The Biomass Expansion Factor (BEF) and the Root-to-Shoot Ratio (R) are variables used to quantify carbon stock in forests. They are often considered as constant or species/area specific values in most studies. This study aimed at showing tree size and age dependence upon BEF and R and proposed equations to improve forest biomass and carbon stock. Data from 70 sample Pinus spp. grown in southern Brazil trees in different diameter classes and ages were used to demonstrate the correlation between BEF and R, and forest inventory data, such as DBH, tree height and age. Total dry biomass, carbon stock and CO2 equivalent were simulated using the IPCC default values of BEF and R, corresponding average calculated from data used in this study, as well as the values estimated by regression equations. The mean values of BEF and R calculated in this study were 1.47 and 0.17, respectively. The relationship between BEF and R and the tree measurement variables were inversely related with negative exponential behavior. Simulations indicated that use of fixed values of BEF and R, either IPCC default or current average data, may lead to unreliable estimates of carbon stock inventories and CDM projects. It was concluded that accounting for the variations in BEF and R and using regression equations to relate them to DBH, tree height and age, is fundamental in obtaining reliable estimates of forest tree biomass, carbon sink and CO2 equivalent.

ResumoO presente trabalho tem por objetivo fornecer uma visão geral do estado da arte na obtenção de estimativa de biomassa e estoque de carbono em formações florestais. Inicialmente realizou-se uma abordagem sobre o aumento da concentração de CO 2 na atmosfera e a mudança ambiental global. Sobre biomassa florestal e seqüestro de carbono, foi apresentada a metodologia citada na literatura para a sua determinação e estimativa, sendo realizado um apanhado geral dos métodos diretos e indiretos e as controvérsias existentes entre eles. Seqüencialmente, fez-se uma abordagem sobre as variáveis e os modelos utilizados em estimativas de biomassa e estoque de carbono em formações florestais, como também foram relacionados alguns dos modelos mais utilizados. Realizou-se ainda um estudo comparativo entre os modelos lineares e não-lineares com relação às suas vantagens e desvantagens para estimar biomassa. Para finalizar, foram citadas as principais estatísticas utilizadas por alguns autores na comparação de modelos visando o melhor ajuste. Palavras-chave: Métodos de estimativa de biomassa; equações alométricas de biomassa; seqüestro de carbono. AbstractThe art state of the forest biomass estimation and carbon in forest formation. The aim of this work is to present a general view of the actual art attainment state of the forest biomass estimation and the carbon stock. Firstly, it was made an approach enquiring the CO 2 concentration increase at the atmosphere and the global environment changes. Furthermore, it was presented the methodology mentioned at the literature involving the determination and estimation of the carbon and forestal biomass kidnapping, in order to write a summary of the direct and indirect methods and their controversies. Afterwards, it was made another approach considering the variables and the models used at the biomass and carbon stock at forest formations estimations, as relating other more well-known methods. In addition to that, it was organized a comparative study between the lineal and non-lineal models, considering the advantages and disadvantages of its biomass estimations. Finally, the main statistics used by some authors at the models comparison aiming the best adjustment were also cited.

RESUMO A implicação da redução das florestas no ciclo do carbono vem criando uma demanda de desenvolvimento de métodos não destrutivos para a determinação de biomassa, elemento importante na modelagem dos ciclos biogeoquímicos. Apresenta-se resultados de teste de metodologia utilizando-se imagens do satélite IKONOS II para estimar biomassa e carbono orgânico em Floresta com Araucária. O desenvolvimento metodológico englobou análise estatística (matriz de correlação) das bandas e índices de vegetação com os dados de biomassa e carbono orgânico, o ajuste e seleção de equações para estimar a biomassa e o carbono orgânico (variáveis dependentes) em função de variáveis provenientes das imagens de satélite, sendo a reflectância das bandas MS-1, MS-2, MS-3, MS-4, Razão de Bandas (MS-4/MS-3), NDVI e SAVI (variáveis independentes), e a quantificação das variáveis dependentes para toda a área de estudo. A utilização de imagens provenientes do satélite IKONOS II apresentou resultados bastante satisfatório, necessitando, no entanto, que modelos matemáticos sejam ajustados de modo a obterem-se melhores resultados. Palavras-chave: sensoriamento remoto; imagens de alta resolução espacial; Floresta Ombrófila Mista; Floresta Subtropical.

