MICHIGAN ACADEMY OF SCIENCE. 
109 
PERMANENT VEGETATION QUADRATS AT DOUGLAS LAKE. 
BY ADA K. DIETZ. 
The following work was carried on during the summer of 1912 at 
the University of Michigan Biological Station at Douglas Lake, Michi- 
gan. In the season of 1911 the areas around the Station were studied 
in a superficial manner. The different associations were noted, fre- 
quency and abundance counts were made, but it was not until the follow- 
ing year that the permanent quadrats were laid out. 
The method of placing the quadrats was as follows: First, a general 
survey of the area was taken, listing all species as to frequency and 
abundance. A typical spot was then located and a quadrat marked off, 
four iron pipes being driven into the corners and wire stretched around 
them to mark off accurately the space from the neighboring area. 
The sun exposure and the physical condition of the soil, to a depth 
of four inches, were noted. All the plants in the quadrat were accurately 
measured and their location marked on cross-section paper. In order to 
facilitate this measuring, cord was used to divide the quadrat into six- 
teen smaller squares. 
The symbol used to represent a plant on the paper was a small circle, 
and beside this was placed the first letter of the genus and species. 
When the plant formed a mat, an outline was drawn around the circle 
to show its size. If small trees were present, their height was measured 
and indicated in the table of symbols. 
In most cases two-meter quadrats were laid out. This size was taken 
in preference to the one-meter quadrat of Clements, as it was considered 
that a more accurate and typical plot could be had. If a different size 
was taken it will be stated when describing the individual quadrats. 
After the work was finished two 4x5 pictures, at right angles to each 
other, were taken of each quadrat. 
The first quadrat was staked out in the Aspen Association. This 
association is most common in the vicinity of Dongas Lake. Fires have 
swept through many times, laying bare the ground, and the aspens are 
the first trees to come in. Here there are many species of the old pine 
vegetation as well as those of the incoming aspens. The first quadrat 
was placed in an unsheltered part, having direct sunlight all day. The 
soil was sandy and very dry, with no underbrush. Pteris aquilina was 
the most common species present, with V actinium next. 
The second quadrat was likewise placed among the aspens but in a 
more sheltered part. It was laid out on a hillside where there were a 
great number of dead branches and underbrush. The soil contained more 
humus and there was more shade. There were many young aspens in 
the surrounding area, some being present in the quadrat. Besides the 
aspens, pine, birch, and oak trees were frequent near the quadrat. 
Still a third quadrat was marked off in this association. The sur- 
rounding area contained a great number of birch trees and the quadrat 
was placed in the dense shade of one of them. The ground was mostly 
