6 BULLETIX 133*7, U. S. DEPAETMEXT OF AGEICULTUEE 
on 34 plantings in Montana, 35 in North Dakota, and 13 in South 
Dakota are given in Table 5. No measurements were made in 
Wyoming. 
EXPERIMENTAL TREE PLANTINGS 
Experimental plantings of trees have been made at the station to 
test the adaptability of different species to prevailing climatic con- 
ditions and to compare the effects of different systems of species com- 
binations, cultivation methods, and spacrngs on the growth of trees. 
These investigations began in 1914. 
VARIETY AND SPECIES TESTING BLOCKS 
This experiment is primarily for the purpose of testing the trees of 
different species or varieties or from different sources as to their 
abihty to survive. It consists of blocks of 100 trees of each Idnd 
under trial. There are at present 94 of these blocks, consisting of 18 
coniferous and 76 deciduous species or varieties of trees. The 
plantings vary from 1 to 9 years in age. The following species 
planted in 1922 have completely died out: Balsam fir (Ahies hal- 
samea), white fir {Ahies concolor) , beech {Fagus americana), large- 
tooth aspen (Populus grandidentata) , mossycup (bur) oak (Quercus 
macrocarpa) , and red oak (Q. rubra). Most of these species probably 
are not adapted to the region, but it is by no means certain that ^vith 
special methods of care and protection during the first season some 
of them might not succeed. Norway maple (Acer platanoides) 
planted in 1922 had practically a perfect stand in 1923, although a 
similar planting of the same species set out in 1915 was entirely dead 
at the end of the first year. Two species were added in 1923 — 
Catalpa hignonioides and C. speciosa. The stand of these was practi- 
cally perfect in the fall. 
SHELTER-BELT COMBINATIONS 
Belts of trees varying in width from 2 to 22 rows were planted in 
the years 1915, 1916, and 1917. The species are arranged in the 
different belts in various combinations and with variations of spac- 
ing distances, as follows: 4 by 4, 4 by 8, 2 by 8, and 6 by 12 feet. 
The following trees in these tests show noticeable losses or damage: 
Norway poplar, Carolina poplar, laurel-leaf "vvoQow, Russian golden 
willow, buffaloberry, and birch. Those that show a uniformly high 
number of survivals are boxelder, green ash, Siberian pea-tree, 
chokecherry, wild plum, northwest poplar, and Chinese elm. In a 
few combinations where the blocks are situated in low places and 
have the benefit of additional moisture tlirough run-off from ad- 
joining land both the willow and poplar are still maintaining a 
vigorous growth. 
An interesting difference in behavior appears in two combinations, 
in one of which green ash and boxelder were planted in alternate 
rows, whereas in the other they were grouped in four adjoining rows 
of each. The ash has developed a much sturdier form of tree where 
it is grouped by itself than where alternated with the boxelder. 
This suggests the advisability, for ash at least, of grouping the 
species in adjoining rows rather than altematiug it with other species. 
In all the plantings in which ash is alternated with boxelder the 
ash has been noticeably suppressed. The competition is not so 
pronounced where ash has been placed beside northwest poplar. 
