Drought effect on high‐altitude forests, Ruahine Range, North Island, New Zealand

Abstract

Summary Shortly before 1917 abnormally high mortality of canopy trees occurred up to the timberline c. 1470 m, in the central Ruahine Range. Rainfall records and historical observations indicate that this resulted from intense drought during 1914–15. Despite the drought damage and the impact ofdeer, the forest regenerated and after 1915 no major source area of coarse sediment developed in Centre Branch of the Waipawa Basin, Forest recovery at the head of the upper Waipawa Basin has produced a timberline which is c. 90 m lower than it was before 1915. On most of the Ruahine Range there is evidence of a recent lowering of timberline which probably also resulted from the 1914–15 drought and which is not associated with decrease of temperature.