What's an Ocular Tube?

ocular tubeAn Ocular tube is nothing more than a tube you hold up to your eye.  It limits the field of view, focusing on a very specific study area.  The one pictured is made of PVC, paper clip wire (for the viewing cross-hairs) and white duct tape to hold the wire in place.  You could make one with a paper towel roll and rubber bands!

The most common use for an ocular tube is to study the percentage of canopy cover in a given study area.  First lay down a Line Transect, then take a one meter stride.  Look straight up through the tube, if the cross-hairs land on vegetation, record a "hit" on your data sheet, if not...record a miss.  If you were to record 10 such observations with, let's say 6 hits, you'd have observed 60 percent canopy cover in that study area!  Simple!

This type of study can be very revealing especially in the study of a riparian area.Ocular Tube Demonstration

Field Investigation Toolkit


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