most represented. On the basis of the presence values, cluster analysis yielded four vegetation groups. Group A was dominated by Carthamus tenuis, group B by Lactuca serriola, group C by Bromus diandrus and group D by Suaeda pruinosa. The application of CCA showed that the percentages of porosity, organic carbon, CaCO3, Cl-, SO4--, HCO3 and cations are the most effective soil variables. Generally, the coastal sector in Egypt suffers from unplanned development and salinization of the soil, so the development of the highway needs a balance between conservation and development.

Effects of soil and space on the woody species composition and vegetation structure of three Cerrado phytophysiognomies in the Cerrado-Amazon transition / Efeito do solo e do espaço sobre a composição de espécies lenhosas e estrutura da vegetação de três fitofisionomias de Cerrado na transição Cerrado-Amazônia

Abstract The Cerrado Biome is considered one of the world's biodiversity hotspots because of its rich biodiversity, the high level of endemism and the increasing threat. The Cerrado is composed by a mosaic of different vegetation types, including physiognomies that vary from grasslands (campo limpo) to savannas (typical cerrado or cerrado sensu stricto) and cerrado woodlands (cerradão). However, the factors that determine the composition of the Cerrado's flora and the structure of the physiognomies that compose this biome are still poorly understood. Here, we investigate the influence of the chemical and granulometric properties of the soil and the effect of geographic distance on the occurrence and abundance of woody species in three Cerrado phytophysiognomies - cerrado woodland (cerradão), dense cerrado savanna and typical cerrado savanna - in the Cerrado-Amazon transition. We tested the hypothesis that the edaphic characteristics and geographic space determine the species composition and the structure of the woody vegetation of these three phytophysiognomies. We demonstrate that the dissimilarities in the structure and composition of the three sites were determined more by space (13% of explanation) than edaphic properties (1%), but primarily by the interaction between these two factors (26%). We conclude that, in situations where the chemical and granulometric properties of the soil are relatively homogeneous, as we found in the present study, geographic distance between sites has a greater influence than variation in the substrate's properties on modelling the occurrence and abundance of the woody plant species in the Cerrado.

Resumo O Bioma Cerrado é considerado um dos "hotspots" mundiais de biodiversidade devido à rica biodiversidade que abriga, ao elevado nível de endemismo e à eminente ameaça. O Cerrado é composto por um mosaico de diferentes tipos de vegetação e inclui fisionomias que variam desde áreas predominantemente graminosas (campo limpo) a savanas (cerrado típico ou cerrado sensu stricto) e florestas (cerradão). Entretanto, os fatores que determinam a composição da flora do Cerrado e a estrutura das fisionomias que o compõem ainda são pouco compreendidas. Aqui, nós avaliamos a influência das propriedades químicas e granulométricas do solo e da distância geográfica sobre a ocorrência e abundância de espécies lenhosas em três fitofisionomias do Cerrado - cerradão (CO), cerrado denso (DC) e cerrado típico (TC) - na transição Cerrado-Amazônia. Nós testamos a hipótese de que as características edáficas e o espaço determinam a composição florística e a estrutura da vegetação lenhosa das três fitofisionomias. Nós demostramos que a dissimilaridade florístico-estrutural entre os três sítios foi mais determinada pelo espaço (13% da explicação) do que pelas propriedades edáficas (1%) e principalmente pela interação entre solo e espaço (26%). Concluímos que, em locais onde as propriedades químicas e granulométricas dos solos são relativamente homogêneas, como no presente estudo, a distância geográfica entre sítios tem mais efeito do que o substrato sobre a ocorrência e abundância de espécies lenhosas de Cerrado.

