Facilitation and competition affecting the regeneration of Quercus pubescens Willd.

AbstractWe investigated the effects of competition, abiotic factors and defoliation on the emergence, survival and growth of downy oak (Quercus pubescens Willd.). Acorns were sown in three types of vegetation (annuals, perennials, perennials and Brachypodium phoenicoides), combined with two abiotic factors (addition of water and nutrients, shade). Three months after emergence, three defoliation treatments were performed including the ablation of stem and leaves, removal of half of the leaves and removal of the half blade of each leaf. Seedlings from heavier acorns emerge more frequently and survive better after browsing than those with a lighter mass. The highest percentages of seedling emergence were observed in the plots with Brachypodium phoenicoides, showing a facilitative effect of grasses. Shade as well as water and nutrient addition increased the survival of seedlings after defoliation. Seedlings whose stems were cut had lower survival rates than controls. Competition with Brachypodium phoenicoides...