Comparison of species richness and frequency cover of forest floor plants and lichens in sites invaded and uninvaded by the invasive club moss 'Selaginella kraussiana' (Kunze) A. Braun.

This study investigated the impacts of invasion by the African club moss (Selaginella kraussiana (Kunze) A. Braun) on forest floor plants and lichens in warm-temperate native forest in New Zealand. Worldwide, some club mosses are known to be invasive, but there is little available information on their impacts. African club moss has naturalised in a number of countries, including New Zealand, and is suspected of having a negative effect on forest floor plants, but little has been published about the actual impact of this species on native plant communities. This study was carried out at Spragg Bush, Waitakere Ranges, New Zealand to compare plant species richness and frequency cover in adjacent forest floor plant communities with and without S. kraussiana using a paired experimental design. Sites invaded by S. kraussiana had significantly lower species richness than uninvaded sites, particularly the number of conifer and flowering plant species (seedlings). Sites invaded by S. kraussiana had a higher total frequency cover than uninvaded sites, but this was not significant. It was not clear if any particular species were affected by invasion of S. kraussiana, as the majority of species restricted to either the invaded or uninvaded sites were only present in one or two of the 26 sites. Multidimensional scaling of the data showed that S. kraussiana sites formed a cluster within a scatter of non-S. kraussiana sites. The possible implications of these results are discussed.