RANGE PRESERVATION AND EROSION CONTROL. 23 



owing to the low moisture content due to exposure and Lowered 

 water-holding power, seed germinate poorly. Moreover, aboui oine- 

 tenths of the plants which do come up die early in the spring while 

 still in the seedling stage. The remainder usually dry up before tin- 

 end of the season. 



Interesting contrasts have been recorded on the mountain ranges 

 of the Manti National Forest as to the rate of revegetation and the 

 character of species being established on overgrazed and subsequently 

 eroded lands as compared with lands which have not been seriously 

 overgrazed, and where the soil, therefore, is relatively productive. 

 During observations extending over four years (1913-1910) it was 

 most exceptional to find on the more seriously eroded soils an increase 

 in the number or appearance of new deep-rooted perennial species of 

 any kind. On the less seriously eroded soils, on the other hand, 

 shallow-rooted perennial species, both seedlings and matured speci- 

 mens have gradually increased in number each season ; and on some- 

 what overgrazed, but not eroded lands, deep-rooted perennials have 

 increased relatively rapidly and steadily. 



On analyzing the data recorded as to the rate and character of 

 the revegetation it was found that by noting the seriousness to which 

 the soil has been eroded, and hence its physical condition, including 

 the relative amount of organic matter contained in it, it is possible 

 to predict with much precision not only the rate at w 7 hich the ground 

 cover may be restored but the- particular kind of plants that will 

 occupy the soil for a temporary period prior to establishment of a 

 permanent vegetation. As a, general thing, manj^ years must lapse 

 before the more desirable forage species can reoccupy the site upon 

 which they formerly predominated. The reestablishment of the 

 deeper-rooted perennial species, if this type of vegetation is desired, 

 and it usualty is, can be accomplished on these eroded soils under 

 range conditions only by certain rather inconspicuous plants first 

 gaining a foothold on the land and gradually reinstating the vege- 

 table matter and plant foods which are invariably lacking. 



The- replacement of one set of plants by another through a series 

 of successive invasions is known as plant succession. Where the fer- 

 tility of the soil has been seriously impaired only rapidly growing 

 and early maturing annual species first occupy the soil. Several 

 species of this type of vegetation begin germination and growth 

 promptly in the spring, and before the soil has dried out to a point 

 where the vegetation wilts beyond recovery and further growth, the 

 plants have developed fully and ripened an abundant seed crop of 

 good germination strength. The ramifications of the roots of these 

 inferior plants through the soil season after season, the aeration 

 of the upper soil layer as a result of the innumerable penetrations 



