182 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



needles in securing quicker germination, larger number of plants per 

 square foot and per pound of seed, and better root systems. 



Two species — noble fir and amabilis fir — regarding whose behavior 

 in the nursery little was known before were made a special subject 

 of study at the Wind River Experiment Station. 



A great many of the experiments concerned with the best methods 

 and seasons for reforestation work were brought to conclusion. All 

 confirm the conclusion previously reported that, in general, planting 

 is much safer than direct seeding and usually less expensive. In 

 the semiarid Southwest planting can now be carried on with reason- 

 able assurance of success. 



Of the more fundamental studies in which progress was made 

 during the year, the studies of forest types deserve particular mention. 

 These studies have an important bearing on practically all other 

 forest problems, such as forest management, reforestation, fire pro- 

 tection, and even land classification. They provide a knowledge of 

 the environment in which the forests grow and of the factors 

 which particularly affect growth, reproduction, and susceptibility to 

 fire and other dangers. Their ultimate object is the quantitative 

 determination of the climatic and soil requirements of different 

 forest types and other plants growing within the National Forests. 

 Such investigations are now being conducted in practically all of the 

 National Forest districts, but are receiving particular attention in the 

 central Rocky Mountains. 



A study of the conditions under which natural reproduction may 

 be expected after cutting or fire in certain forest types, and also of 

 those where artificial methods must be used to bring back the forest 

 cover, received further attention during the year, particularly in 

 the Douglas fir and western white-pine region of the Northwest and 

 the western yellow pine of Arizona. In the Northwest the character- 

 istic capacity of the Douglas fir and western white-pine seed to lie 

 over in the duff and leaf litter for a number of years and sprout up 

 after the forest is burned or cut off has been investigated further as 

 one of the most important facts bearing upon the capacity of the forest 

 to reproduce itself naturally after cutting or burning. In the western 

 yellow pine of the Southwest the study brought out the facts that 

 failure of natural reproduction is due not so much to lack of germi- 

 nation as to the heavy mortality of many young seedlings; that a 

 combination of good seed crops with favorable climatic conditions 

 is required; and that seedlings need the protection of older trees as 

 secured with conservative cutting that leaves merchantable young 

 trees as a basis for a future crop. 



Another important phase of the reproduction study is that of pro- 

 tection from grazing. Very definite results were secured as to the 

 extent and conditions under which grazing proves detrimental to 

 the natural reproduction, and specific remedial measures were evolved. 

 With the development of watering places and the construction of 

 fences, making possible the shifting of stock at will, the system of range 

 management can be further improved so as to coordinate more 

 effectively the best interests of both silviculture and grazing. 



The first series of permanent sample plots established for the pur- 



Eose of studying yield and reproduction of western yellow pine and 

 ►ouglas fir has come up for the first 5-year remeasurement. Although 



