tailieunhanh - Báo cáo lâm nghiệp:"Estimation of crown radii and crown projection area from stem size and tree position"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài:"Estimation of crown radii and crown projection area from stem size and tree position" | Ann. For. Sci. 60 2003 393-402 INRA EDP Sciences 2003 DOI forest 2003031 393 Original article Estimation of crown radii and crown projection area from stem size and tree position Rudiger Grote Chair for Forest Yield Science Department of Ecology and Landscape Management TU Munich Am Hochanger 13 85354 Freising Germany Received 4 July 2001 accepted 17 October 2002 Abstract - This paper describes a method for crown radii estimation in different cardinal directions using tree diameter height crown length and stem position within the stand as independent variables. The approach can serve for the initialisation of crown dimensions if measured crown radii are not available in order to address various research questions. Test calculations are carried out with 4 pure spruce Picea abies L. Karst 5 beech Fagus sylvatica L. and 6 mixed stands with both species. Simulated tree radii crown projection area and canopy cover are compared with measurements and simple estimation procedures based on logarithmic and linear equations. In beech stands and dense spruce stands the estimates with the new approach are similar or superior to those obtained with the other methods. However in sparse plots or in stands which have experienced a recent thinning crown size of trees is overestimated. crown projection area crown radii Fagus sylvatica mixed forests Picea abies Résumé - Estimation des rayons et de la zone de projection de la couronne en utilisant les dimensions de la tige et la position de l arbre. Cet article introduit une méthode mathématique qui permet une estimation du rayon en utilisant seulement les dimensions de la tige de la couronne et la position de l arbre. Cette méthode permet d initialiser les dimensions de la couronne dans le cas où on ne connait pas les rayons pour ainsi traiter de différentes questions scientifiques. La méthode est testée sur de nombreux peuplements d épicéas Picea abies et de hêtres Fagus sylvatica non seulement constitués d une seule essence