First reported in the wild
Invasive species - risk of Medium Impact
Introduction pathways - 1
Release in Nature
Introduction pathways subclass - 1
NAPRA Ireland risk assessed
Tall evergreen tree, one of the tallest species in Ireland, up to 65m (Stace, 1997). Similar in appearance to a fir, though not a true fir.
Conifer monocultures significantly increase the transfer of atmospheric pollutants into terrestrial surfaces than hardwoods or short vegetation, leading to acidification of the soil and ground water (Cannell, 1999). Presence of Douglas fir in European woodlands has been shown to reduce fungal diversity, though the number of species of ground vegetation are similar (Schmid et al., 2014), it is difficult to apply these results to an Irish context due to the paucity of native conifers. Possibly due to the lack of congeners (species of the same genus) P. menziesii, has an extremely low number of arthropod species (87 species) feeding on it in Europe despite 130 years plus of forestry plantation than in its native range (257 spp.) (Roques et al., 2006). Schmid et al (2014) note that invasive arthropods that use Douglas fir as a host may present more of a threat to European biodiversity than the trees themselves (e.g. Dendroctonus pseudotsugae - douglas pine beetle).
Woodland, forest and other wooded land; Constructed, industrial or other artificial habitats
Like most conifers produces male and female cones but it is unknown if the species is seeding widely in Ireland (Preston et al., 2004; Reynolds, 2002). There is a lag between planting and invasion, of 15 years in Catalonia, (Broncano et al., 2005). Seedling density is positively correlated with low tree density, small plantation area and grazing pressure (Broncano et al., 2005) suggesting that trees allowed to establish outside of plantations, in semi natural and natural woodlands, may contribute more to the spread of the species into the wild than areas of plantations.
Pathway and vector description
Cultivated since the 19th century, no reliable information exists on the extent of plantations in Ireland, possibly due to commercial sensitivity.
Mechanism of impact
Widely planted in forestry, also occurs in semi-natural woodlands and parks (Preston et al., 2004).
Established - Widespread, widely sown as a forestry plantation and difficult to distinguish deliberate distribution of plantations from self sown trees in the wild. Possibly under recorded, distribution map as shown likely an artefact of recording effort.
Native to western North America (Preston et al., 2004).
Date of first record category
Fifty year date category
Records submitted to Data Centre in 2021
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How can you help
Report any sightings to the National Biodiversity Data Centre.
Reynolds, S.C.P. (2002) A catalogue of alien plants in Ireland. National Botanic Gardens. Glasnevin, Dublin. Preston, C.D., Pearman, D. A. & Dines, T. D. (2002). New atlas of the British and Irish flora. An atlas of the vascular plants of Britain, Ireland, the Isle of Man and the Channel Islands, Oxford University Press. Cannell, M. G. (1999). Environmental impacts of forest monocultures: water use, acidification, wildlife conservation, and carbon storage. New Forests, 17(1-3), 239-262. Roques, A., Auger-Rozenberg, M. A., & Boivin, S. (2006). A lack of native congeners may limit colonization of introduced conifers by indigenous insects in Europe. Canadian Journal of Forest Research, 36(2), 299-313. Schmid, M., Pautasso, M., & Holdenrieder, O. (2014). Ecological consequences of Douglas fir (Pseudotsuga menziesii) cultivation in Europe. European journal of forest research, 133(1), 13-29. Broncano, M. J., Vila, M., & Boada, M. (2005). Evidence of Pseudotsuga menziesii naturalization in montane Mediterranean forests. Forest Ecology and Management, 211(3), 257-263.