Research suggests taro important crop for early Māori diet

Tuesday, 23 April 2019

Research on Ahuahu-Great Mercury Island, off the northeast coast of Coromandel Peninsula, suggests taro was part of the diet of Māori soon after they arrived in New Zealand.

The finding is seen as contrasting with hypotheses that early settlers initially relied strictly on wild foods.

The researchers from Auckland University and Auckland War Memorial Museum, along with colleagues from overseas, found sediment in swamps on Ahuahu contained the pollen of taro and of leafy greens, such as puha and watercress. The deposits were radiocarbon-dated to the 14th century.

Research team member, Professor Simon Holdaway of Auckland University, said archaeologists had long considered the cooler climate of New Zealand, compared to the warmer climate of Polynesian islands, hindered early attempts by Māori to grow traditional Polynesian crops, such as taro.

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'This evidence for early taro production refutes the long-held view that only kumara could be grown in New Zealand,' he said.

'It indicates Tūpuna Māori may have initially focused on taro and created specialised wetland gardens for the purpose; kumara then became the main crop after AD 1500.'

A report on the research, published in the journal PNAS, said sedimentary charcoal and fossil remains indicated how frequent burning and perennial cultivation overcame the ecological constraints for taro production.

Polynesians introduced the tropical crop taro to temperate New Zealand after 1280, but evidence for its cultivation had been limited, in contrast to abundant evidence of big game hunting, the report said.

Wild food fossils dominated sites from the Polynesian initial colonisation period from 1200-1500 in the subtropical and temperate islands of the South Pacific, most noticeably moa in New Zealand. That supported a long-held hypothesis that foraging and hunting were the main methods used to get food, the report said.

Fossil taro pollen found at Ahuahu provided direct evidence for the flowering of plants. It was also a proxy for perennial cultivation in which plants were left in the soil over multiple growing seasons to produce greater corm volume and yield. Taro rarely produced pollen when harvested annually.

The evidence from Ahuahu suggested taro cultivation may have been confined to northern offshore islands in New Zealand. Forests on those islands were dominated by a greater proportion of low-growing trees, compared to the dense and tall conifer-dominated forests of the mainland.

'Smaller trees, including palms and tree ferns, familiar to Polynesians from their tropical island homelands, are soft-barked, easier to cut down and burn, and produce abundant leaf litter that, in wetlands, produces organic rich soils suitable for immediate taro production,' the report said.

Many weedy plants were likely tended in gardens, or thrived in modified ecological conditions. Māori probably ate some as leaf vegetables or during famines.

There was evidence of a transition from low to high-intensity cultivation after 1500. The absence of taro pollen on Ahuahu could indicate higher-intensity production, or a shift to kumara production.

'Evidence for the local construction of features like hillslope stone alignments after 1600 CE is most likely associated with the expansion of dryland kumara cultivation,' the study said.

'This formed part of a transition that played out across northern New Zealand, but is apparent and early on Ahuahu, due to the preferable ecological and climatic conditions for crop production.'

Ahuahu may have functioned as a nursery or experimental garden before the expansion of crop production to other parts of the country.