24 BOTANICAL GAZETTE [JANUARY 
ones were felled. The age of every tree was then determined by 
counting the annual rings, and note was made in each case of the 
degree of soundness of wood, width of rings, and periods of suppres- 
sion indicated thereby. The cuttings were made at the height of 
about o.3m. An element of error is introduced here, making» 
the age as determined a few years too low. It seemed inadvisable, 
considering the many quadrats to be studied, to use up much 
valuable time in making the counts absolutely accurate. This 
would have involved the cutting of every tree at the surface of the 
ground, a very difficult and slow process. A saw might have been 
used instead of an ax, but when the rings are at all obscure it is 
impossible to count them from a sawed surface. I believe that the 
error introduced does not affect the validity of the results, since it 
is approximately the same in nearly every instance. The method 
on the whole gave excellent results, in the study of the rock shores 
and bogs as well as of the climax forest. Its use was made easy 
by the comparatively small size of the Isle Royale trees. Sixteen 
quadrats were studied in all, comprising 74 units of area, and 
involving the determination of the ages of about goo trees. If 
objection be raised that the method is unduly destructive, it may 
be answered that the cutting over of these small areas produces 
exactly the same effect as does windfall, a process that is continually 
taking place, and thus makes possible a new crop. 
In addition to the statistical study of the trees, careful notes 
were taken of the lower vegetation and the physical factors of the 
habitat. Less detailed studies of many other localities were also 
made for comparison with the quadrats. 
The results of the quadrat studies so far as they concern the 
climax forest will now be given in detail. The first four described 
were located on Smithwick Island; quadrats 5 and 6 were upon the 
main Isle Royale. 
Quadrats on Smithwick Island 
QuaprRaT 1 (fig. 6).—This quadrat exhibits most clearly the 
relations which the different tree species hold to each other and to 
the physical conditions of the habitat. It includes but one spruce, 
an aged giant 250 years old, long past maturity, with sparse foliage, 
