ABSTRACT We analyzed the phenological responses of shrub-tree species of lowland deciduous (LDF) and submontane deciduous (SFD) forests in the Pantanal, and assessed their relationships with climatic factors at the community level and with strategies for seed dispersal. Vegetative and reproductive phenophases of 50 tree-shrub species were monitored monthly (12 months), and their relationship with climatic variables was tested using multiple linear regression. Time of leaf budding differed between areas for autochoric species and between autochoric and anemochoric species at LDF. Leaf fall in communities and functional groups was seasonal and highly synchronous during the dry season (95 % of species). Leaf budding peaked at the end of the dry season with > 80 % synchrony. In general, the species presented low synchrony or asynchrony for flowering phenophases, while fruiting phenophases were weakly seasonal but differed between functional groups. Temperature and precipitation were the regulating factors of vegetative phenophases in LDF, while daylength regulated them in SDF. Abiotic factors only influenced flowering phenophases at the dispersion group level. Only ripe fruits were related to reduced daylength. The phenophases of the deciduous forests of the Pantanal seem to be regulated not only by climatic factors but also by strong endogenous control.

Resumo: As cangas são afloramentos ferruginosos que ocorrem ao sopé do Maciço do Urucum, na Borda Oeste do Pantanal, Corumbá-MS. No Brasil, o conhecimento sobre a florística e ecologia das comunidades vegetais associadas a essas formações ainda é incipiente. Esses habitats estão entre os mais ameaçados e menos estudados do Brasil, devido à sua associação a depósitos de minério de ferro de alta qualidade. Nós apresentamos um cheklist da flora desses ambientes, resultante de diversos esforços de coleta de diferentes autores em 10 áreas do Maciço. Foram registradas 302 espécies distribuídas em 53 famílias botânicas e 175 gêneros. Poaceae (43 espécies), Fabaceae (41), Euphorbiaceae (22), Cyperaceae (19), Malvaceae (19), Convolvulaceae (15), Malpighiaceae (13) e Apocynaceae (11) representaram 60,6% da riqueza específica. Nossos dados adicionam 59 novas ocorrências de espécies de angiospermas para a flora de cangas do Maciço do Urucum. Das espécies apresentadas, 27 ainda não possuíam registro de ocorrência para o Mato Grosso do Sul e três espécies não haviam sido ainda registradas para o Brasil. A alta diversidade e a presença de espécies endêmicas, raras, ameaçadas e/ou ainda não catalogadas para a região do Maciço do Urucum reforça a necessidade de unidades de conservação locais que possam garantir a preservação dessas espécies, uma vez que as áreas de proteção ambiental existentes na região são insuficientes para garantir a manutenção de populações típicas desse habitat.

Abstract: "Cangas" are ironstone outcrops occurring at the foot of the Urucum Plateau, on the western edge of Pantanal, Corumbá-MS. In Brazil, the knowledge about flora and ecology of the plant communities associated with these formations is still incipient. These habitats are among the most threatened and less studied in Brazil because of their association with high quality iron ore deposits. We present a cheklist of the flora from these formations, resulting from different authors' collecting efforts in 10 areas of the Plateau. A total of 302 species have been recorded; they were distributed in 53 botanical families and 175 genera. Poaceae (43 species), Fabaceae (41), Euphorbiaceae (22), Cyperaceae (19), Malvaceae (19), Convolvulaceae (15), Malpighiaceae (13) and Apocynaceae (11) accounted for 60.6% of the species richness. Our data add 59 new occurrences of species of angiosperms to the ironstone outcrops flora in the Urucum Plateau. Among these, 27 species had no occurrence record for Mato Grosso do Sul and three species had not yet been recorded for Brazil. The high diversity and presence of endemic, rare, endangered and/or not yet cataloged species for the Urucum Plateau region, reinforces the need for local conservation units that can guarantee the preservation of these species, since the existing environmental protection areas are insufficient to guarantee the maintenance of typical species from this habitat in the region.

(Aspectos estruturais da comunidade arbórea em remanescentes de floresta estacional decidual, em Corumbá, MS, Brasil). Um estudo comparativo da estrutura da comunidade arbórea entre dois remanescentes de floresta decídua foi conduzido em diferentes altitudes: florestas deciduais de terras baixas (FEDTB) e submontana (FEDSM), localizados em Corumbá, MS, Centro Oeste brasileiro. Amostraram-se indivíduos arbóreos com CAP ³ 15 cm, utilizando-se método de quadrantes. Foram demarcados 80 pontos em FEDTB e em FEDSM 78 pontos foram distribuídos por altitude: 180 m (18 pontos), 220, 260 e 300 m de altitude (20 pontos cada). Em FEDTB foram amostradas 34 espécies, sendo que Calycophyllum multiflorum Griseb., Ceiba pubiflora (A. St.-Hil.) K. Schum. e Anadenanthera colubrina (Vell.) Brenan apresentaram os maiores valores de importância. Na área de FEDSM foram amostradas 33 espécies, sendo que Anandenanthera colubrina, Ceiba pubiflora e Acosmium cardenasii H. S. Irwin & Arroyo foram as mais importantes. O padrão de distribuição das espécies variou ao longo do gradiente altitudinal. Em ambas as áreas, o índice de diversidade de Shannon foi de 2,9 e a Equitabilidade de 0,8, onde as famílias mais representativas foram Fabaceae (8 spp.) e Rubiaceae (4 spp). As florestas estudadas apresentaram baixa densidade de indivíduos por hectare em relação a outros estudos, exceto na área a 300 m. A comunidade arbórea apresentou 22,46% de indivíduos perfilhados e em fases iniciais de sucessão. O dossel variou de 6 a 12 m, com indivíduos emergentes de até 18 m. Estes remanescentes representam fonte de diversidade biológica para a região do Pantanal sendo importantes componentes dos corredores naturais da região.

(Structural features of the arboreal community in remnants of dry forest in Corumbá, MS, Brazil). The structure of the arboreal community of two types of dry forest was compared in an altitudinal gradient of lowland (FEDTB) and submontane (FEDSM) dry forests, in Corumbá, MS, Midwest Brazil. Tree species with circumference at breast height ³ 15 cm were sampled, using the point centered quarter method. In the FEDTB 80 points were demarcated, and in FEDSM 78 points were distributed in the following altitudes: 180 m (18 points), 220, 260 and 300 m (20 points each). In FEDTB 34 species were sampled; Calycophyllum multiflorum Griseb., Ceiba pubiflora (A. St.-Hil.) K. Schum. and Anadenanthera colubrina (Vell.) Brenan have the highest VI values. In FEDSM, 33 species were sampled, and Anandenanthera colubrina, Ceiba pubiflora and Acosmium cardenasii H. S. Irwin & Arroyo were the most important. The distribution pattern of the species varied along the altitudinal gradient. In both forests Shannon's diversity and equitability indexes were 2.9 and 0.8, respectively, and the most representative families were Fabaceae (8 species) and Rubiaceae (4 species). The studied forests have low density of individuals in relation to other studies, except for the track at 300 m. About 22.46% of the individuals of arboreal community had basal ramifications and were in the initial phases of succession. The canopy varied from 6 to 12 m, and emergent individuals of up to 18 m. These remnants represent a source of biodiversity for the Pantanal, being an important part of the natural forest corridors of the region.