16 ELEMENTARY FORESTRY. 



We know that in this section after a prolonged period of 

 severely cold weather, the twigs of Soft Maple, Apple and 

 some other trees have a decidedly shrivelled appearance which 

 disappears after a few days of mild weather. Soft Maple 

 trees standing on dry land will sometime in the spring appear 

 to have been dried out and to have become partly or entirely 

 dead. It is probable that during our coldest weather very 

 little, if any, moisture can be supplied from the roots which 

 may account for this shrivelled condition. 



Second Growth. Sometimes warm, moist weather in late 

 autumn will cause trees to start a strong second growth in 

 October which draws on the stored plant food and perhaps ex- 

 hausts it and winter sets in before v the tissues have again be- 

 come hard and stored with food. In such cases trees are 

 liable to injury. No characteristic of hardiness is more im- 

 portant in plants than that of early maturity of wood. 



One part of the tree may start into growth without regard 

 to the conditions of the other parts. For instance, a branch 

 brought into a warm room in winter without severing it from 

 the tree will grow for some time. Sun scald is probably due 

 to the bark on the side most exposed to the sun starting into 

 growth very early after which a sudden freeze destroys the 

 young cellular tissue. 



SOIL CONDITIONS. 



Water Supply. Water is the most important element in 

 soils for tree growth and the greatest attention must be given 

 to its conservation and distribution through the soil. Trees 

 do not grow to best advantage in very wet or in very dry soil 

 although some can live and almost thrive under such unfavor- 

 able conditions. There is very little land except in the arid 

 region, but that will support some form of tree growth. The 

 soil best adapted to all kinds of trees is one that is moderate- 

 ly but evenly moist, porous, deep and well drained; yet with 

 a subsoil compact enough to transmit the subsoil water from 

 below upwards without its being so solid that it cannot be 

 easily penetrated by the roots. It does not matter about its 

 being stony if it has these qualities. On land that is very wet 

 in this section as the muskegs of northern Minnesota which 

 are covered with Tamarack and Spruce the trees never get to 



