As part of the Montane Alternative Silviculture Systems (MASS) project, this study investigates limits on the growth of montane conifers resulting from varying overstory retention under conventional and alternative silvicultural systems. After harvesting treatments were complete in 1993, Abies amabilis (amabilis fir) and Tsuga heterophylla (western hemlock) seedlings were spring planted in replicated blocks of shelterwood (SW), patch cut (PC), green tree retention (GT) and clearcut (CC) systems. In addition, sub-plots were established within each silvicultural system in which fertilization (at planting) and vegetation control post-planting treatments were applied alone and in combination to test the extent to which growth limitations are related to nutrient availability and vegetative competition. The impact of overstory retention was most pronounced in the reduced light environment of the SW where height growth after seven years was 26-30% lower in both species compared to the untreated CC, GT and PC systems. Although the effect on growth of both species in the SW was mitigated somewhat by fertilization and vegetation control treatments, amabilis fir did not attain free-to-grow height (1.3 m) regardless of post-planting treatment. Time to free-to-grow height in the more open silvicultural systems was reduced in both fir and hemlock with fertilization and vegetation control alone and in combination, except in the CC where the initial growth response to fertilization alone was diminished by the end of the sevenyear study. In contrast to fertilization, the effects of vegetation control on height growth were not apparent until three to five years and seven years after planting in the CC and GT, PC, SW, respectively. Combining vegetation control and fertilization had an additive effect on growth in amabilis fir but not in western hemlock. The effect of silvicultural systems and post-planting treatments on the two species illustrate that both above-and below-ground resource availability (light and nutrients) availability was potentially limiting to growth, particularly in the shelterwood treatment.Key words: MASS, silviculture systems, regeneration, Tsuga heterophylla, Abies amabilis, shelterwood, patch cut, green tree retention, clearcut, fertilizer, vegetation control En tant qu'élément du projet sur les systèmes alternatifs de sylviculture dans la zone montagneuse, cette étude porte sur la réduction de la croissance des conifères alpins à la suite d'une rétention variable du couvert forestier selon des systèmes sylvicoles conventionnels et alternatifs. Suite aux travaux de récolte complétés en 1993, des semis d'Abies amabilis (sapin amabilis) et de Tsuga heterophylla (pruche de l'Ouest) ont été plantés au printemps dans des blocs d'une étude des régimes de jardinage, de coupe partielle, de coupe par troué, de coupe avec rétention d'arbres verts et de coupe à blanc. De plus, des sous-parcelles ont été établies dans chaque régime sylvicole pour lesquels des traitements de fertilisation (au moment de la plantation) e...

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