Claudia Maria Jacobi

Plant communities on ironstone outcrops: a diverse and endangered Brazilian ecosystem

Mountain areas are recognized centres of endemism and diversity on account of their isolation and altitudinal diversity. In tropical regions, mountain tops usually stand as islands of xeric vegetation among mesophytic assemblages. Unlike the vegetation growing on other rock outcrops lithologies, such as inselbergs (granite/gneiss) or campos rupestres (quartz/arenite), ironstone outcrop plant communities still lack systematic studies in Brazil. These outcrops (locally known as canga) share most of the characteristics of other rock outcrops, such as isolation and edapho-climatic harshness, but differ in that they are the object of opencast mining, and thus subjected to irrecoverable degradation. In addition, they are expected to harbour metal-tolerant and hyperaccumulator plant species. A botanical survey of two ironstone outcrop locations in the most important mining region of southeastern Brazil, the Iron Quadrangle, revealed a high within-site (138 and 160 species per site), and between-site diversity (only 27% of common species), totaling 64 families and 234 species among basal families and eudicots (154 species), monocots (68 species), and ferns (12 species). Canga crusts are rich in dicots, several of which play an important role in community structuring, together with the more usual monocot aggregations. Distinct plant communities are found associated to different microhabitats within the iron crust, depending primarily on the amount of soil and moisture retention in the different microtopographies. The environmental uniqueness, high diversity, lack of studies and rapid destruction of these ecosystems pose an immediate challenge for their conservation.

Estudo fitossociológico de uma comunidade vegetal sobre canga como subsídio para a reabilitação de áreas mineradas no quadrilátero ferrífero, MG

This work aimed to characterize the structure and composition of a Rupestrian field over ironstone as a basis for rehabilitation studies of areas degraded by iron mining activities. An ironstone outcrop at Serra do Rola Moca State Park, MG, was studied. In 30 plots of 2 m 2 , 2,151 individuals were found, belonging to 32 species and 16 families, with a diversity of 2.45 nats/ind. Mean height was 15.7 ± 16.3 cm, with 80% below 25 cm. The most important families were Orchidaceae, Poaceae, and Cyperaceae, and the species with highest importance value were Andropogon ingratus (Poaceae), Lychnophora pinaster (Asteraceae), Bulbostylis fimbriata (Cyperaceae), Sophronitis caulescens (Orchidaceae), and Sebastiania glandulosa (Euphorbiaceae). We suggest that these species, together with those presenting clonal growth, such as grasses, sedges and epilythic orchids; facilitators, such as Stachytarpheta glabra and Mimosa calodendron; and those tolerant to heavy metals, such as Vellozia spp., be priority candidates in restoration programs in areas degraded by iron ore extraction.

Soaring Extinction Threats to Endemic Plants in Brazilian Metal-Rich Regions

Environmental degradation due to mining activities is pervasive in most mineral-rich countries and has been given little attention by the authorities. Surface mining frequently targets very specific and evolutionary unique ecosystems, usually on mountaintops, and is characterized by high environmental impact and irreversibility (Jacobi and do Carmo 2008; Gibson et al. 2010). Recently, the negative impacts of coal surface mining were exposed in relation to ecosystem degradation and damages to human health, underlining the need to improve regulatory measures to mitigate them (Palmer et al. 2010). The loss of plant species associated with mineral-rich areas should be added to the list of ecologic and genetic damages recurrently derived from surface-mining activities.

Abiotic factors controlling the establishment and abundance of the invasive golden mussel Limnoperna fortunei

Limnoperna fortunei (Bivalvia, Mytilidae), a freshwater bivalve native to Southern Asia, has been an invasive species in South America since 1991. It spread upstream in the La Plata basin reaching the Paraguay River in the vicinity of the Pantanal wetland, Brazil, around 1998. The role of abiotic factors in controlling establishment and abundance of this species is not well known, making projections of its risk of further spread difficult. This study evaluates the importance of abiotic factors to L. fortunei populations established in rivers of the Pantanal, focusing on larval and juvenile densities and taking advantage of a wide range of seasonal variability in water temperature, flow, dissolved oxygen, and suspended material. Temperature, river stage (influencing several water characteristics) and water velocity are the main variables related to the larval and juvenile densities. In the Pantanal, environmental variables vary over a broader range compared with other South American locations, subjecting L. fortunei to oxygen depletion, low calcium, low pH, and high water velocity and suspended solids, associated with low chlorophyll a concentrations. The combined effect of several of these conditions may explain the relatively low densities in some Pantanal sites. However, they probably will not prevent the persistence of populations in the Pantanal and the eventual establishment of viable populations in upriver systems connected to the Pantanal. These results are pertinent not only to this species but also to other aquatic invasive invertebrates whose expansion may be limited by thermal extremes, episodic oxygen depletion, and waters that are too dilute or acidic for optimal biocalcification.

