L. M. B. Rossi

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.

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.

TROCAS GASOSAS DE PLANTAS JOVENS DE TAXI-BRANCO SUBMETIDAS À VARIAÇÃO DE TEMPERATURA FOLIAR E SUSPENSÃO DA IRRIGAÇÃO

The study aimed to investigate the influence of leaf temperature variation associated with irrigation suspension on gas exchange of seedlings of Sclerolobium paniculatum Vogel. The study was carried out in a greenhouse at experimental area of Embrapa, Amazonia Ocidental. Plants were grown in a greenhouse and, after four months were subjected to three treatments (irrigated maintained until the field capacity, irrigation suspended for eight and 14 days). We evaluated the physiological parameters of gas exchange, net assimilation rate of CO 2 (A), leaf transpiration (E), stomatal conductance ( g s ) and water use efficiency (WUE) which were obtained through a photosynthesis portable meter (CI-340, CID, Inc). The results showed reduction of net assimilation rate of CO 2 depending on the elevation of the leaf temperature and without irrigation. After eight days without irrigation, decreased rates of photosynthetic assimilation of CO 2 in 62, 65, 75, 58, 50 and 64%, and after 14 days the reduction was 80, 85, 85, 84, 86 and 93% compared to plants irrigated maintained at temperatures of 25, 30, 35, 40, 45 and 50 °C, respectively. The leaf transpiration was inversely proportional to rates of net photosynthetic assimilation of CO 2 , which has increased with an increased leaf temperature. The physiological behavior of gas exchange of Sclerolobium paniculatum showed variations both as regards to the effect of leaf temperature as the suspension of irrigation.