22 FIlfST BOOK OF FORE8TKY 



into a dense, luxuriant forest of mixed growth in which 

 ash, oak, basswood, cedar, and cypress are often mixed 

 with scattered cabbage pahiis and yuccas. Evidently it 

 is the effect of soil. 



In North Wisconsin we might see almost tlie same 

 results. The heavy clay soils are covered with a good 

 growth of hardwoods, especiall}'^ birch, elm, and maple, 

 with a goodly sprinkling of conifers, pine, and hemlock ; 

 but as soon as we enter any of the large, sandy districts a 

 regular pinery, almost pure stands of pine, meets our eyes, 

 and wherever the sand is unusually poor, stunted forests 

 of jack pine replace the stately white and Norway pines. 



At the border of the forests, against the prairies, where 

 drought and sand conspire to make forest growth more 

 difficult, the sands are not covered with grasses but with 

 scrub woods of jack pine and scrub oaks. Similar scrub- 

 oak woods cover the Cross Timbers of Texas and portions 

 of other western states. 



From this sketch it appears that fertile loams and clays 

 bear mixed forests composed largely of a variety of trees, 

 mostly hardwoods ; while sandy soils are usually covered 

 with monotonous pineries, composed of one or few kinds 

 of trees. We also note that this distinction is very sharp; 

 that in most sandy regions, whether north or south, the 

 hardwoods are generally unable to replace the pine, and 

 that Avherever they attempt to do so the oak alone is 

 partially successful. 



