ABSTRACT The Caatinga biome in Brazil comprises the largest and most continuous expanse of the seasonally dry tropical forest (SDTF) worldwide; nevertheless, it is among the most threatened and least studied, despite its ecological and biogeographical importance. The spatial distribution of volumetric wood stocks in the Caatinga and the relationship with environmental factors remain unknown. Therefore, this study intends to quantify and analyze the spatial distribution of wood volume as a function of environmental variables in Caatinga vegetation in Bahia State, Brazil. Volumetric estimates were obtained at the plot and fragment level. The multiple linear regression techniques were adopted, using environmental variables in the area as predictors. Spatial modeling was performed using the geostatistical kriging approach with the model residuals. The model developed presented a reasonable fit for the volume m3 ha with r2 of 0.54 and Root Mean Square Error (RMSE) of 10.9 m3 ha–1. The kriging of ordinary residuals suggested low error estimates in unsampled locations and balance in the under and overestimates of the model. The regression kriging approach provided greater detailing of the global wood volume stock map, yielding volume estimates that ranged from 0.01 to 109 m3 ha–1. Elevation, mean annual temperature, and precipitation of the driest month are strong environmental predictors for volume estimation. This information is necessary to development action plans for sustainable management and use of the Caatinga SDTF in Bahia State, Brazil.

In this study we evaluated the floristic composition and changes in stored biomass and dynamics over time in 9 permanent plots monitored by RAINFOR (Amazon Forest Inventory Network) and located in the lowland Amazon rainforest of the Tambopata National Reserve. Data were acquired in the field using the standardized methodology of RAINFOR. The biomass was estimated using the equation for tropical moist forests of Chave et al. (2005). Biomass dynamics were analyzed, in three separated periods from 2003 to 2011. 64 families, 219 genera and 531 species were recorded. The tree floristic composition is very similar in all plots except for one swamp plot, although but it is also evident that two slightly different forest communities exist in the rest of landscape, apparently related to the age of the ancient river terraces in the area. Mortality and recruitment of individuals averaged 2.12 ± 0.52% and 1.92 ± 0.49%, respectively. The turnover rate is 2.02% per year. Aboveground biomass stored in these forests averages 296.2 ± 33.9 t ha-1. The biomass dynamics show a total net gain of 1.96, 1.69 and -1.23 t ha-1 for period respectively. Prior to the drought of 2010 a change in biomass was found 1.88 t ha-1 yr-1 and post drought was -0.18 t ha-1 yr-1 on average, though the difference is not significant. Demographic analysis suggests a dynamic equilibrium in the plots. The negative balance of biomass observed for the period 2008 - 2011 may be due to the drought of 2010, in which half of the monitored plots experienced negative net biomass change due to mortality of individuals selectively affecting the floristic composition.

En este estudio se evaluaron los cambios en la biomasa aérea almacenada y su dinámica en el tiempo en 9 parcelas permanentes pertenecientes a la red de parcelas de RAINFOR (Red Amazónica de Inventarios Forestales) ubicadas dentro del bosque húmedo tropical de la Reserva Nacional Tambopata en la llanura Amazónica. Se tomaron datos en campo con la metodología estandarizada RAINFOR. La biomasa se estimó usando la ecuación para bosques húmedos tropicales de Chave et al. (2005). La dinámica de la biomasa se analizó separándolos por periodos inter censales a partir del año 2003 hasta el 2011. Se registraron 64 familias, 219 géneros y 531 especies. La composición florística es muy similar en todas las parcelas excepto en la parcela de pantano. Son evidentes dos grupos ligeramente distintos y aparentemente relacionados a la edad de las antiguas terrazas fluviales de la zona. La tasa de mortalidad y reclutamiento de individuos presentan valores promedio de 2.12 ± 0.52% y 1.92 ± 0.49%, respectivamente. La tasa de reemplazo es 2.02% anual. La biomasa aérea almacenada fue de 296.2 ± 33.9 t ha-1 en promedio. La dinámica de la biomasa muestra una ganancia neta total de 1.96, 1.69 y -1.23 t ha-1 para cada periodo respectivamente. Antes de la sequía de 2010 se encontró un cambio en la biomasa de 1.88 t ha-1 año-1 y post sequía fue -0.18 t ha-1 año-1 en promedio, aunque la diferencia no fue significativa. El análisis demográfico sugiere un equilibrio dinámico en las parcelas. El balance negativo de biomasa observado para el periodo 2008 - 2011 puede deberse a la sequía del 2010, donde la mitad de las parcelas monitoreadas tuvieron una disminución en las ganancias netas de la biomasa por mortalidad de individuos afectando la composición florística selectivamente.

