Botânica

Asteraceae from Panga Ecological Reserve, Uberlandia, Minas Gerais, Brazil). A systematic treatment of the Asteraceae species is presented here. The ecological reserve, located 30 km S of the city of Uberlândia, has a mosaic of phytophysiognomies of the "Cerrado" domain. The specimens are from collections made since 1986 and are deposited at Herbarium Uberlandense (HUFU) of the Universidade Federal de Uberlandia, Minas Gerais. A total of 98 species distributed in 46 genera was recorded. The genera with the highest number of species are Vernonia (20 spp.), Chromolaena (10 spp.) and Baccharis (8 spp.). Identification key, followed by morphological descriptions of each species, information on distribution and comments on morphological similarities are presented.

This study describes the tree vegetation and soils occurring in a seasonally dry tropical forest (SDTF) and mesotrophic cerradão transition in southwestern Brazil. All trees ≥ 5 cm diameter were measured in 20 plots of 20 × 25 m, 10 in SDTF, and 10 in mesotrophic cerradão. Ten soil samples of 0−20 cm depth were made per plot and mixed in plot groups to produce two composite samples. A total of 71 species was recorded. Anadenanthera colubrina had the highest importance values in both formations. Differences in soil fertility were found between SDTFs (eutrophic soils) and mesotrophic cerradão (mesotrophic soils). A non-metric multidimensional scaling and cluster analysis confirmed the soil fertility segregation, and also showed an agreement between soil fertility and variance in species composition gradients. The mesotrophic cerradão showed higher species richness since it also includes many species typical of more dystrophic and open forms of Cerrado.

Aim The aim of this study was to test the role of environmental factors and spatially autocorrelated processes, such as historical fragmentation and dispersal limitation, in driving floristic variation across seasonally dry tropical forests (SDTFs) in eastern South America.

Sementes comerciais de forrageiras tropicais, pertencente a 26 lotes produzidos em diferentes regiões (safras 2004-05 e 2005-06), foram avaliadas quanto à sanidade. Foram analisadas sementes de cultivares de Panicum maximum (Massai, Mombaça e Tanzânia) e de estilosantes (Estilosantes Campo Grande -ECG). Adicionalmente, avaliou-se a qualidade sanitária de dois lotes de sementes de P. maximum destinados à exportação. Para isso, as sementes foram submetidas ao teste de papel de filtro em gerbox, os quais foram incubados a 20ºC, com fotoperíodo de 12 h, durante sete dias. Os fungos saprófitos ou secundários (FSS) mais frequentemente detectados nos lotes de P. maximum foram Aspergillus sp., Cladosporium sp. e Rhizopus sp., os quais, em geral, apresentaram baixa incidência nas sementes. Quanto aos fungos patogênicos (FP), constatou-se elevado número de lotes contaminados pelos gêneros Bipolaris, Curvularia, Fusarium e Phoma. Em geral, foi elevada a incidência de FP nas sementes de P. maximum. A ocorrência de Phoma sp. foi a mais crítica, pois 81% dos lotes registraram índices superiores a 50%. Nas sementes de 'ECG' foram detectados FSS (gêneros Aspergillus, Cladosporium e Penicillium) e FP (gêneros Bipolaris, Curvularia, Fusarium e Phoma), os quais apresentaram, em geral, baixa incidência. FSS e FP também foram associados às sementes de P. maximum tipo exportação, em alguns casos, com incidência considerável. Os resultados indicaram que em todas as regiões produtoras existiu pelo menos um fator limitante afetando a qualidade sanitária das sementes.

Termos para indexação: caapões, fitossociologia, florística, pantanal, Mato Grosso do Sul Introdução O Pantanal é a maior planície sedimentar inundável do hemisfério ocidental, com extensão de aproximadamente 140.000 km², formada no período quaternário, preenchida com depósitos aluviais dos rios da Bacia do Alto Paraguai (BAP). A baixa declividade dificulta o escoamento das águas e, em combinação com mesorelevo, origina o aparecimento de ambientes característicos, associados à vegetação em mosaico, como as "cordilheiras" (antigos diques fluviais), com vegetação arbórea mais densa. A vegetação seca é interpenetrada por vários tipos de vegetação higrófila nas áreas inundadas (Prance & Schaller 1982).

