Job Descriptions

Woodland firefighter from the U.S. Forest Service.

Inventory Timber Cruiser - Washington State

Inventory timber cruising is analogous to a store taking stock of what they have on the shelves. A timber company needs to know how much volume of what age and type of timber they have on their land to project future harvests and manage the land properly. The following description is of one one particular type of timber cruise. There are many other types. What data is taken depends on the purpose of the cruise.

Planning a cruise begins with aerial photos of the land being taken by airplanes flying at a specified height. Each photo covers approximately one section of land. One section of land is one square mile, or 640 acres. These photos are examined using a stereoscope. Two photographs of the same section are used, but taken slightly offset from each other. These two photographs are called a stereo pair. Taking stereo pairs allows the photographs to be look at three-dimensionally using a stereoscope. From these photos, the timber is typed out by stand, or areas of similar age, size and species of trees. Maps are made of these types and number of plots are determined for the desired intensity of the cruise. More plots means more trees are sampled and the data is of higher accuracy. Taking more plots also costs more in time and money. Plot locations are then marked and determined to be either "count" or "measure" plots. All this information is then given to the timber cruiser who then finds a convenient starting point off a road, section corner, or section line crossing a road. The cruiser then locates their first plot by compass and pacing.

On a "count" plot, the only information recorded is the number of trees of each species by diameter at breast height (dbh). The diameter is taken 4 1/2 feet off the ground on the uphill side of the tree. On a "measure" plot, each tree is recorded individually and the cruiser notes its species, dbh, height, status (live, dead, recently dead), any damage, the cause of the damage, what percent of the volume to deduct because of the damage, and the percent of the tree height that has live limbs. Any of this information can vary depending on the purpose of the cruise. For some cruises, underbrush information or snag count may be recorded, or any other information deemed necessary may be taken.

Successive plots are found by following a compass line and pacing distance. The plot center is marked by hanging a plastic ribbon from a limb and poking a stick in the ground. These are temporary plots only used during the cruise. In another type of cruise, permanent plots may be set up. Plots are circular with variable radii depending on tree size and are known as prism plots. Trees are determined to be in or out of the plot by looking through an instrument in which the cruiser compares each trees dbh to a given scale. The instrument used to determine which trees are in a plot is generally a Relaskop or a prism calibrated to a specific scale. If the tree's dbh is larger than the scale being used, then it is considered to be in the plot and should be recorded. There should ideally be 6-8 trees on a plot and different scales can be used to obtain this, though the scale being used must remain the same for every plot in a given stand.

The timber cruiser carries a compass, a logger's tape to measure distance on one side and dbh's on the other, a Relaskop which contains several scales; it is used to determine which trees are in the plot and also to measure the tree heights, and a data recorder in which the plot information is entered and can be downloaded into a computer. The timber cruiser may also need an increment borer which allows the cruiser to take a sample of a tree to allow age determination, rain gear, caulk boots, and lunch.

I would like to collect descriptions of all types of jobs that forestry and forest products majors could conceivably end up doing in the workplace. This could include (but is not limited to) fire crew, timber marker, log scaler, lumber buyer, computer programmer, University professor, chemical engineer in a pulp mill, etc. If you have forestry experience and would like to contribute, please e-mail me a job description of what you did. I would like a description that would tell someone who has never done the job what it is like. You will remain anonymous unless you tell me specifically to put your name on the job description. I would like to say where the job is, such as Inventory timber cruiser from Washington State. I can't pay you, but you will be helping people decide if this field is for them. Thanks!