Análise e Mapeamento da Fragilidade Ambiental no Município de Inconfidentes – MG

Esta pesquisa teve como objetivo analisar a fragilidade ambiental potencial e emergente do Município de Inconfidentes - MG, baseado no método prescrito por Ross (2012). A metodologia abrangeu, além de atividades de campo, interpolação geoestatística, processamento digital de imagens e análise geoespacial, por meio de álgebra de mapas. Após mapeamento, foram definidas as classes e graus de fragilidade para as variáveis unidades litoestratigráficas, declividades, precipitação pluviométrica, solos e classes de uso da terra e cobertura vegetal. O índice de dissecação do relevo foi determinado segundo a literatura especializada. Os mapeamentos de fragilidade ambiental potencial (FAP) e emergente (FAE) foram obtidos a partir da média ponderada das variáveis geoambientais com seus respectivos pesos. Os resultados demonstraram que cerca de 70% do município possui fragilidade ambiental com classe média, tanto potencial quanto emergente. Os altos índices de fragilidade com classe forte relacionaram-se com as áreas próximas ao leito fluvial do Rio Mogi Guaçu, regiões mais frágeis e propícias aos processos de degradação ambiental. Os estudos de fragilidade emergente, por considerarem as intervenções humanas no meio, exigem, a curto prazo, ações na busca de preservação ambiental, visando evitar a degradação e desestabilização dos sistemas naturais. Considerado políticas conservacionistas e preservacionistas, os estudos de fragilidade com índice de dissecação do relevo (FAPidr e FAEidr) se mostraram mais eficientes para fundamentar estudos de planejamento, zoneamento e gestão ambiental. Analysis and Mapping of Environmental Fragility in the Municipality of Inconfidentes - MGA B S T R A C TThis research aimed to analyze the potential and emerging environmental fragility of the Municipality of Inconfidentes - MG, based on the method prescribed by Ross (2012). The methodology included, in addition to field activities, geostatistical interpolation, digital image processing and geospatial analysis, through map algebra. After mapping, the classes and degrees of fragility were defined for the variables lithostratigraphic units, slopes, rainfall, soils and classes of land use and vegetation cover. The relief dissection index was determined according to the specialized literature. The mappings of potential environmental fragility (PEF) and emerging (EEF) were obtained from the weighted average of the geoenvironmental variables with their respective weights. The results showed that about 70% of the municipality has environmental fragility with medium class, both potential and emerging. The high rates of fragility with strong class were related to the areas near the riverbed of the Mogi Guaçu River, more fragile regions and conducive to environmental degradation processes. Studies of emerging fragility, because they consier human interventions in the environment, require, in the short term, actions in the search for environmental preservation, aiming to avoid the degradation and destabilization of natural systems. Considering of conservation and preservationist policies, the studies of fragility with relief dissection index (PEFrdi and EEFrdi) proved more efficient to support studies of planning, zoning and environmental management.Keywords: Map algebra, geospatial analysis, relief dissection index, geostatistical interpolation, digital image processing.

Leaf Bilateral Symmetry and the Scaling of the Perimeter vs. the Surface Area in 15 Vine Species

The leaves of vines exhibit a high degree of variability in shape, from simple oval to highly dissected palmatifid leaves. However, little is known about the extent of leaf bilateral symmetry in vines, how leaf perimeter scales with leaf surface area, and how this relationship depends on leaf shape. We studied 15 species of vines and calculated (i) the areal ratio (AR) of both sides of the lamina per leaf, (ii) the standardized symmetry index (SI) to estimate the deviation from leaf bilateral symmetry, and (iii) the dissection index (DI) to measure leaf-shape complexity. In addition, we examined whether there is a scaling relationship between leaf perimeter and area for each species. A total of 14 out of 15 species had no significant differences in average ln(AR), and mean ln(AR) approximated zero, indicating that the areas of the two lamina sides tended to be equal. Nevertheless, SI values among the 15 species had significant differences. A statistically strong scaling relationship between leaf perimeter and area was observed for each species, and the scaling exponents of 12 out of 15 species fell in the range of 0.49−0.55. These data show that vines tend to generate a similar number of left- and right-skewed leaves, which might contribute to optimizing light interception. Weaker scaling relationships between leaf perimeter and area were associated with a greater DI and a greater variation in DI. Thus, DI provides a useful measure of the degree of the complexity of leaf outline.