Distribuição do compartimento arbóreo em gradiente de relevo e solos na encosta meridional da Serra Geral, RS / Tree distribution along a relief and soil gradient on the Southern of Serra Geral, Rio Grande do Sul

O presente trabalho foi realizado em fragmento de Floresta Estacional Decidual (29°32'27"S e 53°48'35"W), na Reserva Biológica do Ibicuí-Mirim, localizada no Município de São Martinho da Serra, Estado do Rio Grande do Sul, Brasil, com o objetivo de avaliar as correlações existentes entre a composição florística das espécies arbóreas sobre diferentes condições topográficas e pedológicas sem influência fluvial. Foram instaladas 28 parcelas de 20x20m para amostrar todos os indivíduos com circunferência à altura do peito (CAP)=30cm. Nas parcelas, foram coletadas amostras superficiais de solos (0-20cm) para análise química e granulométrica, além de informações morfológicas dos perfis de solo e topográficas do terreno. Foram registrados 734 indivíduos arbóreos, nos quais, por meio da Análise de Correspondência Canônica (CCA), foi verificada a ordenação ambiental das principais espécies no gradiente topográfico pelas variáveis ambientais de declividade do terreno, cota altimétrica, CTC efetiva, relação Ca/Mg e grau de desenvolvimento do solo. Essas variáveis caracterizaram as diferenças entre as classes de Neossolos do estudo que apresentaram pouco reflexo na distribuição das espécies no gradiente topográfico.

This research was performed in a deciduous forest fragment (29°32'27" S and 53°48'35" W) on the Ibicuí-Mirim biological reserve in the municipality of São Martinho da Serra, in the state of Rio Grande do Sul, Brazil. The aim was to evaluate the correlations between the floristic compositions of tree species growing in different topographical and pedological conditions without river influences. Twenty-eight plots measuring 20x20m were established to test all individuals with =30cm circumference at breast height (CBH). Superficial soil samples (0-20cm) were collected for chemical and granulometric analysis. Also, the morphological characteristics of the soils and the topographical information of the terrain were noted. A Canonical Correspondence Analysis (CCA) was conducted on the 734 individual trees and shrubs that were registered to determine the environmental classification of the species found on the topographical gradient using variables such as terrain declivity, altitude, effective CEC, Ca/Mg relations, and soil development. These environmental variables characterized the differences between the classes of Neosoils in this study that had little influence on the distribution of species on this topographical gradient.

Influence of environmental variables on the shrub and tree species distribution in two Semideciduous Forest sites in Viçosa, Minas Gerais, Brazil

The floristic variations of shrub and tree components were studied in two sites of Semideciduous Forest, initial forest and mature forest, located in the Mata do Paraíso Forest Reserve, in Viçosa, State of Minas Gerais, Southeastern Brazil, in order to analyze the floristic similarity and the correlations between environmental variables and the distribution of tree species in these forests. Individual trees with a diameter at breast height (DBH) ≥ 4.8 cm were sampled in twenty 10 x 30 m plots (10 plots in each site). The plots were distributed systematically at 10 m intervals. The environmental variables analyzed were: the canopy openness and soil chemical and texture characteristics. The two forest sites showed clear differences in the levels of canopy openness and soil fertility, factors that reflect the floristic and successional differences of the shrub and tree component, revealed by the low similarity between these forests by cluster analysis. The canonical correspondence analysis (CCA) of environmental variables and species abundance indicated that the species in these forests studied are distributed under strong influence of canopy openness, moisture and soil fertility. Rev. Biol. Trop. 56 (3): 15571569. Epub 2008 September 30.

Estudiamos las variaciones florísticas de arbustos y árboles en dos sitios de un bosque semicaducifolio, bosque primario y bosque maduro, en la Reserva Forestal Mata do Paraíso, en Viçosa, Estado de Minas Gerais, Sudeste de Brasil, para analizar la similitud florística y las correlaciones entre las variables ambientales y la distribución de tres especies en estos bosques. Árboles individuales con diámetro a la altura del pecho (DAP) ≥ 4.8 cm. fueron muestreados en veinte parcelas de 10 x 30 m (10 parcelas en cada sitio). Las parcelas se distribuyeron sistemáticamente a intervalos de 10 m. Las variables ambientales fueron analizadas así: la abertura del dosel y características químicas y de textura del suelo. Los dos sitios de bosque mostraron diferencias evidentes en la abertura del dosel y fertilidad del suelo, factores que reflejan las diferencias florísticas y sucesionales de arbustos y árboles, revelado por la baja similitud entre estos bosques por medio de análisis de conglomerados. El análisis de correspondencia canónica (CCA) de variables ambientales y abundancia de especies indican que las especies en los bosques estudiados están distribuidas bajo una fuerte influencia de la abertura del dosel, humedad y fertilidad del suelo.