Ch. Ill] WARM TEMPERATE WOODLAND AND GRASSLAND 469 



The north temperate zone possesses, along the coast of California, another 

 district with winter rain and a dry summer, to which also corresponds 

 a xerophilons vegetation of sclerophyllous woods. 



The annual rainfall at San Francisco is 55 cm., at Monterey 40 cm. ; the 

 percentage distribution over the months, according to Woeikoff, for the 

 whole of California is : 



DISTRIBUTION OF RAINFALL THROUGHOUT THE MONTHS OF 

 THE YEAR IN PERCENTAGE IN CALIFORNIA. 



(After Woeikoff, Die Klimate der Erde, I, p. 389.) 



Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. 



20 14 16 8 4 0-3 o-i o-i 0-5 2 11 24 



Full meteorological tables such as those given above do not appear to 

 exist for California. The mean winter temperature at San Francisco is 

 10-5° C.j that of the summer 14-8° C. 



7. CONCLUSION. 



The three forms of rain-climate of the warm temperate belts distin- 

 guished in this chapter can be reduced to two types as regards the conditions 

 of existence of the vegetation. 



The first type meteorologically considered is indeed composed of very 

 heterogeneous elements, as it includes districts with nearly uniform humidity, 

 together with others possessing rain chiefly in winter and early summer, 

 but with dry late summers, and others again with dry winters and wet 

 summers. The character common to all these is that high temperatures 

 favourable to vegetation coincide with abundant precipitations even if only 

 during the early summer. The climate during the hot months therefore 

 resembles a tropical climate and impresses a quasi-tropical character upon the 

 vegetation. Here we find types of vegetation quite similar to those of the 

 tropics and associated with similar conditions as regards atmospheric pre- 

 cipitations. Very abundant precipitations cause the production of temperate 

 rainforest ; rainfall less considerable but occurring during the vegetative 

 season, particularly in the form of frequent rain in early summer, brings forth 

 grassland, and, owing to the mild winter temperature, makes it assume the 

 tropical form of savannah, which with increasing rainfall then passes over 

 into savannah-forest. Irregular precipitations during the period of vegeta- 

 tion interrupted by dry seasons, exclude grassland and cause the occurrence 

 of the most accommodating of all woodland types, thorn-woodland , as forest, 

 bush, or scrub. Still greater drought brings forth desert. 



In districts belonging to the second type, the rainy season coincides 

 with cool winter temperatures. The latter are below the optimum for a 

 number of vegetative processes, including growth, and in some of the dis- 

 tricts concerned occasionally below the minimum. The summer is very dry. 



