Paper No. 7 



MORPHOGENESIS AND MANAGEMENT OF WOODY PERENNIALS IN 



THE UNITED STATES 



By A. Perry Plummer 1 



Woody perennial shrubs and small trees occur 

 as an important part of the ground cover on 

 over 300 million hectares in the United States. 

 On millions of additional hectares, shrubs are im- 

 portant underston 7 in the deciduous and conifer 

 forests east of the Mississippi River and else- 

 where. My emphasis is directed to rangeland as- 

 pects of wood}' vegetation of the West where 

 shrubs are usually not understory. 



Woody perennials occur over nearly the full 

 gamut of climate and soils. They may be found 

 at all altitudinal and latitudinal limits, except 

 where the ground is permanently covered with 

 snow. They are the prevailing cover in the hot 

 deserts below sea level in the Salton Sea basin 

 and in Death Valley, Calif. (5) . 



In various environments, this class of plants 

 functions in many ways to serve mankind. They 

 provide forage for millions of sheep, cattle, and 

 wild animals and are important as a protective 

 cover for these animals, especially when tempera- 

 tures are extremely hot or cold. Without such 

 protective shade, many small animals would be 

 eliminated. Frequently, the shade of this class of 

 plants also provides the microclimate for the 

 growth of a great variety of understory herbs. 



Woody perennials are unexcelled in the ability 

 to grow in sterile and highly salt-impregnated 

 land where they stabilize soils which would 

 otherwise be completely barren and subject to 

 wind and water erosion. In contrast, there are 

 woody perennials which provide important cover 

 in extremely wet, acid conditions. Character- 

 istics that adapt shrubs for particular habitats 

 result in a large variety of ecotypes and biotypes 

 within species (11, 54)- This may be more true 

 for shrubs than for any other class of plants. 



1 Project Leader, Great Basin Experimental Area. In- 

 termountain Forest and Range Experiment Station, F.S.. 

 T.S.D.A., Ephraim, Utah. 



72 



A rationalization has grown up, at least in 

 Western United States, that some woody plants 

 are bad and others are good because of their dif- 

 ferences in aggressiveness, forage value, suscepti- 

 bility to fire, water consumption, and other at- 

 tributes. No doubt there is a considerable bias at 

 times, as to what may be a good or bad woody 

 perennial. Some may be considered good in cer- 

 tain environments and bad in others. 



An outstanding example of this is the widely 

 occurring and variable big sagebrush (Artemisia 

 tridentata Nutt.). On many spring and summer 

 livestock ranges sagebrush is regarded as a com- 

 petitive menace to grassland, and for this reason 

 attempts are made to eliminate it. A large num- 

 ber of mechanical and herbicidal techniques have 

 been devised for reducing it (38, 40, 45). In con- 

 trast, on many winter ranges for livestock and 

 game, big sagebrush is the most important source 

 of forage. Because of its high nutritive value and 

 the fact that in this season it is palatable as well 

 as highly productive, sagebrush has been recom- 

 mended for seeding on extensive winter game 

 ranges in Utah, and is one of the best shrubs avail- 

 able for this purpose. Special effort has been di- 

 rected to aerial planting of sagebrush on large 

 blocks of winter game range in Utah (45). 



A great amount of emphasis has been given to 

 encouraging replacement of woody perennials by 

 herbaceous plants through management practices 

 (39, 48), including artificial treatments and 

 planting adapted species (43, 45). This is usually 

 justifiable, but I have seen some elimination of 

 woody perennials where I thought the judgments 

 were misguided. 



Uncontrolled grazing by livestock over the 

 past century has been the major reason for a de- 

 cline and loss of palatable elements of both woody 

 and herbaceous species. However, major improve- 

 ments have been obtained in some areas through 



