Avery and Burkhart,Chapters 1, 18

Forest Mensuration II

Lecture 1

Introduction to Forest and Natural Resource Measurements

Objectives

• What are forest measurements?• Why measure forest resources?• Types and scales of measurements• Introduction to natural resource

measurements

What are forest measurements?

• “How-to-do-it” for tree overstory, i.e.,timber volume, tree form, growth, cull factors, mortality, etc.

• Deals with direct measurements, sampling, and prediction

There are still many measurement problems for which no perfect solutions exist

Why measure forest resources?

• Forest management requires knowledge of the location and their current features

• The role of measurements is to supply the numerical data required to make management decisions

Accurate measurements allow scientifically sound management decisions being made

• Direct measurements– Tree height– Tree diameter

• Sampling – A portion of the entire resource - expand to

characterize entire resource

• Prediction– Those resources, such as tree volumes, not easily

measured

Types of measurements

Scales of measurements

• Nominal scale– Numbering objects for field identification, e.g., tree number, plot

number

• Ordinal scale– Expressing rank or position in a series, where rank has

meaning, e.g., tree crown classes, lumber grades, site quality classes

• Interval scale– A series of graduations marked off at uniform intervals from an

arbitrary origin, e.g., temperature

• Ratio scale– A series of graduations marked off at uniform intervals from an

origin of absolute zero, e.g., tree height, volume, length of trail, amount of habitat

Standard practices

• Abbreviations and symbols (page 4)• Significant digits and rounding off

– Don’t record more significant digits than were observed– Ignore the 5 when the digit preceding is an even number.

Conversely, if the digit preceding is an odd number? – Rounding off should be carried at least two places beyond

that of the final rounded figures

• Conversions between metric and English units (Page 6 of the textbook)

Natural resource measurements

Forestland

• Features measured: trees• Sampling units: fixed-radius plots, variable

radius plots, strips• Sampling schemes: systematic sampling,

stratified random sampling• Measures: timber volume, wildlife habitat,

forest density

Rangeland

• Features measured: grasses, forbs, shrubs• Sampling units: small square plots• Sampling schemes: systematic sampling,

stratified random sampling• Measures: weight of herbage, grazing

capacity, range condition and trend

Wildlife

• Features measured: animals, habitat• Sampling units: plots, strips, areas• Sampling schemes: direct census, indirect

census, mark-recapture techniques• Measures: animal presence, animal species

richness, animal populations, wildlife habitat suitability

Water resources

• Features measured: water• Sampling units: weirs, flumes, current meters• Sampling schemes: watersheds, stream

reaches• Measures: water quantity, water quality

Recreation

• Features measured: people• Sampling units: visitor days, vehicles, water

usage• Sampling schemes: complete registration,

self registration, surveys• Measures: recreation quality, recreation

opportunity, visitor satisfaction