30 THE BROAD-SCLEROPHYLL VEGETATION OF CALIFORNIA. 



IV. VEGETATION AND HABITAT. 



THE LOCALITY FOR INTENSIVE STUDY. 

 THE PALO ALTO REGION. 



For intensive study of vegetation and habitat it was necessary 

 to find a spot as nearly representative as possible, affording oppor- 

 tunity for comparison of related communities and favorably situated 

 with respect to a base of operations. The vicinity of Palo Alto 

 satisfied these requirements, the botanical laboratory of Stanford 

 University furnishing facilities for indoor work. 



Palo Alto is situated in the central Coast Range region, near the 

 southern extremity of San Francisco Bay, from which it is but 

 3 km. distant. The lowland upon which it lies extends along the 

 southwest shore and is commonly spoken of as a northwestward 

 extension of the Santa Clara Valley. Southwestward from the town 

 rise the Santa Cruz Mountains, the crest, ranging from 512 to 850 

 meters in height, being 11 km. distant. The northeast face of the 

 range is a fault scarp, and therefore abrupt. There is, nevertheless, 

 a zone of foothills between the main mountain front and the valley, 

 in the vicinity of Palo Alto 5 km. broad and attaining a height 

 of 246 meters. The altitude of Palo Alto itself is but 17 meters. 



The topographic diversity just outlined, together with the influence 

 of the ocean, which is distant from Palo Alto 25 km. over the Santa 

 Cruz Range, produces very great climatic differences within short 

 distances. Thus, the annual precipitation at Palo Alto is 66 cm., 

 while on the mountain summits, only 15 km. away, it is 139 cm. 

 (23, p. 186). At the ocean shore the precipitation is again light, 

 75 cm. being recorded at one station. The summer fogs, which 

 regularly cover the mountains but rarely invade the valley, are also 

 of profound climatic importance. 



In correlation with topographic and climatic diversity we find 

 equal diversity in the vegetation. The prevailing type in the fog- 

 bathed mountains is the redwood forest; the well-watered mountains 

 without fog support a vegetation made up of evergreen oaks, madrono, 

 and Douglas fir; the foothills and drier mountain sides are clothed 

 with chaparral except where local conditions, such as steep north 

 slopes, permit the development of oak forest; the gentle slope from 

 foothills to bay was originally covered by chaparral, open oak forest, 

 and salt marsh, all of which have been more or less disturbed by 

 cultural operations. For an account of the redwoods and their 

 relation to rainfall and fog, the reader is referred to a former paper (23). 



JASPER RIDGE. 



The locality chosen for quadrat and instrumental study was one 

 of the higher foothills, 7 km. southwest of Palo Alto, known locally 

 as Jasper Ridge. It is a hilly mass, approximately 10 km. northwest 



