PLANT MORPHOGENESIS FOR SCIENTIFIC MANAGEMENT OF RANGE RESOURCES 



113 



those areas. Hall and Pechanek (17) stated that 

 cheatgrass was probably the most important for- 

 age in southern Idaho. A U.S. Forest Service re- 

 port (51) stated that cheatgrass provided the 

 bulk of early spring grazing for all classes of 

 stock on millions of acres in the Intermountain 

 West. Not only is the forage abundant in good 

 years but it also has a high nutritive value. In 

 Montana, Hurtt (18) found that the condition 

 of horses grazed on cheatgrass pasture compared 

 very favorably with horses grazed on adjacent 

 perennial grass pasture. In southern Idaho, the 

 average grazing capacity of 5 to 8 acres per ani- 

 mal unit month (AUM) is realistic for most of 

 the cheatgrass (26). However, the contrast in 

 yields between poor and good forage years is ex- 

 treme. In southern Idaho under a mean annual 

 precipitation of 18 inches, the yield of cheatgrass 

 in 1943 was 361 pounds per acre, while in the fol- 

 lowing year it was 3,461 pounds per acre — a ten- 

 fold increase. These data illustrate Piemeisel's 

 observation (4.6) that forage production of cheat- 

 grass fluctuates greatly from year to year in re- 

 sponse to weather and is greater than that of 

 perennial grasses. 



The question may be asked, "How did the an- 

 nual range plant community come into being 

 where originally the plant cover was a mixture 

 of perennial grasses and some annual species?" 

 Most range ecologists will concede that in every 

 location where cheatgrass thrives its successful es- 

 tablishment can be associated in some way or 

 other with a disturbance or a deterioration of 

 the range ecosystem. Various factors are respon- 

 sible for this, including fire and abandonment of 

 cropland. Daubenmire (5) considered that, inas- 

 much as cheatgrass does as well as the indigenous 

 species of similar life form, it is a thoroughly 

 naturalized alien in the Agropyronetum. 



In the California annual type, Biswell (4) 

 concluded that the kind of plant cover existing 

 over the region before white man came can never 

 be determined precisely, since there is no early 

 literature that adequately describes it, and vir- 

 tually no samples remain of it. However, many 

 ecologists postulate that the original vegetation 

 in the present California annual range type was 

 a bunchgrass, primarily composed of Stipa spe- 

 cies, plus numerous indigenous annual forbs and 

 grasses of limited plant vigor. 



Management Practices Which May Condi- 

 tion Or Alter Plant Development 



In contrast with the opportunities available 

 to the farmer, the range manager has fewer tools 

 at his disposal to manipulate and manage range- 

 land vegetation. However, because of the more 

 responsive nature and dynamic characteristic of 

 annual plants, management may improve the pro- 

 ductivity and quality of annual rangelands more 

 than those of perennial rangelands. Results of 

 management practices are often obtained the same 

 year in which they are applied. Some of the more 

 common management practices that are useful on 

 annual ranges include grazing management, fer- 

 tilization, seeding, burning, and application of 

 herbicides. In some situations a single manage- 

 ment practice may suffice; whereas, in others a 

 combination of two or more may be necessary to 

 accomplish the desired ends. In practically every 

 case where a management practice is applied, it 

 produces an impact on a particular stage of plant 

 development that alters the course of subsequent 

 growth, and often the impact radiates to the rest 

 of the plant community 



Grazing management practices involve removal 

 of plant tissue. Too early grazing of plant tissue 

 reduces the photosynthetic area of the plant, and 

 cuts down the production of photosynthate to 

 feed the growing plant and to support reproduc- 

 tion. Growing points may be removed; this will 

 thwart further development of certain parts of 

 the plant. 



Range improvement by seeding involves many 

 stages of development, but the most important 

 ones are germination and establishment. Stands 

 will not become established where the existing 

 plant community is not sufficiently open to allow 

 introduction of seeded species. Seeding operations 

 must also give some competitive advantage, by 

 seed placement in a favorable position in the soil 

 or by earlier placement, to provide a time advant- 

 age against early germinating seeds. 



Range fertilization is most efficient if applied 

 when environmental conditions are most favor- 

 able for plant development. In the fall, when 

 seedlings are just developing, root growth and 

 top growth must proceed at a rapid rate in order 

 to develop an adequate root system and sufficient 

 top growth to withstand the cool winter ahead. 

 In the spring, when precipitation and moisture 



