41 



belt. The poplar became eliminated next, and these were followed 

 by boxelder which have practically all died in recent years. The 

 few surviving boxelder trees have suffered heavy killing back. 

 Green ash were in the best condition of any species in 1932, though 

 they showed some damage from borers. Buff'aloberry had suffered 

 very little loss, but the trees presented a very ragged appearance, 

 chiefly as a result of top and side crowding by sharpleaf willow in 

 the adjacent row. Tatarian maple seems to be semihardy. This 

 tree appears to be especially palatable to rabbits, and until the 

 shelterbelt was surrounded by rabbitproof fence in the fall of 1927, 

 trees were killed nearly to the ground each year by rabbits. After 

 1927 these maples made fair growth, though portions of the trees 

 were killed following the dry year 1931. 



COMPARISON OF CULTIVATION, MULCHING, AND LACK OF CULTIVATION 



Comparison was made of clean cultivation, lack of cultivation, and 

 mulching in the care of a shelterbelt. The same species of trees and 

 spacings were used as in the pruning test. The neglected or un- 

 cultivated block was a continual source of weed seed that blew over 

 the adjoining fields. Losses of species were much the same as in 

 the previous experiment. The willow, poplar, and boxelder, how- 

 ever, died out at an earlier age, and the more hardy species, green 

 ash, buff'aloberry, and Tatarian maple, made a slower growth in 

 the noncultivated block than in the blocks of other cultural treat- 

 ments. 



The mulched block of trees was covered with straw to a depth of 

 about 6 inches, and straw was added each year for several years 

 to maintain this mulch. This block of trees did not grow so well as 

 the clean cultivated block, and the less hardy species, willow, poplar, 

 and boxelder, died out at an earlier age. In 1932 all except the 

 hardiest species, ash, buff'aloberry and Tatarian maple, were dead 

 in both blocks. As in other tests the green ash proved hardiest. 



SPECIES BLOCKS 



Blocks of trees, each set in pure stands, were planted in 1918. 

 The species used in this test were Northwest poplar, laurel willow, 

 boxelder, and green ash. Each block was divided, one-half being 

 spaced 4 by 4 feet and the other half 4 by 8 feet. Nearly all the 

 poplar trees died following the winter of 1924-25. The willow trees 

 did not entirely die, but killed back to the ground each winter, and 

 new growth took place from the roots the next spring. These two 

 blocks of trees were pulled in 1930. The boxelder trees grew with 

 but little injury until about 1927. During the years 1930-32 nearly 

 all the boxelders died either in whole or part, and the boxelder block 

 then presented a very ragged appearance. 



The block of ash trees has shown very little killing, although 

 many of the trees appeared to be weakened in the spring of 1932. 

 This was followed by a good recovery, and the trees were in good 

 condition in the autumn except for borer injury. The trees have 

 not made much growth the past few years, the block spaced 4 by 4 

 feet having an average height of 10 feet and a diameter of 1.5 to 3 

 inches, as compared with an average height of 9 feet and a diameter 



