PLANTING INDICATORS. 359 



seedlings or transplants have little chance of survival unless the sod is de- 

 stroyed about them, or unless planting is done during a period of unusual rain- 

 fall. As a desirable precaution under all conditions, the competition of the 

 grass cover should be decreased by such treatment as the density of the sod 

 and the nature of the soil will permit (Bates and Pierce, 1913: 43). By far 

 the most important practice in this connection, however, is the utilization of 

 climatic and seasonal cycles to evade serious drought during the first few 

 years (Hofmann, 1919). 



Use of climatic cycles. — The critical importance of wet and diy periods for 

 planting plans is strikingly shown by the variations in rainfall for the two 

 areas in which afforestation has been tried on a large scale. The lowest rain- 

 fall at Valentine, on the northern edge of the sandhill region of Nebraska, was 

 10 inches in 1894; the highest was 28 inches in 1905. The lowest rainfall at 

 Garden City, in the sandhill region of Kansas, was 9 inches in 1893; the 

 highest was 29 inches in 1898. In both cases the rainfall of the wettest year 

 was practically 3 times that of the driest, and the wettest and driest years 

 departed practically 10 inches from the normal. A somewhat similar con- 

 dition is shown at higher altitudes, where most of the reforestation planting 

 and sowing is done. The base of Long's Peak, altitude 8,700 feet, shows a 

 variation from 14 to 30 inches, while Pike's Peak, altitude 14,100 feet, exhibits 

 a range of 9 to 44 inches. In all of these, the minimum rainfall occurred at 

 the maximum of the 11-year sun-spot cycle, while the maximum rainfall either 

 occurred at the sun-spot minimum or was related to it through the excess- 

 deficit cycle of 2 to 3 years. In planting operations, the minimum is to be 

 avoided at all costs, and this can be done almost certainly by utilizing the 

 date of the maximum of the sun-spot cycle of 11 years. It is almost as im- 

 portant to anticipate a period of several wet years. The correspondence of 

 the wet phase with the sun-spot minimum is not so good as that of the dry 

 phase with the maximum, but it is sufficiently close in time and amount to 

 make a great improvement over present methods. When the excess-deficit 

 cycle is taken into account, the correspondence becomes so close as to warrant 

 the assumption that planting can be planned in such a way as to avoid dry 

 periods and to coincide with wet ones. As already shown in Chapter V, it is 

 necessary to determine the operation of the climatic cycle in the particular 

 region concerned. 



Reforestation indicators. — The first definite proposal to use native plants as 

 indicators of specific planting sites appears to have been made by Zon (1915): 



"The selection of sites suitable for planting in a region which has been 

 stripped of its natural timber is among the most perplexing problems. As 

 long as there is a remnant of the virgin forest left, the latter may serve as a 

 guide in selecting the species to plant on the given site. 



"When, however, as is the case of the Ephraim Canyon and several other 

 canyons on the Manti Forest, the original virgin timber has nearly disappeared 

 altogether, both as the result of severe burns and grazing, and has been re- 

 placed by shrubs, herbaceous vegetation, and wide stretches of aspen cover 

 extending over an area originally occupied by several forest types, the ques- 

 tion of deciding what species to plant on a given site becomes very difficult 

 indeed. In such cases the shrubs and the herbaceous vegetation which occur 

 throughout the canyon can be used to advantage as an indicator of the mois- 



