Distribution of Fine Roots in Three Pinus Radiata Plantations Near Canberra, Australia

Abstract

Frequency distributions of fine roots (0.4—3—mm diameter) at 0—1.5— and 1.5—3—dm soil depths within 1958, 1948, and 1934 plantings of Pinus radiata D. Don, were obtained by soil coring and root extraction by wet sieving, but two other methods gave different results and were less sensitive to possible differences between stands. Fine roots perfuse the 0—1.5—dm soil depth in all stands and are significantly less abundant at 1.5—3 dm. Spatial variation of roots within the stands was independent of the proximity of pine stems. Roots extracted from cores by wet sieving had a bimodal frequency distribution in the 1948 and 1958 plantings. Fine roots can be further categorized into very fine roots having rapid turnover rates and fine roots which may eventually grow into diameter classes over 3 mm. The frequency distributions obtained by random or systematic sampling methods were compared by non—parametric tests and were not significantly different.