Secondary Succession 437 



completely recovered from the soil, and the cleared areas were planted 

 to crops or used as pastures. Beginning shortly after 1830 the open- 

 ing of rich farmlands in the west, the building of railroads, and the 

 growth of industrial centers, brought about the exodus of the farmer 

 from the rocky hillsides of New England that were so difficult to work. 

 The abandoned fields were covered by a thick sod of grass. In this 

 turf the seeds of white pine trees blown from neighboring forested 

 areas found a favorable environment for germination, but other forest 

 trees were not able to establish themselves effectively in the aban- 

 doned fields. The result was that the white pines grew into a dense, 

 uniform stand, and eventually produced a forest in which all the 

 dominant trees were of this species. A few hardwood saplings later 

 became established as an understory throughout the pine forest, but 

 their further growth was suppressed by the pines. 



In the course of fifty years or so, the pines had grown to a size that 

 made a valuable timber harvest possible. Great areas were lumbered 

 off; in regions where lumbering was not carried out the even-aged 

 trees grew old and finally fell. In both situations the trees which 

 then grew into dominant position were not white pines but were 

 hardwood trees that had existed in subordinate position almost un- 

 noticed in the pine forest. Pines will not sprout from stumps, and, 

 being an intolerant species, the pine seedlings are unable to develop 

 in the shade of the mature trees (Fig. 12.5). The root sprouts and 



Fig. 12.5. View of the forest floor in a stand of mature white pines in southern 

 New Hampshire, showing the aljsence of pine seedlings but the presence of beech 



and maple saphngs. 



