Causes of decline in nga roimata o Tohe (Pimelea eremitica)

For Department of Conservation

Research into the causes of decline of the Critically Endangered shrub nga roimata o Tohe (Pimelea eremitica). This species occurs at only one site in Northland, and the number of plants has plummeted in the past decade.

Patterns in seed dispersal interactions across islands

Collaborative project led by Don Drake (University of Hawaii, USA) and Kim McConkey (National Institute of Advanced Studies, India)

Global review of seed dispersal interactions on oceanic islands and changes in community function over time.

Recruitment limitation in the endangered shrub Hebe armstrongii

Hebe armstrongii
Hebe armstrongii

Funded by New Zealand Plant Conservation Network and Brian Mason Trust. In collaboration with Department of Conservation.

The Nationally Endangered shrub Hebe armstrongii has only two populations remaining in the wild. One of these populations has both adult plants and seedlings, but occurs on private land and is not currently protected. The other population is protected on conservation land and has many adults, after successful establishment of nursery-grown plants, but few seedlings. This project aims to determine what conditions Hebe armstrongii needs to regenerate naturally in the wild.

Restoration of the critically endangered dry plains shrub daisy

Dry plains shrub daisy seedlings
Dry plains shrub daisy seedlings

In collaboration with Environment Canterbury and University of Canterbury, with funding from Forest & Bird

The Critically Endangered dry plains shrub daisy (Olearia adenocarpa) is threatened by non-native invasive weeds. Seedling establishment occurs only when invasive grasses are controlled, which requires intensive and ongoing herbicide treatment that is only possible over small areas. This project is investigating less intensive restoration techniques that will enable seedling establishment, and prevent the extinction of this critically endangered species.

 

Seed dispersal by lizards in New Zealand: a review

Raukawa gecko scat containing kawakawa seeds.
Raukawa gecko scat containing kawakawa seeds.

Debra Wotton was invited by SRARNZ (Society for Research on Amphibians and Reptiles in New Zealand) to write a review paper on seed dispersal by lizards. The paper was published in a special issue of the Journal of the Royal Society of New Zealand, to commemorate Tony Whitaker’s contribution to herpetological (reptile and frog) research in New Zealand.

 

 

 

 

Kaitorete 002
Nationally Endangered shrub Muehlenbeckia astonii.

Seed ecology of the endangered shrub Muehlenbeckia astonii

For Landcare Research

Experimental research investigating seed germination, seed longevity, and lizard seed dispersal in a Nationally Endangered shrub. Fieldwork was undertaken at Kaitorete Spit, Canterbury, the stronghold for Muehlenbeckia astonii.

 

 

Literature review on seed dispersal of fleshy-fruited environmental weeds in New Zealand

For Department of Conservation

In collaboration with Kate McAlpine (DOC), Debra investigated which environmental weeds have fleshy fruits adapted for animal dispersal, which animals are the main dispersers of fleshy-fruited weeds, and management implications for weed spread. You can download the paper here.

 

Does seed limitation drive plant rarity?Enys Reserve 003

Funded by FRST NZ Science & Technology Postdoctoral Fellowship and Landcare Research

Field and glasshouse based experiments investigating why some plant species are rare, while other closely related species are common. Debra investigated whether seed supply, safe sites for germination and establishment, or soil feedbacks drive plant rarity, in collaboration with Richard Duncan (University of Canberra), Bill Lee (Landcare Research) and Ian Dickie (Lincoln University).

 

Impacts of weed control on native biodiversity

For Department of Conservation

This literature review identified that weed control often fails to increase native species abundance and species richness. Recruitment of native plants after weed control tends to be limited by seed availability. In many cases, re-invasion by the same weed species or another weed occurs. You can download the publication here.

 

Lizard seed dispersal on Stephens IslandStephens 078

Research carried out in collaboration with Ralph Powlesland (DOC) and Jenny Ladley (University of Canterbury) to investigate whether lizards on Stephens Island (Cook Strait) were dispersing viable seeds.

 

 

 

Ecosystem services provided by the conservation estate

For Department of Conservation

Ecosystem services are the benefits people obtain from ecosystems, such as clean air, fresh water, and the pollination of crops. The aim of this literature review was to find empirical data illustrating the ways in which conservation land and conservation management activities affect ecosystem services. You can download the publication here.

 

Can native plants replace weeds via natural succession?

For Department of Conservation

Controlling weeds is expensive and time consuming, and doesn’t always lead to successful outcomes for native biodiversity. The aim of this literature review was to identify the circumstances under which native plants are most likely to replace weeds through natural succession. This review has led to two subsequent projects, which investigated factors influencing native plant regeneration beneath wilding pines and several ground cover weed species. You can download the publication here.

 

Consequences of disperser loss: kereru and large seeds in NZKONICA MINOLTA DIGITAL CAMERA

Funded by University of Canterbury, Auckland Regional Council, Brian Mason Trust, NZ Federation of Graduate Women and Forest & Bird

Debra conducted this research for her PhD thesis at the University of Canterbury. She set up an experiment to test whether two large-seeded trees (taraire and karaka) are dependent on seed dispersal to regenerate. Her research found surprisingly large effects – seeds that were not dispersed (located beneath the ‘parent’ with the pulp still on, and at high seed densities) were much less likely to survive than seeds that were dispersed (away from the ‘parent’, pulp removed and at low seed densities).

Pest mammals (ship rats and possums) also ate and killed seeds and seedlings of karaka and taraire.

Read media coverage of the research findings here.

 

Frugivory & seed dispersal by common geckosCoprosma propinqua fruits are dispersed by lizards

Funded by Victoria University and Wellington Botanical Society

Debra carried out this research for her MSc thesis, investigating the effectiveness of raukawa geckos (previously called common geckos) as seed dispersers on Mana Island, Wellington. Raukawa geckos were effective dispersers of Coprosma propinqua seeds, removing most ripe fruits and dispersing them up to about ten metres from the ‘parent’ shrub. Geckos did not harm seeds and defecated them in sites suitable for germination.