tailieunhanh - Báo cáo khoa học: "Stem basic density and bark proportion of 45 woody species in young savanna coppice forests in Burkina Faso"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Stem basic density and bark proportion of 45 woody species in young savanna coppice forests in Burkina Faso. | 143 Ann. For. Sci. 57 2000 143-153 INRA EDP Sciences Original article Stem basic density and bark proportion of 45 woody species in young savanna coppice forests in Burkina Faso Robert Nygảrd and Bjorn Elfving SLU Department of Silviculture 901 83 Umeả Sweden Received 24 June 1999 accepted 15 November 1999 Abstract - In total 1287 sample trees were taken from 57 savanna woody species representing 22 families in 5 stands 5-14 years old at 4 sites which has a mean annual precipitation of 620-785 mm in Burkina Faso. Stem discs were taken at one-meter intervals along the tree stem up to a diameter of 3 cm. For 45 of these species with more than 4 stems sampled the stem basic density varied between 301-854 kg m-3. Bark proportion of stem biomass varied between 9-53 . Indications of decreased basic density and increased bark proportion with height of the stem and with decreased stem size was found for several species. Data presented provides a basis for the construction of models to convert standing woody volumes over bark to oven-dry mass whereby the bark proportion of the stem biomass can be determined. specific gravity humidity content indigenous species fuel-wood biomass Résumé - Densité basale de tronc et proportion d ecore de 45 espèces ligneuses issues de taillis dans une savane du Burkina Faso. Un échantillon de 1287 individus appartenant à 57 espèces et 22 familles de ligneux de savane a été coupé au Burkina Faso. Ces individus sont issus de 5 populations âgées de 5 à 14 ans pro venant de 4 sites dont la pluviométrie est comprise entre 620 et 785 mm. Des disques ont été pris à 1 m d intervalle le long de la tige jusqu à un diamètre de 3 cm. Pour 45 de ces espèces comprenant plus de 4 tiges échantillonnées la densité basale a varié entre 301 et 850 kg m-3 et la proportion d écorce entre 9 et 53 . Une diminution de la densité basale et une augmentation de la proportion d écorce en fonction de la hauteur ont été observées pour plusieurs espèces. Les données .