12] VEGETATIONAL TYPES OF TEMPERATE LANDS 349 



including kinds of Spicy-wintergreen {Gaultheria), Barberry {Ber- 

 beris), Currants etc. {Ribes), Rhododendron, Elder (Sambucus), and 

 Blueberries etc. 



4. The so-called ' lake-forest ' of the eastern half of North 

 America, lying between the general northern Hudsonian belt and 

 the deciduous summer forest to the south, and centred on the 

 northern portions of the Great Lakes. The region is one of moderate 

 precipitation (60 to 115 cm.) and considerable temperature extremes, 

 and the forest consists of a single association or associes dominated 



^"^wm 



Fig. 99. — ' Lake-forest ' of southeastern Canada, dominated by White Pine {Piiius 

 strobiis) and Hemlock (Tsitga canadensis), in summer. The undergrowth is mixed 



and relatively sparse. 



by White Pine {Piniis strobiis), Red or Norway Pine (P. resinosa), 

 and Hemlock {Tsuga canadensis). Associated are various broad- 

 leafed deciduous trees of various ecological affinities, making this 

 forest all the more difficult to delimit ; indeed it is now often ques- 

 tioned whether it ought to continue to be recognized as a type. 

 For whether or not it is climax, it is in many respects transitional 

 between the boreal coniferous and southern deciduous forests, from 

 whose migrational buffetings and competition it has suffered. This 

 is reflected in the undergrowth, which tends to be poorly developed 

 owing to the dense canopy but includes many Pteridophytes, 