Abstract: Phytosociology of aquatic macrophytes associated to the Miranda river, Pantanal, MS, Brazil. -This study aimed to analyze quantitatively the community structure of aquatic macrophytes associ-ated to the Miranda river, Pantanal wetland, Mato Grosso do Sul, utilizing two sampling methods: line interception and plots. A total of 36 species were recorded, distributed in 31 genera and 20 families, Poaceae being the family with highest species richness (5 spp.), followed by Malvaceae (4), Asteraceae, Araceae, Convolvulaceae e Polygonaceae represented by three species each one. Polygonum acumina-tum showed highest importance value under both techniques. Shannon diversity index (H') was 2.44 for line interception and 2.47 for plots. The rarefaction curve showed stabilization trend for both methods, indicating sampling sufficiency. The results were similar for both techniques, suggesting that either is appropriate for quantitative surveys of this vegetation.

A apicultura tem estreita relação com o desenvolvimento da flora de uma região, quer pela participação direta das abelhas através da polinização, quer pela ação do homem procurando melhorar as condições apícolas e favorecendo deste modo o meio ambiente Scheren [1].

In order to develop niche models for tree species characteristic of the cerrado vegetation (woody savannas) of central South America, and to hindcast their distributions during the Last Glacial Maximum and Last Inter-Glacial, we compiled a dataset of tree species checklists for typical cerrado vegetation (n=282) and other geographically cooccurring vegetation types, e.g. seasonally dry tropical forest (n=355). We then performed an Indicator Species Analysis to select ten species that best characterize typical cerrado vegetation and developed niche models for them using the Maxent algorithm. We used these models to assess the probability of occurrence of each species across South America at the following time slices: Current (0 ka pre-industrial), Holocene (6 ka BP), Last Glacial Maximum (LGM-21 ka BP), and Last Interglacial (LIG-130 ka BP). The niche models were robust for all species and showed the highest probability of occurrence in the core area of the Cerrado Domain. The palaeomodels suggested changes in the distributions of cerrado tree species throughout the Quaternary, with expansion during the LIG into the adjacent Amazonian and Atlantic moist forests, as well as connections with other South American savannas. The LGM models suggested a retraction of cerrado vegetation to inter-tableland depressions and slopes of the Central Brazilian Highlands. Contrary to previous hypotheses, such as the Pleistocene Refuge Theory, we found that the widest expansion of cerrado tree species seems to have occurred during the LIG, most probably due to its warmer climate. On the other hand, the postulated retractions during the LGM were likely related to both decreased precipitation and temperature. These results are congruent with palynological and phylogeographic studies in the Cerrado Domain.

The objective of this study was to model the potential effect of future climate change on the distribution of a tree species indicator of Cerrado. For the modeling, we used 488 occurrence points of the species and also bioclimatic variables corresponding to 2050 and 2070, for the more optimistic and pessimistic scenarios. All generated models were classified as consistent, getting an area under curve higher than 0.90. The current modeling of Connarus suberosus showed that 88% of the area with a high probability of species occurrence is inside the Cerrado domain. Future projections suggest losses in the environmental suitability area around 40.8% and 44.8% in the optimistic scenario, 61.6% and 81.6% in the pessimistic scenario considering 2050 and 2070, respectively. Furthermore, we found a tendency of the C. suberosus to move in the Atlantic Forest direction. This modeling is an alert that the C. suberosus will suffer from future climate change.

