raunkiaer's life forms ■ 59 



B. Ecological character (growth-form). 



9. Ecological character is expressed partlj^'by descriptive terms 

 and partly by statistical results, as the single adjustment (life- 

 form) valence in a formation is shown by the frequency index 

 as a medium between systematic (species) and ecological units 

 (growth-forms). In this way biological formation spectra may 

 be constructed not only for the ''life-forms" (showing the ad- 

 justment of the species to survive the rigorous season) but also 

 for other biological characters such as xeromorphism (leaf-size, leaf 

 anatomj^ etc.), pollination, and dispersal. 



C. Height and mass 



10. The height of the individual species and the mass of the 

 vegetation are two distinct factors in the physiognomy of a for- 

 mation. As far as chamaephytes and phanerophytes are con- 

 cerned the height is pretty completely expressed in the designa- 

 tion of the life-form (nanophanerophytes, microphanerophytes, 

 etc.), and in investigating a formation of herbaceous plants the 

 height maj^ be determined directly. On the other hand, it is 

 difficult to obtain an exact computation of the mass, for it is 

 impossible in practice to determine its weight or volume, be- 

 sides, such determinations would scarcely characterize the phys- 

 iognomy. Hence we must content ourselves with computations 

 of mass based upon estimates following inspection combined 

 with the valence method determinations. One important feature 

 of the physiognomy of the mass is the proportion of the area 

 covered by the individual species. 



11. The area covered is determined by perpendicular pro- 

 jection upon the substratum and is expressed as the .surface 

 per cent of the area in question. Areal percentage (see Lager- 

 bergs), A%. 



12. The size of the sample plots to be used in determining the 

 areal percent (A%) is a matter of no theoretical significance but 

 of very decided practical importance, the most practical is the 



5 Lagerberg, T., Markflorans analys pa objectiv grund. Skogsvardsforen- 

 ingens Tidskrift, 1914. 



