Alba Valéria Rezende

Diversity, floristic and structural patterns of cerrado vegetation in Central Brazil

The cerrado has been identified as one of the richest and most threatened biomes of the world, but few phytogeographical studies have been undertaken in the region. A total of 70 land systems based on climate, landscape and soils have been identified in the region, but it remains to be seen if the distribution and structure of the plant communities support these divisions. The aim of this work was to compare the floristic and structural similarity of cerrado sensu stricto within and between three physiographic units, named Pratinha, Veadeiros and São Francisco, which contain six land systems in central Brazil and cover 10 degrees of latitude and five degrees of longitude. The woody vegetation of 15 selected sites of the cerrado sensu stricto physiognomy was surveyed under a standardized methodology. The number of species per site varied from 55 to 97, with most sites having around 60 to 70 species, and Shannon´s diversity indices ranged from 3.44 to 3.73, with most sites around 3.5 suggesting high alpha diversity. Sørensen´s floristic similarity index was high, with all Figures above 0.5 between the sites in the same land system in each physiographic unit but low between sites in different land systems in the Veadeiros. Czekanowski similarity indices were lower than Sørensen’s in the comparisons due to a high structural differentiation between the sites. There is a large overlap in species occurrence in the sites but the size of their populations is very different at each site. Therefore, the high beta diversity is mostly due to differences in abundance of species between sites. The sites were separated by physiographic units, considering the first three divisions of TWINSPAN classification. The first axis of DCA ordination showed a gradient going from the cerrado on deep soils in Pratinha, through to those on sandy soils in São Francisco and ending on the shallower soils of the Veadeiros. Land systems conformed well with the floristic and structural variations of the vegetation, indicating their potential use in designing a network of conservation areas in the cerrado region and as a basis for decision-making on management.

Changes in the floristic composition of cerrado sensu stricto in Brazil over a nine-year period.

Changes in floristic composition and structure in a cerrado sensu stricto area were studied over a 9-y period. A sample of 19 (20-m x 50-m) permanent plots was assessed at 3-y intervals from 1985 to 1994, when all stems ≥ 5 cm at 0.30 m above the ground level were measured. There was little change in species composition over the period. Changes in density and basal area of the whole community were in the range of 5% over the 9 y. These parameters fluctuated over the years with the greatest differences found in the comparisons of 1991, 2 y after an accidental fire reached the site, with other years. The changes in density and basal area were greater than in several tropical forests, probably due to disturbances such as fire occurring at 3 to 5-y intervals, The nearly constant density and basal area suggested a highly resilient community.

Efeito de incêndios florestais na estrutura e composição florística de uma área de cerrado sensu stricto na fazenda Água Limpa-DF

This research aimed to evaluate the effect of fire on the structure and floristic composition of a 10 ha cerrado sensu stricto area located at the Ecological and Experimental Reserve of the University of Brasilia, Fazenda Agua Limpa-FAL. Two assessments were conducted in the area: the first, after the area had suffered a criminal fire in 1999, and the second in 2002. A sample of four 20 x 50 m permanent plots was assessed. All individuals with stems 5 cm diameter at 0,30 m (Db) from the ground level were registered, and had their Db and total height measured. Density, basal area, frequency and value of covering index were calculated for the two assessments. The floristic similarity between the two surveys was evaluated for qualitative data (presence and absence of species) based on the Sfrensen Index. Few changes were observed in the floristic composition of the community during the studied period. There was an increase of 125% in density by hectare from 1999 to 2002. A high similarity (Sfrensen Index equal to 0.68)was found between the two assessments while diversity (Shannon Index) was small (about 2.5). This value is smaller than those found in natural areas of the Cerrado sensu stricto at Fazenda Agua Limpa, although it is common in areas with disturbances. Three years after fire 13 new species were verified in the area.

Estoque de carbono em cerrado sensu stricto do Distrito Federal

RESUMO – O objetivo do trabalho foi estimar o estoque de carbono da parte aerea (troncos, galhos e serapilheira) e subterrânea (raizes e solo) da vegetacao lenhosa de um cerrado sensu stricto, localizado na Fazenda Agua Limpa, da Universidade de Brasilia, Distrito Federal. A area de estudo foi amostrada a partir de parcelas de 20 x 50m alocadas sistematicamente. Em cada parcela foram inventariados todos os individuos lenhosos arboreo-arbustivos, vivos e mortos em pe, com no minimo 5 cm de diâmetro tomado a 30 cm do solo. Foram realizadas tambem coletas da biomassa de serapilheira; da biomassa de raizes (fina, media e grossa) e da densidade e teor de carbono no solo. A profundidade maxima adotada para a coleta de biomassa da parte subterrânea foi de 2 m. A maior parte do carbono correspondeu ao compartimento solo (88,7%), superando bastante as raizes (7,3%), onde as concentracoes foram de 271,23 e 22,38 toneladas por hectare, respectivamente. Troncos e galhos totalizaram 8,60 toneladas de carbono por hectare e a serapilheira, 3,62 toneladas de carbono por hectare. Palavras-chave: Estoque de carbono, Biomassa e Cerrado sensu stricto. CARBON STOCK IN CERRADO Sensu stricto IN THE FEDERAL DISTRICT

