Delving into the drylands
Volunteers are unearthing the secret to how plants survive the harsh environment of Central Otago's drylands, with the goal of boosting native plants that once covered the area.
Can the soils below the hardy native plants that have survived more than a century of changes in Central Otago’s drylands tell us how native species might better re-establish in the area?
That’s the subject of a study led by Haehaeata Natural Heritage Trust volunteers in association with Otago University botany scientists on an area of pastoral farming land near Clyde.
Multiple land uses over time mean the soils of Central Otago’s dryland landscape have been turned over and altered throughout the past 150 years, says Dhana Pillai of the Trust.
“Any land below 500 metres in the area has been extensively burned by Māori communities and European settlers, and then was extensively mined in the 1860s for gold. There has also been extensive grazing in the area through the 1900s to the present day.”
Dhana says the different uses have wiped out many native plants but others have come back and regenerated. “The plants that have survived are the tough ones.”
The team's research on the soils of native plants seeks to identify the correct species of symbiotic (mutually beneficial) fungi that may enable native species to better re-establish, with a focus on endomycorrhizal fungi in particular.
Endomycorrhizal fungi are microscopic fungi that survive by living in a host plant's root cells. They make it easier for nutrients to pass between the soil and their hosts and are particularly useful to plants in areas of drought or where soil is nutrient-poor, as they can allow their host plants to out-compete plants that don't have mycorrhizal relationships.
Dhana says there is little research of endomycorrhizal fungi in relation to native plants in New Zealand. “Most research tends to focus on what is going on in the ecosystem above ground, rather than what is going on underground, or has been in relation to commercial growing.”
The research involves analysing the DNA of the soil, which indicates what once lived in the soil. The team is also collecting and preserving RNA (ribonucleic acid) for analysis in the future when further funding allows, because RNA stores genetic information in a different way from DNA and shows what plants are currently living in the soil.
Dry ice preserves soil samples
The study is at three sites on farm land at the southern end of the Dunstan Mountains, where the scientists, led by Associate Professor David Orlovich, carefully gathered soil samples to avoid contamination from beneath 48 plants. Half of the shrubs were thyme and half were the native species Olearia odorata, the scented tree daisy.
Soil samples were taken in both spring and autumn and, in order to immediately preserve the DNA and RNA, scientists used dry ice on the samples. From there the samples were taken back to the university laboratory to extract the DNA.
Dhana says the objective is to get a snapshot of activity in a Central Otago pastoral farm system, including whether there are differences between the soils of native shrubs compared with non-natives.
“We might not be able to see exactly what fungus is growing on what plants, but if we have an idea of those plants growing in the vicinity it could be useful information for what is going on in the soil and relating that to what's happening above ground,” says Dhana.
Trust volunteers were responsible for initiating the study and conducted the vegetation survey and site description of the plots, recording all plant species in the area and measuring soil temperature.
Their soil chemistry results have shown that there is actually little difference between the soils of natives and non-native species.
However, Dhana says the project is still very worthwhile because there is so little information and knowledge about the local biodiversity. “It is wonderful to be able to access the scientists and I hope we can continue that relationship and they are able to keep interested in the trials and continue to work with us.”
The project team is also raising local awareness about the area’s biodiversity, by sharing details at a community event and welcoming Dunstan High Schools students visiting the field site to learn about their work. Dhana says there is high interest in a second event, through which they will share the final results with the community.
Follow the team on Facebook
About the project
This project is led by volunteers of the Haehaeata Natural Heritage Trust (part of the Clyde Railhead Community Eco-Nursery) with support from Otago University and the Otago Participatory Science Platform.
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