Rocky Mou7itain Seedling Growth 103 



and thrift of trees present to shed needles. Both have the effect 

 of preserving the all-important soil moisture, whereas the needles 

 do not furnish nitrogen and other essential elements to the soil 

 until they have changed to humus. It is then that the bacteria, 

 under the proper degree of moisture, temperature, and aeration, 

 liberate from the needles these elements and reduction products, 

 to be re-combined with soluble minerals for the use of the trees. 

 The relative meagerness of the granitic soil, both in quantity 

 and quality, is such that this return of fertility to the soil should 

 not be overlooked as a factor in establishing seedling growth. 



In the Engelmann Spruce, an important factor in the ground 

 cover is dead wood. Trees of all sizes and stages of decay lie 

 thickly upon the ground throughout the greater part of the 

 range of this species. On the more favorable north slopes, re- 

 production has covered the ground thickly and evenly. But 

 that which emanates from under fallen trees is as a rule the 

 largest. On the less favorable slopes, all the reproduction in 

 some situations, and much the best in others, occurs either in 

 clumps at crossings of dead trees, and about snags and piles of 

 rubbish, or in strips along fallen stems. The young spruce pro- 

 fited either by the long-continued snow cover, or the preserved 

 soil moisture, or the fertile humus, or the shade, or the attend- 

 ing coolness and humidity, or other protection, or by some or all 

 of these combined, which the dead wood furnished. It has now 

 served its purpose, and had better be removed, where not too 

 much decayed, in order to lessen danger from fire. But on un- 

 favorable planting areas, if left on the ground, it may serve the 

 same purpose that it has served before. On many inhospitable 

 slopes, this may prove a most important factor. The fire argu- 

 ment bears little weight here, for a dense young stand of 

 spruce without dead wood is far more inflammable than an area 

 thickly strewn with dead wood but without young spruce. There 

 must be fire protection in any case. Quantity and quality of 

 material to be removed, in a climate so inimical to decay, will 

 suffer but little by later removal. The greater care necessary 

 will be offset by growing scarcity of wood. Of course, if left, 

 it will somewhat impede planting operations. But future versus 

 present removal may mean the entire difference between refor- 

 estation and no reforestation. 



No reproduction exists in heavy grass sod, and vice versa. 

 This goes to show what has been shown time and again, that the 



