# Equipment Used to Cruise Timber and How to Use It

Ed. Note: The first essential step toward selling timber or timberland is an inventory. It is a necessary step which enables the seller to set a realistic price on both the wood and the land. The inventory and methods used to determine volumes are also used between sales to make silvicultural and management decisions. Here is the equipment you need, the cruising procedure and how to calculate the cruise.

This report is based on an article written by Ron Wenrich. Ron is a sawmill consultant and has extensive knowledge on how to inventory your forest using the point sampling method. It is written in three parts, this being the first part, and all links included were chosen by the editor.

You could measure every tree and do a 100 percent appraisal, but this is very time consuming and costly to do on large forests. But another way is to use a sampling system. A proven system, called "point sampling," is used regularly by foresters and can be used by timber owners as well. We will discuss point sampling and the equipment you need here.

### Point Sampling

Point sampling is a method of determining the frequency of occurrence of trees throughout the stand using a fixed point. These points can either be random or systematic. What you will be measuring is the basal area of the trees occurring at that point or "plot" center. Basal area is the area of the cross-section of tree stems near their base, generally at breast height, and including bark measured over 1 ac. or ha. of land. This basal area (BA) is then used to calculate the volume of a tree. Basal area increases as stand size and site quality increases.

### Gauges

Some sort of gauge is needed to determine which trees are counted and which trees are not. An angle gauge - either prism (the prism is a wedge-shaped piece of glass that will deflect the image when viewed), string, or stick gauge can be used. Several types of angle gauges can be purchased from any forestry supply company. A stick gauge can be constructed by putting a target on the end of a stick and by keeping a 1:33 ratio. A 1-inch site would be put on the end of a 33-inch stick. You then "eyeball" each target tree with this gauge to find out if it should be included in the sample (more on this in a minute).

It has been suggested that a dime can be used as an angle gauge. As long as a 1:33 ratio is maintained, anything can be used. For a dime, the distance held from your eye would be about 23 inches. A quarter would be held 33 inches away. An alternative to buying an angle gauge would be to build one.

### Build an Angle Gauge

Take a 1-inch piece of sturdy material - plastic, metal, etc.- and drill a small hole to attach a string. Kite string will work well, knotting the string at 33 inches from the gauge and attaching it to the sighting device. Now, when using, simply put the knot between the teeth and sight your gauge with the string completely stretched. An alternative is to put a 1-inch notch in the material which creates a kind of sight.

Before taking to the woods with one of these, you'll need to know how to use one.