Pollen-vegetation relationships in semi-arid southwestern Australia

Pollen deposition within a number of vegetation types in two regions of semi-arid southwestern Australia was studied over a two-year period using pollen traps. The vegetation at each trap location was recorded, and both the pollen and the vegetation data were analyzed using TWINSPAN and Detrended Correspondence Analysis, in order to facilitate the comparison of the vegetation and pollen assemblages. patterns of pollen deposition observed suggested moderately strong relationships between the vegetation and the pollen assemblages, although some of the vegetation details were not always well reflected in the pollen assemblages. The pollen assemblages were aggregated by the multivariate analyses into groupings similar to those produced by the vegetation data, pointing to the strength of the relationship between the two. It was possible to distinguish a number of vegetation types on the basis of pollen assemblages. Typically woodland sites in the Kalgoorlie region had high frequencies of Eucalyptus pollen associated with low pollen frequencies of Acacia and other trees. Understorey components were also reflected in the pollen assemblages. Acacia and mixed scrub sites showed the highest frequencies of Acacia pollen with low to moderate pollen frequencies of Eucalyptus, low Casuarina and often high values of Callitris/Actinostrobus. Scrub-heath vegetation typically had high frequencies of Callitris/Actinostrobus, moderate to high Myrtaceae undifferentiated, low to moderate Eucalyptus and low Acacia, Asteraceae and Chenopodiaceae/Amaranthaceae pollen frequencies. Thickets had high pollen inputs of dominant local taxa combined with low frequencies of Acacia and Chenopodiaceae/Amaranthaceae, and moderate Eucalyptus pollen frequencies. Hummock grassland and Chenopod low shrubland pollen assemblages reflected the local vegetation and had low frequencies of pollen likely to have a regional source, such as Eucalyptus, Casuarina and Callitris/Actinostrobus. (C) 1999 Elsevier Science B.V. All rights reserved.