b NORTH AMERICAN FAUNA 70 



similar to that presented by Franklin and Dyrness (1973). Some of the 

 departures between the system used here and that of Franklin and 

 Dyrness (1973) are mentioned in the following discussion of plant 

 communities of Jackson County. 



Four plant communities occur in Jackson County. Scientific names 

 of the vegetation are from Randall (1964). 



Chaparral-Oak Community. — The Chaparral-Oak area of the 

 Lower Rogue River and Bear Creek valleys is considered a probable 

 postglacial relict (Detling 1961) related to the California chaparral 

 formation south of the Siskij^ou Mountain barrier. In Jackson County 

 this area from the valley floor to about 762 m is more arid and has 

 hotter day-time temperatures than the surrounding areas. Land not 

 under cultivation or uninhabited is dominated by island groves of 

 Quercus garryana and Q. kelloggii, with an understory of Ceanothus 

 cuneatus and Arctostaphylos viscida. Ceanothus cuneatus and Arcto- 

 staphylos viscida may be found throughout the valley and foothills 

 growing in dense brushfields or mixed with Quercus groves. Much of 

 the area is characterized by large open fields of dwarf grasses and short- 

 lived annuals that usually die by mid-June because of lack of precipi- 

 tation. Such fields frequently stand under 2.5 cm or more of water 

 during mnter. 



The eastern Bear Creek foothills are characterized by larger and 

 more abundant Quercus groves, scattered trees of Pinus ponderosa, and 

 an understory of Rhus diversiloba (Fig. 2). Most of the southern and 

 western slopes of Roxy Ann Peak and Baldy are dominated by nearly 

 impenetrable Rhus diversiloba, often over 3 m high, interrupted only 



Fig. 2. Foothills east of Medford. Quercus groves and Pinus ponderosa are the 

 predominate trees. Ceonothus and Arctostaphylos spp. occupy most of the 

 foreground. Elevation, about 610 m. 



