[Show abstract][Hide abstract] ABSTRACT: In South America, the largest savanna region is located in Brazil, and is called Cerrado, and as in other savannas, the fire regime is an important factor in the evolution of the landscape and, consequently, of the vegetation (Gottsberger and Silberbauer-Gottsberger 2006a). In savannic physiognomies the presence of trees is greater in areas protected from fire, especially in dry-shrub savannas, where protection allows the regeneration of the woody component (Moreira 2000). In general, the absence of fire benefits the woody component and increases the structural complexity of vegetation, while the passage of fire benefits the non-woody component and increases the presence of herbs and subshrubs in the landscape (Mistry 1998). In the Cerrado, most of the ongoing studies on dynamics have focused only on the tree layer (Libano and Felfili 2006; Aquino et al. 2007; Roitman et al. 2008, Carvalho and Felfili 2011). Studies that directly focus on understanding the temporal dynamics of the herbaceous and shrub layer over the years are still scarce, especially with regard to the grassland physiognomies of the biome (Eugênio et al. 2011). The Cerrado phytogeographical domain has a very heterogeneous physiognomy, that ranges from open grasslands to dense forests, but which has as the most common formation the savannic physiognomy, known as cerrado sensu stricto (Oliveira-Filho and Ratter 2002; Ab'Sáber 2003; Ribeiro and Walter 2008). The grassland formations include wet grassland (campo limpo), dry-shrub grassland (campo sujo) and "campo rupestre" (rupiculous field grassland) (Ribeiro and Walter 2008), and until 2007 these occupied 7% of the entire Cerrado. In the Federal District alone, they covered a total of 6,164 ha (Sano et al. 2007). The dry-shrub grassland (Campo sujo) is one of the Introduction The dynamic process in a community is characterized by patterns, mechanisms and, in many systems, successive disturbances are important sources of changes in the landscape (Glenn-Lewin and van der Maarel 1992). The progression of changes in the composition and structure of a community over time, due to disturbances in the environment, is conceptualized as a succession process or directional change (Buchanan 1982). Studies of temporal dynamics for grassland sites report that the suppression of disturbances such as fire plays a crucial role in the floristic and structural changes of these communities (San José and Fariñas 1991; Moreira 2000; Behling et al. 2007; Kahmen and Poschlod 2008; Ravi and D'Odorico 2009). Changes over time are related to differences in species abundance and composition, differences in the spectrum of life forms and functional characteristics. The suppression of fire in savannas intervenes in natural ecological processes, and in more open areas like grasslands, a gradual increase in the density of woody and fire-sensitive species can be seen (San José and Fariñas 1983; 1991; Silva et al. 2001; Durigan and Ratter 2006; Gardner 2006; Pinheiro and Durigan 2009). Savannas are considered dynamic ecotones, distributed between grassland formations and more densely vegetated areas (Coutinho 1978, Roitman et al. 2008). In these landscapes grasses and trees coexist, influenced by interactions with the climate, soil and disturbances such as fire, and fluctuations in any of these factors may result in an increase in certain life forms (Roitman et al. 2008). The intensification or suppression of disturbances modifies the composition of species in an area. The landscape is altered by the exclusion of sensitive species in the first case, and by the exclusion of resistant species in the second (Libano and Felfili 2006). Abstract: Studies of temporal dynamics for grassland sites report that fire suppression plays a crucial role in floristic changes. The objective of this study was to verify whether after seven years without fire, communities showed variations in terms of composition, life forms, pollination and dispersal syndromes. The first survey (T0) was conducted from September 1999 to October 2000, while the second (T1) took place from August 2006 to August 2007. The floristic results in T1 were compared with the survey in T0 through the Sorensen similarity index and Chi-square tests. Over time, there were differences in the composition, life forms and pollination and dispersion syndromes. The evidence of changes suggests that the frequency of the fire regime can be considered the main agent for change in the flora of these communities.
Check List: Journal of species list and distribution. 05/2013; 9(3):487-503.
[Show abstract][Hide abstract] 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.
