SOME SAMPLING CHARACTERISTICS OF A POPULATION OF RANDOMLY DISPERSED INDIVIDUALS

As our knowledge of plant communities increases, greater emphasis is being placed on the methods used to measure the characteristics of these communities. Succeeding decades have shown a trend toward the use of quantitative methods, with purely descriptive studies becoming less common. One reason for the use of quantitative techniques is that the resulting data are not tinged by the subjective bias of the investigator. The results are presumed to represent the vegetation as it actually exists; any other investigator should be able to employ the same methods in the same communities and secure approximately the same data. If such is not the case, the so called quantitative methods are worse than valueless, since they lend an aura of false accuracy that may be very misleading. To make certain that his results are reproducible, the worker must be sure that his sample is adequate, that the location of his sample has been made without bias, and that the limitations of his method are understood. The student of plant communities is concerned with the distribution of objects in space. His first problem is the determination of the kinds of plants present and their relative numbers. Since it is usually impossible to examine all of the plants present, he confines himself to some kind of a sample of the vegetation. This may be in the form of area samples. as quadrats or belt transects; line samples, as in