Invasion risks posed by ornamental freshwater fish trade to southeastern Brazilian rivers

A model was developed to assess the risk of invasion of ornamental non-native fishes to six rivers in the state of Minas Gerais ,southeastern Brazil, with focus on species popularity. Thirty-nine aquarium shops, in six cities, were visited monthly fromJanuary to December 2007. In each city, fish species were identified, and their biology and invasion history information wasobtained from the literature. We calculated the annual frequency of occurrence and average number of specimens monthlyavailable in stores. Quarterly water temperature and dissolved oxygen data from 1997 to 2007 were obtained for the Velhas,Muriae, Uberabinha, Sapucai-Mirim, Doce and Todos os Santos Rivers from public databases. The invasion risk of each specieswas assessed through a model comprising nine parameters grouped in four variables: (i) Invasiveness (thermal and dissolvedoxygen ranges, diet, parental care or fecundity), (ii) History of invasions (establishment), (iii) Propagule pressure (commerci alsuccess, comprising annual frequency of occurrence and number of specimens available monthly at stores), and (iv) Invasibility(water temperature and dissolved oxygen in the target river compatible with the species ranges). Of the 345 ornamental fishspecies for sale, 332 are non-native to either Minas Gerais (n = 151) or Brazil (n = 194). Based on the proposed cutting values , inparticular the compatibility between species and recipient thermal ranges, five ornamental non-native species (

A vegetação de canga no Quadrilátero Ferrífero, Minas Gerais: caracterização e contexto fitogeográfico

Abstract The vegetation in cangas (ironstone outcrops) houses dozens of rare species, several taxonomic novelties, and high alpha and beta diversity. Using a database consisting of 1080 angiosperm taxa, the vegetation associated with cangas in the Iron Quadrangle was characterized by its floristic elements, growth forms, and most frequent physiognomies. We analyzed the geographic distribution and the phytogeographic dominions of the 980 species. Also, in order to verify distinctions between canga vegetation in relation to five areas embedded in rupestral systems of Minas Gerais and Bahia, we analyzed the similarity of 920 angiosperm genera based in the species number. Compared to other rocky systems, especially those within the Espinhaco Range, canga vegetation is distinguished by the greater influence of floristic elements from the Atlantic dominion, greater frequency of arboreal and shrubby sinusiae, high abundance of genera like Solanum and Cattleya , and little physiognomic representation of some typically ‘campos rupestres’ genera. This distinction appears to be correlated with the geographic location of the Iron Quadrangle as well as the mineral and geomorphological characteristics of cangas.

Ecology of neotropical mistletoes: an important canopy-dwelling component of Brazilian ecosystems

Ervas-de-passarinho tem sim sido regularmente estudadas em paises temperados por afetar negativamente especies cultivadas e florestas manejadas. Em comparacao com ambientes temperados pouco se conhece sobre a ecologia das ervas-de-passarinho neotropicais. Desta forma, e necessario maior conhecimento sobre o grupo porque sao importantes elementos de comunidades vegetais, atuando como recurso-chave para polinizadores, dispersores de sementes e herbivoros. Atraves de uma combinacao de trabalhos classicos ja publicados com evidencias empiricas recentes, nos apresentamos padroes emergentes da interacao entre ervas-de-passarinho com os organismos associados e questionamentos para estudos adicionais. Existe um crescente interesse neste grupo no Brasil. E embora existam informacoes sobre dispersao de sementes, estudos sobre biologia reprodutiva sao raros e representam um campo a ser explorado. O conhecimento da biologia basica das ervas-de-passarinho sera relevante para modelar sua distribuicao espacial usando uma abordagem metapopulacional ou epidemiologica. Nesta revisao nos sumarizamos os principais estudos conduzidos na regiao Neotropical para fornecer um panorama atual das pesquisas desenvolvidas, bem como novas ideias para futuras investigacoes, especialmente no Brasil.