[Show abstract][Hide abstract] ABSTRACT: This study was carried out on a fragment of semi-deciduous forest in Pirenópolis, Goias, Brazil and investigated the changes in the photon flux density in relation to silvicultural interventions that aimed at increasing growth of tree species but without allowing invasion by exotic species that could influence the dynamics of natural regeneration. The design was a randomized block in factorial, testing the differences between silvicultural treatments, seasons and heights in the understory (1.30 m versus at the ground level). We tested two intensities of selective cutting of individual trees and vines in the forest. The treatments were sufficient to alter the understory light, both in the dry season and rainy season, in agreement with the hypothesis tested. The shading in the control area was 97% in the rainy season and 86% in the dry season, showing significant differences with the shading associated with silvicultural treatments, which ranged from 93% to 94% in the rainy season and from 77% to 80% in the dry season. This study may assist this forest management system for semi-deciduous forests in Central Brazil, and should be linked to population studies and community, preserving the forest fragments found in the region and generating numerous environmental benefits and extra income for the rural population.
Revista Árvore 12/2012; 36(6):1135-1144. · 0.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The study was conducted in a Brosimum rubescens Taub. monodominant forest in Nova Xavantina, Mato Grosso state (14 49.8 0 S and 52 9.6 0 W), in the transition zone between the Cerrado and Amazonian Forest in central Brazil. The structure and dynamics of the natural regeneration was compared over a five-year period to identify patterns that affect seedling establishment and explain the maintenance of B. rubescens dominance. We raised the following questions: how does the structure and dynamics of a mono-dominant forest regeneration vary over time? What patterns affect seedling establishment and help to explain the maintenance of the monodominance of B. rubescens? Natural regeneration was sampled in 30 plots of 1 m Â 1 m (seedlings), 2 Â 2 (saplings), 5 Â 5 (poles) and 10 Â 10 (treelets). In the first inventory, the natural regeneration structure was characterized by a higher concentration of individuals in lower height classes and the largest number of seedlings of B. rubescens may be related to rainfall distribution in previous years. Seedling establishment may be limited by drier periods such as "El Niño" events, or by specific light conditions reaching the forest floor. Formation of a persistent seedling bank may provide a competitive advantage for the regeneration of B. rubescens in conditions of gaps pre-opening thus contributing to monodominance maintenance.
[Show abstract][Hide abstract] ABSTRACT: A large number of studies describes the structure and composition of cerradão, however there is no standardization regarding data collection, rendering it difficult to conduct ample comparisons and the emergence of a structural and floristic profile for the cerradão. Our aim is to establish a structural-floristic profile of the cerradão woody component and verify the overlap of forest, savanna and generalist species. We conducted the vegetation survey in sites in six states: DF, MG, MS, MT, PI and TO. The cerradão did not present a homogenous structure or floristic consistency among sites, presenting itself as a heterogeneous phytophysiognomy. Structurally it presented great variations, with both open and closed formations (density 652-1732 ind. ha-1; basal area 12.83-22.45 m2 ha-1). Species richness varied from 49 (MS) to 129 (MT). Floristical variation and dissimilarity was strong among the six sites with only six species occurring in all sites, where as 184 species are exclusive to one site. Although species composition is comprised of a mixture of forest and savanna species, we detected a greater participation of savanna species, with the exception of the MT site that presented a larger proportion of forest species. The general floristic and structural dissimilarity pattern observed indicate a great heterogeneity of cerradão woody flora distribution following the general patter for the Cerrado biome.
[Show abstract][Hide abstract] ABSTRACT: Cerradão vegetation shares many species with savanna and forest areas and is one of the most vulnerable phytophysiognomies in the Cerrado (Brazilian savanna) biome. The floristic composition of the Cerradão Biological Reserve was examined between September/2007 and November/2008. A total of 282 species distributed among 194 genera and 75 families were encountered, demonstrating proportions of 0.91 herbaceous species and 0.54 shrub species for each tree species. Fabaceae, Asteraceae, Rubiaceae, Poaceae, Myrtaceae, Malpighiaceae, and Melastomataceae were the most species-rich families. Fully 72.3% of the species of this dystrophic cerradão were shared by cerrado and forest vegetations, while 60.43% were shared by other cerradão sites, although the largest proportion of species (91%) were shared with cerrado sensu stricto. No species was found to be exclusive to this cerradão site, but approximately 95% of all species were native to the Cerrado biome.
