Terrestrial carbon stock mapping is important for the successful implementation of climate change mitigation policies. Its accuracy depends on the availability of reliable allometric models to infer oven-dry aboveground biomass of trees from census data. The degree of uncertainty associated with previously published pantropical aboveground biomass allometries is large. We analyzed a global database of directly harvested trees at 58 sites, spanning a wide range of climatic conditions and vegetation types (4004 trees ≥ 5 cm trunk diameter). When trunk diameter, total tree height, and wood specific gravity were included in the aboveground biomass model as covariates, a single model was found to hold across tropical vegetation types, with no detectable effect of region or environmental factors. The mean percent bias and variance of this model was only slightly higher than that of locally fitted models. Wood specific gravity was an important predictor of aboveground biomass, especially when including a much broader range of vegetation types than previous studies. The generic tree diameter-height relationship depended linearly on a bioclimatic stress variable E, which compounds indices of temperature variability, precipitation variability, and drought intensity. For cases in which total tree height is unavailable for aboveground biomass estimation, a pantropical model incorporating wood density, trunk diameter, and the variable E outperformed previously published models without height. However, to minimize bias, the development of locally derived diameter-height relationships is advised whenever possible. Both new allometric models should contribute to improve the accuracy of biomass assessment protocols in tropical vegetation types, and to advancing our understanding of architectural and evolutionary constraints on woody plant development.

. 2008. Estimation of biomass and carbon stocks: the case of the Atlantic Forest. Biota Neotrop. 8(2): http://www.biotaneotropica.org.br/v8n2/en/abstract?point-ofview+bn00108022008. Abstract:The main objective of this paper is to present and discuss the best methods to estimate live above ground biomass in the Atlantic Forest. The methods presented and conclusions are the products of a workshop entitled "Estimation of Biomass and Carbon Stocks: the Case of Atlantic Rain Forest". Aboveground biomass (AGB) in tropical forests is mainly contained in trees. Tree biomass is a function of wood volume, obtained from the diameter and height, architecture and wood density (dry weight per unit volume of fresh wood). It can be quantified by the direct (destructive) or indirect method where the biomass quantification is estimated using mathematical models. The allometric model can be site specific when elaborated to a particular ecosystem or general that can be used in different sites. For the Atlantic Forest, despite the importance of it, there are only two direct measurements of tree biomass, resulting in allometric models specific for this ecosystem. To select one or other of the available models in the literature to estimate AGB it is necessary take into account what is the main question to be answered and the ease with which it is possible to measure the independent variables in the model. Models that present more accurate estimates should be preferred. However, more simple models (those with one independent variable, usually DBH) can be used when the focus is monitoring the variation in carbon storage through the time. Our observations in the Atlantic Forest suggest that pan-tropical relations proposed by Chave et al. (2005) can be confidently used to estimated tree biomass across biomes as long as tree diameter (DBH), height, and wood density are accounted for in the model. Resumo: O principal objetivo deste artigo é apresentar e discutir a melhor forma para estimar a biomassa viva acima do solo (BVS) na Mata Atlântica. A biomassa viva acima do solo em florestas tropicais esta contida principalmente nas árvores. A biomassa das árvores é uma função do seu volume de madeira, obtido do diâmetro e da altura, de sua arquitetura e da densidade de sua madeira (peso seco por unidade de volume fresco). Ela pode ser quantificada pelo método direto (destrutivo) ou pelo método indireto onde a quantificação da biomassa é feita através de modelos matemáticos. Os modelos alométricos podem ser específicos para um determinado local, quando elaborado para um ecossistema particular, ou gerais, que podem ser utilizados em para estimar a biomassa em diferentes locais. Para a Mata Atlântica, a despeito de sua importância, existem somente duas medidas diretas de biomassa de árvores, que resultaram em modelos alométricos específicos para essas florestas. Para selecionar um ou outro modelo alométrico para estimar BVS, disponível na literatura, é necessário levar em conta o a questão a ser respondida e a facilidade com a qual é possível medir...

P P P P Pala ala ala ala alavras-cha vras-cha vras-cha vras-cha vras-chav v v v ve -eeee -Amazônia, Brasil, Biodiversidade ABSTRA ABSTRA ABSTRA ABSTRA ABSTRACT -CT -CT -CT -CT -(Floristic composition and phytosociology of a cerrado sensu stricto in Água Boa -MT). The study was carried out in Água Boa municipality district -MT, in the Araguaia Valley, in a transitional zone between Cerrado and Amazonian. There is a mosaic of vegetation types with the predominance of savannas physiognomies. The aim of this work was to study the floristic composition and the phytosociology of the Cerrado sensu stricto in Água Boa. Ten random plots of 20x50m (1000m²) were sampled. The minimum diameter for measurement of the woody plants was 5 cm at the ground level. Besides the sampling with identification in loco of the species, collection incursions were made in the plots and in nearly areas, to enlarge the study of the floristic composition. Thirtyfour botanical families distributed in 60 genera and 80 species were found. The family Leguminosae presented the largest number of species (10), followed by Myrtaceae (7), Vochysiaceae (6) and Malpighiaceae (5). Other 19 families were represented by only one species. The species with higher Index of Importance Value were Curatella americana, Qualea parviflora Mart., Callisthene fasciculata Mart., Mezilaurus crassiramea (Meiss) Taub. and Byrsonima crassa Nied. Thirteen species were represented by only one individual. The density was of 995 plants/ ha and the basal area was of 7,5 m 2 /ha. The Shannon index (H') was 3,69 evidencing the high diversity of the area.

Estimou-se a produção de serapilheira e a taxa de decomposição do material foliar em uma área de cerradão, fisionomia pouco estudada a esse respeito e muito ameaçada, principalmente no Estado de São Paulo. No período de estudo, a quantidade total de serapilheira produzida foi de 5646,9 kg.ha-1.ano-1, onde a fração 'folhas' teve a maior participação, contribuindo com 4081,2 kg.ha¹.ano-1, seguida pela fração 'ramos' (1066,1 kg.ha-1.ano-1), 'estruturas reprodutivas' (434,1 kg.ha-1.ano-1) e 'miscelânea' (65,5 kg.ha-1.ano-1). A produção de serapilheira foi altamente estacional e correlacionou-se negativamente com a umidade relativa do ar e com a temperatura média do ar. A produção foliar correlacionou-se negativamente com a umidade do ar, precipitação e temperatura média do ar. Não houve diferença significativa entre a produção de serapilheira desse estudo e a encontrada em duas outras áreas com cerradão e mata mesófila semidecídua, porém essas fisionomias vegetais diferiram significativamente da produção em outra área com cerrado sensu stricto. A taxa de decomposição (K) obtida para o material foliar foi de 0,56, com o tempo para decomposição de 50% do material estimado em 1,8 anos e o tempo de renovação do material foliar em 2,3 anos.