A pequena produção e a exploração sustentável de madeira na Amazônia

This research estimate the potential and importance of the small holder for wood supply to the logging industry in the Transamazonic. Using satellite images, secondary and primary data the research showed the potential and the sustainability of the small production to supply the industry. Using a conservative estimate per hectare it was possible to estimate a area of 841,954 ha per year to exploit in the region which would be equivalent to the production of 10,000 families or 18% of the total estimated family in the region. This is equivalent to 1/25 of the actual estimate of production in the region. In general, the large potential of the small production are overlooked but when calculated for a large region it can show the potential for increase of income and forestry sustainability.Esta pesquisa estima o potencial e a importância do pequeno produtor para o abastecimento da indústria madeireira na Transamazônica. Através de imagens de satélites, dados secundários e dados primários o trabalho mostra o potencial e sustentabilidade da pequena produção abastecer a indústria. Considerando uma estimativa conservadora de produção madeireira estima-se uma área de 841.954 ha por ano o que equivaleria a exploração de madeira de 10.000 famílias por ano ou 18% do total estimado de famílias para suprir a demanda atual da indústria nesta área a preço de mercado. Isso equivale a um volume que é 1/25 da atual estimativa para a produção de madeira na região provenientes de outros estudos. Em geral a pesquisa tem focado no manejo florestal de industria madeireira, mas uma análise mais ampla do potencial madeireiro da pequena produção, quando calculado para uma regiao, pode ser usado para trazer o desenvolvimento econômico integrando desenvolvimento agrícola com desenvolvimento florestal

Modeled interactive effects of precipitation, temperature, and [CO2] on ecosystem carbon and water dynamics in different climatic zones

Interactive effects of multiple global change factors on ecosystem processes are complex. It is relatively expensive to explore those interactions in manipulative experiments. We conducted a modeling analysis to identify potentially important interactions and to stimulate hypothesis formulation for experimental research. Four models were used to quantify interactive effects of climate warming (T), altered precipitation amounts [doubled (DP) and halved (HP)] and seasonality (SP, moving precipitation in July and August to January and February to create summer drought), and elevated [CO2] (C) on net primary production (NPP), heterotrophic respiration (Rh), net ecosystem production (NEP), transpiration, and runoff. We examined those responses in seven ecosystems, including forests, grasslands, and heathlands in different climate zones. The modeling analysis showed that none of the three-way interactions among T, C, and altered precipitation was substantial for either carbon or water processes, nor consistent among the seven ecosystems. However, two-way interactive effects on NPP, Rh, and NEP were generally positive (i.e. amplification of one factor's effect by the other factor) between T and C or between T and DP. A negative interaction (i.e. depression of one factor's effect by the other factor) occurred for simulated NPP between T and HP. The interactive effects on runoff were positive between T and HP. Four pairs of two-way interactive effects on plant transpiration were positive and two pairs negative. In addition, wet sites generally had smaller relative changes in NPP, Rh, runoff, and transpiration but larger absolute changes in NEP than dry sites in response to the treatments. The modeling results suggest new hypotheses to be tested in multifactor global change experiments. Likewise, more experimental evidence is needed for the further improvement of ecosystem models in order to adequately simulate complex interactive processes

Does the disturbance hypothesis explain the biomass increase in basin-wide Amazon forest plot data?

Positive aboveground biomass trends have been reported from old-growth forests across the Amazon basin and hypothesized to reflect a large-scale response to exterior forcing. The result could, however, be an artefact due to a sampling bias induced by the nature of forest growth dynamics. Here, we characterize statistically the disturbance process in Amazon old-growth forests as recorded in 135 forest plots of the RAINFOR network up to 2006, and other independent research programmes, and explore the consequences of sampling artefacts using a data-based stochastic simulator. Over the observed range of annual aboveground biomass losses, standard statistical tests show that the distribution of biomass losses through mortality follow an exponential or near-identical Weibull probability distribution and not a power law as assumed by others. The simulator was parameterized using both an exponential disturbance probability distribution as well as a mixed exponential-power law distribution to account for potential large-scale blowdown events. In both cases, sampling biases turn out to be too small to explain the gains detected by the extended RAINFOR plot network. This result lends further support to the notion that currently observed biomass gains for intact forests across the Amazon are actually occurring over large scales at the current time, presumably as a response to climate change. (Résumé d'auteur