Successful translocation of the threatened New Zealand root-holoparasite Dactylanthus taylorii (Mystropetalaceae)

Abstract

The conservation and translocation of threatened holoparasitic flowering plants provide added challenges due to their complete host dependency and often large knowledge gaps of their autecology. Here, we present the first successful, quantified field trial to establish from seed populations of dactylanthus (Dactylanthus taylorii, Mystropetalaceae), a threatened New Zealand endemic root-holoparasitic angiosperm. Establishment was monitored at four sites at Waipapa, Pureora Forest Park. The impact of two different sowing methods (broad- and central-sown), canopy state (as a proxy for soil moisture levels) and three dominant host species were tested. Establishment of dactylanthus was confirmed in 22 out of 24 plots 10 years after sowing, with earliest emergence after 4 years. Average and maximum inflorescence numbers per plot were similar to those of protected wild populations. The only open-canopy site performed worse in comparison with a closed-canopy site sharing the same dominant host species; differences in root availability and survival of the desiccation-sensitive seeds were regarded as the most likely explanations. Host species dominance had a significant impact on inflorescence numbers, indicating host preference in the species despite a wide host range. In contrast to longer-established wild populations, most of which are male-biased, female inflorescences strongly outnumbered males, considered as evidence of environmental sex determination and sex-switching of individuals. Findings from this study have increased our knowledge of the biology of dactylanthus, confirmed translocation as an effective tool in the conservation of the species and should be applicable for the protection of threatened parasitic plants species elsewhere in the world.