Establishment and growth in seedlings of Fagus sylvatica and Quercus robur:: influence of interference from herbaceous vegetation

The interference from natural vegetation on the establishment and growth in Fagus sylvatica L. and Quercus robur L. was studied on an open site starting from bare soil. Four treatments were applied: herbicide, herbicide plus fertilization, mowing, and untreated control. Seedlings of beech and oak were spring planted side-by-side in two subsequent years and monitored through the 1995, 1996, and 1997 growing seasons. Interference had a strong negative influence on the seedling shoot dry mass, leaf area, relative diameter growth, leaf nitrogen concentration, and leaf water potential and conductance. Oak had a shorter period of transplanting shock, a higher relative growth rate during interference from vegetation, and deeper roots than beech. Therefore, oak is more easily established than beech, which initially may need more intense site preparation. Neither fertilization compared with vegetation control only, nor mowing compared with untreated control, influenced seedling growth. Low soil water potential had a strong influence on seedling growth, although the competing vegetation at the same time reduced light, soil temperature, and the soil nitrogen concentration.