REPRODUCTION OF WESTERN YELLOW PINE. 67 



the weedlike plants which are usually present in a subdued form 

 under the trees spring up quickly after the trees are removed and 

 within five years, if their growth is not interfered with, they develop 

 a cover which is much denser and more luxuriant than normal grass 

 areas. When this stage is reached the soil moisture becomes more 

 completely exhausted in stump patches than elsewhere. If pine 

 seedlings can secure a foothold before the herbaceous growth becomes 

 too dense, or if the latter is held in check by proper grazing or other 

 means, they develop much more vigorously in the stump patches 

 than in other situations (PL XII) ; but if from lack of seed 

 or other causes germination is deferred several years after cut- 

 ting and the herbaceous plants are not kept down, the pine seed- 

 lings which do start find themselves in a veritable jungle of vines 

 and other leafy herbage which not only robs the seedlings of mois- 

 ture but in many cases completely covers and chokes them out. The 

 stump patches, because of the palatability of their forage plants, are 

 very closely cropped where stock is permitted to graze. This gives 

 the pine seedlings a chance, provided that they, too, are not devoured, 

 as is the case on improperly grazed sheep range. 



A comparison of various situations with respect to the progress 

 of the large stand of seedlings which originated in 1919 brings out 

 the following relations. On sheep range the stump patches are very 

 closely cropped, so that scarcely a pine seedling remains alive, and 

 those living are usually injured; but in adjoining bunch-grass areas 

 considerable numbers of seedlings have escaped injury because of 

 the protection of the grass, which is but lightly grazed by sheep. On 

 stump patches from which all grazing has been excluded for 10 years, 

 almost every seedling has been choked out by the luxuriant herba- 

 ceous cover. On areas which were heavily grazed by cattle and sheep 

 up to 1919 and subsequently excluded to sheep, pine seedlings in 

 stump patches are from two to three times as large as those of the 

 same age outside the stump patches. The conclusions to be drawn 

 from the above relationships are unmistakable. Disregarding the 

 damage by sheep grazing, which will be more fully discussed under 

 " Grazing," this fact stands out so plainly * that it can not be over- 

 looked : Western yellow pine seedlings grow best where they are 

 unhampered by the root competition and shade of older trees or 

 herbaceous vegetation. Organic matter added to the soil by the 

 decay of leaf litter and roots and the aeration provided by large 

 roots are undoubtedly important contributory factors in the vigorous 

 growth of seedlings in stump patches. The forest should be so man- 

 aged that these conditions as well as the moisture made available 

 when mature trees are cut may be utilized by pine seedlings rather 

 than by herbaceous plants. 



