PLANT MORPHOGENESIS FOR SCIENTIFIC MANAGEMENT OF RANGE RESOURCES 



73 



the application of managed grazing. Some of 

 these have been helpful in restoration of browse 

 as well as herbs {25, 26, 28, 38, 39, 48,51). 



Observations of grazing animals, as well as 

 many chemical analyses and digestibility trials, 

 show that woody perennials provide nutrients, 

 such as protein and vitamins, which keep graz- 

 ing animals healthy and vigorous through a con- 

 siderable part of the year when herbaceous plants 

 are dry and dormant and lack good nutritional 

 qualities {12, 13, 14, 16, 19, 34, 51,53). Hence, it 

 is important on many ranges that woody peren- 

 nials represent a fair degree of balance with 

 herbs. Managing to maintain this balance is a 

 major problem for the future. 



Characterization Of Western Shrublands 



Estimated hectares of the six major shrubland 

 types in the Western United States, shrubs that 

 characterize each type, and the approximate range 

 in average annual precipitation for each area are 

 shown below. These types are comprised of several 

 species, and only the major ones are mentioned in 

 this discussion or noted as follows: 



NORTHERN DESERT SHRUBS: 



Precipitation, 125-375 mm.; 100 million hectares 

 Big sagebrush {Artemisia tridentata Nutt.) 

 Black sagebrush {A. arbuscula Nutt. nova 



[A. Nels.] Conq.) 

 Rubber rabbitbrush {Chrysothammus nause- 



osus [Pall.] Britton) 

 Small rabbitbrush {C. viscidiforus [Hook.] 



Nutt.) 

 Nevada ephedra {Ephedra nevadensis Wats.) 

 Spiney sage {A. spinescens DC, Eaton) 

 Blackbrush {Coleogyne ramosissima, Torr.) 

 Fourwing saltbush {Atriplex canescens 



[Pursh.] Nutt.) 

 Spiney hopsage {Grayia spinosa [Hook.] 



Moq.) 

 Winterfat {Eurotia lanata [Pursh.] Moq.) 



JUNIPER & PINYON 



Precipitation 200-275 mm.; 36 million hectares 

 Utah juniper {Juniperus osteosperma Torr. 



Little) 

 Sierra juniper {J. occidentalis Hook.) 

 Two-leaf piny on pine {Pinus edulus En- 



gelm.) 



Single - leaf pinyon pine {P. monophylla 



Torr. & Frem.) 

 Big sagebrush 

 Black sagebrush 

 Rubber rabbitbrush 

 Cliffrose {Cowania mexicana D. Don) 

 Antelope bitterbrush {Purshia tridentata, 



Pursh. DC) 

 Green ephedra {Ephedra viridis Cov.) 

 MOUNTAIN BRUSH: 



Precipitation 300-750 mm.; 6 million hectares 

 Gambel oak {Quercus gambelii Nutt.) 

 Big sagebrush 

 Mountain snowberry {Symphoricarpos oreo- 



phillus A. Gray) 

 Black chokecherry {Prunus virginiana mel- 



anocarpa [A. Nels.] Sarg.) 

 True mountain mahogany {Cercocarpus 



montanus Raf.) 

 SALT DESERT SHRUBS : 

 Precipitation, 100-350 mm.; 28 million hectares 

 Black greasewood {Sarcobatus vermiculatus 



Hook.) 

 Shadescale saltbush {Atriplex conferti folia 



Torr. & Frem) 

 Gardner saltbush {A. gardneri Moq. D. 



Dietr.) 

 Fourwing saltbush 

 Spiney sagebrush 

 Spiney hopsage 

 Winterfat 

 CHAPARRAL: 



Precipitation, 250-1,000 mm. ; 12 million hectares 

 Turbinella oak {Quercus turbinella Green) 



and other live oaks 

 Buckbrush {Ceanothus spp. L.) 

 Manzanita {Arctostaphyllos spp. Adams.) 

 Chamise {Adenostoma fasciculatum H. & A.) 

 SOUTHERN DESERT SHRUBS : 

 Precipitation, 200-750 mm. ; 150. million hectares 

 Velvet mesquite {Prosopis juliflora [Swartz.] 



DC.) 

 Creosotebush {Larrea divaricata Cav.) 

 Tarbush {Flourensia cernua DC.) 

 Saguaro {Cereus giganteus Engelm.) 

 Joshua tree {Yucca brevifolia Engelm.) 

 Blackbrush 

 Fourwing saltbush 

 While ecotones between types may be quite 

 distinct, in many places there is abundant inter- 



