A Biltmore stick is a simple, inexpensive, and very useful tool for measuring tree heights and diameters. It does the job of a diameter tape and clinometer, at a fraction of the cost, and it can also be used to fight off snakes or clear brush during inventory operations. To function properly, the Biltmore Stick must be custom fitted to the user by first measuring his/her arm length. Based on this measurement, the appropriate height and diameter scales are inscribed on the stick. This is what is being done in the picture. The Biltmore sticks are being made by the participants in a workshop on "Sustainable Management of Oaxaca's Dry Forests" that Silvia Purata (see Alebrijes) and I gave in 2004.
Instructions for making your own Biltmore stick can be found here.