Revista Brasileira de Botânica 12/2011; 35(4):377-384.
[Show abstract][Hide abstract] ABSTRACT: Dendrometer bands are used to make repeated measurements of tree radial growth. Two types of dendrometers are used worldwide, the industrial and the homemade. Homemade dendrometers prevail in Brazilian forestry studies, but researchers have trouble constructing and installing them. An easier solution is to use industrial dendrometer bands, but they are not produced in Brazil and, therefore, are expensive and might not be appropriate for local environmental conditions. We analyzed trunk growth measurements each month (from February 2008 to January 2009) using both industrial (imported) and homemade (national components) dendrometer bands installed on 20 trees of Acacia tenuifolia in a seasonally dry forest on limestone outcrops in central Brazil. Cost-benefit comparative analysis of measurements and prices indicates that homemade dendrometer bands have all benefits, and none of the problems, of the imported industrial dendrometer bands, such as the following: (1) similar precision of measurements (correlation analysis: r > 0.930, P < 0.01; permutation t-test: P > 0.55), (2) much lower costs (10 to 15 times cheaper), (3) easily manipulated and installated in the field, and (4) absence of some damage to tree trunks that are caused by industrial dendrometers.
[Show abstract][Hide abstract] ABSTRACT: The goal of this work was to investigate the floristic and structural changes in a seasonally dry deciduous forest on limestone outcrops in the municipality of Iaciara (14º03'53"S; 46º29'15"W), northeast Goiás, Central Brazil, after a 6-year interval (2000-2006). Due to the biotic limitations of marked seasonality and stressful edaphic conditions (rocky and shallow soils), we hypothesized that the tree community would show rapid dynamics, but without pronounced changes in floristic composition and structure. Changes in floristics and structure were investigated through comparisons between two consecutive inventories in permanent plots (25 sampling units of 20 x 20 m randomly located in the forest) for the years 2000 and 2006. All trees with dbh > 5 cm were sampled, measured, and structural, phytosociological and diversity parameters were calculated. Rates of mortality and recruitment were calculated, and indirect gradient analyses (DCA) were applied to test the structural changes between the plots. The rates of mortality (2.77 %.year-1) and recruitment (4.43 %.year-1) were high showing rapid community dynamics. However, the rapid dynamics did not promote qualitative (species richness) and quantitative (phytosociological structure, diversity and gradient analysis) changes, supporting the hypothesis and showing high stability across the interval.
[Show abstract][Hide abstract] ABSTRACT: A criação de áreas protegidas configura-se como uma das principais estratégias de
conservação dos recursos naturais, em particular a biodiversidade. Não é a única, mas tem
importância destacada. Especialmente em países cujo crescimento econômico baseia-se
no setor primário, incorporando solo e água, essas áreas são uma forma direta de evitar
que determinados territórios sejam destruídos pela exploração predatória. Confirmando
a importância desta estratégia, a Conferência de Nagoya, ocorrida em outubro de 2010,
recomendou que os países ampliassem a representação dos ecossistemas em áreas protegidas para pelo menos 17%.
No Cerrado, não é significativo o número e o tamanho das áreas protegidas. Apenas
4% estão sob a forma de terras indígenas, cuja finalidade primordial é a segurança das
populações indígenas, muito embora tenham papel evidente face à conservação dos recursos naturais. Não mais que 8%, número que é superestimado, do bioma contam com
algum tipo de unidade de conservação. Cerca de 63% dessas pertencem à categoria de
Área de Proteção Ambiental, que, infelizmente, não vêm demonstrando efetividade na
função de conservar a biodiversidade pois o desmatamento em seu interior em quase
nada difere daquele praticado no entorno. As reservas legais e as áreas de proteção permanente nos imóveis rurais também enfrentam elevada descaracterização. É o que se
verifica de forma mais clara na porção sul do Cerrado: São Paulo, Minas Gerais, Goiás,
Mato Grosso e Mato Grosso do Sul.
