Folia Forestalia Polonica, series A, 2009, Vol. 51 (2), 138–144 ORIGINAL ARTICLE Received 13 November 2009 / Accepted 27 November 2009 IntroductIon There is a strong conviction among scientists that forest is one of the most effective carbon sequestration sinks (e.g. Righelato and Spracklen 2007). Hence, afforestation of post-agricultural and marginal areas is the simplest method of carbon accumulation increase (Niu and Duiker 2006). Apart from carbon sequestration in tree biomass, the ex- istence of forest guarantees an increase in retention of this element in soil as well as prevention from its release. In case of no forest management, the carbon budget of large forest areas stays in the state of dynamic balance governed mostly by global climate factors that modify processes occurring in tree stands. In turn, manage- ment activities performed in forests, i.e. such silvicul- tural treatments as PCT (pre-commercial thinning) or thinnings of this type, their frequency and intensity, decisions on the cutting age, a harvesting system, or management of post-cutting remains cause changes in the forest carbon budget. Current carbon accumulation Effect of the cutting age and thinning intensity on biomass and carbon sequestration – the Gubin Forest District case study Michał Zasada , Karol Bronisz, Szymon Bijak, Albert Dudek, Arkadiusz Bruchwald, Rafa Wojtan, Robert Tomusiak, Agnieszka Bronisz, Lech Wróblewski, Kazimierz Michalak Department of Dendrometry and Forest Productivity, Faculty of Forestry, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland, phone: +48 22 59 38 089, fax: +48 22 59 38 008, e-mail: Michal.Zasada@wl.sggw.pl AbstrAct The goal of presented study was to determine possible impact of the cutting age and thinning intensity on biomass and carbon sequestration. Analyses were based on the inventory data from the Gubin Forest District processed for a 10-year period using the Polish empirical stand growth models. The variants with less intensive thinning treatments and higher cutting age favour biomass accumulation in the short-time horizon. At the same time, an increase in the cutting age leads to a drastic limitation of the possibility of timber utilisation, which may negatively affect inancial condition of the district as well as signiicantly inluence long-term forest sustainability. A decade-long analysis proved no inluence of the cutting age and thinning intensity on current volume increment i.e. current ability of stands to absorb carbon dioxide. Longer prediction is required in order to recognise directions of changes in the increment. Keywords growth model, silvicultural scenario, simulation, carbon sequestration, thinning, cutting age