Review of the phytogeography of Cape York Peninsula: a flora that illustrates the development of the Australian sclerophyll biota

Paleontological records from north-eastern Australia suggest that Cape York Peninsula is likely to have retained a warm and humid environment throughout the Cenozoic. The cooling and drying trend of the last 15 million years has been moderated on Cape York Peninsula by its position on the northern leading edge of the continent, its maritime or aquatic influences and partly montane topography. Cape York Peninsula shares a close geographic relationship with New Guinea, with 40% of its species shared, but has a distinctively separate flora that includes 330 bioregionally endemic plant species and five bioregionally endemic plant genera. Comparison with the monsoon savanna areas of Western Australia (Kimberley) and Northern Territory (Top End) suggests that Cape York Peninsula has a much richer rainforest flora. The non-rainforest flora of all three areas contains a significant regional element. The Peninsula has a mix of plant communities that are similar to those identified from Australia’s vegetation in the Cenozoic including rainforest, woodlands and grasslands. Cape York Peninsula demonstrates the mosaic of these environments, which were typical of much of Australia during the Cenozoic but which were lost in most areas during the cooling and drying of the Pliocene and Quaternary. The fossil record and dated phylogenies suggest that some of the taxa first evident in Australia during the Cenozoic are still growing on Cape York Peninsula. In the Myrtaceae and Poaceae, Cape York Peninsula demonstrates nationally and internationally significant taxonomic diversity. Its taxa are related to many that emerged in the forests of the Paleocene and to taxa which became dominant following the drying of the Miocene. The Peninsula contains elements which represent both older and modern lineages of many families in Australia. The phytogeographic significance of Cape York Peninsula is that it has a highly diverse flora, which contains plant communities and taxa that demonstrate the development of the sclerophyll biota in Australia during the Cenozoic.