SUITABILITY OF <em>EUCALYPTUS</em> <em>GRANDIS</em> AND <em>E. </em> <em>MICROCORYS</em> AS WINDBREAK SPECIES IN TROPICAL NORTHERN AUSTRALIA

Abstract

A study was conducted on the Atherton Tablelands of tropical north Australia to compare the suitability of Eucalyptus grandis and E. microcorys for forming windbreaks. Wind speed was measured at various distances from the leeward side of each of the E. grandis and E. microcorys windbreaks, both 13 years old and consisting of five rows of trees. The species were measured for their height, diameter at breast height (DBH), crown length (between the rows) and width (along the row), number of branches per tree, bole length (height to the lowest branch) and windbreak porosity. The E. microcorys windbreak had a uniform porosity both vertically and horizontally while the E. grandis windbreak had uneven porosity with some obvious gaps at the base (up to 8 m from the ground). E. grandis was significantly taller and longer in bole length but lower in number of branches per tree than E. microcorys at age 13 years. Wind speed was reduced more by the E. microcorys windbreak than by the E. grandis windbreak. E. miirocorys appears to be a suitable species for windbreaks whereas E. grandis does not.