Growth of Seven-weeks Fern (Rumohra adiantiformis) in the Southern Cape Forests: Implications for Management

SYNOPSIS

Fronds of the fern Rumohra adiantiformis are picked in the southern Cape forests and exported. Harvested fern rhizomes produce smaller fronds. Recruitment of juvenile plants to a marketable size class, and recovery in frond size of experimentally defoliated fern rhizomes is slow, no net increase in the size of new fronds having been observed over 34 months. Rhizomes extend horizontally 10 mm to 250 mm per year just below the litter layer, and it is possible that this is an adaptation to patchy and low availability of light or nutrients on the forest floor. The fern can respond to fertilisation and is 20 times more productive under nursery conditions than in the wild. Natural R. adiantiformis populations appear unable to maintain their quality when harvested but nursery production of fronds may offer a viable alternative for fern exporters.

Key words:

• fern
• growth
• recruitment
• forest