168 THE PLANT LIFE HF MARYLAND 



and ( 'hestnut. It is probable that the latter areas are slightly older 

 geologically than the "meadow," and they appear to have progressed 

 a step in the evolution of a lowland forest. 



The succession as just detailed proceeds upon the assumption that 

 the area was clear at the beginning, and that adult pines were 

 present in the neighborhood to furnish seed. Neither of these as- 

 sumptions is necessarily true for a given area, though in most cases 

 they are true. If a tract does not enter upon these chapters of its 

 history in the condition of an abandoned field but as a partially 

 cleared wood-lot, the point at which the succession begins will of 

 course vary according to the kinds of trees which were present on 

 the tract when the cutting was done. In this connection one fre- 

 ijiirntlv hears the saying "If you cut off the pines, oaks make their 

 appearance, and if you cut off oaks, pines spring up." If this state- 

 ment were taken to indicate that the succession might take place 

 in either direction, it would be incorrect, but it states a partial 

 truth. It has already been shown that pines are in an untouched 

 tract replaced by oaks in the coirrse of time; this change may be 

 hastened by the agency of man, for in a pine forest old enough to 

 be cut for timber there is sure to be an undergrowth of oak which 

 is then given a chance to develop. Hence the first part of the 

 statement is readily explained. The second part, to the effect that 

 pines succeed oaks, seems to be true only in case the whole of a 

 forest cover is removed, and in such a way as to seriously damage 

 the seedlings and saplings of oak, hickory, etc., and thus admit 

 enough light for the growth of the pine seedlings, which soon over- 

 lop the oak seedlings on account of the rapid growth of the former, 

 and thus achieve a temporary victory. If many seedlings of oak 

 are left by the woodman, competition ensues between the oaks and 

 pines. If selective cutting has been practised, the oak and hickory 

 seedlings at once shoot up, and pine seedlings do not obtain the 

 necessary light, for they are extremely intolerant. Thus an oak 

 forest may be followed by another of the same kind. 



Let us next suppose that no mature pines are present in the 

 neighborhood — a condition which rarely occurs. In such a case 

 the history of the tract depends on its level. If the tract is mod- 

 erately low, seeds of Sweet Gum and Maple are apt to be sown on 



