Crown mirror - densiometer

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General description

The crown mirror consists of a gimble grip, where a plumb tube is installed with a mirror and a visor cross. The visor cross divides the canopy into 4 quads. The crown mirror densiometer is a device to plumb crown width, crown radius, crown area shadow or the crown projection to estimate the degree of canopy. A plumb-pipe with a mirror and a cross line are gimballed.

Figure 1: Crown mirror

Handling

To project the crown margin down to the ground, a manual lead and a line can be used to mark the crown limit on the ground – later the crown area can be measured at the ground.

Figure 2: Live view measuring crown margin

To measure the canopy margin walk around the perimeter observing the corresponding crown and leave the line on the ground. A field survey with the crown mirror densiometer can be improved by using additionally e.g. a walktax for the crown area conduction.

Advantages	Disadvantages
hinges with ball bearings	no application to measure or calculate directly canopy cover values