310 



there are many prairie species around the trees, there are plenty of 

 young oaks, Quercus velutlna, in all stages of development. They 

 grow quite easily and are able to replace the pine — not merely to dom- 

 inate the region with the dying of tlie pines as is the case with the 

 prairie plants. In the openings in the denser parts of the pine area, 

 the pioneer species that come in are forerunners of both the prairie 

 and the oak forest. Seedling oaks are rather plentiful and occur at 

 various distances from the parent trees, from which acorns were 

 probably carried and stored by birds, especially crows and blue jays. 

 If the oaks are present in any number they determine which succes- 

 sion is to take place. 



Finns strobits occurs rather commonly throughout the association, 

 but it is rather more abundant in the more xerophytic and less fertile 

 soils. It acts as a pioneer for this association, and even now is very 

 gradually reproducing itself on the edges of the prairie and marshes 

 or in broken places in the prairie. This, however, is taking place 

 much more slowly than the occupation of the pine land by oaks. The 

 densest growth of pine is formed largely of Piiiiis laricio and Pinits 

 silvestris, growing in separate groves. 



LIST OP THE SPECIES OF THE PINE EOREST ASSOCIATION 



Dominant Species 

 Finns strolms Finns sp. ? 



Finus laricio Larix dccidua 



Finns silvestris 



Secondary Species 

 Smilacina stellata Folygonatuni coinnintafuni 



Oenothera rhomhipetala Aster azurens 



Anem o n e cylindrica 



Relic species which are very abundant 

 Jnniperus conimnnis depressa Solidago neiii oralis 



Jnniperns horizontalis Euphorbia corollata 



Arctostaphylos nva-nrsi Lithosperiiinm giuclini 



Relic species which are not abundant 



Blynins canadensis Artemisia candata 



Aster dnmosus Salix syrticola 



Prunus pumila Arabis lyrata 



Salix glancophylla Sorghastnini nutans ^ 



Jnncns baltkns littoralis Calamoinlfa longifolia 



Fanicnm virgatnvi Koclcria crisfata 



