GERMINATION AND EARLY GROWTH OF SOWN QUERCUS-ROBUR L IN RELATION TO SOIL PREPARATION, SOWING DEPTHS AND PREVENTION AGAINST PREDATION

A field experiment was established in the autumn of 1992 in order to s tudy predation of acorns, germination and early growth of oak seedling s. The experiment was established on a clearcut and an adjacent oak sh elterwood in southern Sweden. In the experiment, a total of 6 840 acom s were sown. The sowing was carried out with different vegetation cont rol and soil preparation treatments and with different planting depths . The germination percentage was highest for acorns sown at five cm de pth and lowest for acoms sown on top of the soil, and lower for acorns sown in areas where the humus layer had been removed than in areas wh ere the humus layer was retained. There was no difference in the perce ntage germination after two growing seasons between acorns sown inside the shelterwood and acoms sown on the clearcut. The height of the see dlings was lowest when the humus was removed while the number of leave s per seedling was lowest for seedlings in untreated areas after two g rowing seasons. Furthermore, seedlings in untreated areas showed the l owest relative height growth rate during the second growing season. In spite of higher biomass of ground vegetation in undisturbed areas com pared to treated areas, no effect of the soil and vegetation control t reatments could be found on soil water potentials. The soil temperatur e and photosynthetic active radiation at seedling level were higher in areas where soil preparation and vegetation control had been performe d. However, it was concluded that neither low soil water availability nor low light levels could be the only cause of lower relative height growth rate during the second growing season for seedlings in undistur bed areas.