Advanced Regeneration in the IDF Forests at Opax Mountain

Jaana Kaipainen
Pasi Puttonen MoFR, Research Branch, Victoria
Alan Vyse, MoFR, Southern Interior Forest Region

Abstract

The overall purpose of this study is to investigate what factors lead to a successful post-release growth of advanced regeneration in the Interior Douglas-fir biogeoclimatic zone (IDF). In the winter of 1991/1992 several treatments were created in the Opaz Mountain area. The patch cut areas include both small group selection cuts (openings 0.1 ha and 0.4 ha in size) and small patch clear-cuts (1.7 ha in size) with either low (20%), high (50%) and moderate (i.e. 50% volume removal with 25% of the area left as no harvesting reserves. From 232 permanaent 10 m2 inventory plots a number of stand and tree characteristics were recorded. Preliminary results are available of density of advanced regeneration, number of germinants, height and height distributions, relative height growth rate, base diameter distribuitions, live crown, stem form and tree figor, stocking status at the site. The density of advanced regeneration varied between 430 and 7700 stems per hectare. Most of the advanced regeneration was established in the humus on relatively flat surfaces. Germinants were scarce both in the treatment areas and in the untreated controls. The relative height growth rate has significantly increased from the year 1992 - also in the control areas. Seedling survival in the logging depended on the intensity of the logging. In patch cut areas 90% of the seedlings, 70% of the seedlings in the 50% uniform and 35% uniform removals were estimated to be lost due to the logging. In 20% uniformly logged area approximately one fifth of the seedlings were damaged by the logging. Almost half of the total number of the advanced regeneration in the study area were not likely to become crop trees because of the severe stem deformities or poor vigour. Repeated defoliation by insects (western spruce budworm - Choristoneura occidentalis) has decreased the number and quality of advanced regeneration. Most likely, lack of available microsites (soil disturbance) has kept the number of new germinants low.