ABSTRACT
The factors that cause spatial diversity to vary across time and environments are examined empirically for both Australia and China. Three measures of diversity (richness, dominance, and evenness) are modeled using panel data for eight shires in New South Wales, Australia (1983 to 1997) and seven provinces in China (1982 to 1995). Using Zellner’s seemingly unrelated regression (SUR), a number of factors are identified as significant determinants of spatial diversity across these different states and provinces. Variety characteristics (yield, quality, maturity, height) features of the research system (rate of variety release, level of local adaptation of varieties), and the characteristics of the physical environment (such as moisture regime and irrigation, erosion, salinity, soil variability, multiple cropping) are shown to be important factors in explaining the observed varietal diversity. This improved knowledge of the key factors involved provides a basis for managing diversity in the future.
