In a two-cut, alternate strip clearcutting system in upland black spruce, the main factors influencing black spruce regeneration in the first-cut strips were strip width, natural seeding period, amount of receptive seedbed and topographic position. In the three study areas, 80-m strips yielded over 60% stocking and over 7 500 seedlings per hectare with a 4-year natural seeding period. Narrower strips 40 m and 20 m wide showed increasing levels of reproduction. Four years of natural seeding gave better natural regeneration than two years. Seedling density and frequency in quadrats were correlated with the amount of receptive seedbed. Regeneration was more abundant on drainageways and lower slopes, and less abundant on upper slope and crest sites. For successful regeneration under similar climatic and physiographic conditions, strip widths should be no more than 80 m, and leave times no less than 3 years. It is essential to scarify the upland mineral soil sites, but scarification of lowland sites is not recommended, especially where there is abundant Sphagnum.
Factors Affecting Natural Regeneration of Tropical Forests across a Precipitation Gradient in Myanmar