Teor de umidade e densidade básica da madeira de nove espécies comerciais amazônicas

Este trabalho teve como objetivo agrupar especies com caracteristicas de teor de umidade e densidade basica da madeira semelhantes para compor cargas mistas de especies para secagem em câmaras industriais de secagem da madeira. Foram amostradas nove especies em floresta de terra firme na Amazonia Central com tres repeticoes por especie. Em todas as especies os teores de umidade nao diferiram entre base e topo do tronco, o que confere estabilidade da madeira durante o processo de secagem. Os valores de densidade basica variaram de 0,561 a 0,904 g cm-3. A partir do presente estudo foi possivel separar as especies em tres grupos com base na densidade basica e teor de umidade, o primeiro com as especies Minquartia guianensis, Lecythis poiteaui, Mezilaurus itauba, Manilkara huberi e Brosimum rubescens que sao consideradas madeiras pesadas (densidade variando de 0,835 a 0,904 g cm-3) , de secagem mais lenta ou dificil. O segundo grupo contem as especies Clarisia racemosa e Ocotea rubra (densidade media de 0,665 e 0,720 g cm-3, respectivamente) e o terceiro grupo com as especies Parkia paraensis e Brasimum parinarioides que apresentam densidade media e secagem rapida (densidade de 0,561 e 0,588 g cm-3, respectivamente).

Geoprocessamento como ferramenta de apoio à gerência de pavimentos em estradas florestais.

This purpose of this research was to apply geoprocessing techniques for data acquisition, preparation, georeference, and display for assessing quality standards of forest roads and mapping critical points of the timber transportation, which contribute to support the development of a pavement preventive and ordinary maintenance program. First, the road pavement integrity and condition were assessed by conducting a continuous survey on road defects and estimating the NPRCI (Non-Paved Road Condition Index). The georeferenced dataset, the sampling unit’s allocation, and the road network spatial location were conducted using satellite (CBERS-II) and SRTM imagery and GPS field data. The road identification and the assessment of pavement condition were based on a detailed field survey, which revealed the road pavement conditions and derived useful supporting information regarding the most critical parts of the forest road and its defect severity, also pointing out practical measures to fix them, estimating costs for the required road maintenance. The Geoprocessing techniques, GPS, remote sensing dataset, and GIS showed to be efficient tools for identifying, mapping, and quantifying this natural phenomenon in the region being studied and may support the definition of maintenance program of non-paved forest roads. Results showed that the GIS could integrate the dataset containing standards of forest road ordinary operation and maintenance to a geographic database, which subsequently allowed to georeference, manipulate, and display this information on thematic maps.

CARACTERIZAÇÃO FLORÍSTICO-ESTRUTURAL E GRUPO SUCESSIONAL DE ESPÉCIES ARBÓREAS NO BIOMA CERRADO DO ESTADO DE TOCANTINS, BRASIL

The objective of this study was to characterize the floristic composition, vegetation structure and ecological group of tree species in a cerradão forest (Cerrado biome) of Palmas, Tocantins State, Brazil. A forest inventory was performed in an area of 10.15 hectares, using systematic sampling with plots of 400 m2, in which all standing trees, alive and dead, that had diameter at breast height (DBH) ≥ 5 cm were sampled and identified. A linear plateau regression model (LPR) was used for sample sufficiency analysis. The Shannon index (H’) was used for assess the floristic diversity, and the Importance Value Index (IVI) for assess the horizontal structure. The forest was classified in three strata according to vertical structure analysis. The LPR showed that the sampling size was adequate. The predominate species in the area were Myrcia splendens, Emmotum nitens and Qualea parviflora, and species from the families Fabaceae and Chrysobalanaceae. The pioneer (613 individuals ha) and climax (530 individuals ha) species were the predominating groups. Regarding the richness index, the number of climax (57 species) and pioneer (25 species) species stood out. The alpha floristic diversity was 3.35 nats individuals and the Pielou equability value J = 0.76. The diametric distribution showed a negative and balanced exponential pattern. Regarding the vertical stratification, the smallest amount of individuals was in the upper stratum (13%) and the highest in the mid stratum (63%) and in the lower stratum (24%). The use of floristic composition tools with horizontal and vertical structure analysis was effective for understand the tree community, which may be considered structured and diverse, thus able to restructure possible disturbances when preserved.

Avaliação da amostragem aleatória de ramos para quantificar a produção de frutos de Caryocar brasiliense Camb. (Caryocaraceae).

