BUSH-HARVESTING OF THE SEDGE CAUSTIS-BLAKEI REDUCES VEGETATIVE GROWTHAND SEED SET

Substantial quantities of the native sedge, Caustis blakei Kukenthal ( commonly called koala or foxtail fern) are harvested from naturally oc curring populations in south-east Queensland as cut foliage and export ed to Europe, USA and Japan. Light harvesting (30%) of stems of C. bla kei reduced the number or size of marketable stems but did not alter t he number and length of new stems. Moreover, mean dry weight of harves ted stems significantly reduced over time, suggesting that even light harvesting was probably not sustainable under the dry conditions exper ienced. Plants that were harvested 3 times per year had more marketabl e stems than plants that were harvested once or twice per year at the same annual intensity. Despite the infertility of the soil in the expe rimental site, the amount of nutrients removed by harvesting stems was low and may not be the major factor reducing growth. We suggest that limited carbohydrate supplies due to low water supply and harvesting ( particularly moderate and heavy harvesting) might be the major causes of reduced growth. Regeneration of fire-sensitive species such as C. b lakei is likely to be prejudiced by harvesting. Harvesting removed spi kelets and reduced the number of spikelets on new stems. Although only a small number of fruit were removed in this experiment, the commerci ally harvested stems represent the current season's stems and are the most fecund. This loss could be significant as C. blakei sets few frui t in any one year. It is recommended that harvesting should be limited to only 30% of the current season's stems with a limit of 15% during dry seasons, instead of the present harvesting limits of '30% of green stems' or '30% of the plant'. In the longer term, propagation and com mercial production will be necessary to supply the demand for cut stem s on both export and domestic markets.