Cii.III] WARM TEMPERATE WOODLAND AND GRASSLAND 459 



can hold its own against wood, in a climate that suits it. In the pampas 

 district grass is driven out only where water is very abundant in the soil, as 

 for instance along the banks of rivers. In fact, as the tables show, the 

 pampas climate is a perfect grassland-climate, with its rainfall not more 

 than moderate but well distributed, and its humid moderately warm vege- 

 tative season. In addition, the strong winds of the pampas, with moderate 

 atmospheric humidity, represent a factor hostile indeed to woodland but 

 innocuous to grassland. 



The spread of the grass towards the east is opposed by the reduced rain- 

 fall, and, as may be inferred from the considerable number of hours of 

 sunshine, by its less equable distribution in time ; this latter is revealed by 

 statements of travellers, who describe the climate as dry compared with 

 that of the pampas. That the climate in the espinal-formation is directly 

 unfavourable to grass appears from the observation of Lorentz that grasses 

 rarely reoccupy clearings to any large extent ; indeed they frequently spring 

 up only under the shelter of trees from a soil resembling a threshing-floor 

 in its bareness. 



That woods thrive under such circumstances is a consequence of the 

 accommodating power of xerophilous thorn-bush. There is also in their 

 favour that, in opposition to the pampas, calms predominate over windy 

 weather. 



North Patagonia climatically resembles West Argentina, and possesses 

 a similar vegetation, chiefly formed of shrubs, which are very scanty in the 

 desert-like interior. 



Warm Temperate Grassland Climate. 



PAMPAS. 



SAN JORGE (CENTRAL URUGUAY). 



32 43' S., 56 8' W., 122 meters above sea-level. 



(From Meteorol. Zeitschr., 1886, p. 324.) 



