EFFECTS OF BILBERRY (VACCINIUM-MYRTILLUS L) LITTER ON SEED-GERMINATION AND EARLY SEEDLING GROWTH OF 4 BOREAL TREE SPECIES

Laboratory and greenhouse bioassays were used to test for inhibitory e ffects of senescent and decomposed leaves and aqueous extract from bil berry (Vaccinium myrtillus L.) against seed germination and seedling g rowth of aspen (Populus tremula L.), birch (Betula pendula Roth.). Sco ts pine (Pinus sylvestris L.), and Norway spruce [Picea abies (L.) Kar st.]. Aqueous extracts from bilberry leaves were inhibitory to aspen s eed germination and seedling growth and also induced root damage and g rowth abnormalities. Addition of activated carbon removed the inhibito ry effects of extracts. Senescent leaves reduced pine and spruce seed germination, but rinsing of seeds reversed this inhibition. Senescent leaves were more inhibitory than decomposed leaf litter, suggesting th at the inhibitory compounds in bilberry leaves are relatively soluble and released at early stages during decomposition. Spruce was generall y less negatively affected by litter and aqueous extracts than the oth er tested species. This study indicates that chemical effects of bilbe rry litter have the potential to inhibit tree seedling recruitment, bu t these effects were not consistently strong. Phytotoxicity is unlikel y to be of critical importance in determining success for spruce seedl ing establishment.