Effects of shade on growth and mortality of maple (Acer pseudoplatanus), ash (Fraxinus excelsior) and beech (Fagus sylvatica) saplings

We compared shade tolerance of maple, ash and beech in the sapling stage from two sites with rich soils differing in water supply, growing in dense thickets underneath a beech shelterwood of varying canopy densities. Shade tolerance was described by two components: mortality in shade and height growth in high light. At low light, beech showed the least mortality, maple the highest and ash in between on both sites. The decline with increasing light was steepest in beech and more gradual with ash and maple. At similar to 15 per cent above canopy light, all three species approached zero mortality. Beech as the most shade-tolerant species had the highest survival rate under low light and the least length growth rate under high light (> 17 per cent). Ash had a lower survival rate at low light than beech and a highest growth rate at high light. Maple showed a bit weaker trade-off with the lowest survival rate but a growth rate inferior to ash. On the better water-supplied site, height growth was significantly superior in all three species only under high light. On the basis of these results, silvicultural conclusions are drawn with respect to appropriate light levels and cutting types.