Sprinkler storage of windthrown Pinus radiata at Balmoral, New Zealand

Abstract

Sprinkling of 43,000m³ of windthrown Pinus radiata sawlogs was carried out at Balmoral state Forest, New Zealand from 1976 to 1980. This project investigated the microbial flora which had developed after three and four years sprinkling and determined the change to wood microstructure and related properties. Earlier stages of microbial colonisation were studied in an experimental logpile of P. radiata. After four years sprinkling static bending tests showed an increase in the modulus of rupture and elasticity and no change in the work to maximum load. More brittle fractures were found when compared with fresh wood but no change in the hardness of the sprinkled wood could be detected. Loss of ray tissue and degradation of pit torus and margo was found three years' sprinkling and in addition, some degrade to S₃ tracheid wall layers after four years' sprinkling. The permeability of four years sprinkled wood to a non-polar liquid was greatly increased but only slightly increased for water. The results indicate that overtreatment in commercial treatments could be experienced. Fungi isolated from the logpile after three years could be placed in the first stages of published fungal successions in wood: however, after four years' sprinkling the appearance of some basidiomycetes indicated a change in the succession. Conditions prevailing in the logpile after four years' sprinkling revealed that oxygen was not limiting while temperatures were adequate to support fungal growth. However, bacterial isolates did inhibit growth of a selected rot fungus. This suggests that the mechanism which restricted the growth of woodrot fungi after four years' sprinkling involved established bacteria. Investigations of the early stage microbial succession in sprinkled P. radiata showed a variety of bacterial taxa. Grouping of all the isolated bacteria using degradation of cellulose, pectin and starch as the major characters was not successful. Water sprinkler storage of P. radiata proved satisfactory for three years but some strength changes and rot developed after four years.