tailieunhanh - Báo cáo lâm nghiệp: "The angular distribution of diffuse photosynthetically active radiation under different sky conditions in the open and within deciduous and conifer forest stands of Quebec and British Columbia, Canada"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: "The angular distribution of diffuse photosynthetically active radiation under different sky conditions in the open and within deciduous and conifer forest stands of Quebec and British Columbia, Canada" | Ann. For. Sci. 63 2006 43-53 INRA EDP Sciences 2006 DOI forest 2005096 43 Original article The angular distribution of diffuse photosynthetically active radiation under different sky conditions in the open and within deciduous and conifer forest stands of Quebec and British Columbia Canada Fidji GENDRONa b Christian MESSiERa Ernest LOa Philip G. COMEAUc a Groupe de recherche en écologie forestière interuniversitaire GREFi Département des sciences biologiques Université du Québec à Montréal case postale 8888 succursale Centre-Ville Montréal QC H3C 3P8 Canada b Current address Luther College University of Regina Regina Saskatchewan S4S 0A2 Canada c Department of Renewable Resources University of Alberta Faculty of Agriculture Forestry and Home Economics University of Alberta 442 Earth Sciences Building Edmonton Alberta T6G 2E3 Canada Received 17 December 2004 accepted 24 August 2005 Abstract - The angular distribution of diffuse photosynthetically active radiation PAR was characterised in the open and beneath deciduous and conifer forests in Quebec and British Columbia Canada under overcast and clear sky conditions using a restricted field of view light sensor and hemispherical canopy photographs. The angular distribution of PAR was described by the relative light reading RLR . In the open on overcast days light was best characterized using the standard overcast sky distribution with the light intensity at the zenith set to four to five times greater than the light intensity at the horizon. RLR under forest stands was found to decrease with decreasing elevation angles under both overcast and clear sky conditions. Aspen Populus tremuloides Michx. and Jack pine Pinus banksiana Lamb. stands transmitted more light from a relatively wider angle around the zenith than the spruce Picea glauca Moench Voss and Picea mariana Mill. BSP stands which transmitted light mainly from the zenith. RLR estimated with the hemispherical canopy photographs RLRhc_corr generally .