Priscyla Maria Silva Rodrigues

The Physical Environment of Rupestrian Grasslands (Campos Rupestres) in Brazil: Geological, Geomorphological and Pedological Characteristics, and Interplays

The Rupestrian Grassland is a vegetational complex with grassy to shrubby formations that occur throughout the high mountains of Brazil, usually formed by structurally resistant rocks, little affected by late tectonics, and strongly eroded and weathered under long term geological stability. RGC is closely associated with high altitude landsurfaces, in which several factors have a determinant role: (1) extreme oligotrophy, and acid, nutrient-depleted parent materials; (2) resistance to weathering and erosion (chemical and physical); (3) constant wind exposure; (4) intense fire regime. Variations of RG phytophysiognomies are basically due to soil depth (edaphic factor), drainage and landscape stability and evolution. Landforms (geomorphological attributes) affect the RGC at continental scales (high landsurfaces), regional scales (regional landforms, such as escarpments, valleys, slopes) and local scales (soil depth, stoniness, rockiness, drainage). The most common occurrence of RGC in Brazil is on Quartzite and metarenites, followed by canga and other Fe-rich substrates, igneous rocks and metamorphics, hence displaying a high diversity of substrates, with a major trait of extreme soil oligotrophy and acidity, and crucial variations in soil depth. The occurrence of well-documented areas of RG on Granitic and gneissic terrains imply that even richer rocks, submitted to long term weathering and erosion, can lead to similar soils on Highlands, where rock outcrops are also common (e.g. Caparao, Itatiaia, Brigadeiro, Serra dos Orgaos). RGC can occur immersed in different domains (Atlantic Forest, Caatinga, Cerrado), regardless of present day climates, since it represents an edaphic climax of long-term development. The widespread distribution of comparable RGC, from Amazonia (Carajas, Roraima, Pacaas Novos, Cachimbo) to the Central Plateau (Santa Barbara, Ricardo Franco, Pirineus) and Northeastern and Southeastern Brazil (Caparao, Espinhaco, Sincora, Jacobina, Itatiaia, Serra dos Orgaos, Brigadeiro, Carangola) raises the unresolved question of phylogenetic ancestry, age and similarities (floristic, structural) between those isolated islands of Rupestrian vegetation. These aspects are central to the evolution of Brazilian Biomes, representing key issues to resolve the late Quaternary Refuge Theory controversy, and test the validity of island biogeographical isolation theories.

Landforms and soil attributes determine the vegetation structure in the Brazilian semiarid

The semiarid region of Brazil consists of a great variety of landscapes, soils and vegetation forms, with complex interrelations. In order to better understand this interplay, we posed two questions: Are there greater pedological similarities among the different landforms of the same catena or among the same landforms from different catenas? Which soil attributes could be the most important to segregate communities of plants? We sampled soils and vegetation on different landforms in four different catenas and performed NMS (non-metric multidimensional scaling) and ANOVA (analysis of variance) to address the first question; also, we carried another NMS following GLM (general linear model regression) to answer the second question. The first NMS indicated the existence of a fertility gradient, grouping communities in relation to similar landforms, confirmed by ANOVA. The second NMS indicated the same gradient whereas the GLM showed that is controlled by aluminum saturation, sodium saturation, phosphorous and sand content. One extreme of the gradient has uplands associated with cerrado vegetation forms whereas the other extreme slopes were associated with dry forests. The lowlands associated with dry forest represent the central position of the fertility gradient. In general, soils at similar landforms showed greater pedological similarity, and their physico-chemical attributes determined the formation and structure of vegetation. This similarity across the same landform refers to the comparable soil formation at each landform and soil age at landscape scale. The characteristics of the vegetation and soils in the Brazilian southern semiarid region indicated a previously wetter climate, during which deep weathered latosols (oxisols) were formed and remain as relics in the present semiarid.

Caracterização física de frutos e putâmens e taxa de ataque por Carmenta sp. a pequizeiros (Caryocar brasiliense Camb.) no norte de Minas Gerais

The pequi tree is a native species of brazilian savanah, which fruits are explored in an extractivist form, having a huge economic importance. The long periods of availability of the fruits, together with the heterogeneity of the productive regions, leads to an inference of the existence of differences among their physical characteristics. Thus, this study aimed to compare the physical characteristics of pequi tree fruit collected in three municipalities in the north of Minas Gerais state, and to verify if the attack by insects is directly related to its biometrical characteristics. We sampled 10 individuals and collected 20 fruits from each tree, in Montes Claros, Mirabela and Japonvar, municipalities, totalling 200 fruits per area. The physical variables of the fruits and pits, the number of little fruits (frutilhos), pits and seeds, and the percentage of intact and damaged fruits and pits were determined. The results indicated that there are physical differences among the collected areas, with the region of Japonvar having the most vigorous pits, with the lowest rates of attack by the pequi fruit borer. In addition, skin thickness and length of fruits from Japonvar and Mirabela, respectively, had relations with the percentage of attack by Carmenta sp. These differences found among the areas may be associated with the climatic and edaphic influences of these regions, which may also highlight the linkage to the genetical composition aspects of the pequi.

