tailieunhanh - Báo cáo lâm nghiệp: "Influence of tree species on gross and net N transformations in forest soils"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Influence of tree species on gross and net N transformations in forest soils. | Ann. For. Sci. 64 2007 151-158 INRA EDP Sciences 2007 DOI forest 2006099 151 Original article Influence of tree species on gross and net N transformations in forest soils Bernd ZELLERa Sylvie RECOUSb Morgan KUNZEa Judicael MOUKOUMIc Micheline COLIN-BELGRANDa Séverine BlENAIMEa Jacques RANGERa Etienne DAMBRINEa aINRA Nancy UR 1138 Biogéochimie des Écosystèmes Forestiers 54280 Champenoux France b INRA Unité d Agronomie Laon-Reims-Mons rue F. Christ 02007 Laon Cedex France c LIMOS UMR 7137 CnRS-UHP Nancy I BP 239 54506 Vandreuvre--les--Nancy Cedex France Received 23 May 2006 accepted 18 October 2006 Abstract - We compared N fluxes in a 150-year-old Fagus sylvatica coppice and five adjacent 25-year-old plantations of Fagus sylvatica Picea abies Quercus petraea Pinus laricio and Pseudotsuga menziesii. We measured net N mineralization fluxes in the upper mineral horizon A1 0-5 cm for 4 weeks and gross N mineralization fluxes for two days. Gross rates were measured during the 48-h period after addition of 15NH4 and 15NO3. Mineralization was measured by the 15NH4 dilution technique and gross nitrification by 15NO3 production from the addition of 15NH4 and by 15NO3 dilution. Net and gross N mineralization was lower in the soil of the old coppice than in the plantations both on a soil weight and organic nitrogen basis. Gross nitrification was also very low. Gross nitrification measured by NO3 dilution was slightly higher than measured by 15NO3 production from the addition of 15NH4. In the plantations gross and net mineralization and nitrification from pool dilution were lowest in the spruce stand and highest in the beech and Corsican pine stands. We concluded that 1 the low net mineralization in the soil of the old coppice was related to low gross rate of mineralization rather than to the concurrent effect of microbial immobilisation of mineral N 2 the absence of nitrate in the old coppice was not related to the low rate of mineralization nor to the absence of .