University Of Waikato Researchers To Uncover Secrets Of Our Planet

Three University of Waikato-led projects will unearth new knowledge of our natural environment after receiving a total of $1.9 million in Marsden funding.

The studies are among 13 new University of Waikato-led research programmes supported by the Marsden Fund this year.

Reading the history of global photosynthesis in icecore bubbles

Hidden in bubbles within polar ice is a story waiting to be told: changes in the rates of photosynthesis (how plants convert carbon dioxide and light into sugars for growth) on land and in the ocean. The bubbles show how this has been influenced by human activity, like changing land use and burning fossil fuels, over past centuries.

Like all animals, we humans depend on plants’ photosynthesis for oxygen to breathe, food to eat and fibre for housing and clothes. If we can understand how photosynthesis has changed in the past we have a better chance of predicting how it might respond to future climates, which is vital for the long-term survival of the planet.

This study aims to interpret changes in the composition of oxygen in air bubbles within ice cores from Antarctica and the Arctic over the last 12,000 years. Professor Margaret Barbour and her team will use knowledge of leaf water isotopes, including how the structure of leaves affects the water within them, to deepen understanding of how photosynthesis has changed over time.

"We hope to demonstrate that water transport processes happening within individual leaves have influenced oxygen in the earth's atmosphere,” says Professor Barbour. “We will then use this knowledge to reinterpret the ice core record of photosynthesis over time."

Inside the mind of the honeybee

Honeybees are not only important for honey production – they also help pollinate food crops and many other plants. But populations are in dangerous decline worldwide, partially due to human activities.

Dr Megan Grainger will study how toxic metals present in the environment from human activities incorporate into honeybees’ brains, and what impact this has on their colonies over multiple generations. Unlike many other toxins, metals do not break down to less toxic products, which means they accumulate in bees and in their hives.

“I’ll be studying bee colonies placed on land contaminated by cadmium from fertilisers, for example,” says Dr Grainger. “I’ll monitor the health and productivity of the colonies over several years, measuring parameters such as the size of their larvae, their travel habits, and the presence of parasites.

“Comparing this information with the level of toxic metal contamination we see in bees’ brains will help unravel how the metals affect colonies out in the real world.

“Ultimately, this is about finding ways to reduce harm to honeybees long term so we can reverse their global decline in population.”

Reconciling New Zealand beech trees with their estranged cousins

The southern beech trees (Nothofagus) that dominate large areas of New Zealand’s native forests have close relatives in South America and Australia. A Kiwi traveller who knows their trees will probably have no difficulty recognising the Chilean or Tasmanian relatives of our beech trees, but might be surprised by the different ways beeches interact with other tree species across time and space in those countries.

Ecologists working in these three regions have come to different conclusions about the conditions that determine where southern beech trees grow best. How can this be?

Associate Professor Chris Lusk and his colleagues in New Zealand, Chile and Australia will test a new explanation for the divergent behaviour of southern beeches in these regions. Beech trees in all three countries share a special type of mycorrhiza (plant-fungus partnership) that distinguishes them from most other tree species in the temperate rainforests of the southern hemisphere.

“The fungi involved may be able to ‘hack’ the nitrogen cycle, giving beeches a nutritional advantage in some situations,” says Dr Lusk. However, chemical differences between the soils of New Zealand, Chile and Tasmania affect this type of mycorrhiza, determining whether beeches win or lose in competition with other tree species.

“By looking at the effects of climate and soils on this special relationship between beech trees and fungi, our study will reveal previously undocumented influences on forest development hidden belowground,” says Dr Lusk.

All three projects will commence in 2021.

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