Ecological effects of invasive European bird cherry (Prunus padus) on salmonid food webs in Anchorage, Alaska streams

Thesis (M.S.) University of Alaska Fairbanks, 2011Invasive species are a concern worldwide as they can displace native species, reduce biodiversity, and disrupt ecological processes. European bird cherry (Prunus padus) (EBC) is an invasive ornamental tree that is rapidly spreading and possibly displacing native trees along streams in parts of urban Alaska. The objectives of this study were to: 1) map the current distribution of EBC along two Anchorage streams, Campbell and Chester creeks, and 2) determine the effects of EBC on selected ecological processes linked to stream salmon food webs. Data from the 2009 and 2010 field seasons showed: EBC was widely distributed along Campbell and Chester creeks; EBC leaf litter in streams broke down rapidly and supported similar shredder communities to native tree species; and EBC foliage supported significantly less terrestrial invertebrate biomass relative to native deciduous tree species, and contributed significantly less terrestrial invertebrate biomass to streams compared to mixed native vegetation, but riparian EBC did not appear to affect the amount of terrestrial invertebrate prey ingested by juvenile coho salmon (Oncorhynchus kisutch). Although ecological processes did not seem to be dramatically affected by EBC presence, lowered prey abundance as measured in this study may have long-term consequences for stream-rearing fishes as EBC continues to spread over time.US Fish and Wildlife Service, USDA Forest Service, Alaska EPSCoR, Institute of Arctic Biology, and the Department of Biology and Wildlife at UAFIntroduction. Influence of riparian vegetation on stream salmonid food webs ; Riparian vegetation type can affecdt invertebrate prey for stream salmonids ; Effects of invasive riparian plants on stream food webs ; Potential effects of European bird cherry on salmonid food webs -- ch. 1. The abundance and distribution of invasive Prunus spp. in riparian forests along streams in Anchorage, Alaska -- ch. 2. Leaf litter processing is similar between native plants and invasive European bird cherry in urban Alaskan streams -- ch. 3. Invasive European bird cherry disrupts stream-riparian linkages: influence on terrestrial invertebrate prey subsidies for juvenile coho salmon -- Conclusion