APPLICATION OF PHYTOSOCIOLOGICAL TECHNIQUES 29I 



Table 11. The leading tree species on a sample plot of equatorial rain forest at 



Miicambo, arranged according to their "importance value indices," or the sum of 



relative densities, frequencies, and dominances (Cont.) 



Importance 

 Family value index 



Pouteria caimito Sapotaceae 2.52 



Iryanthera paraensis Myristicaceae 2.46 



Manilkara huberi Sapotaceae 2.43 



Dendrobangia boliviana Icacinaceae 2.31 



Pouteria sp.? Sapotaceae 2.06 



Trattinickia rhoifolia Burseraceae 1.93 



Caryocar villosiim Caryocaraceae 1.91 



Neea sp.? Nyctaginaceae 1.37 



Enterolobitim schomburgkii Leguminosae 1.35 



plays an important role in giving the species its high rank. Eschweilera 

 odora, the second ranking species, has an index of 21.61. This is made up of 

 11.26 per cent relative density, 6.71 per cent relative basal area, and 3.64 

 per cent relative frequency, in which density plays the most important role. 



The combined indexes of all species total 300. The live leading species 

 (table 11) together have 86.15 points, and the 44 species together have 229 

 of the 300 points. The relative insignificance of the vast majority of the 

 species is thus made clear. 



Family dominance. There are some types of vegetation in which no species 

 or combination of a few species attains dominance in the community, but 

 dominance occurs for the combined species of a family (Richards, 1952). 

 This question was investigated for the forest at Mucambo, with the results 

 shown in table 12. The Burseraceae is found to be the leading family, the 

 sum of the index values of its eight species being 47.92. This family is fol- 

 lowed by the Lecythidaceae, Vochysiaceae, and Leguminosae, each succeeding 

 one being about 10 points less than the preceding family. Inasmuch as the 

 Burseraceae with 47.9 points make up only about 18 per cent, there clearly 

 is no family dominance in this community. 



Life form and leaf size. It is well known that there is some correlation 

 between the physiognomy of vegetation and its environment. One of the most 

 successful methods of investigating this relationship on an extensive scale 

 is that of the life forms of Raunkiaer (1934). His limited classes, easy of 

 determination and readily subject to statistical comparisons, have been 

 widely used. Although only a few concrete data are available, it has long 



