Seedling recruitment, seed persistence and aspects of dispersal ecology of the invasive moth vine, Araujia sericifera (Asclepiadaceae)

Abstract

We investigated germination, seedling emergence and seed persistence of the invasive moth vine (Araujia sericifera Brot.) under controlled and field conditions in south-eastern Queensland. Fresh seed showed high viability (99.5%) and germinated readily, with 97.2% of all recorded germinations occurring within 14 days. Mean germination rates ranged from 74 to 100% across the range of temperature (10/20°C, 15/25°C and 20/30°C alternating 12-h thermoperiods) and light (0- and 12-h photoperiods) treatments. Germination was significantly reduced only under cool, dark conditions. In a 24-month field experiment, seedling emergence was greatest for seeds buried at 1 cm (mean = 96.3%), intermediate for seeds buried at 5 cm (mean = 62.7%) and least for surface-sown seeds (mean = 30.7%). Seed persistence under field conditions was low, declining rapidly to 3.9% at 6 months and to 0.67% at 24 months. Moth vine’s capacity to germinate readily and the rapid depletion of seeds under field conditions indicate that the species has a transient seed bank in south-eastern Queensland. In an additional experiment testing the capacity of seeds for secondary dispersal by water, the mean floating time of seeds was 15.4 days, suggesting that water could act as a secondary dispersal vector, contributing to long-distance dispersal. We recommend that surveillance methods for detecting moth-vine populations should consider both water-flow patterns and wind direction.