Sampling populations without choosing the answer
| English | Français |
|---|---|
| population/ˌpɒpjʊˈleɪʃn/ | population |
| quadrat/ˈkwɒdræt/ | quadrat |
What would explain this observation?
- A field edge looks richer in plants than its centre. Choosing only the richest patches would build the desired result into the sampling method.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- A population 种群 consists of organisms of one species in a defined area. Random quadrats 样方 estimate density without deliberately selecting patches. A transect investigates change along an environmental gradient.
- quadrat: A defined area used for sampling; population: Organisms of one species in a defined area.
Which method investigates change from a path into woodland?
Estimate total abundance by multiplying mean density by area, with consistent units. This assumes sampled areas represent the habitat. Patchiness and too few samples widen uncertainty.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Estimate total abundance by multiplying mean density by area, with consistent units. This assumes sampled areas represent the habitat. Patchiness and too few samples widen uncertainty.
- Choose coordinates with random numbers before visiting the patches. Record quadrat area and counting rules. For a transect, use fixed distances and measure a relevant abiotic variable. Do not damage habitats or sample unsafe locations.
Which two habits make the investigation or model in this case more defensible?
Choose coordinates with random numbers before visiting the patches. Record quadrat area and counting rules. For a transect, use fixed distances and measure a relevant abiotic variable. Do not damage habitats or sample unsafe locations.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: five 0.25 square metre quadrats contain 3, 4, 6, 5 and 2 plants. Mean count = 20/5 = 4. Density = 4/0.25 = 16 plants per square metre. Estimated abundance in 100 square metres = 16 × 100 = 1,600 plants.
Mean count is 6 in a 0.5 square metre quadrat. Find density per square metre. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
Mean count is 6 in a 0.5 square metre quadrat. Find density per square metre.
The result is 12 . Known: five 0.25 square metre quadrats contain 3, 4, 6, 5 and 2 plants. Mean count = 20/5 = 4. Density = 4/0.25 = 16 plants per square metre. Estimated abundance in 100 square metres = 16 × 100 = 1,600 plants.
Check the conclusion and its limits
- Quadrats suit organisms that do not move quickly. A food chain arrow shows the direction of energy transfer, not the direction a predator travels.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Sampling only the most crowded patches gives an unbiased population estimate. This claim is false: Quadrats suit organisms that do not move quickly. A food chain arrow shows the direction of energy transfer, not the direction a predator travels.
Sampling populations without choosing the answer: Estimate total abundance by multiplying mean density by area, with consistent units. This assumes sampled areas represent the habitat. Patchiness and too few samples widen uncertainty.
Sampling only the most crowded patches gives an unbiased population estimate.
Quadrats suit organisms that do not move quickly. A food chain arrow shows the direction of energy transfer, not the direction a predator travels.
A defined area used for sampling: write the technical term.
quadrat means A defined area used for sampling.