Effect of industrial air pollution on wild plant seed germination and seedling growth

Germination of the following wild plant seeds was studied: bilberry (Vaccinium myrtillus L.), cowberry (V. vitis-idaea L.), bog bilberry (V. uliginosum L.), black crowberry (Empetrum hermaphroditum Hagerup), bearberry (Arctostaphylos uva-ursi (L.) Spreng.), bunchberry (Chamaepericlymenum suecicum (L.) Aschers. et Graebn.), cottongrass (Eriophorum polystachion L.), goldenrod (Solidago lapponica With.), fireweed (Chamaenerion angustifolium (L.) Scop.), marsh cinquefoil (Comarum palustre L.), cloudberry (Rubus chamaemorus L.), and Scots pine (Pinus sylvestris L.). The seeds were collected at different distances from the source of industrial air pollution (Severonickel smelter complex, Murmansk region). The task was the assessment of potential possibility of restoring corrupted north forest plant communities via seed propagation. By the response of reproductive structures to stressor, investigated species were divided into 3 groups: tolerant (members of the genus Vaccinium and Ch. angustifolium); moderately tolerant (C. palustre, E. polystachion, A. uva-ursi, and R. chamaemorus); and sensitive (P. sylvestris, E. hermaphroditum, and S. lapponica). Laboratory seed germinability of Vaccinium species was high (> 90%) regardless of the levels of Ni and Cu accumulation in the seeds and the index of technogenic load, whereas this index in E. hermaphroditum and P. sylvestris seeds was significantly reduced with the increase in the heavy metal contents in the seeds. The greenhouse experiments with the seeds of three Vaccinium species collected in the background area and in the zone of the highest pollution and germinated on the forest litter from the same sites and observation for seedling development allow us to conclude that a potential possibility of these species to seed propagation are not limited by their seed viability even under conditions of the highest technogenic load. In sites of environment pollution, the high metal content in the upper soil layer is the main factor limiting plant seed propagation.