The ecology and conservation of the endangered endemic shrub, Kōwhai NgutukākāClianthus puniceus in New Zealand

Abstract

Common in cultivation in New Zealand and elsewhere, natural populations of kōwhai ngutukākāClianthus puniceus (Fabaceae), an endangered New Zealand shrub, are rare in the wild (29 populations). Populations are generally composed of only a few plants occurring on north-facing (sunny) bluffs, cliffs, and lake and river margins, or on hillslopes in seral scrub communities. At these remaining sites, plants were found to be mostly multi-stemmed, with a low, spreading growth habit. Turnover of stems was high, each plant losing and gaining approximately two stems per year. Asexual reproduction occurred within populations by layering of branches up to 4m from the parent plant. This characteristic improves persistence on sites, but genetic variability within populations is probably low. Populations produce abundant seed, suggesting adequate pollination, but passive dispersal appears to limit spread. However, seed can survive for decades dormant within soil seed banks before germination. High foliar element concentrations suggest high herbivore preference. Continuing threats to C. puniceus populations are loss of habitat, browsing by introduced mammals and molluscs, competition with adventive weed species for establishment on open sites, and overtopping within seral communities.