Biomass, harvestable area, and forest structure estimated from commercial timber inventories and remotely sensed imagery in southern Amazonia

The purpose of this study was to determine if spatially-explicit commercial timber inventories (CTI) could be used in conjunction with satellite imagery to improve timber assessments and forest biomass estimates in Amazonia. As part of a CTI, all commercial trees ≥45 cm DBH were measured and georeferenced in 3500 ha of a logging concession in NW Mato Grosso, Brazil. A scientific inventory was conducted of all trees and palms ≥10 cm DBH in 11.1 ha of this area. A total of >20,000 trees were sampled for both inventories. To characterize vegetation radiance and topographic features, regional LANDSAT TM and ASTER images were obtained. Using a stream network derived from the ASTER-based 30 m digital elevation model (DEM), a procedure was developed to predict areas excluded from logging based on reduced impact logging (RIL) criteria. A topographic index (TI) computed from the DEM was used to identify areas with similar hydrologic regimes and to distinguish upland and lowland areas. Some timber species were associated with convergent landscape positions (i.e., higher TI values). There were significant differences in timber density and aboveground biomass (AGB) in upland (6.0 stems ha−1, 33 Mg ha−1) versus lowland (5.4 stems ha−1, 29 Mg ha−1) areas. Upland and lowland, and timber and non-timber areas could be distinguished through single and principal component analysis of LANDSAT bands. However, radiance differences between areas with and without commercial timber on a sub-hectare scale were small, indicating LANDSAT images would have limited utility for assessing commercial timber distribution at this scale. Assuming a 50 m stream buffer, areas protected from logging ranged from 7% (third order streams and above) to 28% (first order and above) of the total area. There was a strong positive relationship between AGB based on the scientific inventory of all trees and from the commercial timber, indicating that the CTI could be used in conjunction with limited additional sampling to predict total AGB (276 Mg ha−1). The methods developed in this study could be useful for facilitating commercial inventory practices, understanding the relationship of tree species distribution to landscape features, and improving the novel use of CTIs to estimate AGB

When big trees fall: Damage and carbon export by reduced impact logging in southern Amazonia

We examined carbon export in whole logs and carbon accumulation as coarse woody debris (CWD) produced from forest damage during all phases of the first and second year of a certified reduced impact logging (RIL) timber harvest in southern Amazonia. Our measurements included a 100% survey of roads and log decks, assessment of canopy damage and ground disturbance in skid trails and tree-fall gaps, and measurement of carbon exported from the site in logs. Log deck and road construction crushed one and five trees in the 10–60 cm diameter at breast height (DBH) class per hectare logged, disturbed areas of 24 and 100 m2 ha−1, respectively, and together disturbed about 1% of the forest. On average 1.1–2.6 trees ha−1 were harvested over the two years. Logged gaps constituted the greatest disturbance on an area basis (4–10% of the forest) and CWD generation (1.9–4.4 Mg ha−1 logged). In gaps, felled trees severed or crushed 10 trees ≥10 cm DBH per tree logged, which corresponded to 1.7 Mg ha−1 of CWD per tree logged. Crown height – measured from the first bifurcation to the top of the crown – rather than tree height was the better predictor of gap size formed from tree felling (R2 = 0.41). Logging activities significantly reduced leaf area in roads, log decks and gaps, with the greatest reduction (48%) in log decks and least in logged gaps and roads (28–33%) compared to undisturbed forest. A total of 37 species were harvested, with 36% of the total trees harvested and 48% of the total carbon exported from the site in three of the most common species. Logging damage produced 4.9–8.8 Mg C ha−1 logged of CWD from all phases of the operation. Carbon export in whole logs (2.1–3.7 Mg C ha−1 logged) represented 1–3% of the total standing forest carbon ≥10 cm DBH (138 Mg C ha−1). The mean carbon ratio (per hectare logged) of C in CWD to C exported in logs was 2.4. The disturbance, damage, carbon export and CWD data we present advances understanding of the effect of selective logging on tropical forest dynamics of the Amazon Basin. Our results indicate that certified timber harvest in Amazonia under RIL is a viable forest management option to reduce damage and CWD production compared to conventional logging (CL) practices; however, the benefits of disturbance reduction from RIL relative to CL are only realized at greater volumes of timber extraction

Análise das políticas públicas: uma proposta metodológica para o estudo no campo da prevenção em Aids Public policies assessment: a methodological proposal for the study in the field of Aids prevention

As políticas públicas são respostas do poder público para problemáticas sociais. Elas são estratégias de grande relevância para o enfrentamento da Aids e desenvolvimento de ações de prevenção da infecção do HIV, pois institucionalizam no setor público de saúde ações sistemáticas para esse fim. Elas se estruturam numa rede de determinantes que delineiam os caminhos a serem trilhados pelo gestor público. Nesse contexto, entram em jogo diversos atores, com diferentes interesses e poder de barganha político-econômica, negociação de concepções de mundo, estratégias de ação e campos de luta por direitos e deveres sociais. É uma disputa de saberes e interesses travada no campo político, permeada por aspectos sócio-culturais e econômicos. Neste sentido, o presente trabalho objetiva uma discussão conceitual sobre esse tema, desenvolvendo a concepção teórica sobre a análise de políticas, enquanto uma metodologia de estudo, compreendendo as categorias: atores, conteúdo, contexto e processo, onde, nessa última, se delimitam especificamente os processos de construção de agenda, formulação e implementação de uma política. Esse quadro teórico é desenvolvido centrando a temática da prevenção da Aids, contextualizada no cenário brasileiro, a partir da qual são elencados alguns entraves das políticas propostas, articulando-as às considerações de especialistas que buscam reorientar as intervenções públicas de prevenção à Aids.<br>Public policies are the response of public power to social issues. They are very relevant strategies to face AIDS and the development of prevention measures concerning HIV infection, for they institutionalize systematic actions in the public health sector with this purpose. They are structured in a network of directives that establish the routes to be followed by public officials. Within this context, different actors are part of the game, with different interests and social and political bargaining powers, world concepts negotiation, actions strategies within the field of social rights and duties. It's a struggle of knowledge and interests in the political ground permeated by social, cultural and economic aspects. Therefore, this paper engages in a concept discussion of the theme, developing a theoretical concept of policies assessment from the viewpoint of a methodological study comprising the following: actors, content, context and process, process circumscribing specific agenda designing processes, policy formulation and implementation. This theoretical scenario is developed focusing on the theme of AIDS prevention, the context being the Brazilian environment from which some of the constraints of policies proposals are listed and linked to specialists'considerations pursuing a reorientation of public interventions concerning AIDS prevention