The Effects of Wind on the Extension Growth of Pinus contorta Douglas

The effect of wind on the extension growth of young Pinus contorta was investigated using a controlled environment wind tunnel. Extension rates of leader and lateral shoots were reduced by about 20 per cent by high wind speed. The ratio of the final length of the laterals to that of the leaders (‘apical control’) was unaffected, as was the radial growth of stems. Water potentials were slightly higher in plants subject to high wind. In another experiment, rates of needle extension were reduced 30 per cent by wind. The experiments are discussed in relation to field observations by others and it is argued that wind is a potent ecological factor adversely affecting tree growth.