José Eugênio Côrtes Figueira

Saurocory in Melocactus violaceus (Cactaceae)1

The button cactus, Melocactus violaceus (Cactaceae), occurs in open, sandy soils in southern Brazilian coastal areas. The fruits of this species are pink, cone-shaped, and have a high water content and low sugar concentration. The fruits of M. violaceus develop while completely protected inside the cephalium and are driven out by internal pressure when ripe. Fruits can be exposed in only a few minutes during the hottest part of the day, and they become easily visible over the cephalium. They are expelled more quickly when temperature is high and lizards are more active. During the dry season these fruits appear to be eaten exclusively by the lizard Tropidurus torquatus (Tropiduridae). The cephalium is positioned close to soil level and the bright color of the fruits apparently improves fruit detection. Lizards defecate viable M. violaceus seeds. These seeds germinated quickly under laboratory conditions, while seeds collected directly from ripe fruits did not germinate under the same conditions. Cactus and fruit morphology, and the diurnal pattern of fruit release, may represent a suite of adaptations for dispersal by Tropidurus torquatus.

Dung Beetles along a Tropical Altitudinal Gradient: Environmental Filtering on Taxonomic and Functional Diversity.

Mountains provide an interesting context in which to study the many facets of biodiversity in response to macroclimate, since environmental conditions change rapidly due to elevation. Although the decrease in biodiversity with increasing elevation is generally accepted, our understanding of the variation of functional diversity along altitudinal gradients is still poorly known. The partitioning of diversity into spatial components can help to understand the processes that influence the distribution of species, and these studies are urgently needed in face of the increasing threats to mountain environments throughout the world. We describe the distribution of dung beetle diversity along an altitudinal gradient on a tropical mountain in southeastern Brazil, including the spatial partitioning of taxonomic and functional diversities. The altitudinal gradient ranged from 800 up to 1400 m a.s.l. and we collected dung beetles at every 100 m of altitude. We used the Rao Index to calculate γ, α and β diversity for taxonomic and functional diversity of dung beetles. Climatic, soil and vegetation variables were used to explain variation in community attributes along the altitudinal gradient. Dung beetle richness declined with altitude and was related to climatic and vegetation variables, but functional diversity did not follow the same pattern. Over 50% of γ taxonomic diversity was caused by among altitudes diversity (β), while almost 100% of functional diversity was due to the α component. Contrasting β taxonomic with β functional diversity, we suggest that there is ecological redundancy among communities and that the environment is filtering species in terms of the Grinnellian niche, rather than the Eltonian niche. β taxonomic diversity is caused mainly by the turnover component, reinforcing the hypothesis of environmental filtering. Global warming may have strong effects on mountain communities due to upslope range shifts and extinctions, and these events will lead to an even larger than previously expected loss of diversity as dung beetles γ taxonomic diversity is caused mainly by the β component.

Effects of the parasitism of Struthanthus flexicaulis (Mart.) Mart. (Loranthaceae) on the fitness of Mimosa calodendron Mart. (Fabaceae), an endemic shrub from rupestrian fields over ironstone outcrops, Minas Gerais State, Brazil

