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Featured project - Tackling Bittercress on South Georgia

Reproduced from the South Georgia Newsletter, October 2010.

Kelvin Floyd has travelled a long way to advise the South Georgia and the South Sandwich Islands (GSGSSI) on how to continue the battle against the invasive bittercress plant. The New Zealander's long previous experience tackling invasive plant species in some remote and inhospitable areas qualifies him to take a fresh look at the ongoing battle to contain the plant and ultimately eradicate it. It is currently known to grow in two areas, at KEP and below Brown Mountain. Kelvin will spend about six weeks here assessing the problem, trialling different herbicides and spraying to contain the plant. GSGSSI has asked him to come up with a plan to get rid of the invasive bittercress. He is also setting up a database to record all efforts made, which will make recording the work done so far and assessing the success of the spraying regime much easier. When he leaves he will write a report advising GSGSSI on what further steps they make take to tackle the problem, one he describes as “very doable”.

He has been working for twenty years in conservation, with many different organisations, on both plants and animals. He is currently employed by Te Ngahere Ltd of Auckland, NZ, a company specialising in ecological restoration.

Kelvin Floyd spraying one of the main bittercress areasIt has been lucky that there was not a large accumulation of snow this past winter so the ground is already mostly snow-free, and his visit has also coincided with an unusually protracted period of calm weather allowing spraying most days. Whilst here he is conducting trials with five different herbicides - two knock-down herbicides and three pre-emergence ones that should prevent seeds already on the ground germinating. If successful the latter could really cut down the amount of time that needs to be spent spraying during the summer growing season, but disturbance in the sprayed areas by wildlife such as the fur seals may make this less effective than it would be if a complete undisturbed blanket of spray could be maintained.

- Photo: Kelvin Floyd spraying one of the main bittercress areas.

So far Kelvin describes his work as “going well”; there is a lot less bittercress than he expected and the scale of the infested areas is not too daunting. He has worked successfully in much bigger and more difficult environments than here. For instance the volcanic island of Rangitoto in Auckland harbour, which is hard to walk on lava fields where they are tackling a dozen invasive plants all at once.

Attempts made to tackle the bittercress in previous years have been effective. The plant has been knocked back to a low incidence in some areas where it was well established before. He says this as a positive sign that the seed bank is becoming exhausted in those areas, something he thinks bodes well for overall success eradicating the plant. “The time the seed remains viable in the soil is the big unknown here”, he said. “That is the million dollar question. No one knows the answer, and as we don't know that, I can't say how long the spraying regime will need to be kept up, but to be successful there will need to be continued spraying until the seed bank is exhausted.”

Whilst here, he is also looking at the other invasive plants in the Grytviken area and starting control of them. He is not tackling the dandelion or mouse-eared chickweed, two invasive non-native plants which it is too late to hope to control, being too widespread and well established, but he is tackling other plants like the sheep sorrel and yarrow. He suggests that eventually it will also be necessary to look at tackling introduced plants in other areas of the Island.

Kelvin Floyd will write a report and make recommendations to GSGSSI on how to continue tackling the bittercress.

“This is a great place”, he said, “and you have to manage your environment. You can't just sit back and not worry about these things. If you have got invasives, you need to do maintenance. The work is not just to eradicate the bittercress but to ensure you are not introducing new plant species and to keep an eye out that nothing strange is going on.”

Project index
S.H.16 Causeway Alliance Pest
   Control
Jaggers Bush
Hochstetter Pond
Rangitoto Island plant pest management
Weed Control on offshore islands
Whangaparaoa Training Centre
   restoration
Tackling bittercress
Beach access, Kennedy Park
Skills involved
Auditing and inspections
Ecological surveys
Pest plant control
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