Decretar unidades de conservação não é tarefa que se realiza sem forte componente
político, capacidade de negociação e base técnico-científica. Regiões em que a agropecuária está totalmente consolidada ou sob franca expansão, e primazia de terras privadas,
encontram resistências mais agudas. Isso explica por que se expandiu, nos últimos anos,
a criação de UCs em sua maioria na Amazônia, sob terras públicas federais. No Cerrado,
há ainda a particularidade de que se trata de um bioma pouco conhecido e valorizado
dentro e fora do Brasil. No cenário internacional é até difícil falar do que se trata, pois sua
tradução para o termo “savanas brasileiras” pouco diz a respeito de sua diversidade, que
se parece mais como um grande mosaico vegetacional, de exuberância que certamente
agradou aos primeiros habitantes que por ele chegaram há milhares de anos atrás.
A dificuldade de criação é maior quando se refere a reserva extrativista. Essa categoria, nascida no seio do movimento dos seringueiros da Amazônia e incorporada no
Sistema Nacional de Unidades de Conservação, sem dúvida alguma precisa de adaptação
para as áreas de Cerrado. Pois as populações tradicionais do bioma mantêm relações com o ambiente de forma distinta daquela de ambientes tipicamente florestais. Nele, a prática
do agroextrativismo e o uso múltiplo dos recursos naturais e da policultura parecem mais
evidentes. E a isso se associa um problema: enquanto houve maior visibilidade para a situação dos extrativistas da floresta, o que levou a angariar alguma atenção das políticas e
apoio social, apenas muito recentemente o mesmo ocorreu quanto aos agroextrativistas
do Cerrado – e, por que, não da Caatinga.
O presente estudo constitui um conjunto de levantamentos sobre a vegetação e o uso
tradicional da flora nativa de duas áreas no norte de Minas Gerais, ambas localizadas na
Bacia do Rio São Francisco: Buritizeiro e Ibiaí. Nessas, há demandas das populações por
criação de áreas protegidas destinadas a lhes garantir segurança fundiária, proteger o seu
modo de vida e conservar os recursos naturais. São áreas que se destacam pela importância biológica, considerada como “alta” e “extremamente alta” pelo exercício de priorização realizado pelo MMA em 2006 (“Áreas e Ações Prioritárias para a Conservação, Uso
Sustentável e Repartição dos Benefícios da Biodiversidade Brasileira”). Nas duas regiões,
as populações fazem uso econômico de plantas medicinais (pelo extrativismo), enquanto
outras utilizam os rios de forma tradicional, pela prática que marcam os ribeirinhos.
Os estudos aqui reunidos decorrem de uma iniciativa do Núcleo Cerrado e Pantanal
(NCP) do Ministério do Meio Ambiente (MMA). Com o apoio financeiro da Secretaria de
Recursos Hídricos também do MMA, o Núcleo viabilizou a contratação de consultores para
realização de estudos inerentes à criação de unidades de conservação. E a parceria firmada
com a Universidade de Brasília (UnB), por meio do Centro de Referência em Conservação
da Natureza e Recuperação de Áreas Degradadas (CRAD), tornou possível a reunião de
dados e informações relevantes sobre a região, suas populações e seus recursos.
Esta publicação pretende a demonstrar a associação entre práticas tradicionais e os conhecimentos científicos trazidos pelas ciências florestais. E, nessa direção, concorrem para
a manutenção e a integridade do singular saber sobre os “gerais” mineiros, quase baianos.
A divulgação dos estudos técnico-científicos aqui sistematizados almeja contribuir
para que o processo de criação de áreas protegidas no Cerrado seja fortalecido e que,
fundamentalmente, porções de seu território estejam resguardados da degradação que
atualmente consome metade da vegetação original do bioma.
