Brazil Eucalyptus Productivity Project

Collaborators: Dan Binkley, Colorado State University; Jose L. Stape, North Carolina State University and IPEF (Piracicaba, Brazil); Aracruz Celulose, Cenibra, Copener Florestal, Internacional Paper, Suzano Bahia Sul Celulose, Votorantim Celulose e Papel, Veracel Celulose, V & M Florestal, IPEF, CIRAD

Understanding why tree productivity declines with forest age is a universal phenomenon, important to forest managers, and a fundamental problem in forest biology. Working with fast growing trees allows quicker answers and easier manipulations to understand the phenomenon. Results from a 7-year study in Hawaii showed that productivity declines in fast-growing trees were similar to those in subalpine forests, but happened in 5 years, not 150. Results also showed that reduced canopy photosynthesis and changes in carbon allocation were important causes of the decline, and that the decline was less under more fertile conditions. The Hawaii study raised important questions that remain unanswered: first, why does photosynthesis decline, when all the canopy characteristics show it should remain high? Second, does the differentiation of the trees into dominants, intermediates, and suppressed trees that occurs at the same time the decline starts have any effect on the decline? In partnership with CSU, University of Sao Paulo, and 8 pulp and paper companies, we are leading a large experiment to answer these questions. Because the decline in productivity with age and the differentiation into dominants and others are universal for forests, we expect that the answers we find with fast growing trees will apply to forests everywhere. Major findings: Reduced atmospheric humidity during dry periods reduced Eucalyptus GPP and wood production, even in irrigated plots with no soil moisture limitation. Soil water deficit increased the proportion of GPP used belowground compared to the irrigated plots (Stape et al. 2008). Fertilization and irrigation experiments applied can be used to calibrate and test physiologically-based models. Such models represent the effects of environmental variation on wood production better than empirical modal (Stape et al. 2004a). Wood production per unit of water use increased as annual precipitation increased. Coarse root biomass increased as a proportion of the total as precipitation decreased (Stape et al. 2004b). Girdling could not separate autotrophic and heterotrophic respiration in Eucalyptus because girdling does not kill their root systems (Binkley et al. 2006). Dan Binkley’s BEPP Page IPEF BEPP Page		BEPP Participants March 2007 Jose L. Stape at Aracruz Sapflow Installation
Publications and Presentations Binkley D, JL Stape, WL Bauerle and MG Ryan. 2009. Explaining growth of individual trees: Light interception and efficiency of light use by Eucalyptus at four sites in Brazil. In Press, Forest Ecology and Management (July 2009). Hubbard RM, JL Stape, MG Ryan, AC Almeida and J Rojas. Effects of irrigation on water use and water use efficiency in two fast growing Eucalyptus plantations. Submitted to Forest Ecology and Management (April 2009). Ryan MG, MA Cavaleri, A Almeida de Campi, R Penchel, RS Senock and JL Stape. 2009. Wood CO2 efflux and foliar respiration for Eucalyptus in Hawaii and Brazil. Tree Physiology 29: 1213–1222. Stape JL, D Binkley and MG Ryan. 2008.  Production and carbon allocation in a clonal Eucalyptus plantation with water and nutrient manipulations.   Forest Ecology and Management 255: 920-930. Stape JL, MG Ryan and D Binkley. 2004a. Testing the 3-PG process-based model to simulate Eucalyptus growth with an objective approach to the soil fertility rating parameter. Forest Ecology and Management 193:219-234. Stape JL, D Binkley and MG Ryan. 2004b. Eucalyptus production and the supply, use and the efficiency of use of water, light and nitrogen across a geographic gradient in Brazil. Forest Ecology and Management 193:17-31. Binkley D, JL Stape, EN Takahashi and MG Ryan.  2006.  Tree-girdling to separate root and heterotrophic respiration in two Eucalyptus stands in Brazil.  Oecologia 148: 447-454.		Ana Carnaval Marrichi Measuring Photosynthesis
Home	Back