Seasonal leaf dimorphism in Potentilla argentea L. var. tenuiloba (Jord.) Sw. (Rosaceae)

A pattern of seasonal changes in the morphological and anatomical leaf traits is reported for Potentilla argentea L. var. tenuiloba (Jord.) Sw. of temperate-climate areas in central Poland. Leaf area, perimeter, dry mass and lamina thickness were measured in summer and autumn leaves of the same individuals. Dissection index, density and specific leaf area were calculated. Significant differences were obtained between summer and autumn leaves obtained from the same individuals. The shapes of leaves of the P. argentea plants varied in the extent of incisions between teeth and the number of teeth on the margins. Fully expanded autumn leaves were larger in weight and area than summer leaves. The autumn leaves had lower leaf mass area and density than the summer leaves. Leaves were covered by considerably more trichomes in summer than in autumn. Anatomical leaf structure also changed with the season. The summer leaves were thick, with a lower number of chloroplasts in the cells of the compact mesophyll. Autumn leaves are thinner, with loose mesophyll. Chloroplasts from the two seasonal types of leaves differ on account of starch grain and plastoglobule content. The large variations in leaf density and thickness recorded here confirm great differences in cell size and amounts of structural tissue within species. Seasonal dimorphism of leaves may result from seasonal drought or from seasonality in leaf production, leaf fall or incoming solar radiation. Within this new context of seasonal leaf dimorphism, P. argentea can still be distinguished by the absence of deeply divided leaflets on late-formed leaves. The results confirmed the presence of several morpho- anatomical leaf traits of P. argentea that allow the species to adapt to environmental seasonal conditions.

Lithologic and morphometric characteristics of the Chure River Basin, Central Nepal

The Chure River Basin (CRB) is a small basin (width 5.75 km, length 9.74 km, perimeter 32.35 km and area 35.23 km2) with three sub-watersheds, and is crossed by the Tribhuvan Highway that may be threatened by riverine and allied processes. The geology and morphometry of the basin were studied to search for status of the basin development andriver dynamism. The Chure River is a sixth order river fed by rainstorm, and has length ratio of 2.79, indicating nearly three times the average length of its fifth order segment, showing notable competency. The mean bifurcation ratio of the Chure River is 3.20, showing immature nature of the CRB. Drainage texture (DT) varies from moderate (0.64–0.96) to very fine (0–0.32). The Chure River is sinuous (K =1.18).The relative relief (RR) is moderately low (15–30) to moderately high (120–240) and dissection index (DI) is moderate (0.2–0.3) to high (0.3–0.4). The CRB carries varied lithology; gravelly to coarse sandy and medium sandy and muddy, from the north to the south extension of the basin. Fine to very fine DT found in large areas because of loosely consolidated and soft lithology. Even where rocks are stiff, the presence of discontinuity has perhaps influenced the DT. Very fine to fine DT coupled with elongate nature of the basin (as indicated by low value of form factor, 0.37) is vulnerable to greater competency of the river during high rainfall.RR slope and DI are found to be high in the cliff- forming lithology (stiff and well cemented), and low in other areas. High dissection, high slopes and high relief show active and immature nature of the CRB, indicating susceptibility of further incision of the Siwalik Hills and aggravation of erosion and slope movements by the immature rivers in the CRB. Presence of knick points along the river profile reflects affinity of the river to incision. The sinuosity, radius of curvature, and bifurcation ratio, all indicate immaturity of the basin. The hypsometric analysis indicates inverse relationship between the elevation and the cumulative %area, showing active erosional condition of the basin. DOI: http://dx.doi.org/10.3126/bdg.v15i0.7416 Bulletin of the Department of Geology, Vol. 15, 2012, pp. 35-48