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

Sebastian Avi Holzapfel,John Dodgson,Maheshwaran Rohan

doi:10.1007/s11258-015-0556-7

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.

Highlights

Despite a high percentage of rare or threatened species among holoparasitic angiosperms globally, little research has been undertaken on the establishment of populations (Marvier 1996), even though the need has been recognised. This seems due to the complication of having to consider both the species and their hosts in any management (Arunachalam et al 2004; Kuijt 1969; Marvier and Smith 1997) and because knowledge of basic aspects such as habitat and host requirements are not well understood for many of the holoparasitic families (Atsatt 1983; Bolin et al 2009; Musselman and Press 1995; Pennings and Callaway 2002) apart from agricultural crop-damaging taxa (Mescher et al 2009; Press and Graves 1995; Weber and Forstreuter 1987)
Despite earlier optimism about the ease of experimental germination and cultivation of holoparasitic plants (Heinricher 1907; Kuijt 1969), only very few germination trials have been described in the literature
The species is classified as threatened (Nationally Vulnerable—Conservation Dependent) and a national management programme has been in place since 1993 (Holzapfel et al 2002; La Cock et al 2005)

Summary

Introduction

Despite a high percentage of rare or threatened species among holoparasitic angiosperms globally, little research has been undertaken on the establishment of populations (Marvier 1996), even though the need has been recognised This seems due to the complication of having to consider both the species and their hosts in any management (Arunachalam et al 2004; Kuijt 1969; Marvier and Smith 1997) and because knowledge of basic aspects such as habitat and host requirements are not well understood for many of the holoparasitic families (Atsatt 1983; Bolin et al 2009; Musselman and Press 1995; Pennings and Callaway 2002) apart from agricultural crop-damaging taxa (Mescher et al 2009; Press and Graves 1995; Weber and Forstreuter 1987). Host presence was usually assumed critical for germination despite evidence to the contrary (Holzapfel 2001)

Methods

Results

Conclusion