Brushtail possum (Trichosurus vulpecula) damage and abundance in a New Zealand Pinus radiata plantation: A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Agricultural Science (Hons.) at Lincoln University

Abstract

Field trials were undertaken during summer 1996/1997 in a Pinus radiata plantation near Whangamata, New Zealand, to assess the levels of possum damage and determine how this was related to stand maturity, understorey composition and possum abundance. Based on a review of previous surveys, a new damage scoring system was developed. Using this system, the overall proportion of pine trees (greater than 3 years of age) with possum damage was found to be very low (3.6 % of 1744 trees surveyed). However, damage levels varied markedly between plantation blocks (0% - 30%; 36 blocks). The majority of possum damage involved needle clipping and damage to lateral branches. Damage levels were related to the maturity of the stand and understorey species composition, rather than possum density per se. Possum densities were highest near plantation block margins, so these margins are likely to be effective sites to implement possum control. Given the low damage levels recorded, the cost-effectiveness of current possum control efforts in pine plantations is uncertain and would benefit from further economic analysis.