A team of plant ecologists wants to study how the abundance and distribution of halophytic (salt-tolerant) plants change with increasing distance from the high-tide mark across a salt marsh.
Suggest a systematic sampling method they should use to investigate this distribution.
Explain one limitation of using a line transect compared to a belt transect for this investigation.
The ecologists recorded the number of individuals of 5 plant species in a representative salt marsh plot. Their data is shown in the table below:
| Plant species | Representative number of individuals per plot (nnn) |
|---|---|
| Sea aster | 12 |
| Sea lavender | 18 |
| Glasswort | 15 |
| Cordgrass | 25 |
| Common saltmarsh grass | 10 |
Calculate the Simpson's Index of Diversity (DDD) for this data using the formula:
D=1−∑(nN)2 D = 1 - \sum \left(\frac{n}{N}\right)^2 D=1−∑(Nn)2Show your working. Give your final answer to 3 decimal places.
The ecologists struggled to distinguish between two closely related species of sea lavender (Limonium vulgare and Limonium humile) and decided to group them both under the single category 'Sea lavender'.
Explain how this decision might affect the calculated value of DDD.
