José Roberto Rodrigues Pinto

Perfil florístico e estrutura da comunidade arbórea de uma floresta de vale no Parque Nacional da Chapada dos Guimarães, Mato Grosso, Brasil

The purpose of the present study was to describe the floristic composition and the structure of the arboreal community of a valley-forest in Veu de Noiva waterfalls, Chapada dos Guimaraes National Park, Mato Grosso, Brazil. The floristic and phytosociological analyses aimed at assessing, respectively: (a) the influence of the main Brazilian phytogeographic provinces on the floristic composition of the valley-forest studied, and (b) the role of the most important tree species in terms of abundance, ecological group, and stature at maturity. Every tree with stalk circumference at breast height (CBH) ³ 15 cm found within 36 quadrats of 30 x 10 m was sampled. 172 species of trees belonging to 133 genera and 61 families were registered. The floristic profile showed strong links with both the Amazonian and Atlantic (sensu lato) forests, reinforcing the transitional nature of that community. The most important tree species, in terms of value of importance, were also important in other surveys carried out in the region.

Does size matter? Conservation implications of differing woody population sizes with equivalent occurrence and diversity of species for threatened savanna habitats

The Cerrado stands out from other savannas of the world for hosting the highest biodiversity and for its ongoing massive destruction. Savannas on plain relief and with deep soils (DS) in Central Brazil have been widely converted into agropastoral ecosystems. In contrast, savannas on steep relief with shallow and rocky soils (RS) have been considered as future biodiversity refuges in Central Brazil. In this study, we show that adjacent DS and RS savanna sites (each with ten 1-ha plots) differ based on their woody species population sizes, but not based on species occurrence or diversity. In addition, we discuss the implications of these results for species conservation. Our research indicates that the DS and RS savannas are complementary, but not equivalent, regarding their representation of savanna vegetation in Central Brazil. We hypothesize that if RS savannas become the only refuges for savannic vegetation, widespread biodiversity losses will occur in the short term (through loss of exclusive and habitat-specialist species) and long term (due to fragmentation, reductions in population size and loss of genetic variability). Thus, we suggest that the consideration of savannas on distinct substrates should be considered for improving conservation decision-making and initiatives and can be beneficial when expanding or creating new conservation units.

Influence of edaphic variables on the floristic composition and structure of the tree-shrub vegetation in typical and rocky outcrop cerrado areas in Serra Negra, Goiás State, Brazil

The present study analyzed the influence of edaphic variables on the floristic compositions and structures of the arboreal and shrub vegetation of typical cerrado (TC) and rocky outcrop cerrado (RC) communities in the Serra Negra mountain range in Piranhas Municipality, Goias State, Brazil. Ten 20×50m plots were established in each community, and all individuals with minimum diameters ³5cm measured at 30cm above soil level were sampled. Composite soil samples were collected at 0-20cm depths in each plot for physical and chemical analyses. The proportions of above-ground rock cover work also estimated in each RC plot. A total of 2,009 individuals (83 species, 69 genera, and 34 families) were recorded. Qualea parviflora was the only species consistently among the 10 most structurally important taxa in both communities, and was considered a generalist species. The observed and estimated species richnesses were greater in RC than in TC, although plant basal areas and heights did not differ between them. There were positive correlations between rock cover×plant density and rock cover×basal areas. TWINSPAN and PCA analysis separated the TC and RC plots, and three RC habitat specialist species (Wunderlichia mirabilis, Norantea guianensis, and Tibouchina papyrus) were identified. Soil variables were found to have greater effects on the species compositions of the TC and RC sites than the geographic distances between sampling plots. According to CCA analysis, the exclusive (or more abundant species) of each community were correlated with soil variables, and these variables therefore determined the selection of some species and influenced the differentiation of the vegetation structures of the communities studied.

Dinâmica estrutural da comunidade lenhosa em Floresta Estacional Semidecidual na transição Cerrado-Floresta Amazônica, Mato Grosso, Brasil

Understanding ecological processes, especially the structural and floristic changes in natural ecosystems, is essential before conserving and/or restoring these areas. The aim of this study was to assess the changes that occurred in the woody plant community from 2003 to 2008. Sixty permanent plots of 10 x 10 m were established, in which all individuals with diameter at breast height > 5 cm were sampled. A total of 1,140 ind. ha-1 were recorded in 2003 (basal area 24.35 m2 ha-1) and 1,071 ind. ha-1 in 2008 (basal area of 22.04 m2 ha-1). The recruitment (2.76% year-1) did not compensate mortality (3.95% year-1) and the basal area gain (0.54% year-1) did not exceed the loss (3.77% year-1). Because of this unbalance, the half-life (17.3 years) was lower than the doubling time (29.9 years), resulting in low stability (12.6 yrs) and replacement (23.6 yrs) in relation to other seasonal forests. The parameters of community and species dynamics suggest that the forest is undergoing changes characterized mainly by the density and biomass reduction of trees, which may be related to an increase in lianas, an early rebuilding phase of the forest silvigenetic cycle or even the severe drought that occurred in the region in 2005.

