Alternative Views

The preceding analysis concludes that both long distance dispersal and former land connections have played a role in the ancestry of the New Zealand flora. This would, I think, be the majority view at the present time, but there are alternatives: on the one hand Mildenhall¹⁵ considers the possibility of long distance dispersal even for Nothofagus, while on the other the 'panbiogeographers' do not think speculation on dispersal has any value when trying to explain the presence of certain taxa on isolated islands.¹⁶

Alternatives to long distance dispersal as an explanation for the floras of isolated islands include the suggestion of Melville¹⁷ and others that there was formerly a continent, Pacifica, which rifted into a number of fragments that drifted through the Pacific and eventually became incorporated into various continents on the Pacific rim. If true, this would mean that the isolated central Pacific islands or their predecessors may have been close to continental fragments in the past and could have page 25derived the nuclei of the present island floras from them. It is further suggested that Pacifica was originally sited in the south-west Pacific and that it may have provided the sediments that now form the rocks of eastern New Zealand.

Carey¹⁸ has promoted a different idea for some time — that the earth is expanding. When it was much smaller all the present land areas were together without intervening oceans. As the earth expanded the land areas moved apart and the new basins between them became filled with water derived from the earth's interior. In this case too the islands of the young small Pacific Ocean could have derived their floras from the then nearby continents.