40 CIKCULAK 4 21, IT. S. DEPARTMENT OF AGRICULTURE 



damage, and a few of them died. The ponderosa pine and the 

 Scotch pine were still in good condition in 1932. They have ex- 

 tended their branches enough to cover most of the space between 

 them and have become very valuable, both for wind protection and 

 as snow traps. 



In the spring of 1917, three rows of Chinese elm were planted on 

 the north side of the garden, and a row of Siberian pea-tree was 

 planted between the north row of Chinese elm and a strip of sod 

 bordering the cultivated land. The Chinese elm made a remarkable 

 growth, and by 1925 they were the tallest trees on the station. Nearly 

 all of these trees were still alive in 1932, though there was some killing 

 of branches following the winters of 1930-31 and 1931-32. The row 

 of trees next to the garden is several feet taller than the row next 

 to it, and this row in turn is taller than the row bordering the Si- 

 berian pea-tree. This difference is accounted for by the fact that 

 the trees on the side next to the garden are able to draw upon the 

 cultivated soil in the garden for moisture. No doubt the second row 

 also obtains some moisture from the garden. This has been a great 

 benefit to the trees but not to the garden crops. Occupation of the 

 soil by tree roots has made unproductive for garden crops a space 

 approximately 40 feet wide bordering the Chinese elm. 



The row of Siberian pea-tree between the Chinese elm and the sod 

 is an example of survival under adverse conditions. This row is so 

 overshadowed by the Chinese elm, and has such a small area of cul- 

 tivated ground from which to draw moisture, that it has had a severe 

 struggle for existence. In spite of the adverse conditions, practically 

 all the trees have lived and there has been no killing of branches. 

 Naturally these trees have grown very slowly, but their survival 

 shows that they are able to withstand the most severe conditions. 



PRUNING AND SPACING EXPERIMENT 



In 1918 three blocks of trees were planted for a pruning demonstra- 

 tion. One of the blocks was to be pruned high, one medium, and 

 one left unpruned. Each block was planted to 10 rows of trees 

 arranged in the following order: (1) Buffaloberry • (Lepargyrea 

 argentea (Pursh) Greene) ; (2) willow {Salix sp.) ; (3) boxelder; 

 (4) green ash; (5 boxelder; (6) Northwest poplar; (7) green ash; 

 (8) boxelder; (9) laurel willow; and (10) Tatarian maple (Acer 

 tataricum L.). The trees were spaced 4 by 4 feet in half of each 

 block and 4 by 8 feet in the other half. 



The evil effects of pruning were apparent as soon as the trees had 

 reached a height of 7 or 8 feet. The pruned blocks of trees were en- 

 tirely unsatisfactory for catching snow or providing protection from 

 the wind. The ground in the pruned block was almost invariably 

 blown free from snow, while drifts*of snow collected in the unpruned 

 block. Trees in the unpruned block were more vigorous than those 

 in the pruned blocks, and the survival was better. A shelterbelt in 

 this section should be left unpruned, in order that it may catch the 

 snow that would otherwise drift around the farm buildings. The 

 water from the melting snow furnishes a much needed supply for the 

 trees. 



The willows were the first to die, except for end trees which 

 were able to send their roots into the cultivated area outside of the 



