Survival and growth responses of native and introduced vines in New Zealand to light availability

Abstract

Clematis vitalba, Lonicera japonica, and Passiflora mollissima are three introduced vine species which have become naturalised in New Zealand. Their light requirements and growth rates were compared with those of two common native vine species (Muehlenbeckia australis and Parsonsia heterophylla) by growing plants under irradiance levels corresponding to 40%, 7%, 3.5%, and 2% of available sunlight (expressed as relative irradiance (% RI)). Weedy vines are characterised by a high degree of shade tolerance and a rapid growth rate in high-light environments. Clematis vitalba and Lonicera japonica have their light compensation points at 1.0% RI and 0.9% RI, respectively, and both species show high maximum growth rates. The native vine Parsonsia heterophylla has the lowest light compensation point (Passiflora mollissima and the native Muehlenbeckia australis have higher light compensation points (2% and 1.8% RI, respectively) and the growth responses shown by these two species in the experiment indicate that their potential for rapid growth will only be realised in high-light environments.