Ecosystem Measurement

If you know WHY you’re measuring, then you’ll know WHAT to measure.

Types of data abundance density evenness biomass

Types of data, continued coverage = proportion or percent of ground

covered over by a particular species

(i.e. how much shade?)

Types of data, continued DBH = diameter at breast height

(diameter of trunk at 1.5 m)

Types of data, continued dendrology = tree rings

Usually collected from core samples

Data: age of tree,

climate conditions

Yikes!!Go out and measure every tree?

No way!! Instead you choose an appropriate sampling method.

4 sampling methods:1. plot

2. transect

3. point-quarter

4. photogrammetry

Plot sampling AKA “quadrat” rectangle or square 1 m2 to 100’s m2

randomly selected replicated

Plot sampling is used to measure plant communities, sessile communities, soil fauna, animal burrows, benthos

Types of data from plot sampling species density, evenness, coverage, biomass (in aquatic systems)

Transect Sampling (3 types)

1) Belt transect sampling long, narrow strip of terrain same type of data as plot sampling used to study contiguous communities or

seres of ecological succession

2) Line-intercept transect straight line through ecosystem (rope or

tape-measure) any plant that touches the line is counted or

the diameter of plant on line is measured data will give species density, evenness,

and coverage

3) Strip census transect The researcher walks on straight line

through ecosystem counting visible animals or animal sign

e.g. birds, butterflies, roadkill, scat, etc. There are mathematical techniques that

will convert data into population densities, etc.

.... to review

What is a plot sample?

What are the 3 types of transect samples?

Point-quarter sampling “plotless” method has reliability issues: plants must have

random distribution!!!

Point-quarter, continued Researcher randomly selects points within

ecosystem & marks each with a flag. Each point represents center of compass

with 4 quarters (N, W, S, E) quarter = quadrant (not quadrat)

Point-quarter, continued In each quarter, measure the distance from

center point to center of nearest individual plant

Only one plant per quarter is measured Combine the data (if reliable) to find

species density, evenness & coverage

Photogrammetry

“remote sensing”

Photogrammetry, continued photos taken from airplanes & matched to

GPS digital or infra-red film

Photogrammetry is used to identify vegetation, soil & forest types, to measure tree height

Photogrammetry is used also for mapping potential tree harvest zones

and access roads, for identifying riparian zones, for monitoring stream-channel shifts,

and to assess landslide risk, evaluate reforestation progress, and study health of individual trees (leaf

density in crown).

... to review

Pros & cons of pt-1/4 sampling?

Uses of photogrammetry?

Why sample? Ecological reasons 1. 2. 3. 4.

Economic reasons 5. 6. 7. 8.