The simplest of all methods of monitoring a site is to establish some permanent photo points and take photographs every year or so, and to take a regular traverse through the bush. The methods described here are for the enthusiast who wants to go a bit further. There are several ways to do this. The area of a site can be estimated by tracing it from an aerial photograph onto graph paper. Measure accurately the length of one fence line to get a scale if you don't have the scale already.
Some government agencies have a point method which can be used with an aerial photograph.
A transparency with these dots is placed onto the plant to be measured. The dots are counted to give the area. On large sites or where plants are too dense to count, the quarter method of plotless sampling works well. Each arm of the cross indicates a quadrant. A further method of measuring density is to use quadrants of known area, distributed at random, around the site.