tailieunhanh - Báo cáo khoa học: "Structure and yield of all-sized and even-sized Scots pine-dominated stands"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Structure and yield of all-sized and even-sized Scots pine-dominated stands. | 111 Ann Sci For 1994 51 111-120 Elsevier INRA Original article Structure and yield of all-sized and even-sized Scots pine-dominated stands E Lãhde o Laiho Y Norokorpi T Saksa The Finnish Forest Research Institute Box 18 FIN-01301 Vantaa Finland Received 4 June 1993 accepted 22 September 1993 Summary This study is based on material collected in southwestern Finland using a systematic temporary circular plot line survey method. A total 0Í 273 sample plots were included in the study. These plots represented Scots pine Pinus sylvestris L -dominated stands established on dryish mineral soil sites. In half of the sample plots the stand structure was all-sized e stem distribution resembled an inverted letter J . Even-sized stand structure stem distribution resembled a normal distribution applied in the case of 31 of sample plots while 17 were irregularly uneven-sized in structure. The number of trees per hectare in the all-sized stands was more than twice that of evensized stands. The mean annual increment increased along with an increase in growing stock volume. The volume in even-sized stands was higher than in all-sized stands but their mean annual increment was equal. Nevertheless in stands with equal average volume 125 25 m3 ha the mean annual increment in all-sized stands was one third higher than in even-sized stands. stand structure yield stem distribution all-sized even-sized Resume Structure et rendement de peuplements irréguliers et réguliers à majorite de pin Sylvestre. Cette étude est basée sur du materiel récolté dans le sud-ouest de la Finlande 1951-1953 au moyen d une méthode statistique à base de placettes d echantillonnage circulaires temporaires systématiques alignées. L etude comprenait un total de 273 placettes d echantillonnage. Ces placettes représentaient des peuplements de pin Sylvestre Pinus sylvestris L établis sur des terrains à sol mineral sec. Dans la moitié des placettes d echantillonnage la structure du peuplement était irrégulière c .