Individual-level management trade-offs for populations of Dactylanthus taylorii (Balanophoraceae)

Abstract

In general, the conservation of plants often focuses on reducing the number of species that may feed on a plant species. Caging is one of the effective methods that conservationists use. In this study, I examined how such caging may affect the persistence of the wood rose, Dactylanthus taylorii, on Little Barrier Island, New Zealand. The probability of increase in these populations should improve because of caging. I tested this prediction. The caging also excludes the pollinators of the wood rose and I corrected for this using hand pollination of the individual clumps used in the study. The caged clumps had more intact inflorescences and non-damaged buds than those without cages. However, the seed densities in the soil samples were not different between the caged and the non-caged clumps. I propose three explanations. Firstly, the non-caged clumps may improve their productivity in response to the feeding by the herbivores. Secondly, feeding by kiore may help the pollination of the damaged but surviving inflorescences on the non-caged clumps of the wood rose. Finally, hand pollination may not compensate for the exclusion of pollinators when the clumps are caged. The results suggest that caging of clumps of the wood rose may have small value when the browsers destroy the inflorescences and hand-pollination cannot be frequent. Caging clumps of the wood rose did not affect the population resilience of this species on Little Barrier Island.