Principles of Vegetation Measurement & Assessment and Ecological Monitoring & Analysis

## Units and Numbers

Numbering systems and conversions

### Numbering Systems: Duo, Hex, and Decimal

Although many people like to say we live in a decimal (i.e., base 10) world this is not completely true. Our currency is in the decimal system as everything is multiples of 10 or 100. e.g., 100 cents in a dollar.  Natural resource inventories in the U.S. are collected with a mixture of decimal (e.g., 100 links in a chain) and the duodecimal (e.g., base 12) numbering system, where examples include 12 inches in a foot.

Other numbering systems are all around us. For example, time is in the sexagesimal (i.e., base 60), with 60 seconds in a minute and 60 minutes in an hour. Also if you do any sort of computer programming, you will also run across the hexadecimal system (i.e., base 12). In short, the world can be a confusing mass of numbers.

### Numbering Systems: English and Metric Units

In natural resource measurements two types of measurement systems are commonly used. Namely, the Metric and English systems.  In the U.S., the metric system is used alongside the English system, which has its origins from the colonial days and is often called the Imperial system in Canada and Great Britain. The English system is generally used by land and resource managers. The Metric system is predominantly used by scientists and is most often the units reported in scientific journals and proceedings. It is essential to know both systems and how to convert between them.

The SI (Système International) System are standard measures that have been repeated in multiple observations. Future attempts to make similar measurements can be compared against these defined standards. We use predominantly these 4 in natural resources:

• Length = meter (m): The length of light traveled in a vacuum in 1/299792458 seconds.

• Mass = kilogram (kg): The mass of a certain cylinder of platinum-iridium alloy held in a vault in Sevres, France.

• Time = seconds (s): 9192631770 vibrations of the radiation emitted at a specific wavelength of cesium-133.

• Temperature = Kelvin (K): 1/273.15 of the thermodynamic temperature of the triple point of water.

• Others SI measures include the ampere, mol, and candela.

Common English measures of length and area are:

• 1 foot = 12 inches

• 1 log = 2 sticks = 16 feet

• 1 chain = 4 rods = 22 yards = 66 feet = 100 links

• 1 square chain = 66 x 66 feet

• 1 acre = 10 sq chains

• 1 square mile = 640 acres

### Numbering Systems: Common Conversions

To convert between the metric and English systems (and vice versa) there are a series of standard conversion formulas. Please refer to the following worksheets as these are the conversion formulas used most commonly in natural resource measurements: Common Conversions or Useful Rangeland Conversions

 Summary Questions Describe different natural resource examples where units of length, area, and temperature would be commonly measured. Explain why standard measures are important? How would you convert between units of kg per hectare and lbs per acre? Advanced Questions: What type of base does degrees on a compass have?