Geographic distribution

Cardiac steroids occur ia small amounts ia various plants with a wide geographical distribution. The purple foxglove Di talispurpurus has been used for centuries as both a dmg and a poison. Isolation and characterization of the various cardiac steroids have been reviewed (122,123). 

Known world coal reserves in 1990 were estimated to be about 1000—1600 biUion metric tons (4). The geographic distribution of these reserves is widespread, but about two-thirds of this coal resides in the United States, People s RepubHc of China, and the Commonwealth of Independent States. 

Raw data must be analyzed and transformed into a format useful for specific purposes. Summary tables, graphs, and geographic distributions are some of the formats used for data display. Air quality information often consists of a large body of data collected at a variety of locations and over different seasons. Table 15-3 shows the tabular format used by the California Air Resources Board to reduce ozone hourly measurements to a format which shows information about compliance with air quality standards (6). The format has location, maximum values, annual means, and number of occurrences of hourly values above a given concentration as a function of the month of the year. One can quickly determine which areas are violating a standard, at what time of the year elevated concentrations are occurring, and the number of good data points collected. 

Figure 8. Geographical Distribution of Bicarbonate/Sulphate Ratio in the Surface Waters of Eastern Canada Indicating the Regions of Significant Acidification, adapted from reference 34.

Fig. 17-6 Calculated geographical distribution of the climate forcing (W/m ) by anthropogenic greenhouse gases alone, from pre-industrial periods to ca. 1990. From IPCC (1995), after Kiehl and Briegleb (1993). See text for interpretation. (Reprinted by permission from IPCC.)...

The survey of geographical distribution patterns of secondary plant constitnents starts with examples that come, more or less, from within continents. In many examples, the patterns of variation involve comparatively small areas, a few connties perhaps, and could be referred to as local whereas in others, considerably larger areas are involved, often several states or provinces, or even large pieces of a country. In most cases, however, the regions nnder consideration lie within a single continental land-mass. A few examples come from island systems (e.g., New Zealand) where the existence of major landmasses separated by a small stretch of water does not appear to have had an effect upon the distribution reported, or at least none has been reported. 

Rick, C. M. and Fobes, J. F. 1975. AUozymes of Galapagos tomatoes polymorphism, geographic distribution, and affinities. Evolution 29 443 57. 

Sewell, M. M., Parks, C. R. and Chase, M. W. 1996. Intraspecific chloroplast DNA variation and biogeography of North American Lin odendron L. (Magnoliaceae). Evolution 50 1147-1154. Shapiro, J. A., Steffens, J. C. and Mutschler, M. A. 1994. Acylsugars of the wild tomato Lycopersicon pennellii in relation to geographic distribution of the species. Biochem. Syst. Ecol. 22 545-561. 

Thompson, P. A. 1973. Seed germination in relation to ecological and geographical distribution. 

Have a broad geographic distribution, especially if comparison of ecosystem changes in different regions of the country is desired... 

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