GRS Densitometer User Information
The GRS Densitometer™ is used with the line-point transect method of sampling. The line-point transect sampling requires the field technician to tally the existence of vegetation (and other landscape features) present (covering) the different points along a transect. The GRS Densitometer enables the field technician to easily extend or view the location of each transect point up into the canopy and accurately determine whether or not a tree's crown covers the point and should be tallied. In addition, this tool can also be turned upside down to view towards the ground and estimate what ground or near ground features cover a transect point.
The GRS Densitometer contains a mirror, sighting marks (guides), and leveling vials allowing the user to project a vertical line-of-sight either up into the canopy or down to the ground. The field technician can simply look through the GRS Densitometer, level the two bubble vials, align the sighting marks, and then tally the feature(s) covering the sighting mark (intersection of cross-hairs or dot). Depending on the type of survey you are preforming, you can record the various characteristics of the vegetation and/or landscape feature(s) that cover or intersect the sample point location.
The vegetation and landscape characteristics recorded at each point in the transect can include a wide variety of vegetation and non-vegetation conditions. Data regarding species, size, height, status, ground condition, soils, fire-fuels, and relative canopy position are just some of the features that can be collected and summarized for each transect or set of transects.
Unlike other common methods of estimating canopy cover, the GRS Densitometer line-point transect technique provides an objective and standardized means of collecting vegetation/land cover feature cover estimates which generates consistent results amongst users of different levels of experience. In addition this technique can be integrated in to most field data data sampling procedures and can, in many cases, replace existing methodologies.
For estimating canopy cover, the line-point transect sampling method has been shown to be a more accurate, unbiased, and consistent approach than other cover estimation methods, such as spherical mirrors or photo samples. The line-point transect method has been used for many years in rangeland and vegetation studies, but was difficult to implement in forested environments. Now, GRS presents a simple, lightweight tool for implementing this sampling procedure.
For additional information, please review the following paper:
''The Estimation of Forest Vegetation Cover Descriptions Using a Vertical Densitometer.''
To download GRS Densitometer documentation open
''GRS Densitometer Documentation''
Visit/join our GRS Densitometer Users Group.