The control agents are expected to reduce the number of stems and the number of plants per area. Smaller quadrats are justified at high purple loosestrife abundance to reduce the amount of work. Quadrats of less than 1 square meter in size have a high potential of loosing all purple loosestrife plants which in turn would require a change to the sample unit size. To avoid this, the recommended quadrat size is 1 square meter. A minimum of 5 quadrats have to be established at any one site to allow useful statistical analysis.
Various methods are available to randomize the quadrat placement.
The vegetation map of Form 1 could be used to divide the area into identical quadrats. Once you have determined the sample quadrat location it should be marked with permanent stakes. Avoid trampling of vegetation at subsequent visits to your sites. Metal galvanized pipe could be driven into the ground at the four corners of each sampling quadrat. Allow them to stick out for up to two feet to make relocating the quadrat easier.