Comparing square and rectangular spacings in Eucalyptus nitens using a Scotch plaid design

A spacing experiment using a Scotch plaid systematic design was established to investigate a wide range of square and rectangular spacings on the growth and branching habit of Eucalyptus nitens (Deane et Maiden). The Scotch plaid covered stockings ranging from 278 to 2500 stems per hectare (SPH). Spacings used ranged from a rectangularity of 1, for square spacing, to 3, with a spacing of 6 m 2 m. The design used here effectively resulted in single tree plots. The ®rst 6 m of stem was assessed for branch size and direction. The experiment was measured at age of 5 years. There were no signi®cant differences for tree growth between square and rectangular spacing for E. nitens. The number of branches greater than 35 mm increased rapidly at lower stockings. There were no differences in largest branch size with rectangular spacing compared with equivalent square spacing. For the experiment more rectangular spacing had signi®cantly fewer large branches (>35 mm diameter) than square spacing, though the difference was not great. There was no between row bias of large branches with rectangular spacing and there was no signi®cant bias in an E±W direction and only a slight bias to a northerly (Sun) direction. The number of large branches increased signi®cantly with height over the assessed 6 m of stem. Because there were no adverse effects of rectangular spacing, on growth or branching habit of E. nitens, rectangular spacing could be used in the establishment of plantations, providing ̄exibility of layout of the plantations and thus improving machine access between rows for weed management and other maintenance operations. # 2000 Elsevier Science B.V. All rights reserved.