Florestas estacionais e áreas de ecótono no estado do Tocantins, Brasil: parâmetros estruturais, classificação das fitofisionomias florestais e subsídios para conservação

O objetivo deste estudo foi descrever a riqueza, estrutura e diversidade de especies arboreas em areas de Floresta Estacional e ecotono (Floresta Estacional/Floresta Ombrofila) no estado do Tocantins, buscando subsidios para a conservacao, manejo florestal, compensacao de reserva legal e recuperacao ambiental, alem de discutir as identidades fitogeograficas em comparacao com outras florestas do Brasil. Em 18 bacias hidrograficas, conduziu-se amostragem da vegetacao arborea (DAP > 5 cm) de 22 areas (amostras) por meio do inventario de 477 parcelas de 400 m². Foram elaboradas analises de classificacao pelo metodo TWINSPAN, em duas escalas distintas. A primeira avaliou a diversidade beta entre as parcelas amostradas no estado do Tocantins e a segunda buscou analisar a similaridade das florestas do Tocantins em relacao a outras florestas do bioma Cerrado e suas areas de tensao ecologica. As florestas amostradas apresentaram ampla variacao em termos de riqueza (33 a 243 especies), densidade (486 a 1.179 ind.ha-1), area basal (14,04 e 37,49 m².ha-1), indices de diversidade (H´ = 2,75 a 4,59) e de equabilidade (J´= 0,72 a 0,86). As analises de classificacao convergiram para resultados comuns, identificando quatro ambientes dissimilares em termos floristicos e estruturais no estado do Tocantins: Floresta Estacional Decidual, Floresta Estacional Semidecidual, ecotono Floresta Estacional Semidecidual/Floresta Ombrofila e ecotono Floresta Estacional Decidual/Floresta Ombrofila. A fim de manter a diversidade de plantas e de ambientes na regiao de transicao Floresta Amazonica e Cerrado, sugere-se que o processo de criacao de unidades de conservacao no estado do Tocantins deva ser intensificado e tenha como base para selecao das areas criterios biogeograficos.

The tree-shrub vegetation in rocky outcrop cerrado areas in Goiás State, Brazil

We describe the floristic composition of the tree-shrub vegetation in 10 areas of rocky outcrop cerrado in Goias State, Brazil. Ten 20×50m plots (totaling 1ha) were established and all of the individuals with diameters at 30cm above soil level (DB30) ³5cm were included in the sampling. Comparative analyses of the flora were realized using similarity indices (Sorensen and Czekanowski), classification analysis (TWINSPAN), and the Mantel test. A total of 13,041 tree-shrub individuals were sampled, distributed among 219 species, 129 genera and 55 families. Fabaceae was the most well-represented family, followed by Myrtaceae, Melastomataceae, Vochysiaceae, Malphigiaceae, and Rubiaceae. Fully 42.3% of the comparisons evaluated by the Sorensen index were >0.50, while all the values were <0.50 for the Czekanowski index, with the exception of Jaragua and Mara Rosa areas. The TWINSPAN classification generated four divisions and, in general, only the differences in the size of the population were responsible for the groupings. The Mantel test indicated that there was no relationship between floristic similarity and the distances between the areas (r=0.32, P=0.05). It therefore appears that the areas of rocky outcrop cerrado in Goias State are relatively floristically homogeneous and that they are principally distinguished by the differences in the sizes of the populations of their dominant species, and the presence of exclusive species in certain areas.

Fenologia e produção de frutos de Caryocar brasiliense Cambess. E Enterolobium gummiferum (Mart.) J.F.Macbr. em diferentes regimes de queima

The knowledge of plant reproductive and vegetative periods is extremely important for seed harvesting and seedling production. Interactions between the Cerrado (Brazilian Savanna) biota and fire are of extreme interest because these factors are intimately related and could be determinant in plant populations maintenance. For 12 months, we studied the phenology of two Cerrado native species (Enterolobium gummiferum (Mart.) J.F.Macbr. and Caryocar brasiliense Cambess.) under two fire regimes: the first was burned every two years on August (PBM) in a control site without fire for 14 years (PC). Uniformity tests were made to verify seasonality of each phenological phase. The model selection with Akaike information criterion was made using climatic variables of the study region to identify which variables better describe the phenological phases. Fruit production was estimated for both treatments. Almost every phenophase showed production peaks, except for leaf sprout of C. brasiliense in PC and leaf fall of C. brasiliense in the two treatments, and E. gummiferum in PC. In general, the phenological behaviour of both species did not differ from other studies. However, fire retarded the leaf renewal and inhibited the reproductive phases of C. brasiliense, similar to previous results for other Cerrado native species in regions with burn incidence.