2 edited by Iona'i Ossami de Moura, 12/2010; Ministério do Meio Ambiente., ISBN: 978-85-7738-149-4
[Show abstract][Hide abstract] ABSTRACT: (Diversity and community structure of cerrado sensu stricto on rocky outcrops of the Pireneus State Park, Goiás). This study was conducted within the Pireneus State Park and its objective was to analyse the floristic composition and community structure of the woody layer of the cerrado sensu stricto on rocky outcrops and to compare with other places. The study area is located at 15°48'42"-47" S and 48°52'40"-63" W, with average altitude of 1,310 m. Ten 20 m × 50 m (1,000 m2) plots were randomly located and all woody individuals of 5 cm diameter at 30 cm from the ground level were identified and measured. Sixty five species belonging to 51 genera and 35 families were found. The richest families in species were: Myrtaceae (eight spp.), Fabaceae (seven spp.) and Melastomataceae (six spp.). The 12 species with highest VI were responsible for more than 50% of total density and dominance. The density was 1105 individuals ha-1 and basal area was 11.03 m2 ha-1. Shannon's diversity index (H') was 3.65 nats ind-1. These values are high and are within the range of other studies in cerrado sensu stricto. TWINSPAN classification of the Pireneus State Park's plots showed that this cerrado is composed by species characteristics of the site like Schwartzia adamantium (Cambess.) Bedell ex Giraldo-Cañas, Alchornea triplinervia (Spreng.) Müll. Arg. and Clusia burchellii Engl., generalist species of "cerrado region" and also by species more common in gallery forests, and present similar structure to this vegetation in other edaphic conditions.
Revista Brasileira de Botânica 09/2010; 33(3):455-467.
[Show abstract][Hide abstract] ABSTRACT: This study was undertaken in the gallery forests of Sete Cidades National Park (PNSC), a priority area for conservation of the Cerrado. The objective was to study the floristic composition, phytosociology and diversity of the gallery forests distributed along the river courses located in PNSC and also evaluate floristic similarity between these forests and others in the Cerrado biome. The tree vegetation (DAP > 5 cm) was sampled in four sections of forest in the Park, each subdivided into transects (50 m apart and perpendicular to the main stream), where 56 plots (10 x 10 m) were systematically sampled totaling 0.01 ha. 75 tree species were found belonging to 64 genera and 30 families. The Fabaceae (with 14 species) was the richest family in the sample. Virola surinamensis was the main species, according to the importance value index (IVI). Absolute density was 1,146.43 ind haֿ¹ and basal area was 26.55 m² haֿ¹. Alfa diversity obtained by the Shannon index (H) was 3.53 and Pielou equability (J) was 0.82. Beta diversity between the Park and other locations in the Cerrado was high. The PNSC gallery forests had high levels of richness and floristic diversity, sharing species with forests in different locations and with typical species of other biomes, proving that the Park is geographically located in an ecotone.
[Show abstract][Hide abstract] ABSTRACT: Natural regeneration and structure and their relationship to environmental variables were studied in three sections of a gallery forest, in Eastern Mato Grosso, Brazil (14º43′S and 52º21′W). The assumption was that natural regeneration is constrained by environmental determinants at all stages of development of the tree community. The objective was to analyse the forest structure and to verify the relationship between species distribution and abundance at different stages of regeneration and environmental variables. In each section, 47 contiguous (10x10m) permanent plots were established to sample trees (gbh≥15cm), following a systematic design. Seedlings (0.01 to 1m height), saplings (1.01 to 2m) and poles (from 2.01m height to gbh<15cm) were sampled in sub-plots of 1x1m, 2x2m and 5x5m, respectively. In each plot, soil properties, gaps projection, bamboos, rocky cover, declivity and depth of ground watertable were determined. The relationships between the environmental variables with trees and seedling communities were assessed by canonical correspondence analysis. In spite of the sections being near to each other, they presented large differences in floristics, structure and site conditions. The forest soil presented a low cation exchange capacity and a high level of Al saturation. The occurrence of bamboos and gaps and the depth of ground watertable limited the occurrence of poles and trees. The high degree of structural heterogeneity for each regeneration category was related primarily to a humidity gradient; but soil fertility (Ca+Mg) was also a determinant of seedling and sapling communities.
