By Alexa Cook
Conservationists are fighting to save New Zealand's most threatened tree by using DNA profiling and cracking down on possum control.
There are only 14 rātā moehau trees left in the wild, found at the top of North Island near Spirits Bay in the Unuwhao Forest and Te Paki. Out of those, just five have the distinct genotypes needed for genetic diversity, which is crucial to its survival.
A fully grown rātā moehau tree, Photo: Peter de Lange
Department of Conservation (DOC) principal science advisor Peter de Lange said without intervention the future was bleak for the 35 metre high, white flowering tree, also known as Bartlett's rātā. Until the DNA profiling done early last year, DOC didn't realize that three of the five genotypes needed to cultivate genetically fit trees were on iwi land.
Mr de Lange said possum control and DNA testing of the trees there had been difficult because of treaty settlement complications with Ngāti Kuri and Te Aupouri. "Unfortunately for many reasons possum control wasn't done to the levels that it should have been and a lot of the trees that were found there in 1991 and 1992 have been browsed to death."
DOC also had problems with the trees they were cultivating and re-introducing to the forest because they were technically 'inbred,' he said. "Plants that were able to be managed on the public conservation land; the plants have grown up and been planted diectly back into the wild and initially they looked like they were doing really well. "But four or five years later all of them, or most of them, had died or shrunk in size, and we now know that this is what we call 'inbreeding depression,' those plants are not genetically fit."