New Zealand Journal of Forestry (1993) 38(3): 25–27
©New Zealand Institute of Forestry
Growing durable hardwoods - a research strategy
The Special Purpose Species research group of the NZ Forest Research Institute is undertaking a project to investigate timber tree species that have naturally durable heartwood in contact with the ground.
Trees have been planted on farms to produce material for posts and other exterior uses, occasionally with success, but farmers are still faced with uncertainties in choice of species, seed source, siting and silvicultural management. Hardwood tree species with suitable wood properties that have been considered for this purpose include Eucalyptus muelleriana, E. globoidea, E. pilularis, E. microcarys, Syncarpia glomulifera, Catalpa spe-ciosa, Robinia pseudoacacia, and Castanea sativa.
This paper gives a brief history on the growing and use of these species, summarises the information available and presents a strategy for future research. Until now, there has not been a research programme to compare the species, identify the best seed sources, describe the siting requirements, test spacing regimes or to measure growth of naturally durable hardwoods.
The economic prospects for some of these species may improve if concern about the depletion of tropical rainforests has an effect in the market and pressure from environmental groups leads to a re-evaluation of naturally durable timbers for use as posts and poles.
The research strategy outlined includes: % collection of growth data from existing stands throughout NZ; » species trials on different sites for all eight species; % provenance trials for E. muelleriana; % silvicultural trials for R. pseudoacacia.