Evaluation of the Potential of Sequestration of Atmospheric Carbon in a Portuguese Eucalypt Stand after Felling

• Autor(a) principal: Rodrigues,Abel
• Data de Publicação: 2012
• Outros Autores: Pita,Gabriel
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://scielo.pt/scielo.php?script=sci_arttext&pid=S0870-63522012000100001
• topic: Carbon uptake; stomatal control; seasonality; coppice; mature root system

In Portugal, eucalypt (Eucalyptus globulus Labill.) stands aimed mainly for pulp production, occupy an area of 739,515ha, corresponding to 23% of total forest area. The main objective of this work was to report the recovery of seasonal pattern of GPP in a eucalypt site in Pegões (Southern Portugal) after a felling carried out in October - November 2006. The site was part of a 300 ha eucalypt stand, located in Herdade da Espirra, with a density of about 1100 trees/ha. The stand was intensively managed as a coppice under a twelve year productive cycle and characterized by a 12-month growing period. Carbon fluxes data in this site have been measured by eddy covariance in the period 2002-2010. A prolonged two stage drought in 2004 and 2005, when rainfall was reduced to values of 50% below the long-term mean term, and the clear cutting, followed by the start of a new production cycle, changed the carbon sink ability of eucalypt stand. In the period prior to cutting GPP (2204 g m-2) was maximum in 2002 decreasing to a minimum of 1255.1 g m-2 in 2005 at the peak of the drought. Eight months after the felling young shoots emerging from stumps grew strongly and the new trees reached an average 8m height in 2010. In June 2007 the eucalypt stand recovered its carbon sink capacity with an annual GPP of 1621.6 g m-2 in 2010. Seasonal patterns of GPP in 2008 and 2009 with maximum carbon uptake occurring from mid-February to mid-October were almost opposite to that of the period before the felling when leaf stomatal control prevented major water losses under summer water stresses. The fast recovery of the young eucalypt stand was due to the maintenance of a viable and mature root system. In 2010 GPP monthly variation showed a pattern analogous to the period prior to drought.