A lesson from Bass Strait on connectivity conservation

Isolation effects on the distributions of plant species in fragmented forests appear to be weak over tens to hundreds of years and strong over geological eras. The 250 km wide, 6.5 millennia old Bass Strait, and other millennium-scale disjunctions in the range of Eucalyptus regnans forests, were used to determine the effects of intermediate periods of isolation on plant species occurrence and composition. Three of six floristic communities were found on both sides of Bass Strait. The residuals from multiple regression models using climatic variables on the latitude vector were not explained by latitude, indicating negligible isolation effects from Bass Strait. However, there was a lesser compositional effect of disjunctions within land masses than between land masses, suggesting some effect of the larger barrier. No species that commonly occurred with E. regnans and were largely confined to wet forest exhibited absences from any region where the climate and soils were within their range. If areas isolated from each other for millennia can maintain their vascular plant biota, the expenditure of conservation funds on creating corridors to connect large areas separated by anthropogenic landscape modification might require more justification than it is currently afforded.     

PREHISTORIC FLINT MINES AND THEIR IDENTIFICATION AS SOURCES OF RAW MATERIAL

This paper is a statistical and geological study of the results of analysis of flint from British and West European flint mines, carried out by emission and atomic absorption spectroscopy. Groups of flint specimens were studied from each geographically separate flint mining area. Flints were analysed for a group of easily measured trace elements shown by previous work to be generally present. The ratios between the trace elements form a consistent pattern for each flint mine and statistically valid differences of pattern can be recognized between different flint mines. A geological investigation shows that the measured trace elements may be derived from clay minerals and explains geographical and statistical variation in the composition of flint in terms of its mode of origin in the chalk. An advanced statistical technique allows individual flint specimens of unknown origin to be attributed by their composition to one or other of the identified flint sources. The archaeological implications of this study are discussed.