Cintia Rodrigues de Souza

Rapid tree carbon stock recovery in managed Amazonian forests

While around 20% of the Amazonian forest has been cleared for pastures and agriculture, one fourth of the remaining forest is dedicated to wood production. Most of these production forests have been or will be selectively harvested for commercial timber, but recent studies show that even soon after logging, harvested stands retain much of their tree-biomass carbon and biodiversity. Comparing species richness of various animal taxa among logged and unlogged forests across the tropics, Burivalova et al. found that despite some variability among taxa, biodiversity loss was generally explained by logging intensity (the number of trees extracted). Here, we use a network of 79 permanent sample plots (376 ha total) located at 10 sites across the Amazon Basin to assess the main drivers of time-to-recovery of post-logging tree carbon (Table S1). Recovery time is of direct relevance to policies governing management practices (i.e., allowable volumes cut and cutting cycle lengths), and indirectly to forest-based climate change mitigation interventions.While around 20% of the Amazonian forest has been cleared for pastures and agriculture, one fourth of the remaining forest is dedicated to wood production [1] . Most of these production forests have been or will be selectively harvested for commercial timber, but recent studies show that even soon after logging, harvested stands retain much of their tree-biomass carbon and biodiversity [2,3] . Comparing species richness of various animal taxa among logged and unlogged forests across the tropics, Burivalova et al. [4] found that despite some variability among taxa, biodiversity loss was generally explained by logging intensity (the number of trees extracted). Here, we use a network of 79 permanent sample plots (376 ha total) located at 10 sites across the Amazon Basin [5] to assess the main drivers of time-to-recovery of post-logging tree carbon ( Table S1 ). Recovery time is of direct relevance to policies governing management practices (i.e., allowable volumes cut and cutting cycle lengths), and indirectly to forest-based climate change mitigation interventions.

Avaliação e efeito da compactação do solo, devido à freqüência de tráfego, na produção de madeira de eucalipto

RESUMO – A compactacao do solo devido ao trafego de maquinas de colheita de madeira, assim como a extensao da area impactada, constitui fator de preocupacao, em virtude da possibilidade de efeitos prejudiciais para o crescimento da floresta. O objetivo deste trabalho foi avaliar os efeitos da frequencia de trafego de um trator mais carreta na compactacao do solo e na produtividade de um plantio de Eucalyptus grandis, no final da primeira rotacao de sete anos. A compactacao do solo, avaliada por meio da densidade e resistencia a penetracao, foi determinada para tratamentos com 1, 3, 5, 10 e 20 passadas do veiculo carregado com 12,5 estereos de madeira, com peso total de oito toneladas, alem de uma testemunha sem a ocorrencia de trafego. Apos as cinco primeiras passadas ocorreram cerca de 80% do adensamento total do solo, resultante das 20 passadas, sendo recomendado restringir o trafego de veiculos dentro do talhao na menor area possivel, diminuindose a extensao de possiveis efeitos da compactacao sobre o povoamento florestal. Contudo, nessa situacao em particular a compactacao do solo nao prejudicou o crescimento das arvores em nenhum dos tratamentos avaliados.

Carbon recovery dynamics following disturbance by selective logging in Amazonian forests

When 2 Mha of Amazonian forests are disturbed by selective logging each year, more than 90 Tg of carbon (C) is emitted to the atmosphere. Emissions are then counterbalanced by forest regrowth. With an original modelling approach, calibrated on a network of 133 permanent forest plots (175 ha total) across Amazonia, we link regional differences in climate, soil and initial biomass with survivors’ and recruits’ C fluxes to provide Amazon-wide predictions of post-logging C recovery. We show that net aboveground C recovery over 10 years is higher in the Guiana Shield and in the west (21 ±3 Mg C ha-1) than in the south (12 ±3 Mg C ha-1) where environmental stress is high (low rainfall, high seasonality). We highlight the key role of survivors in the forest regrowth and elaborate a comprehensive map of post-disturbance C recovery potential in Amazonia. DOI: http://dx.doi.org/10.7554/eLife.21394.001

Comportamento de espécies florestais em plantios a pleno sol e em faixas de enriquecimento de capoeira na Amazônia

Foram avaliadas especies florestais nativas e exoticas em duas condicoes de plantio: a pleno sol e em faixas de enriquecimento de capoeira, a fim de gerar tecnologias para incorporacao ao processo produtivo de areas alteradas na regiao amazonica para minimizar a pressao do desmatamento sobre a floresta natural. Os dados analisados (DAP, altura, volume por hectare e sobrevivencia) referem-se a idade de seis anos. No plantio a pleno sol, a especie que apresentou o melhor desempenho foi Ceiba pentandra, com medias de DAP de 19,6 cm, altura de 10,2 m e volume de 390,9 m3 ha-1. Hymenaea courbaril tambem apresentou crescimento satisfatorio, com medias de 11,5 cm de DAP, 10,8 m de altura e 144,8 m3 ha -1 de volume. Nos plantios de enriquecimento de capoeira, a Carapa guianensis foi a especie que apresentou o melhor desempenho, com 8,3 cm de DAP, 6,4 m de altura e volume de 54,8 m3 ha -1. Acacia mangium e Sclerolobium paniculatum apresentaram crescimento superior, mas as taxas de sobrevivencia foram muito baixas nas duas condicoes de plantio.

