REVISED EXAM 2 TECH: Vegetation sampling & measurement

What is vegetation in wildlife studies?

A single plant or an entire plant community.

What does vegetation type refer to?

Differences among plant communities or stands (e.g., marsh vs prairie).

What is vegetation structure?

Spatial arrangement of individuals in a stand, including live and dead plants, natural or introduced.

Why measure vegetation?

To estimate carrying capacity, assess habitat components, monitor management impacts, and track species trends.

What assumptions underlie vegetation sampling?

Knowledge of study species, objectives, plant identification skills, and existing protocols.

What factors influence study site selection?

Topography, soil, management history, water access, vegetation types, human disturbance, and survey feasibility.

What are the main sampling methods for vegetation?

Points & lines (transects), quadrats, plotless distance methods, and photo points.

What is a quadrat?

A fixed boundary frame for measuring density, biomass, cover, and frequency.

How is quadrat size determined?

Depends on plant size, distribution, density, and species-area curves.

What quadrat shapes are used?

Square (most common), circular (less perimeter, good for sod-forming plants), rectangular (reduces variability in sparse areas).

How should quadrats be placed?

Randomly within the habitat of interest, optionally stratified by homogenous sections.

What is stratified sampling?

Dividing a diverse site into more uniform sections and sampling separately.

Why avoid edge effects in sampling?

Edges (e.g., roadsides) may not represent the interior vegetation.

Define frequency in vegetation sampling.

Number of quadrats in which a species occurs; reflects abundance and distribution.

Define density in vegetation sampling.

Number of individuals per unit area (plants/m²); distinct from cover.

When are distance measures used?

For large, scattered plants like trees; density calculated from average spacing.

What are plotless density techniques?

Methods that require no quadrats; best for randomly distributed plants; faster in sparse areas.

Define biomass.

Weight of all plant tissues (above- and below-ground); indicates forage availability, energy storage, and ecological dominance.

Define cover.

Percentage of ground area occupied by plants; indicates species dominance and habitat quality.

What is bare ground measurement used for?

Assessing soil exposure, erosion risk, and ground cover protection.

What is vegetation structure?

3D arrangement of plants horizontally and vertically; indicates species dominance, habitat quality, and ecological processes.

How is horizontal cover measured?

Canopy, foliar (leaves only), basal (plant bases), gap intercept, line-intercept, or point-intercept methods.

What is gap intercept?

Measures spacing between canopy or basal gaps to indicate erosion risk and vegetation patterns.

How is line-intercept cover calculated?

(Canopy length intercepted / transect length) × 100.

When is point-intercept method used?

For vegetation <1 m tall; records hits on basal, foliar, and canopy cover.

What is the Daubenmire cover class method?

Ocular estimates of plant cover into classes; fast and effective for small plants.

How is tree canopy cover measured?

Spherical densitometer (sky reflection) or sighting tubes (vertical projection).

What is vertical plant structure?

Height, cover, and layers; assessed via vertical plots or visual obstruction methods.

What is a Robel pole used for?

Measuring visual obstruction from a fixed height/distance; index of biomass and cover.

How is vegetation height measured?

Woody: max height in a cylinder; herbaceous: tallest plant; averaged along transects.

Why measure biomass?

Forage availability, plant dominance, energy storage, hydrologic impact, and fire risk assessment.

How is biomass directly measured?

Clip vegetation, dry samples, and convert to standard units.

How is plant community composition assessed?

Density, cover, biomass, species richness, and relative contribution.

Define alpha, beta, gamma diversity.

Alpha: within-site richness; Beta: diversity across sites; Gamma: landscape-level diversity.

What is DBH in trees?

Diameter at breast height (1.37 m); used for structure and growth estimates.

How is tree age determined?

Counting rings on cut or cored trees using an increment borer.

What are plant applications of radiometric measurements?

Quantify visible, IR, UV light; monitor phenology, NPP, biomass, and land-use change.

What is NDVI?

Normalized Difference Vegetation Index; measures greenness using near-infrared vs red light.

What does NDVI indicate?

Vegetation density, plant health, leaf area index, drought stress, and phenology.

What is the Green Wave Hypothesis?

Migrating animals track high-quality forage at the leading edge of spring green-up.

How do bison illustrate the Green Wave?

Grazing intensity alters vegetation greenness, timing, and duration across Yellowstone grasslands, measured by NDVI.