Biodiversity and sampling
| English | Chinese | Pinyin |
|---|---|---|
| ecosystem | 生态系统 | shēng tài xì tǒng |
| niche | 生态位 | shēng tài wèi |
| biodiversity | 生物多样性 | shēng wù duō yàng xìng |
| abundance | 丰度 | fēng dù |
| quadrat | 样方 | yàng fāng |
| transect | 样带 | yàng dài |
| mark-release-recapture | 标志重捕法 | biāo zhì zhòng bǔ fǎ |
| Simpson's index | 辛普森指数 | xīn pǔ sēn zhǐ shù |
The variety of life
- An ecosystem 生态系统 is all the living things in an area plus their non-living surroundings.
- A niche 生态位 is a species' particular role and place within it.
- Biodiversity 生物多样性 measures the variety of life — at three levels.
Biodiversity sampling lab
Choose the sampling method or index that matches the field question.
An ecosystem is:
An ecosystem includes the living community and the abiotic surroundings; a niche is a species' role within it.
Three levels of biodiversity
- the number and range of different ecosystems and habitats.
- the number of species and their abundance 丰度 (how common each is).
- the genetic variation within each species.
Biodiversity is measured at three levels: ecosystems, species, and the genes within a species
Biodiversity is measured at three levels: ecosystems/habitats, species/abundance, and:
The three levels are ecosystem diversity, species diversity (and abundance), and genetic diversity.
Sampling an area
- You can't count everything, so you take samples. Random sampling avoids bias.
- quadrats 样方 — square frames to count species inside them.
- transects 样带 — counting along a line across the area.
- mark-release-recapture 标志重捕法 — for moving animals: mark and release some, then see what fraction of a later catch is marked.
Quadrats, transects and mark-release-recapture
Why is random sampling used?
Choosing positions by chance avoids bias, so the sample fairly represents the whole area.
Random sampling is used so the sample is not biased and fairly represents the whole area.
Picking spots by chance (e.g. with coordinates) stops you only choosing the interesting-looking places.
Match each sampling method to what it is for.
Quadrats and transects sample plants/slow organisms; mark-recapture estimates mobile animals; Simpson's index summarises diversity.
You mark 20 woodlice and release them. Later you catch 25, of which 10 are marked. Estimate the population (first catch × second catch ÷ marked in the second).
Population ≈ (20 × 25) ÷ 10 = 50. The marked fraction of the second catch (10/25) reflects the marked fraction of the whole population (20/N).
Measuring diversity
- Simpson's index 辛普森指数 of diversity turns biodiversity into a single number.
- A higher value means more diverse — and usually more stable.
A higher Simpson's index of diversity means the area is:
Simpson's index gives a single diversity number; higher means more diverse and generally more stable.
You've got it
- ecosystem = living + non-living; niche = a species' role
- biodiversity has three levels: ecosystems/habitats, species + abundance, genetic variation
- sample with quadrats & transects (fixed organisms) and mark-release-recapture (moving animals); use random sampling
- Simpson's index: higher = more diverse (and usually more stable)