Simulação de estratégias de manejo florestal na Amazônia com o uso do modelo SYMFOR

The SYMFOR model was used to simulate the ecological processes of tree growth, mortality and recruitment, and the forest management processes, in the terra firme forests of the eastern Amazon. The simulation utilized all the trees that have a diameter greater than 5 cm, from 40 permanent sample plots of 1 ha each (36 logged and 4 unlogged). The stand was measured in 1984, logged in 1985 and remeasured in 1986, 1988, 1990, 1994, 1996 and 2004. Ten species groups are used to describe the natural processes affecting tree behavior. Model performance compares the simulation results with real data describing the forest recovery for 19 years following logging. The treatments, combinations of logging intensities (15%, 25% and 35% of the total volume of the trees higher than 60 cm of DBH had been tested) and thinning intensities (0%, 30%, 50% and 70% of the original basal area) were analyzed as management strategies. The model was applied to simulate current forest management practice in the Brazilian Amazon, with 30 m3 ha−1 of timber extracted with a cutting cycle of 30 years. Results show that the similarity among observed and simulated data for SYMFOR validated the model to represent the dynamics of the unlogged forest. In the simulation of the current management practice applied in the Amazon forest, it is suggested that the financial benefits decrease with successive harvests and, consequently, the timber volume cannot be sustained.

Predição da distribuição diamétrica de uma floresta manejada experimentalmente através de um Sistema de Equações Diferenciais

The aim of this study was to evaluate the prognosis of the diameter structure of an experimentally managed forest, utilizing a system of differential equations of the first order, adjusted for each treatment. The basic data were obtained from the Bom Manejo Projet (Embrapa Eastern Amazon/CIFOR/ITTO), carried out in the Monte Dourado Forest Company (Jari) area, Vitoria do Jari, Amapa, Brazil. The statistical delineation was designed as random blocks with three replications. The treatments applied were combinations of logging intensities (15%, 25% and 35% of the total volume of the trees larger than 60 cm of DBH) and thinning intensities (0%, 30%, 50% and 70% of the original basal area). The non-logged forest was used for the control plots. Stand development was monitored through 40 permanent sample plots of 1 ha each (36 logged and 4 unlogged). The stand was measured in 1984, logged in 1985 and remeasured in 1986, 1988, 1990, 1994, 1996 and 2004. All the trees with DBH ≥ 20 cm were measured. While keeping the same simplicity of transition matrix based models, the proposed model allows for determining the state of the system for any given point in time, not being confined just for multiplying time intervals as was the former. This method was verified for different evaluation periods and the results showed that not even the longer periods of projections (break-even point) will be enough to restore the initial conditions of the stand.

Dinâmica e estoque de carbono em floresta primária na região de Manaus/AM

This study analyzed data from three forest inventories conducted in the Experimental Forest, which belongs to Embrapa Western Amazon basin and is located at km 54 on BR-174, Manaus / AM. The aim was to study forest dynamics - the rates of recruitment, growth and mortality - in addition to carbon storage in an area of primary forest, without any intervention. The surveys were conducted in the years 2005, 2007 and 2010 in 15 permanent plots of 1 hectare each. There, all trees with diameter at breast height (DBH) above 10 cm were measured. We calculated the rates of recruitment and mortality, the periodic annual increments (PAIs) in terms of DBH, basal area and volume, fresh and dry biomass above the soil and total carbon storage in the vegetation. The recruitment rates were 2.0 percent and 1.8 percent, and mortality were 0.95 percent and 1.3 percent for the periods between 2005 and 2007 and 2007 and 2010, respectively. The volume was 345.62 m3 ha-1 for the year 2005, rising to 360.67 m3 ha-1 in 2010 with PAIs of 4.32 m3 ha-1 yr-1 between 2005 and 2007 and 1.31 m3 ha-1 yr-1 between 2007 and 2010. The total carbon storage increased from 173.63 t C ha-1 in 2005 to 181.01 t C ha-1 in 2010, confirming that the forest accumulated carbon in the period, acting as a sink.

Carbon stock and dynamics in a managed forest in Central Amazon

The Amazon forest has been in evidence in global discussions about their role in control of global climate change, both by the ability to emit greenhouse gases into the atmosphere via burning or thinning, how to absorb carbon from the atmosphere by through the growth of the stand. This study analyzed data from a forest managed in 1987, in Manaus/AM. This work aimed to study the carbon stock and dynamics. The forest inventories were conducted in 15 hectares of permanent plots. The average rates of recruitment were 4.9%, 4.8%, 3.7% and 5% for control treatments and logging of 1/3, 1/2 and 2/3, respectively, and the average mortality rates were 3.1%, 6%, 4.8% and 6.7%, for control treatments and logging of 1/3, 1/2 and 2/3, respectively. The basal area (23.1 m2 ha-1 in 2005, 23.6 m2 ha-1 in 2007 and 23.7 m2 ha-1 in 2010), the volume (345 m3 ha-1 in 2005, 351.3 m3 ha-1 in 2007 and 353.7 m3 ha-1 in 2010) and the carbon content (149.2 t ha-1 in 2005, 151.8 t ha-1 in 2007 and 152.6 t ha-1 in 2010) increased in all measurements. However, the statistical difference between these values was not significant, so it was concluded that the forest was in equilibrium with the atmosphere during the period evaluated. A comparison of the carbon stock of the years measured with the stock pre-exploratory, in 1986, showed that in 2010 the carbon stock equaled the content before logging, meaning the forest recovery.