. The distribution of vegetation in the United States, as related to climatic conditions. Phytogeography. 380 ENVIRONMENTAL CONDITIONS. We have prepared another chart of this kind by superimposing the chart of the physiological summation indices of temperature for t&e average frostless season (plate 40 and fig. 1) upon that of the precipi- tation-evaporation ratio for the average frostless season (plate 57 and fig. 16), and the result is shown in figure 19, where the broken lines represent temperature conditions and the full ones represent condi- tions of moisture. On this chart each of th
. The distribution of vegetation in the United States, as related to climatic conditions. Phytogeography. 380 ENVIRONMENTAL CONDITIONS. We have prepared another chart of this kind by superimposing the chart of the physiological summation indices of temperature for t&e average frostless season (plate 40 and fig. 1) upon that of the precipi- tation-evaporation ratio for the average frostless season (plate 57 and fig. 16), and the result is shown in figure 19, where the broken lines represent temperature conditions and the full ones represent condi- tions of moisture. On this chart each of the five temperature provinces is subdivided into four moisture provinces and the country is thus represented as a mosaic of small areas of various shapes and sizes, each area being characterized by a certain range and amplitude of the temperature index and also of the moisture index. Following our previous usage, climatically descriptive adjectives may be employed. Fig. 19.—Two cliniPiisiorial moisture-temperature provinces, hein^ a combination of figures 1 and 16. Broken lines limit temperature efficiency provinces (fij:. 1), full lines limit precipitatiou- evaporation provinces, (fig .10). (See also Plates 40 and .57.) in designating these ranges of index values, and two such adjectives suffice to describe any one of the irregular areas shown on the chart. Thus, we may refer to the wanfi semiarid province, the incdium humid province, the cool semihu7?iid province, etc., each of these provinces including the coincident or overlapping portions of the corresponding temperature and moisture provinces. An examination of figure 19 shows, however, tliat several different geographical areas may be characterized by the same pair of adjectives, and these may be designated by geographically dcscripti\'e terms,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectphytoge, bookyear1921