Variações na altitude podem propiciar mudanças na composição florística e fisionomia das formações vegetais. Este trabalho tem o objetivo de descrever a flora e a estrutura de comunidades arbóreas ao longo de gradiente altitudinal na morraria do Urucum, Corumbá, Mato Grosso do Sul, Brasil. Foram instaladas 10 parcelas contíguas de 10mx20m em cada altitude (100, 200, 300, 500 e 700m), totalizando 1ha amostrado. Foram registrados todos os indivíduos arbóreos vivos, incluindo palmeiras, com diâmetro à altura do peito ≥ 5cm. Foram amostrados 1295 indivíduos pertencentes a 32 famílias e 74 espécies. Fabaceae e Meliaceae foram as famílias mais representativas da base da morraria, e Fabaceae e Myrtaceae as do topo. A composição florística variou ao longo do gradiente de altitude, desde Floresta Estacional Semidecídua Submontana (de 100 a 500m) até Savana Florestada (a 700m). A estrutura das comunidades arbóreas também variou segundo o gradiente altitudinal, com alternância das espécies com maior índice de valor de importância (IVI). Nas cotas mais altas, houve diminuição da altura média dos indivíduos, e aumento da área basal e da dominância de espécies. Essas mudanças podem estar relacionadas às características físicas do solo, uma vez que na cota de 700m ocorre um solo raso, que apresenta somente o horizonte A. Palavras-chave: floresta semidecídua; cerradão; Maciço do Urucum; borda oeste do Pantanal. ABSTRACT COMPOSITION AND DISTRIBUTION OF TREE SPECIES IN AN ALTITUDINAL GRADIENT, URUCUM MOUNTAINS, BRAZIL. Altitudinal variation can promote changes in floristic composition and physiognomy of the vegetation. This research aims to describe the floristic composition and structure of tree communities along an altitudinal gradient in the Urucum mountains, Corumbá, Mato Grosso do Sul, Brazil. Ten contiguous plots of 10m x 20m were established in each altitudinal levels (100, 200, 300, 500 and 700m), performing 1ha at all. We surveyed all trees, including palms, with diameter at breast height ≥ 5cm. We found 1295 trees belonging to 32 families and 74 species. Fabaceae and Meliaceae were the most common families at lower altitude, and Fabaceae and Myrtaceae at higher altitude. Floristic composition changed from the base to the top of the study area, i.e. from submontane semideciduous forest (100 to 500m) to woodland savanna (700m). Also, the community structure changed at the same direction, with the species of greater importance value index (IVI) changing in each level. Altitude average height decreased, and basal area and dominance of specimens increased in higher altitudes. These changings may be related to soil physical properties, since at 700m soil is shallow, presenting only an A horizon.

The evolutionary processes underlying the high diversity and endemism in the Cerrado, the most extensive Neotropical savanna, remain unclear, including the factors promoting the presence and evolution of savanna enclaves in the Amazon forest. In this study, we investigated the effects of past climate changes on genetic diversity, dynamics of species range and the historical connections between the savanna enclaves and Cerrado core for , a tree species widely distributed in the biome. Totally, 40 populations distributed in the Cerrado core and Amazon savannas were analyzed using chloroplast and nuclear DNA sequences. We used phylogeographic, coalescent and ecological niche modeling approaches. Genetic data revealed a phylogeographic structure shaped by Pleistocene climatic oscillations. An eastern-western split in the Cerrado core was observed. The central portion of the Cerrado core harbored most of the sampled diversity for cpDNA. Ecological niche models predicted the presence of a...

This study describes the influence of edaphic factors on the floristic composition of an area of cerradão (woodland savanna) in the city of Campo Grande, located in the Brazilian central-west. In 10 plots (5 × 20 m each), we evaluated all trees with a diameter at breast height ≥ 4.77 cm. Soil samples were analyzed for each plot in order to determine edaphic variables correlated with species composition. We sampled 1180 individuals of 61 species. The evenness index was 0.74, which indicates uneven distribution of species, which was explained by a high abundance of Qualea parviflora, Curatella americana, Qualea grandiflora, Terminalia argentea and Astronium fraxinifolium. We registered more trees in the smallest diameter class and in the middle layer of the vertical structure. The soil was dystrophic with a clay texture, which explains the higher abundance of species related to dystrophic cerradão. However, we also found some trees typical of mesotrophic cerradão and deciduous forests, which could be attributable to the presence of patches of fertile soil within the dystrophic cerradão or could indicate that those mesotrophic species are tolerant of lower levels of soil nutrients.

Large areas in the Pantanal wetland are covered by monodominant formations, e.g. typical landscapes with local names such as “paratudal”, dominated by T. aurea. Studies on structure of these formations generally include only woody strata, consequently the species richness registered is usually low due to the absence of the ‘ground layer’ of herbaceous and others low species. We recorded 13 species, 12 genera and 11 families for the arboreal stratum. Considering arboreal flora without the dominant (T. aurea) individuals showed great establishment in relation to the flood level between 35 – 45 cm while the individuals of the dominant species of 30 – 45 cm. The diameter distribution revealed that the population of T. aurea did not show the reverse J curve, the usual pattern for species in constant regeneration, also evidenced in inconstant Licourt quotient, indicating an episodic recruitment that could lead to future changes in structure. In the herbaceous strata we recorded 78 species...