Bergman and Slallard: climax formations 371 



The secondary succession which follows clearings of upland 

 deciduous forests consists of the following stages : 



(1) Andropogon-Stipa Associes 



(2) Corylus-Kubus Associes 



(3) Populus-Betula Associes 



(4) Accr-Tilia Association 



(1) A)idropogon-Stipa Associes 



Fires in deciduous forests rarely gain headway as under pines. 

 However, where a deciduous forest joins a prairie or a meadow 

 which is burned occasionally or annually, the fire tends to destroy 

 the edge of the forest, and in time the climax forest may be replaced 

 by the prairie, which can maintain itself if burning continues. 



Consocies : In parts of Meeker, Otter Tail and Crow Wing coun- 

 ties, small areas of prairie often join tracts of the climax forest. 

 In such areas Andropogou furcatiis and Stipa sparfea are the con- 

 socies. Andropogon is generally much more abundant than Stipa, 

 the latter occurring as families or colonies in the Andropogon areas. 



Secondary species : Other grasses such as Andropogon sco- 

 parius, Agropyrum caninum, Agrostis hiemalis and Koeleria cristata 

 are to be found usually with the consocies. The following herbs 

 are characteristic: Campanula rotundifolia, Achillea lanulosa, 

 Phlox pilosa, Heuchera hispida, Petalostemon candidits, Solidago 

 nem oralis and S. missouriensis. 



When clearings are cultivated for a time and abandoned, the 

 succession differs from that just described. Cultivation destroys 

 all the under-shrubs and the succession must begin at a lower stage. 

 This stage is an herbaceous associes of the uncultivated clearings. 

 Abandoned fields are soon covered with weeds and grasses which 

 are more or less abundant in poorly cultivated fields. The herba- 

 ceous associes of the deciduous area in main is similar to that of the 

 coniferous area (see page 349). However, where the deciduous 

 clearing is near the prairie more of the prairie species invade. 



(2) Corylus-Rubus Associes 



The Andropogon-Stipa associes. will be maintained as long as 

 the fires recur with sufficient frequency to kill out any invading 

 shrubs or trees, as for example when an area is burned annually. 

 Prairie that has developed as the result of repeated burning of an 



