Seedling establishment microsites of exotic conifers in chionochloa rigida tussock grassland, otago, new zealand

Abstract

Seedling establishment microsites of Larix decidua, Pinus contorta, and Pinus nigra were examined in relatively intact Chionochloa rigida tussock grassland. Seedlings established most frequently on the southern side of tussocks, and seedling growth rates of Pinus contorta and Pinus nigra increased with proximity to tall tussocks. Chionochloa rigida was the tussock grass species most frequently occurring closest to seedling Pinus, and the shorter Festuca matthewsii to Larix decidua. Most Pinus contorta and Pinus nigra seedlings occurred under a tussock canopy. However, Pinus nigra and Larix decidua occupation rates of the between canopies class were much higher than that of the under canopy class. Occupation rates of under canopy and between canopies classes were similar in Pinus contorta. Favourable microsites for conifer establishment had sparse, low-growing intertussock vegetation over bare soil or bryophytes. Conifer establishmentcouldbereducedby grassland management that reduces the availability of favourable microsites by increasing the density of tussock bases, encouraging a continuous tussock canopy, increasing the cover and density of intertussock vegetation, and by control of seed sources. © 1989 Taylor & Francis Group, LLC.