EFFECTS OF PRE-GERMINATION TREATMENTS AND STORAGE ON GERMINATION OF Astronium fraxinifolium SCHOTT (ANACARDIACEAE) DIASPORES

Este trabalho teve como objetivo avaliar a germinacao e a capacidade de armazenamento de diasporos de Astronium fraxinifolium. Para o experimento de germinacao, utilizaram-se seis tratamentos pre-germinativos: tratamento controle (diasporos intactos); diasporos imersos em agua a temperatura ambiente (25o C) por 5 min.; diasporos imersos em agua a 70° C por 5 min.; diasporos imersos em agua a 100° C por 5 min.; diasporos imersos em solucao de hipoclorito de sodio (1:1000) por 2 min.; e diasporos escarificados mecanicamente, com lixa no 80. Para determinar a capacidade de armazenamento, foram testados dois diferentes tipos de embalagem (saco de papel permeavel e vidro transparente) e duas condicoes ambientais (câmara fria e condicoes de laboratorio). Foram realizados testes de germinacao antes do armazenamento (tempo zero) e apos 60, 120, 180, 240, 300 e 360 dias de armazenamento. Os efeitos dos diferentes tratamentos pre-germinativos e das condicoes de armazenamento na germinacao dos diasporos foram avaliados por meio da ANOVA, seguida do teste de Tukey. Em relacao aos tratamentos pre-germinativos, foram observadas altas taxas de germinacao nos tratamentos com imersao em hipoclorito (98,0 ± 4,22%), controle (97,0 ± 4,83%), imersao em agua destilada a temperatura ambiente (96,0 ± 6,99%) e imersao em agua aquecida a 70oC (83,0 ± 29,08%). Dessa forma, os diasporos de Astronium fraxinifolium nao apresentaram dormencia. No armazenamento, os diasporos permaneceram viaveis durante todo o periodo de estudo, apresentando altas porcentagens de germinacao, com excecao do tratamento em saco de papel acondicionado em câmara fria, que perdeu a viabilidade no oitavo mes de armazenamento, nao sendo, portanto, um metodo de armazenamento recomendado para esta especie.

Richness and structure of the tree component and soil characteristics of a gradient of riparian forest in Minas Gerais, Brazil

This study aimed to relate variations in richness and tree community structure to soil characteristics in a gradient of riparian forest, at Parque Estadual da Mata Seca, north of Minas Gerais. Studies of soil characteristics and the richness and structure of trees (DBH 5 cm) were conducted in 39 plots of 400 m2, divided equally into three sections previously selected, these being: São Francisco (lower moisture), Meio (flooding during most of the year) and Lagoa da Prata (flooding during the rainy season). The analysis of topsoill (0-20 cm) showed significant differences between the different forest sections. In all three environments were sampled 2482 individuals belonging to 36 species, 31 genera and 16 plant families. There were significant differences for the different sections in the Shannon diversity index, number of individuals, basal area and absolute dominance. The diameter distribution of the community had a great number of individuals concentred in the smallest classes, decreasing gradually. It is noteworthy that the basal area and density of subjects 1 Recebido em 08.11.2012 aceito para publicação em 06.11.2013. 2 Programa de Pós-graduação em Botânica, Universidade Federal de Viçosa, UFV, Brasil. E-mail:. 3 Departamento de Engenharia Florestal, Universidade Federal de Viçosa, UFV, Brasil. E-mail:. 4 Departamento de Biologia Vegetal, Universidade Federal de Viçosa, UFV, Brasil. E-mail:. 5 Programa de Pós-Graduação em Ciências Biológicas da Universidade Estadual de Montes Claros, UNIMONTES. E-mail:. 6 Programa de Pós-graduação na Universidade Federal de Viçosa, Laboratório de ecologia e restauração florestal. E-mail:.This study aimed to relate variations in richness and tree community structure to soil characteristics in a gradient of riparian forest, at Parque Estadual da Mata Seca, north of Minas Gerais. Studies of soil characteristics and the richness and structure of trees (DBH 5 cm) were conducted in 39 plots of 400 m 2 , divided equally into three sections previously selected, these being: Sao Francisco (lower moisture), Meio (flooding during most of the year) and Lagoa da Prata (flooding during the rainy season). The analysis of topsoill (0-20 cm) showed significant differences between the different forest sections. In all three environments were sampled 2482 individuals belonging to 36 species, 31 genera and 16 plant families. There were significant differences for the different sections in the Shannon diversity index, number of individuals, basal area and absolute dominance. The diameter distribution of the community had a great number of individuals concentred in the smallest classes, decreasing gradually. It is noteworthy that the basal area and density of subjects