Allelopathic potential of western bracken

Abstract

In laboratory studies, water-soluble extracts from senescent western bracken (Pteridium aquilinum [L.] Kuhn var.pubescens Underw.) fronds reduced germination of western thimbleberry (Rubus parviflorus Nutt.) and delayed germination of salmonberry (R. spectabilis Pursh.), but did not affect Douglas fir (Pseudotsuga menziesii [Mirb.] Franco). In greenhouse studies, unincorporated western bracken litter reduced emergence of all three species but did not influence root and shoot length or dry weight. However, bracken litter incorporated into the soil reduced both shoot length and dry weight of western thimbleberry seedlings. Allelopathic interactions may explain the relative absence of woody shrubs such as western thimbleberry and salmonberry from sites dominated by western bracken.