EFFECT OF WIND ON THE EARLY GROWTH OF FIVE TREE SPECIES PLANTED TO FORM WINDBREAKS IN NORTHERN AUSTRALIA

Abstract

The effect of wind on the early growth of five species, Callistemon salignus, Eucalyptus microcorys, E. tessellaris, E. torelliana and Melaleuca armillaris, planted to form windbreaks was examined on two adjacent paddocks on the tropical Atherton Tablelands of north Australia. In Paddock 1, trees of C. salignus, E. microcorys and M. armillaris, were grown with and without wind protection using Zea mays (maize). In Paddock 2, trees of all the five species mentioned above were planted with three treatments: (1) protected by an existing perimeter mound for 12 months, (2) protected by Zea mays (maize) for 5 months and (3) no wind protection. Wind direction and speed were measured at intervals of two hours at both the open and the perimeter mound sheltered areas using an automatic weather station. Tree angle to ground, height and crown size were measured at age 5 months on Paddock 1 and at age 12 months on Paddock 2. Trees of each species leaned over as a result of wind. Tree height and crown growth were significantly reduced by wind. Trees protected for 12 months suffered less wind effect than trees protected for only the first 5 months. E. microcorys appeared to be more susceptible to wind damage than the other species studied. It is suggested that resistance to wind damage should be an important criterion for species selection when forming windbreaks in windy areas.