4 CIRCULAR 491, U. S. DEPARTMENT OF AGRICULTURE 



virgin pastures. The extreme slowness with which blue grama 5 

 and many of the taller grasses became reestablished was responsible 

 for this qualitative condition of the vegetation on abandoned areas. 



Vegetative portions of stoloniferous or rhizomatous grasses ap- 

 peared to be capable of renewing active growth after a limited period 

 of light cultivation and desiccation. Most of the tufted grasses 

 failed to survive light cultivation. Seeds of buffalo grass and other 

 hard-seeded species appeared to be capable of remaining in cultivated 

 soils and emerging after several years of light cultivation. 



Abandoned areas enclosed and grazed with adjacent virgin pas- 

 tures recovered more rapidly than those grazed by themselves. Live- 

 stock apparently were helpful in disseminating the seed of buffalo 

 grass, since numerous seedlings of this species were noted emerging 

 from the droppings of cattle. Grazing, unless extreme, also favored 

 the spread of buffalo grass by reducing the shade and competitive 

 effect of weeds and taller grasses. Other species, however, were de- 

 layed in recovery by close grazing of fields and adjacent pastures, 

 which reduced seed production, hampered seedling survival, and 

 promoted soil blowing. 



The proximity of tilled fields and the resultant damage from soil 

 blowing greatly delayed recovery in many instances. Much damage 

 resulted from the smothering effect of wind-deposited silt. The 

 scarifying action of dust-laden winds seriously contributed to the 

 death of many pasture plants in the region. Small pastures, often 

 wholly surrounded by cultivated fields, suffered more injury than 

 large areas. 



Damage from soil blowing usually was more noticeable on sandy 

 soils than on soils of heavier texture, but recovery on the sand, when 

 protected from excessive grazing and wind erosion, was more rapid 

 than on the heavier soils. Kecovery on sandy areas was not only 

 delayed by soil blowing but also by the absence of stoloniferous 

 species and the scarcity of rhizomatous species. Under certain con- 

 ditions blowout grass, prairie sandgrass (sand reedgrass), and giant 

 reedgrass had rhizomatically stabilized active dunes and were being 

 gradually replaced by more palatable species. Cultivation, abandon- 

 ment, and eventual reestablishment of grasses on sandy soils resulted 

 in satisfactory control of sand sagebrush and other undesirable weedy 

 shrubs, leaving many abandoned fields with a cover superior to adja- 

 cent untilled pastures. Reporting on similar results in Canada, Clarke 

 and Tisdale (12) stated that when a good stand was obtained on an 

 abandoned field it was much more productive than the native sod. 



On all soils succession of growth on abandoned fields assumed four 

 rather distinct but overlapping stages. These are listed in order of 

 dominance within each group: (1) Annual weeds and annual grasses; 

 (2) the less palatable short-lived perennial grasses, and biennial and 

 perennial forbs; (3) short-lived perennial grasses, perennial forbs, 

 and a few long-lived perennial grasses; (4) dominant and secondary 

 perennial grasses, accompanied by varying quantities of other plant 

 species, depending on environmental conditions. 



Sand dropseed, red three-awn, and bluestem (western wheatgrass) 

 were usually the first perennial grasses to become established on aban- 



5 The scientific names, accredited common names, and locally recognized and other 

 synonyms for this and other grasses mentioned are listed in the Appendix, p. 54. 