Similaridade florística entre estratos da vegetação em quatro Florestas Estacionais Deciduais na bacia do Rio São Francisco

Resumo Este estudo descreveu e comparou a similaridade floristica de tres estratos de quatro fragmentos de Floresta Estacional Decidual. Os fragmentos estudados estao distribuidos na Bacia do Sao Francisco, tres em Minas Gerais e um na Bahia. A amostragem da vegetacao seguiu o protocolo da Rede de Parcelas Permanentes nos biomas Cerrado e Pantanal para os estratos arboreo, de arvoretas e juvenil. Foram contabilizadas a riqueza de especies e familias em cada area e estrato. A similaridade entre os estratos de cada area foi obtida por diagramas de Venn e indices de Jaccard e Czekanowski, ja para a analise da similaridade entre os fragmentos, em cada estrato, foram calculados apenas os dois indices. Os quatro fragmentos e os tres estratos apresentaram baixa relacao floristica, ou seja, baixo compartilhamento de especies. As diferencas entre os estratos podem ser reflexo de variacoes ambientais ao longo do tempo, assim como da capacidade de reproducao das especies dos estratos superiores. Ja as diferencas entre as areas devem-se a distribuicao geografica, que gera variacoes ambientais, as quais podem estar favorecendo a ocorrencia de especies adaptadas as condicoes de cada fragmento, contribuindo para uma composicao floristica diferenciada. Alem disso, os contatos vegetacionais (ecotonos) provavelmente tambem contribuiram para as diferencas floristicas observadas. Floristic similarity between strata of vegetation in four Deciduous Seasonal Forest in Sao Francisco River Abstract This study described and compared the floristic similarity in four Deciduous Seasonal Forest fragments, and assessed the floristic relations between the tree (adult), the treelet and the sapling stratum. The fragments studied are distributed in Minas Gerais State and in Bahia State, Brazil. The vegetation sampling method followed the protocol of the “Rede de Parcelas Permanentes nos biomas Cerrado e Pantanal” for the tree, treelet and sapling strata. The floristic similarity between the fragments was obtained based on Jaccard and Czekanowski indices. Besides the similarity indices, Venn diagrams were drawn for the strata within each area. The four fragments and the three strata of each fragment presented low degrees of species sharing. The floristic differences among the strata may be due to environmental variations throughout time as well as the reproductive capacity of the species differentiated among the years. Besides the geographic distance (neutral theory), the environmental variations between the areas and the vegetation contacts (ecotones) with other biomes may have favored the occurrence of species adapted to the conditions of each fragment, which contributed to the distinct floristic composition.

Structure and floristic relationships between Cerrado sensu stricto sites on two types of substrate in northern Cerrado, Brazil

We described and compared the floristic composition, richness, species diversity and structure of the tree-shrub component in pairs of Typical Cerrado (Cerrado Tipico) and rocky outcrop Cerrado (Cerrado Rupestre) in two localities in Tocantins State. In each locality, we set up 10 plots of 20 × 50 m at a site, the Cerrado Tipico and other Cerrado Rupestre, and sampled the individuals with Db30cm ≥ 5 cm. The rocky outcrop Cerrado did not present any trend towards lower richness and basal area compared to the Cerrado on deep soil. Few species occurred across the four sites and only two important species (Anacardium occidentale and Qualea parviflora) in the four vegetation structure were common to both environments assessed. Furthermore, the occurrence of habitat-specialist species of rocky outcrops and high altitudes (Mimosa claussenii, Tibouchina papyrus, Schwartzia adamantium and Wunderlichia cruelsiana) and the high dissimilarity among sites suggest that altitude is the main responsible for the floristic dissimilarity, followed by the influence of substrate type. Therefore, the information with respect to phytophysiognomy type as a parameter to select areas for conservation, by itself, does not effectively ensure biodiversity preservation, owing to the existing flora heterogeneity not only at local but also at regional scale, revealed by the floristic and structural particularity of each site.

Species distribution models of rare tree species as an evaluation tool for synergistic human impacts in the Amazon rainforest

Abstract In the present work, we have considered the vulnerability of some rare tree species to human disturbances in a high biodiversity tropical region. In this context, we aimed to evaluate the combined effect of deforestation and artificial flooding of the large Jirau hydroelectric reservoir on potential distribution areas of 13 locally rare tree species in the southwestern Brazilian Amazon. We performed species distribution modeling (SDM) by using the environmental distance algorithm. Based on these models, we found new sites and subsequently applied rapid ecological assessment to collect further species occurrence data. Additional SDMs were carried out using MaxEnt to determine the potential distribution areas of these rare species. We found that artificial flooding and deforestation caused combined losses of potential distribution areas of rare tree species between 8 and 39% of the total area. The most vulnerable species were Semaphyllanthe megistocaula (K. Krause) L. Andersson (Rubiaceae) (39%), Chrysophyllum colombianum (Aubrév.) T.D. Penn. (Sapotaceae) (34%), Lacunaria jenmanii (Oliv.) Ducke (Quiinaceae) (32%), Brosimum parinarioides Ducke (Moraceae) (32%) and Xylopia benthamii R.E. Fr. (Annonaceae) (30%). These results indicate an additive effect of human disturbances such that artificial flooding, when combined with deforestation, has an overall effect by orders of magnitude. SDMs can be effectively used as a predictive tool in the assessment of human impacts on rare tree species in tropical forests. The results also showed different vulnerability among the rare species, and these results may indicate that some species are more seriously threatened by the extreme loss of potential distribution areas.