Northwest Of South Island Research Articles

Earthquake impacts in old‐growth Nothofagus forests in New Zealand

Abstract. Six stands located on different land forms in mixed old‐growth Nothofagus forests in the Matiri Valley (northwest of South Island, New Zealand) were sampled to examine the effects of two recent large earthquakes on tree establishment and tree‐ring growth, and how these varied across land forms. 50 trees were cored in each stand to determine age structure and the cores were cross‐dated to precisely date unusual periods of radial growth. The 1968 earthquake (M = 7.1, epicentre 35 km from the study area) had no discernible impact on the sampled stands. The impact of the 1929 earthquake (M = 7.7, epicentre 20 km from the study area) varied between stands, depending on whether or not they had been damaged by soil or rock movement. In all stands, the age structures showed a pulse of N. fusca establishment following the 1929 earthquake, with this species dominating establishment in large gaps created by landslides. Smaller gaps, created by branch or tree death, were closed by both N. fusca and N. menziesii. The long period of releases (1929–1945) indicates that direct earthquake damage was not the only cause of tree death, and that many trees died subsequently most likely of pathogen attack or a drought in the early 1930s. The impacts of the 1929 earthquake are compared to a storm in 1905 and a drought in 1974–1978 which also affected forests in the region. Our results confirm that earthquakes are an important factor driving forest dynamics in this tectonically active region, and that the diversity of earthquake impacts is a major source of heterogeneity in forest structure and regeneration.

A New Fossil Species of ShearwaterPuffinusfrom the Late Quaternary of the South Island, New Zealand, and Notes on the Biogeography and Evolution of thePuffinus gaviaSuperspecies

A new, extinct species of Puffinus (Aves: Procellariidae) is described from fossil bones found in caves in the west and north-west of South Island, New Zealand. The new species is smaller in all dimensions than either Puffinus gavia or P. huttoni, with which it forms a natural group. It is known from deposits dating from at least 20 000 years b.p. to others less than 600 years old. The distribution as presently known includes the west and north of the South Island, New Zealand, from Takaka Hill (41°s) in north-west Nelson, to near Punakaiki, at 42°S. The three taxa had allopatric breeding distributions. This is the first extinct procellariid to be described from New Zealand. As with other avian taxa that survived to the present millenium, it was probably exterminated by the Kiore Rattus exulans, which was introduced by Polynesians less than 1000 years ago.