RESUMO – (Efeitos do parasitismo de Struthanthus flexicaulis (Mart.) Mart. (Loranthaceae) na aptidao de Mimosa calodendron Mart. (Fabaceae), um arbusto endemico dos campos rupestres sobre canga, em Minas Gerais, Brasil). As plantas parasitas (ervas-de-passarinho) podem alterar o crescimento, reproducao e fisiologia das hospedeiras. Mimosa calodendron (Fabaceae) e uma leguminosa abundante nos campos rupestres sobre canga, frequentemente atacada pela hemiparasita Struthanthus flexicaulis (Loranthaceae). O objetivo deste trabalho foi avaliar as consequencias do parasitismo de S. flexicaulis na aptidao de M. calodendron. Foram avaliadas a intensidade de parasitismo e mortalidade em mimosas de diferentes tamanhos, e comparadas a cobertura foliar e a producao de frutos e sementes em individuos parasitados e nao parasitados. Mais de 65% da populacao de 1.820 individuos estavam parasitados. A densidade de mimosas influenciou positivamente o parasitismo. As taxas de parasitismo e de mortalidade foram maiores nas mimosas de maior porte. As plantas hospedeiras muito parasitadas apresentaram de 75 a 95% de reducao da cobertura foliar e sua producao de frutos foi cerca de 25% das nao parasitadas. Embora nao tenha sido detectada diferenca estatistica no numero de sementes produzidas por vagem, o peso das sementes foi menor nas mimosas parasitadas. O parasitismo por S. flexicaulis, por reduzir as taxas de sobrevivencia e fecundidade de M. calodendron, pode modificar sua estrutura e dinâmica populacional. Palavras-chave: Canga, Mimosa, parasitismo, sucesso reprodutivo, Struthanthus

Habitat loss and mammalian extinction patterns: are the reserves in the Quadrilátero Ferrífero, southeastern Brazil, effective in conserving mammals?

Habitat loss is considered to be the principal cause of the local extinction of mammals worldwide. We assessed the extinction pattern of medium- and large-sized mammals caused by the effects of habitat loss in reserves in the Quadrilátero Ferrífero, southeastern Brazil, and discussed the effectiveness of these natural remnants for conserving mammals. A literature review and field collections were conducted from 2006 to 2011 to estimate the composition and richness of mammals in nine remnants of different sizes, including reserves and non-protected areas. A species–area relation and a nested subset analysis were performed, and a degree of sensitivity to habitat loss was obtained for each species according to its frequency of occurrence. Forty-five species of mammals were recorded. There was a strong species–area relation involving the legal size of reserves. High species richness was associated with large reserves, and the z value was within the range of very isolated continental remnants. The mammalian community exhibited a nested occurrence pattern, suggesting that most species were part of a more continuous ecosystem and that non-random extinction caused by habitat loss occurred in southeastern Brazil. The negative relation found between species frequencies and body weights suggested that selective species loss is associated with decreases in the size of the reserves. The estimated viable size required to conserve all of the sensitive species is greater than the size of the largest reserve inventoried. We recommend the aggregation of neighboring natural remnants and the creation of new reserves to reduce extinction risks.

Fire in Rupestrian Grasslands: Plant Response and Management

Plant communities and species composing rupestrian grassland complexes within Brazilian savannas show varied responses to fire, and display similarities with other fire-prone ecosystems. Shallow, nutrient-poor soils subjected to severe water stress favor grasslands which carry fire in a landscape punctuated or crossed by rocky outcrops, riverine forests and other forest patches that act as barriers to fire. The long-term fire regime in these physiognomies is largely unknown, but, in post-European colonization times, the use of fire to livestock (cattle) pastures management and arson, most commonly in the dry season, have dominated the fire dynamics of these ecosystems. Several traits of rupestrian grassland plant species allow them to survive some fire regimes and/or take advantage of the post-burn environment, suggesting an ancient role of fire in their evolution and in defining agricultural practices. Fire management must consider the intrinsic heterogeneity and socioeconomic complexities of rupestrian grasslands landscapes. Evaluation and adaptation of strategies, ranging from protecting target areas from fire to applying prescribed patchy burning, and guaranteeing dialogue regarding people’s needs, practices and knowledge, like those related to cattle raising and everlasting flowers harvesting, must be assured for the accomplishment of biodiversity conservation and sustainability goals. Decision-makers are encouraged to work in partnership with ecologists, policy-makers, and local communities, in an adaptive management approach.

