As individual plants vary in their tolerance to drought, the predicted increase in drought events with climate change may result in shifts in competitive balance, and with it, unpredictable impacts on plant communities. If weeds are among those better able to withstand drought, they may increasingly displace native species. The aim of this study was to investigate drought tolerance of three potential new weeds in New Zealand, at an early stage of their spread: Archontophoenix cunninghamiana (H.Wendl.) H.Wendl. & Drude, Psidium guajava L. and Schefflera actinophylla (Endl.) Harms. Seedlings of these three alien plant species were exposed to two different drought regimes (21 and 51 days without water) in a shadehouse experiment. Seedling growth and soil moisture was measured regularly during the drought and a subsequent recovery period. Mortality of all species was nil, and the shorter drought (i.e. 21 days) had no effect on the growth of any of these three alien species. However, the longer drought (i.e. 51 days) reduced leaf biomass of A. cunninghamiana, and reduced growth rates, leaf and total biomass of P. guajava. The drought tolerance of A. cunninghamiana and particularly S. actinophylla shown in this study may be an important factor assisting their potential spread with climate change.
Cite this article as:
Sheppard, C.S. (2014). The effect of drought on growth of three potential new weeds in New Zealand. Plant Protection Quarterly 29(2), 54-60.