Evaluation of yield regulation options for primary forest in Tapajo ´s National Forest, Brazil Paul R. van Gardingen a, * , Denis Valle b,c , Ian Thompson c a University of Edinburgh, Centre for the Study of Environmental Change and Sustainability, The King’s Buildings, West Mains Road, Edinburgh EH9 3JN, Scotland b Instituto do Homem e Meio Ambiente da Amazo ˆnia (IMAZON), CEP 66060-160 Bele ´m, Brazil c Projeto Dendrogene, EMBRAPA, CEP 66095-100 Bele ´m, Brazil Received 23 November 2005; received in revised form 25 April 2006; accepted 17 May 2006 Abstract The sustainability of a range of forest management scenarios were evaluated for the Tapajo ´s region of the Brazilian Amazon using the growth and yield simulation model, Simflora, a derivative of the model SYMFOR developed for application in Indonesia. A simulation of current management regulations based upon a maximum extracted volume of 35 m 3 ha 1 and a 30-year cutting cycle was found to be unsustainable. A range of alternative specifications for the control (regulation) of harvested timber yield were compared, along with associated estimates of timber increment and description of the ecological composition of the stand. The alternative scenarios included cutting cycles ranging from 10 to 60 years and maximum yields from 10 to 40 m 3 ha 1 . The maximum commercial volume increment predicted in this study was 0.33 m 3 ha 1 . It was observed that the highest rates of volume increment were associated with high logging intensities. The study produced a limited number of potentially sustainable options for the Tapajo ´s forest. The best of these were the combinations of 10 m 3 ha 1 yield and a cutting cycle of 30 years or 20 m 3 ha 1 with a 60-year cutting cycle. The analysis suggested that the sustainability of both of these options was ‘‘marginal’’ and suggested adopting a precautionary approach of an additional limit for yield to be no more than 33% of standing commercial volume until more data are available. Analysis of the ecological data from the simulations clearly demonstrated that the composition of the managed forest is likely to differ significantly from that observed in primary forest. The most significant likely change is a reduction in the proportion of trees in the emergent ecological group. This observation raises the issue that stakeholders should not expect tropical forests that are managed for production to ever be identical in structure or composition to primary forests. It also suggests that additional technical measures will be required to promote the regeneration and growth of current emergent species if these are to be maintained in managed forests in the Amazon. The study concludes that there cannot be a single system of yield regulation or forest management that will fit all contexts (social, ecological, environmental and economic) or management objectives held by various stakeholders in the Amazon. # 2006 Elsevier B.V. All rights reserved. Keywords: Sustainable forest management; Amazon; Modelling; Timber certification; Brazil; Yield regulation 1. Introduction The Amazonian rain forest is the world’s largest contiguous area of tropical forest (Dubois, 1991; Asner et al., 2004), being recognised for its high biodiversity and importance to global climate (Malhi et al., 2002). Selective logging is one of the main land uses in the Amazon, being very important for the regional economy. From 1996 to 2003, logging occurred at a rate of 10–20 thousand km 2 year 1 , being responsible for an estimated annual round-wood production of 27–50 million m 3 , employing 350 thousand people and generating gross annual revenue of US$ 2.5 billion (Nepstad et al., 1999; Lentini et al., 2003; Asner et al., 2005). Currently, with very few exceptions, logging activity is part of agricultural frontier expansion and follows the world-wide pattern of the boom-bust cycle (Vincent, 1992; Schneider et al., 2000). In order to avoid the loss of forest cover and its benefits (e.g. watershed, soil and nutrient conservation, and the preservation of biodiversity), sustainable forest management has been proposed as a solution (Schmidt, 1991; Whitmore, 1991; Pearce et al., 2003). www.elsevier.com/locate/foreco Forest Ecology and Management 231 (2006) 184–195 * Corresponding author. Tel.: +44 131 650 7253; fax: +44 131 650 7863. E-mail address: p.vangardingen@ed.ac.uk (P.R. van Gardingen). 0378-1127/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.foreco.2006.05.047