An evaluation of contemporary savanna fire regimes in the Canastra National Park, Brazil: Outcomes of fire suppression policies

Fire has shaped plant evolution and biogeochemical cycles for millions of years in savanna ecosystems, but changes in natural fire regimes promoted by human land use threaten contemporary conservation efforts. In protected areas in the Brazilian savannas (Cerrado), the predominant management policy is fire suppression, reflecting a cultural heritage which considers that fire always has a negative impact on biodiversity. Here we compare resultant fire-regimes in Canastra National Park (CNP), southeast Brazil, associated with areas under and without fire suppression management, based on a 16-year Landsat imagery record. In open grasslands of the Canastra plateau (CP), firefighting is undertaken under government-sanctioned regulation, whereas in the Babilonia sector, non-sanctioned fire management is undertaken by small farmers to promote cattle grazing and cropping. Fire regimes in the Canastra sector are characterized by few, very large, late dry season wildfires recurring at intervals of two years. Fire regimes in lowlands of the Babilonia sector are characterized by many small-scale, starting at the beginning of the dry season (EDS). In Babilonia uplands fire regimes are characterized by higher frequencies of large fires. The study illustrates major challenges for managing fire-prone areas in conflict-of-interest regions. We suggest that management planning in CNP needs to effectively address: i) managing conflicts between CNP managers and local communities; and ii) fire management practices in order to achieve more ecologically sustainable fire regimes. The study has broader implications for conservation management in fire-prone savannas in South America generally.

Spatial distribution of nests inDiadasina distincta (Holmberg) (Hymenoptera: Anthophoridae)

Rubink (1982) used nearest-neighbor analysis to detect the effect of conspecifics in the nest-site selection of a fossorial wasp. The application of the same methods was suggested by him to ascertain the role of conspecifics in nesting aggregations of fossorial bees, where the influence of prey stealing would be irrelevant to conspecific repulsion. We attempted to test Rubinks suggestion in an aggregation of several hundreds of nests from an Anthophoridae solitary bee at the Campus-Pampulha of the Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. Data on the biology of this bee will be published elsewhere by Martins and Antonini. The spatial distribution of 209 nests of Diadasina distincta, located in a 44 x 32-cm 2 area in the middle of the nesting aggregation, were drawn on a transparent plastic surface in July 1991. We used nearestneighbor analysis (Clark and Evans, 1954) and Nth-order reflexive-neighbor analysis (Clark and Evans, 1955; Clark, 1955) to compare the nest distribution with random distribution models. Nearest-neighbor analysis compares the mean distance between nearestneighbor nests (?a) in the aggregation with the mean expected distance (?e) in a population with the same density and random distance distributions. The ratio ?a/?e indicates the degree of departure from randomness. Nth-order reflexive-neighbor analysis compares the number of groups containing one or more individuals with the expected number of groups from a random population with the same number of points. We considered a group as a hierarchical collection of points whose interdistances are smaller than the distances to other individuals outside the group. A large group may contain

Wildfires and their impact on the water supply of a large neotropical metropolis: A simulation approach

Hydrological models are powerful tools to simulate the behavior of the water cycle in terrestrial systems and their water interface, including modifications resulting from anthropic activities. In such environments the water stocks depend heavily on the vegetation cover and the ecosystem services derived from it, as part of the interaction soil-plant-topography. Wildfires are disturbances capable of breaking the foundations of these delicate systems. We used the Soil and Water Assessment Tool (SWAT) to simulate the effects of vegetation fires on drainage basins, on the water supply of one of the largest Brazilian urban agglomerations. The model was fed and calibrated with historical hydroclimatic series (calibration January 2001-December 2008, validation January 2009-December 2015). The adjusted model allows to predict the impacts of fire extension on infiltration and runoff, a valuable information for land management, aiming at protecting aquifer recharge. The model predicts a scenario of large range fluctuations characterized by pulsed floods in the rainy season and drought in the dry season. The loss of protective vegetation cover due to fire reduces infiltration and increases runoff. This compromises groundwater recharge, leading to high deficits in groundwater storage and reducing the baseline flow of headsprings.