166 THE FORMATION 
plants are especially small and crowded, as in alpine meadows. The loca- 
tion of the quadrat is based upon the general rule, but since its especial 
task is the determination of the greatest variable in vegetation, viz., number, 
it is necessary io use more quadrats, and to place them in areas which show 
the greatest differences in the mixture of species. For example, it was 
found that a half dozen list quadrats, when carefully located in the prairie 
formation, gave results almost identical with those obtainable from a larger 
number. With a little experience, the various degrees of mixture can be 
picked out superficially, and the corresponding number of quadrats es- 
tablished. If a single list quadrat is to be made. for a formation or station, 
such a time should be selected as will make it possible to cover the greatest 
number of plants. Fortunately, this usually falls near the middle of the 
summer, when the remains of spring plants are still in evidence, and the 
autumn ones are sufficiently developed to be recognizable. In taking the 
census of different aspects, the quadrat should be made as near the middle 
of the period as is possible. : : 
205. Manner of use. In listing a quadrat, i. e., counting the individuals 
of each species, the plan followed is to list the smaller, less conspicuous 
plants first, since they are apt to be tramped down. As a rule, the outside 
tapes and the taller species afford sufficient landmarks. When this is not 
the case, the measure tape is used, and the individuals of all species are 
checked as they are found, while in the first method one species, rarely two, 
is taken at a time. In cases of peculiar difficulty, it may be permissible to 
pull or break plants as they are counted, but ordinarily this can and should 
be avoided. Clusters, and bunches of stems from the same root are counted 
as single plants, and the number of stems indicated by an exponent. In 
the case of bunch grasses, each bunch counts as one plant. 
206. Table of abundance. The species are arranged in the final list 
in the order of their numerical importance, and are divided into groups 
which correspond to the different degrees of abundance. The latter 
are arranged in two series, based upon the fact that association is by 
groups or by individuals. The table of abundance, based upon a 2-meter 
quadrat rather than upon the 5-meter one, by means of which the earlier 
results were obtained, is as follows: 
Social exclusive, no other species of vascular plants present 
social inclusive, above 100 
gr! gregarious! 100-50 copious! _—cop? 
gr? gregarious?” 50-25 copious? _— cop? 
gr® gregarious? 25-10 copious® —_— cop? 
sg subgregarious 10- 5 subcopious sc 
vg vixgregarious 5-1 sparse sp : 