[Show abstract][Hide abstract] ABSTRACT: Herbivores and pathogens with acute host specificity may promote high tree diversity in tropical forests by causing distance- and density-dependent mortality of seedlings, but evidence is scarce. Although Lepidoptera larvae are the most abundant and host-specific guild of herbivores in these forests, their impact upon seedling distributions remains largely unknown. A firm test of the mechanism underpinning the Janzen-Connell hypothesis is difficult, even for a single tree species, because it requires more than just manipulating seeds and seedlings and recording their fates. Experimental tests require: (1) an insect herbivore that is identified and highly specialised, (2) linkage to an in situ measure (or prevention) of herbivory, and (3) evaluation and confirmation among many conspecific adult trees across years. Here we present experimental evidence for a spatially explicit interaction between newly germinating seedlings of a Neotropical emergent tree, big-leaf mahogany (Swietenia macrophylla, Meliaceae), and caterpillars of a noctuid moth (Steniscadia poliophaea). In the understory of a southeastern Amazon forest, the proportion of attacks, leaf area lost, and seedling mortality due to this specialised herbivore peaked near Swietenia trees, but declined significantly with increasing distance from mature fruiting trees, as predicted by the Janzen-Connell hypothesis. We conclude that long-distance dispersal events (>50 m) provided an early survival advantage for Swietenia seedlings, and propose that the role of larval Lepidoptera as Janzen-Connell vectors may be underappreciated in tropical forests.
[Show abstract][Hide abstract] ABSTRACT: The Capetinga gallery forest is located at Agua Limpa Farm, in the Federal District, Brazil. The floristic composition and structure of the natural regeneration at the edges and in the interior of the gallery forest at the watershed of the Capetinga stream was studied to detect floristic and structural patterns related to the forest environments. Thirty (5x5m) plots were placed in each environment to sample saplings, individuals from 1,0m high with diameter at the steam base under 5,0cm. Within these plots, (2x2m) sub-plots were allocated to sample seedlings, individuals lower than 1,0m height. The sampled plots were distant to the stream bank to minimize the humidity effect. Shannon & Wiener diversity index varied from 2,86 (seedlings at the edges) to 3,51 (saplings at the interior) and it was higher in the interior for both categories. Sørensen s similarity index varied from 0.474 for seedlings (comparing edges with interior) to 0.735 (seedlings and saplings at the edges). Czekanowski indices were low and reflected the high differentiation in structure from plot to plot in the same gallery forest. TWINSPAN classification suggested two distinct communities for saplings for both conditions, formed by species accordingly to their requirements for light and water. No differentiation was detected for seedlings between the environments indicating a low response of plants at an early stage to the environmental conditions within the forest. The Capetinga gallery forest suffered disturbances by fire and the small variations in species composition and vegetation structure between environments suggests that most of the natural regeneration is tolerant to light.
[Show abstract][Hide abstract] ABSTRACT: The Capetinga gallery forest is located at Agua Limpa Farm, in the Federal District, Brazil. The floristic compositionand structure of the natural regeneration at the edges and in the interior of the gallery forest at the watershed of the Capetinga stream was studied to detect floristic and structural patterns related to the forest environments. Thirty (5x5m) plots were placed in each environment to sample saplings, individuals from 1,0m high with diameter at the steam base under 5,0cm. Within these plots, (2x2m) sub-plots were allocated to sample seedlings, individuals lower than 1,0m height. The sampled plots were distant to the stream bank to minimize the humidity effect. Shannon & Wiener diversity index varied from 2,86 (seedlings at the edges) to 3,51 (saplings at the interior) and it was higher in the interior for both categories. Sørensen s similarity index varied from 0.474 for seedlings (comparingedges with interior) to 0.735 (seedlings and saplings at the edges). Czekanowski indices were low and reflected the high differentiationin structure from plot to plot in the same gallery forest. TWINSPAN classification suggested two distinct communities for saplings forboth conditions, formed by species accordingly to their requirements for light and water. No differentiation was detected for seedlingsbetween the environments indicating a low response of plants at an early stage to the environmental conditions within the forest. TheCapetinga gallery forest suffered disturbances by fire and the small variations in species composition and vegetation structurebetween environments suggests that most of the natural regeneration is tolerant to light.