ECOLOGY. 317 



Park and savannah are evidently different expressions of the same climatic 

 tendency as wrought out in the ecotone between grassland and forest at the 

 foot of mountain ranges generally or all over their slopes when they are low, 

 as is often true in the Coast Ranges. Savannah is practically confined to 

 such, with occasionally a slight development at the alpine timber-line, but 

 natural parks are regular successional features of the valleys in the montane 

 and subalpine forests of the Sierra Nevada, Cascade, and Rocky Mountains. 

 Perhaps the most striking examples of the latter are found on Mount Rainier, 

 where the deep snows are a contributing factor. The Coast Ranges of 

 California furnish what is at first glance a puzzling arrangement of grass- 

 land, savannah, natural parks, and climax forest relicts on northerly slopes, 

 but repeated study supports the conclusion that these are primarily a response 

 to climatic cycles as expressed locally in slope-exposure and regionally in 

 proximity to the ocean and hence in precipitation. 



The Original Vegetation of Death Valley, by F. E. Clements. 



The reconstruction of the original grassland vegetation of the Colorado and 

 Mohave Deserts (Year Book 21, p. 350) rendered it probable that relicts of a 

 similar grassland would be found in Death Valley, and an expedition with 

 this as one of the chief objects was made into the latter in early spring. The 

 floor of the valley proper, consisting of the periodically dry plain of the 

 Amargosa River, is so intensely saline that the only grasses found were 

 Sporobolus wrighti and Distichlis spicata. About Bennett's Well these were 

 sufficiently abundant to maintain a small herd of cattle. It is probable that 

 annual grasses develop in the less salty areas during a normal season, but 

 none were seen in this year of exceptional drought. Over the extensive plain 

 above Furnace Creek Wash, Stipa speciosa and Eriocoma cuspidata were very 

 frequent, the individuals often being so abundant as to give the appearance 

 of savannah to the Larrea climax. On lava ridges with their greater water- 

 supply owing to the reduced competition of the shrubs, Aristida purpurea 

 was the chief grass, with more or less Stipa, Trisetum pulchellum, and several 

 annual grasses, such as Festuca tenella and Bromus rubens. The best relict 

 areas were naturally found at the higher levels, the north slope of the Avawatz 

 Mountains at about 4,000 feet yielding the best picture of original conditions. 

 Here Stipa speciosa was dominant on south subslopes in an open savannah of 

 low shrubs, frequent mats of Hilaria jamesi and rigida with subcopious 

 Aristida and Stipa on the east, and Poafendleriana, Stipa, and Hilaria on the 

 north subslopes. With the exception of Hilaria jamesi and Poa, which occur 

 in the general region, all of these are likewise found in protected areas in the 

 Mohave Desert, especially in sand with its more constant water-supply, and 

 it seems certain that the same grassland climax occupied both regions before the 

 last dry phase, which permitted the entrance of the Larrea-Franseria climax. 



Application of the Relict Method, by F. E. Clements. 



The basic importance of relict species and communities for tracing the 

 major changes in vegetation has been further exemplified in the study of the 

 various climaxes. Such changes are usually the result of the shift of the 

 climatic cycle, or of grazing, cultivation, or fire. Each of these processes is in 

 general typical of a certain region or climax, and its effects, though not con- 

 fined to it, can best be investigated there. Thus, while climatic changes have 

 clearly left their mark on each of the great formations, this is most pronounced 



