The natural grasslands of Cape York Peninsula, Australia. Description, distribution and conservation status

Abstract

The grasslands of Cape York Peninsula in monsoonal north Queensland, Australia represent extensive examples of this formation that have been relatively undisturbed by agricultural development. Fourteen grassland units are mapped on the basis of their relationship to soils and landforms. Nine grassland communities were derived from a floristic analysis of the site data, and are related to the mapping units. Half of the grassland map units have less than 10% of their area protected in conservation reserves. The annual forb sickle pod Senna obtusifolia is considered to be the most serious exotic weed at present, because it dominates large areas of unreserved Imperata cylindrica grassland, a community that does not occur extensively elsewhere in Australia. Wetland exotic grasses that are being actively promoted for agriculture pose a potential threat to the Oryza grasslands that occur over large areas of the seasonally flooded coastal plains. It is recommended that further exotic pasture species should not be grown on Cape York Peninsula unless their containment can be assured. Some grasslands appear to be maintained by fire. Data are provided that demonstrate the conversion of some grassland types to woodlands in the last 30 years, and it seems probable that the change is a result of altered fire regimes. Even if adequately reserved, appropriate fire management is required to maintain the grasslands of Cape York Peninsula.