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Studies of a vegetation transect through brigalow ( Acacia harpophylla ) forest in central Queensland
Author(s) -
JOHNSON R. W.
Publication year - 1980
Publication title -
australian journal of ecology
Language(s) - English
Resource type - Journals
eISSN - 1442-9993
pISSN - 0307-692X
DOI - 10.1111/j.1442-9993.1980.tb01254.x
Subject(s) - ordination , detrended correspondence analysis , vegetation (pathology) , ecology , transect , gradient analysis , geography , evergreen , biology , medicine , pathology
Vegetation and environmental data were collected in 182 contiguous plots along a belt transect, 3.7 km long, in central Queensland through a relatively undisturbed forest dominated by brigalow (Acacia harpophylla). A subset of eighty‐nine plots using percentage cover of 128 species was classified using a polythetic agglomerative approach. Dual stand and species ordinations by principal component analysis and reciprocal averaging were also undertaken.The cluster analysis and ordination of unstandardized cover data, grouped stands on the basis of abundance of the predominant canopy species, but only where these species were true dominants such as Macropteranthes leichhardtii did these same groupings appear in the ordination of standardized data. The latter ordination was ecologically more satisfying, but the complementary species ordination was unsatisfactory. The vegetation‐species complex was best explained by dual species and stand ordinations using presence‐absence data. Reciprocal averaging appeared to produce a marginally better ordination than principal component analysis. An ordination of eleven environmental factors indicated soil profile and presence of gilgai were the most important environmental variables. The ordination was enhanced by varimax rotation which focused on a more homogeneous environmental gradient and coincided more closely with the vegetation ordinations. An ordination using both species and environmental factors substantiated the explanation of the vegetation‐environmental complex derived from separate ordinations. The main gradient revealed from the ordinations appeared to be a mesic‐xeric gradient stretching from Macropteranthes leichhardtii semi‐evergreen vine thicket at the mesic end diverging through various A. harpophylla ‐ dominant communities to A. harpophylla ‐ Eucalyptus melanophloia woodland on duplex soils and Dichanthium affine grassland on clay soils. Six plant communities are defined and described and each related to a particular set of environmental conditions. These communities are bonewood (Macropteranthes leichhardtii) ‐ semi‐evergreen vine thicket, brigalow (Acacia harpophylla) ‐ semi‐evergreen vine thicket, brigalow (A. harpophylla) continuum (clay soils) , Dichanthium affine grassland, brigalow (A. harpophylla) continuum (duplex soils) and brigalow (A. harpophylla) ‐ silver‐leaved ironbark (Eucalyptus melanophloia) woodland.