Stocks of dead wood or necromass represent an important portion of biomass and nutrients in tropical forests. The objectives of this study were: 1) to evaluate and compare the necromass of "terra firme" and lowlands forests, (2) to study the relationship between necromass, above-ground biomass and wood density, and (3) to estimate the necromass of the department of Madre de Dios, Peru. Stocks of necromass and above-ground biomass were estimated at three different locations using permanent plots and line intercept transects. The average volume of necromass for the three sites was 72.9 m3 ha-1 with an average weight varying between 24.8 and 30.7 Mg ha-1, depending on the estimations of dead wood density used for the calculations. Terra firme forests had significantly higher stocks of necromass than lowland forests. The amount of necromass was 11% of the total above-ground biomass in Madre de Dios forests. The total stock of carbon stored in dead wood for the entire department of Madre de Dios was estimated to be approximately 100 mega tonnes of carbon. This is ten times more than the annual fossil fuel emissions of Peru between 2000 and 2008. The substantial stocks of necromass emphasize the importance of these types of field studies, considering that this component of tropical forest carbon cannot be detected using other methods such as satellite remote sensing.

La cantidad de madera muerta o necromasa representa una importante porción de la biomasa y de los nutrientes en los bosques tropicales. Los objetivos de este estudio son: 1) hacer una evaluación y comparación entre la necromasa de los bosques de altura o tierra firme y los bosques inundables o bajíos, (2) estudiar las relaciones entre la necromasa, la biomasa aérea y la densidad de madera del bosque, y (3) proporcionar una primera estimación de la necromasa para todo el departamento de Madre de Dios. La necromasa gruesa y la masa aérea vegetativa fueron estudiados en tres diferentes lugares utilizando parcelas permanentes y líneas de intersección. El promedio del volumen de madera muerta gruesa fue de 72,9 m³ ha-1, con un peso entre 24,8 y 30,7 Mg ha-1 dependiendo de la densidad de madera muerta usada en los cálculos. Los bosques de tierra firme contienen significativamente más madera muerta que los bosques inundables. La necromasa constituye 11% de la masa aérea vegetativa almacenada en los bosques de Madre de Dios. Finalmente, se estima que el departamento de Madre de Dios contiene alrededor de 100 mega toneladas de carbono en su madera muerta. Este valor es bastante alto, siendo diez veces más que la emisión anual de combustibles fósiles de Perú entre 2000 - 2008. Esta substancial porción de la necromasa enfatiza la importancia de estos tipos de estudios de campo, considerando que este componente de carbono en el bosque tropical no se logra detectar con otros métodos como la detección remota por satélites.

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 as variáveis independentes do modelo. Preferencialmente, deve-se utilizar modelos que apresentem estimativas mais acuradas, entretanto modelos mais simples (aqueles com apenas uma variável independente, normalmente o DAP) podem ser utilizados quando o foco for o monitoramento das variação no estoque de carbono através do tempo. Observações para a Mata Atlântica sugerem que o modelo pan-tropical proposto por Chave et al. (2005) podem ser utilizadas com confiança entre os biomas, uma vez que o mesmo engloba o DAP a altura e a densidade da madeira. Na Mata Atlântica, onde as lianas, bambus, palmeiras, fetos arborescentes e epífitas são um importante componente do sistema, recomenda-se a quantificação dos mesmos. Este artigo é o resultado do workshop "Estimativa da biomassa e estoques de carbono: o processo de Mata Atlântica", realizado em Ubatuba, São Paulo, Brasil, entre 4 e 8 de Dezembro de 2006 como parte do projeto temático BIOTA/FAPESP "Composição florística, estrutura e funcionamento da Floresta Ombrófila Densa dos Núcleos Picinguaba e Santa Virgínia do Parque Estadual da Serra do Mar", BIOTA Gradiente.

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. In Atlantic Forest, we recommend the quantification of biomass of lianas, bamboo, palms, tree ferns and epiphytes, which are an important component in this ecosystem. This paper is an outcome of the workshop entitled "Estimation of Biomass and Carbon Stocks: the Case of Atlantic Rain Forest", that was conducted at Ubatuba, São Paulo, Brazil, between 4 and 8 December 2006 as part of the Brazilian project "Ombrophylus Dense Forest floristic composition, structure and function at the Núcleos Picinguaba and Santa Virginia of the Serra do Mar State Park", BIOTA Gradiente.