 GRS Densitometer |
  Introduction Who uses it today? Where can I buy one? Online registration GRS Scientific papers |
The GRS Densitometer is used with the point-transect method of
sampling. The GRS Densitometer is a tool that uses a mirror to project a view of the
sample location point in the canopy above to the person holding the Densitometer on the
ground. 
Unlike other
methods of determining canopy closure, the GRS Densitometer can be aligned to give an
exact vertical line-of-sight into the canopy. Mounted inside the viewing tube are two
bubble-line level vials. The field technician can simply sight through the Densitometer until
the vials' bubbles are both level, then record the characteristics of the feature(s) that covers the point when the 'dot' is centered in the circle.
Using this sampling tool, canopy data collection becomes efficient, accurate, and
repeatable.
The user records sample characteristics, as indicated by the GRS Densitometer, at pre-determined
intervals along a transect. This method of sampling is more accurate and consistent 
than other cover estimation
methods. Spherical mirrors, which are bulky and inaccurate, can be replaced
by the GRS Densitometer. The point transect method has been used for many years, and
finally there exists a simple, lightweight tool for implementing this sampling procedure.
Please see K. Stumpf's conference paper: ''The Estimation of Forest Vegetation Cover Descriptions Using a Vertical Densitometer.''