Modeling the potential distribution of the invasive golden mussel Limnoperna fortunei in the Upper Paraguay River system using limnological variables

The invasive golden mussel, Limnoperna fortunei (Dunker, 1857), was introduced into the La Plata River estuary and quickly expanded upstream to the North, into the Paraguay and Paraná rivers. An ecological niche modeling approach, based on limnological variables, was used to predict the expansion of the golden mussel in the Paraguay River and its tributaries. We used three approaches to predict the geographic distribution: 1) the spatial distribution of calcium concentration and the saturation index for calcium carbonate (calcite); 2) the Genetic Algorithm for Rule-Set Production (GARP) model; and the 3) Maximum Entropy Method (Maxent) model. Other limnological variables such as temperature, dissolved oxygen, pH, and Total Suspended Solids (TSS) were used in the latter two cases. Important tributaries of the Paraguay River such as the Cuiabá and Miranda/Aquidauana rivers exhibit high risk of invasion, while lower risk was observed in the chemically dilute waters of the middle basin where shell calcification may be limited by low calcium concentrations and carbonate mineral undersaturation.

Pollination of two species of Vellozia (Velloziaceae) from high-altitude quartzitic grasslands, Brazil

The pollinators and breeding system of two species of Vellozia (Velloziaceae) from high-altitude quartzitic grasslands in SE Brazil were studied. Vellozia leptopetala is shrubby and grows solely on rocky outcrops, V. epidendroides is herbaceous and grows on stony soils. Both bear solitary, hermaphrodite flowers, and have massive, short-lasting annual blooms. We evaluated the level of self-compatibility and need for pollinators of 50 plants of each species and 20-60 flowers per treatment: hand self- and cross-pollination, spontaneous pollination, agamospermy and control. The behavior of floral visitors on flowers and within plants was recorded. Both species are mostly self-incompatible, but produce a small number of seeds by self-fertilization. The pollen-ovule ratio suggests facultative xenogamy. They were visited primarily by bees, of which the most important pollinators were two leaf-cutting bees (Megachile spp.). Vellozia leptopetala was also pollinated by a territorial hummingbird. Low natural seed production compared to cross-pollination seed numbers suggests that pollen limitation is the main cause of low seed set. This was attributed to the combined effect of five mechanisms: selfing prior to anthesis, enhanced geitonogamy as a result of large floral displays, low number of visits per flower for the same reason, pollen theft by many insect species, and, in V. leptopetala, delivery of mixed pollen loads on the stigma as a consequence of hummingbird promiscuity.

Life-forms, pollination and seed dispersal syndromes in plant communities on ironstone outcrops, SE Brazil

Afloramentos rochosos tem um papel importante na diversidade vegetal de ecossistemas montanos. As cangas (afloramentos ferruginosos) estao entre os litotipos menos conhecidos e mais ameacados do sudeste do Brasil, devido as atividades minerarias. Alem da composicao de especies, um aspecto fundamental para promover sua conservacao e restauracao e o conhecimento das formas de vida, sindromes de polinizacao e dispersao de sementes dominantes. As analises foram baseadas em listas floristicas publicadas de cangas do sudeste do Brasil. Um total de 353 especies de angiospermas (70 familias) foi distribuido entre as duas fisionomias predominantes (areas abertas e capoes de mata) em cangas. Dezesseis familias foram responsaveis por 70% do total de especies. Comparado ao espectro normal de Raunkiaer, fanerofitos estiveram super-representados e terofitos sub-representados. Os primeiros foram a forma de vida predominante em capoes, enquanto que os hemicriptofitos o foram em areas abertas. A entomofilia foi a sindrome de polinizacao dominante em ambos os habitats. A zoocoria foi dominante em capoes e foi ultima em areas abertas, onde a anemocoria e autocoria prevaleceram. Considerando que ambas as fisionomias estao sujeitas as mesmas condicoes climaticas, os resultados corroboram a influencia de componentes geoedaficos nos tres atributos analisados.