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5.18 Management of Shelterbelts
Authors: J D TomblesonPublication: , Volume Section 5 – Plantation silviculture, pp 18, Dec 2023
Abstract: Managing shelterbelts for timber production is not new. Shelterbelts planted on the Canterbury Plains during the 1840s provided timber for the construction of the earliest houses built of radiata pine in New Zealand. Many developments aimed at increasing log quality and profitability have occurred since those early plantings. In 1961 a single-row radiata pine shelterbelt was established near Rotorua which was designed and managed to provide both shelter and timber production. The low shelter was provided by slow-growing mixed conifer species including Leyland cypress and Japanese cedar, planted adjacent to an existing barberry hedge. At age 22 years the shelterbelt contained 400 trees per kilometre, and yielded a merchantable log volume of 1200 m3 per kilometre which was made up of 468 m3 of pruned butt logs, 648 m3 of unpruned sawlogs and 84 m3 of pulp logs. Based on current (2004) log prices the shelterbelt was estimated to have a net value of approximately $100,000 per kilometre. From a practitioner’s viewpoint the Waikite shelterbelt demonstrated that a single row of radiata pine, conventionally pruned, and incorporating a slower growing species can yield high quality logs without apparently compromising shelter value. An extensive series of studies evaluating mature radiata pine shelterbelts located in the Central North Island and Canterbury regions showed that shelterbelt tree and log characteristics (with the exception of branch size) can be simulated using the integrated stand modelling system STANDPAK. Modification to enable STANDPAK inputs and outputs to be made on a per kilometre of shelterbelt basis, along with the incorporation of a growth model developed for shelterbelts is available for users to evaluate.