Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Simulated soil CO2 efflux and net ecosystem exchange in a 70-year-old Belgian Scots pine stand using the process model SECRETS. | 31 Ann. For. Sci. 58 2001 31-46 INRA EDP Sciences 2001 Original article Simulated soil CO2 efflux and net ecosystem exchange in a 70-year-old Belgian Scots pine stand using the process model SECRETS David A. Sampson Ivan A. Janssens and Reinhart Ceulemans Department of Biology University of Antwerpen UIA 2610 Wilrijk Belgium Received 13 December 1999 accepted 18 September 2000 Abstract - Within the framework of the EU ECOCRAFT European collaboration on CO2 responses applied to forests and trees we developed a stand scale process model to simulate short-term carbon C and water fluxes from a mixed coniferous deciduous forest in Northern Belgium 51 31 N 4 22 E . The model termed SECRETS is a sequential multi-species and multiple layer simulator that uses process modules adapted from several sources. Namely we adapted BIOMASS maintenance respiration and water balance and coded the sun shade model photosynthesis modified for forest species and the GRASSLAND DYNAMICS soil carbon and nitrogen models. In this contribution we simulate carbon fluxes for a 70-year-old Scots pine Pinus sylvestris L. stand and we introduce an approach to characterize uncertainty in the model outputs. Simulated annual gross primary productivity GPP for 1997 and 1998 was 1 965 and 1 888 g C m-2 respectively. Soil respiration was 25 495 g C m-2 a-1 and 27 505 g C m-2 a-1 of the GPP in 1997 and 1998 respectively in this slow growing Scots pine stand. Heterotrophic respiration RH accounted for roughly 32 of the total soil C efflux for both years. Simulated daily fluxes for net ecosystem exchange NEE suggested C uptake throughout most but not all of the spring and summer but net release during mid-autumn to early winter periods for both years. Our base estimates of NEE ranged from 385 g C m-2 a-1 in 1997 to 310 g C m-2 a-1 in 1998. However the uncertainty in NEE varied from 167 to 509 g C m-2 a-1 and 138 to 392 g C m-2 a-1 in 1997 and 1998 respectively. Thus this stand may be accumulating C at a rate