Accurate forest parameters are essential for forest inventory. Traditionally, parameters such as diameter at breast height (DBH) and total height are measured in the field by level gauges and hypsometers. However, field inventories are usually based on sample plots, which, despite providing valuable and necessary information, are laborious, expensive, and spatially limited. Most of the work developed for remote measurement of DBH has used terrestrial laser scanning (TLS), which has high density point clouds, being an advantage for the accurate forest inventory. However, TLS still has a spatial limitation to application because it needs to be manually carried to reach the area of interest, requires sometimes challenging field access, and often requires a field team. UAV-borne (unmanned aerial vehicle) lidar has great potential to measure DBH as it provides much higher density point cloud data as compared to aircraft-borne systems. Here, we explore the potential of a UAV-lidar system (GatorEye) to measure individual-tree DBH and total height using an automatic approach in an integrated crop-livestock-forest system with seminal forest plantations of Eucalyptus benthamii. A total of 63 trees were georeferenced and had their DBH and total height measured in the field. In the high-density (>1400 points per meter squared) UAV-lidar point cloud, we applied algorithms (usually used for TLS) for individual tree detection and direct measurement of tree height and DBH. The correlation coefficients (r) between the field-observed and UAV lidar-derived measurements were 0.77 and 0.91 for DBH and total tree height, respectively. The corresponding root mean square errors (RMSE) were 11.3% and 7.9%, respectively. UAV-lidar systems have the potential for measuring relatively broad-scale (thousands of hectares) forest plantations, reducing field effort, and providing an important tool to aid decision making for efficient forest management. We recommend that this potential be explored in other tree plantations and forest environments.

(10, 17, 18, 30). O estudo indicou também que a permanência da espécie na futura estrutura da floresta não é garantida pela grande quantidade de indivíduos nas classes de diâmetros menores, mas sim pela capacidade de competição que a espécie apresenta.Palavras-chave: Distribuição diamétrica, dinâmica florestal e floresta de Araucária. DIAMETRIC STRUCTURE CHANGES IN A OMBROPHYLLOUS MIXED FOREST BETWEEN 1979 AND 2000

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Abstract& Key message In this paper it is shown that a simultaneous adjustment provides more efficient estimates of total tree biomass than with independent modelling for biomass estimates by compartments (canopy, bole and roots).

Foi avaliada a estrutura vertical de um fragmento florestal com Araucaria angustifolia na região Centro-Sul do Paraná. O estudo foi realizado com base em parcelas amostrais permanentes, totalizando 3,5 ha, instaladas na Estação Experimental de São João do Triunfo-PR. Foram examinadas a estratificação vertical e a posição sociológica nos anos de 1995 e 1998. Utilizou-se o diagrama h-M e a Posição Sociológica para representar a estratificação vertical da floresta. O diagrama dividiu a floresta em três estratos (I: altura superior a 27 m; II: entre 23 e 27 m; III: inferior a 23 m). Das 65 espécies identificadas em 1995, apenas 5 apresentaram indivíduos emergentes no estrato I. Araucaria angustifolia foi a espécie que apresentou a maior posição sociológica (PS = 24,91%), encontrando-se distribuída nos três estratos. Nectandra grandiflora (PS = 9,80%) foi uma espécie típica de ocorrência em dois estratos, enquanto Ilex paraguariensis (PS = 6,20%) fez-se presente em apenas um estrato. No período de 3 anos (de 1995 a 1998) houve pouca alteração na estrutura vertical da floresta em apreço. VERTICAL STRUCTURE OF A FRAGMENT OF MIXED ARAUCARIA FOREST IN CENTER-SOUTH PARANA STATE, BRAZIL Abstract The vertical structure of a fragment of mixed Araucaria forest, located in Center-Southern Parana State, Brazil, was analyzed. The study was based on data collection in four permanent sample plots, comprising 3.5 ha, established at the São João do Triunfo Experimental Station. The vertical stratification and the sociologic position of the component tree populations were examined for data collected in 1995 and 1998. The h-M diagram and the Sociologic Position were used as reference to represent the vertical structure of the forest. The diagram divided the forest in three strata (I: tree height over 27 m; II: 23 to 27 m; III: less than 23 m). Among the 65 species identified in the forest in 1995, only five participated in the first story (stratum I) Araucaria angustifolia was the species of greatest Sociologic Position (PS = 24.91%), occurring in all the three strata. Nectandra grandiflora (PS = 9.80%) was a typical species occurring in two stories, whereas Ilex paraguariensis (PS = 6.20%) was an example of species appeared in a single story. During three years (1995 to 1998) no remarkable change was noticed in terms of vertical structure in the forest.