Germination characteristics of Melaleuca ericifolia Sm. (swamp paperbark) and their implications for the rehabilitation of coastal wetlands

Abstract

Swamp paperbark, Melaleuca ericifolia Sm., is a small, clonal tree that occupies fresh- and brackish-water wetlands across south-eastern Australia. Seeds collected from Dowd Morass, a secondary-salinised Ramsar-listed wetland of the Gippsland Lakes region in eastern Victoria, showed very low viability (< 6%), with less than 50% of the seeds germinating even under ideal laboratory conditions. Greatest germination occurred with surface-sown seeds, germinated in darkness at a mean temperature of 20°C and salinity < 2 g L^–1. At 20°C, maximum germination occurred at a salinity of 1 g L^–1; germination fell rapidly at a near constant rate with increasing salinity. Lower temperatures, while moderating the inhibitory effects of salinity, markedly reduced germination; higher temperatures increased the inhibitory effects of salinity and light and reduced overall germination rates. Seeds subjected to brief inundation with saline water germinated rapidly if flushed by, and subsequently grown under, freshwater conditions. Specific timing of management interventions, particularly manipulations of water regime to control salinity regimes, are required if germination of M. ericifolia on the landscape scale is to be successful. Even so, the low overall viability of the seeds would present difficulties to large-scale, seed-based rehabilitation efforts.