42 BULLETIN 149 7, U. S. DEPARTMENT OF AGRICULTURE 
The effect of grass and other low vegetation on the planted trees 
is not as well marked. It has been brought out that furrow planting 
or the removal of a square of sod in slit planting results in somewhat 
better survival and that the difference is probably due to the elimina- 
tion of the root competition of the grass and brush for the first few 
years. It is generally stated and it seems reasonable to believe that 
the competition of sod for moisture causes losses of the planted trees. 
In this study, however, the percentages of the trees living in planta- 
tions with different quantities of sod, sweet fern, blueberry, brake 
fern, hazelnut, or raspberr}^ do not show significant differences. The 
results on sites where the hazel was thick were usually poor, but this 
was due partly and perhaps chiefly to the damage by rabbits, which 
abound on such areas, rather than to the direct competition of the 
hazel. 
Shade of the natural vegetation may sometimes be more beneficial 
to the planted trees than the competition of its roots is detrimental. 
Although this effect did not appear in the study of plantations in the 
Lake States, it has been demonstrated by 2-1 stock in experimental 
northern white pine plantations in Massachusetts (Ip2) where 57 per 
cent without shade lived, and 85 per cent with some shade. Similar 
tests with 2-0 stock yielded 33 and 69 per cent respectively. Root 
competition accounted for 10 per cent of the loss of the unshaded ; and 
of the shaded, 20 per cent. The removal of the grass in July in a 
northern white pine plantation in New York {50) resulted in heavy 
losses, attributable directly to the exposure. 
The areas occupied by patches of mosses and lichens, which are 
frequently found on the dry sandy sites, are apparently extremely 
unfavorable to the establishment of planted trees, the mosses and 
lichens themselves or the soil conditions presumably preventing other 
forms of vegetation from becoming established there. For example, 
a mixed plantation of Norway and jack pine on an area with 35 per 
cent cover of moss had only 21 per cent of the trees of each species 
living, whereas a plantation under otherwise similar conditions but 
without the moss had 59 per cent of the jack pine and 50 per cent of 
the Norway pine living. Whatever the cause, living trees were rarely 
found in these patches of moss, and a plantation with much of its -area 
occupied by the moss had a correspondingly low survival of trees. 
A thick growth of laurel, such as is characteristic of some low sandy 
soils, is also unfavorable to the establishment and growth of planta- 
tions. Only 25 per cent of the jack pine and 40 per cent of the Nor- 
way pine remained in a mixed planting of the two species under a 45 
per cent cover of laurel, whereas a similar planting without the 
laurel had 48 per cent and 56 per cent of the trees living. The 
average annual height growth with the laurel was 0.33 foot for 
jack pine and 0.23 foot for Norway pine, and without the laurel 
0.56 and 0.31 foot, respectively. 
The combined effect of all the foregoing causes, including weather, 
fire, animals, insects, diseases, careless planting, poor stock, and com- 
petition, has resulted in losses of not more than 10 to 50 per cent 
of the trees. On the whole, therefore, no one of these causes, which 
are often indistinguishable, can be said to be prohibitive of forest 
planting in the Lake States. 
