a8 LIGHT IN RELATION TO TREE GROWTH. 
also its ability to endure low light intensities; that is, its tolerance. 
The best way to obtain such figures would be to determine the rela- 
tive heights of trees which have grown without any influence upon 
one another, but under a uniform shading of some other stand. 
Since, however, such conditions were hard to find, Medevev, who was 
the author of this method, made use of the numerous results of his 
forest measurement work and of the data obtained in measuring 
sample areas, especially in the forests of Transcaucasus, where an 
unusual number of observations were made on spruce (Picea orien- 
talis) and on Scotch pine. 
He found, on the basis of such measurements, that the relative 
height of spruce is from 1.762 to 1.338, or on the average 1.500 times 
greater than that of pine; in other words, that the tolerance of spruce 
is one and a half times greater than that of pine. In the same way 
the following figures were obtained for the light relations of other 
species: 
SpEUCEH OPRIGEG) ALOU BING CPTI a oa eee 1. 500 
Pine (Pins). to Ditch, (Betula yes oe bo ae Eee Boer cea oe eevee =) de doo 
Beech #CE Gaus) tOiSpEUCe sy CRTC Ce) se Se ee ree a 1. 029 
Hornbeam=(Carpivus) to peech Ch agus) = oS ee eee eee . 918 
Yew: Pavusy) sto beech CHGgus) 22 ee ae eS A ee 2. 816 
Wir CA0tes) 1 60 SPRUCE CRC CCCs) ease aera eee Eee es mae oS) TS EE Ete a 1.125 
Basswood,-Ciihea) to beech) Chagus)\ a= 0a ee ee eee . 849 
Oak. (Quercus) to hornbeam (Cerpinus) —__-___-_---_-_-= ices . 855 
Aspen. GPopulus)<to: pine, CPinius)\ 2a 2 eee ee ae AOR ReneS fe S9 
ASHVGHECeinus) to DITeh {CB Clu) ae’ Se ee eee ey bebe ie LAO. 
If birch, as the most light-needing species, be taken as a unit, the 
relative tolerance of the other species would be expressed as follows: 
BSCS GPCL UUs) ae Oe 1.000 | Hornbeam (Carpinus)—~~__—-_~ 1. 889 
Pine SCP Se = SS is eee ae Toooe |S DEUCE {CPICCG) = sae == ae eee 2. 000 
ASH CRRGCIIUS eae Se a t.4007| Beech (Paqus) 2222 2 ea aS 
Aspen CHOPIEUIES ) = = pane ee se ae 1.598 | Fir (Abies nordmanniana)_____ 2. 450 
Oak" (Quer cis) bss EE 1.645Yvew. CRALUS) = SS) ieee ens 5. T95 
Basswood CR tlig,) e225 es ae be 1. TAT 
Medevev’s method, although less subjective than some of the others 
suggested, is nevertheless not entirely reliable, since it is still an open 
question whether or not the distribution of growth in a tree depends 
exclusively, or even chiefiy, upon light. Investigations have shown 
that while the growth in diameter of suppressed trees is from one- 
third to two-fifths as much as that of dominant trees, their height 
growth is from two-thirds to three-fourths as much. 
According to Hartig (1891: 271-274), the distribution of the in- 
crement of a tree is influenced by the density of the stand and whether 
the tree is dominant, intermediate, or suppressed. In dominant 
trees the increment is chiefly in the lower part of the trunk; in sup- 
pressed trees, in the upper part. Suppressed trees sometimes show 
