l66 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 to 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, wdien 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 