Estudos sobre tecnicas de amostragem adequadas e precisas para quantificar a producao de frutos de especies nativas do Cerrado ainda sao muito raros, o que configura uma lacuna para a formulacao de Planos de Manejo Sustentaveis para o Bioma. Este estudo foi realizado em uma area de cerrado sensu stricto, localizada na Reserva Ecologica e Experimental da Universidade de Brasilia, Distrito Federal, com o objetivo de avaliar a eficiencia da amostragem aleatoria de ramos para quantificar a producao de frutos de Caryocar brasiliense Camb. (pequi). Na area de cerrado sensu stricto previamente inventariada floristicamente, foi selecionado um individuo de Caryocar brasiliense em periodo de frutificacao para aplicacao da amostragem aleatoria de ramos. A producao de frutos foi estimada pelo metodo de amostragem aleatoria de ramos, testada por duas tecnicas de selecao de ramos: probabilidade uniforme e probabilidade proporcional ao diâmetro do ramo. A validacao do metodo foi feita pela comparacao com a producao real quantificada pelo censo dos frutos. O erro de amostragem para uma intensidade amostral de dez caminhos foi igual a 99,92 % usando a tecnica de probabilidade uniforme para selecao de ramos e igual a 61,45 % usando a tecnica de probabilidade proporcional ao diâmetro. Concluiu-se que a amostragem aleatoria de ramos, empregando as tecnicas de probabilidade uniforme e de probabilidade proporcional ao diâmetro, foi imprecisa e inexata para o caso estudado. Por essa razao, e necessario realizar novos estudos e propor modificacao na tecnica de amostragem aleatoria de ramos que permita gerar estimativas da producao de frutos de Caryocar brasiliense com pequeno erro de tendencia e de amostragem.

Estimativa do volume de madeira partindo do diâmetro da cepa em uma área explorada de Floresta Amazônica de Terra Firme.

This research aimed to estimate the volume of trees of a “terra-firme” tropical forest, considering only the diameter at stump height (d 0 ), as independent variable. The area being studied is located in Breu Branco, Para. A total of 113 trees with DBH ≥ 51 cm, of different species and diameter classes, were selected to determine the observed cubic volume of the commercial trunk. The trees were rigorously cubed by the method of Hohenadl considering the division of the commercial trunk in ten sections of equals lengths, and the volume of each section of the trunk was determined by the Smalian formula. Equations were adjusted to estimate the commercial volume of the trees in function of d 0 and in function of DBH, for comparisons. Results showed that d 0 had a high correlation with the commercial volume of trees within the area of forest of “terra firme” and it can be used for the adjustment of mathematical models in order to estimate the commercial volume of trees. No significant difference between the observed and the estimated volume of trees – generated by the adjusted linear equation in function of d 0 – was found.

Renda bruta de múltiplos produtos de madeira em povoamentos de Pinus taeda submetidos a diferentes densidades de plantio e regimes de desbaste: abordagem experimental

Este artigo avalia experimentalmente o efeito de diferentes densidades de plantio e regimes de desbaste no Valor Presente Bruto da receita (VPB), advinda da producao de multiplos produtos de madeira em povoamentos de Pinus taeda. Os dados advem de um experimento implantado no municipio de Jaguariaiva, Parana, onde foram avaliados 5 espacamentos: 2,5 x 1,2 m; 2,5 x 2,0 m; 2,5 x 2,8 m; 2,5 x 3,6 m e 2,5 x 4,4 m. Cinco regimes de desbaste foram confrontados: corte final aos 15 anos, sem desbaste; corte final aos 20 anos, sem desbaste; desbaste sistematico na 6a linha aos 9 anos e corte final aos 20 anos; desbastes seletivos por baixo, com reducao de 50% do numero de arvores aos 9 e 15 anos e corte final aos 20 anos; e desbaste sistematico na 6a linha combinado com seletivo de 50% aos 9 anos, seletivo de 50% aos 15 anos e corte final aos 20 anos. O experimento fatorial foi analisado por meio de ANOVA e pelo teste de Tukey. Os resultados mostram diferencas significativas a 1% entre os espacamentos e entre os regimes de desbaste, sendo a interacao entre ambos tambem significativa. Evidenciou-se que, para a variavel VPB, a combinacao ideal e o emprego de um espacamento menor, isto e, povoamento mais denso, como 2,5 x 1,2 m, combinado com a realizacao de desbastes mais frequentes, aos 9 e aos 15 anos, preferivelmente com a adocao de desbaste sistematico na primeira intervencao. Essa combinacao foi a que determinou a maior renda bruta no presente estudo, a qual diferiu estatisticamente dos demais tratamentos. Isto revela a importância de proceder analise experimental dos regimes de manejo, permitindo, assim, decidir com melhor juizo a opcao que gera a maior renda bruta.