Báo cáo khoa học: Discussion about the articles by E Lahde et al in Ann Sci For (1994) 51, 97-120: Structure and yield of all-sized and even-sized conifer-dominated stands on fertile sites and Structure and yield of all-sized and even-sized Scots pine-dominated stands Pierre

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Báo cáo khoa học: "Discussion about the articles by E Lahde et al in Ann Sci For (1994) 51, 97-120: "Structure and yield of all-sized and even-sized conifer-dominated stands on fertile sites" and "Structure and yield of all-sized and even-sized Scots pine-dominated stands" Pierre" Discussion Discussion about the articles by E Lahde et al in Ann Sci For (1994) 51, 97-120: Structure and yield of all-sized and even-sized conifer-dominated stands on fertile sites and Structure and yield of all-sized and even-sized Scots pine-dominated stands Pierre Duplat (Office national des forêts, département des recherches techniques, 77306 Fontainebleau, France) plot is considered as a stand, with EachI have some reservations about 2 papers itsinventory, its total stem volume (tariffby E Lähde et al in Annales des Sciences function(s)?), its dominant height and itsForestières (1994) 51, 97-120, entitled: total stem current increment.Structure and yield of all-sized and even-sized conifer-dominated stands on fertile Precise criterions, applied to the all-sites and Structure and yield of all-sized species diameter histogram of each stand,and even-sized Scots pine-dominated make it possible to decide whether it belongsstands. or the other of 2 groups of structure: to 1 all-sized and even-sized; 83% of the I will express the most important ones stands may thus be classified in 1 or thereferring to the first paper, the second one other group, and constitute the material forusing the same methodology. the study. The stands belonging to each large group of structure are classified into 2 groups ofINTRODUCTION composition, depending on whether they include less or more than 120 broad-leavedThe material used comes from the third trees per hectare: coniferous, mixed.national forest inventory 1951-1953 in The yield of each group structure x com-southwestern Finland, on Myrtillus type sites the basis of 2 results: is position judged onor more fertile ones: temporary plots, 1 000 of current increments for stands the mean2m in size, inventory by species and diam- - given standing volume (137 < V ≤ with aeter class starting from the 2-6 cm class, /ha) 3 167 mmeasure of dominant height (100 largesttrees/ha), and estimation of current volume the of relative current increments mean - (increment/volume) of all stands in theincrement over the 5 preceding years (byboring every tree?). group. explicit objective of An the paper is to For even-aged stands, dominant height is conclusion, in this region and on to a not a site index by itself, as it depends oncomethese sites, about which structure, which age at a given site quality.composition, or which combinations, are uneven-aged stands, it could roughly For farbetter volume is concerned. yield as as by assumed, if the 100 largest trees/ha were In my opinion, the method used and cur- more or less at the same stage of maturity insorily described does not fulfill this expec- every stand, but nothing ensures that thistation;I will explain why. here. Given the criterions used to is the case classify the stands into groups of structure, Current increment of a stand, at a given it is even likely that the all-sized grouptime, mainly depends: includes part of the young even-agedi) on the quality of the site where it grows stands.ii) on its specific composition So, site quality ...