While participating in last month’s Burnaby Lake BioBlitz on behalf of the garden, local bryologist Steve Joya introduced me to this moss species and suggested it would be a good Botany Photo of the Day.
When the words “invasive alien plant species” pop up, people tend to think of large plants that affect the landscape on a human scale: kudzu or Japanese knotweed or Gunnera tinctoria. Few people will initially imagine an invasive moss, but Campylopus introflexus fits the profile: it is a rapidly-dispersing foreign organism that displaces native organisms in the ecosystem. Native to the southern hemisphere (southern South America, southern Africa, southern Australia, and various oceanic islands, Campylopus introflexus has made the distant leap into Europe and North America–and is rapidly spreading.
In North America, the first record of the species (sometimes commonly referred to as heath star-moss) is from the gravel roof of a building at Humboldt University in Arcata, California. It has since spread throughout coastal western North America — in the span of 35 years. Several examples of its impact on a native ecosystem are available from the European Network of Invasive Alien Species. From the Campylopus introflexus factsheet (PDF), which details its spread in Europe after a 1941 initial observation in England:
Carpets of Campylopus introflexus markedly reduce the regeneration of Calluna vulgaris…in the field in a Danish heathland. The reduction in the number of germinating Calluna vulgaris seeds may be caused by lack of light as well as desiccation in the dense moss carpet. In the Netherlands typical grasses and herbs as well as lichens and other mosses of the dune vegetation have been out-competed by the aggressive moss due to acidification of otherwise calcareous dunes…The decline of the Tawny Pipit (Anthus campestris) as breeding bird in The Netherlands was probably caused by the decrease of suitable breeding habitat, open short grasslands, due to the invasion of Campylopus introflexus, which formed dominant and dense stands. A further consequence of these closed moss carpets was a decline of arthropods as food source for these birds…In Iceland Campylopus introflexus invades high-temperature geothermal areas often with species rich moss flora. Some very rare species have already been affected…
Please consult the factsheet for references to the observations, as well as images illustrating this moss species acting as an invader.
Art resource link: the American Society of Botanical Artists has a touring exhibition of major US public gardens called Losing Paradise? Endangered Plants Here and Around the World. Fortunately for those of us who don’t have the opportunity to visit, we can enjoy excerpts from the exhibit online on the weblog Losing Paradise?. Link is via the Plant Conservation Alliance’s native-plants mailing list.