THE FOREST NURSERY 293 



variety of coniferous and broad leaved species in northern Italy and 

 elsewhere in southern Europe, it is very little used in forest 

 nurseries in the United States. The chief objection to it is the 

 unequal distribution of the shade and the interference of the trees 

 with the working of the soil. The trees also compete with the 

 nursery stock for the moisture and available plant nutrients in the 

 soil. As a rule, the trees should stand at intervals of about 20 feet. 

 Their moving shade not only protects the young plants but also 

 contributes to the comfort of the laborers in working the nursery. 



Seedbeds under a live cover are usually made from 3 to 6 feet 

 in width and of variable length, often the entire length of the 

 compartment. The most usual width is 4 feet, as a wider bed is 

 more difficult to weed and manage. 



In some parts of Europe a live cover is formed by growing hemp 

 or some other rapidly-growing species along the south border of 

 narrow seedbeds which checks the wind and provides adequate 

 protection from the sun. 1 Alder is sometimes grown in the seed- 

 bed with various coniferous species. It soon grows above the 

 conifers and forms a nurse crop or live cover from 1 to 5 feet in 

 height. The alder plants are at first from 8 to 10 inches apart 

 and are gradually thinned out. Not only do they shade the 

 conifers but they also improve the quality of the soil. 



28. SHADING SEEDLINGS WITH ARTIFICIAL COVERS. Several 

 forms of artificial cover are used for shading seedbeds. In most 

 localities they have proved less costly and more successful than 

 live or natural ones. The degree of shading can be controlled 

 better and they do not compete with the growing stock for soil 

 moisture and nutrients. All forms of artificial cover may be 

 classed under the following heads: 



a. High covers. 



b. Low covers. 



The former are raised sufficiently high above the seedbeds to per- 

 mit horses to pass beneath in working the soil. Low covers are 

 removed in the formation and working of the seedbeds. 



29. High Covers. High covers are continuous over the entire 

 compartment. Posts sufficiently long to reach 8 feet above the 

 surface of the seedbeds are set upright in the soil at intervals of 

 from 9 to 12 feet. Slender poles or scantlings are spiked to the 



1 Woolsey, T. S.: A glimpse of Austrian forestry. (Proc. Soc. Am. For., 

 vol. IX, p. 23. 1914.) 



