Effets de l'éclaircie précommerciale et de la fertilisation sur un gaulis de 10 ans à dominance de bouleau jaune

Abstract

One yellow birch was selected every 4.5 metres in a sugar maple-yellow birch sapling stand, and released from competition by removing all stems whose crown extended into a column of equal radius (R) from the stump to the top of the tree. The experiment comprises three studies and includes four thinning intensities (R=0 m, R=0,5 m, R= 1,0 m, R= 1,5 m) and five fertilization treatments (three with N-P-K and two with N). Dbh, story and natural pruning data were taken on 2 258 yellow birches distributed in 48 sample plots; heights were measured on 10 per 100 of the trees.Five years later, the results of the three studies show that dbh growth increased with thinning intensity and tree dominance; for the heavy release (R15) the dbh increment is 3.9 cm for the dominants, 3.1 cm for the codominants and 2.6 cm for the intermediates. However, heavy release interferes temporarily with natural pruning.The presence of N and K increased in the foliage of yellow birch with fertilization but height increment was not affected and diameter increment was slightly higher with the moderate release (R10). Key words: Sapling, thinning, crop-tree release, fertilization, growth, natural pruning, Betula alleghaniensis (Britt.).