ABSTRACT
Plot sampling often is used where the populations of interest comprise elements that are distributed spatially over a landscape, e.g., plants, ant hills, wildlife dens, etc. Sampling over the landscape usually relies on an areal sampling frame because of the infeasibility of compiling a list frame of individual elements or clusters of elements. By an areal sampling frame we mean a device, such as a map or a GIS, that permits the selection of any point location within a region, denoted by A, on which all the discrete elements Uk , k D 1; : : : ; N , are situated. Sampling locations are point locations, which ordinarily are selected uniformly at random from the continuous areal frame. A sampling location may serve as the center point of a circular plot, the centroid or a corner point of a rectangular plot (quadrat), or it may be distinct from the plot, where the sampling protocol indicates the distance and direction from the sampling location to a plot with a prescribed shape and size. Plots of any shape are permissible, but shapes other than circular or rectangular are rarely employed in practice. The elements that occur within a plot constitute a probability sample of the population of discrete elements.
