The New Zealand subantarctic islands are home to the southernmost-growing trees in the southwest Pacific. In sheltered locations, some Dracophyllum have been shown to reach more than four metres in height, with their growth hypothesised to be controlled by temperature. By measuring the thickness of annual tree rings, Dracophyllum provides the possibility of developing a natural weather record back to the 19th century.
Dracophyllum trees on Campbell Island (52˚S)
The research program
On the subantarctic islands, peat exposures show Dracophyllum once grew above present day tree line. Here we find there was a major collapse in the altitudinal limit of growth between approximately 2000 and 1000 years ago suggesting westerly winds were stronger at this time.