Taxonomy, ecology, and conservation of Sporadanthus (Restionaceae) in New Zealand

A new species, Sporadanthus ferrugineus (Restionaceae), is described from the peat bogs of the northern North Island, New Zealand. It is distinguished from S. traversii by its more robust, brittle culms with swollen bases, different coloured rhizome scales and culms, and smaller, dehiscent fruit. In the past S. ferrugineus has been referred to Sporadanthus traversii, which is now treated as a Chatham Island endemic. Because of this past confusion a detailed description for S. traversii is also provided and a lectotype for the species selected. The ecology of both species of Sporadanthus is reviewed. There are marked differences in their preferred habitats and response to fire. In particular, Sporadanthus ferrugineus is a late-successional species of raised peat bogs. Within these ecosystems, S. ferrugineus is eliminated by fire and re-establishment is from seed subsequently deposited by remnant plants. Following fire, S ferrugineus takes five years to recolonise former habitat and requires 12 years or more to re-establish itself fully within the peat bog vegetation. Sporadanthus traversii is less specialised, colonising a variety of mid- to late-successional peat habitats on the Chatham Islands, as well as coastal cliff scarps, peaty dune hollows, and lake margins. Although S. traversii is also eliminated by fire, it can re-establish itself through activation of dormant seed within a few months of a fire. The possibility that S. traversii has become more common as a result of increased fire frequency on the Chatham Islands is discussed.