I am going to estimate the population of woodlice in parts of the school ground, using Lincoln Index.

AS and A Level Maths

ESTIMATING THE POPULATION OF WOODLICE IN

PARTS OF THE SCHOOL GROUND

Aim: - I am going to estimate the population of woodlice in parts of the school ground, using Lincoln Index.

Materials

White trays, gloves, nail polish and spoon.

This investigation would be performed, using the mark-release recapture technique.

Method

A certain area is marked out and then by lifting up stones and pieces of decaying wood, woodlice found are picked up by using a spoon and placed in a white tray.

The amount of woodlice caught is counted and then each woodlouse is marked with the nail polish in such a way that will not harm them or attract predators. The woodlice are then released into their habitat and allowed to mix with the rest of the population. After two days, woodlice are then caught from the same location and the amount caught is recorded, along with the number of the woodlice that have already been marked from the first sample.

Result

Lincoln Index

Total population = (S1 x S2)/ m

Total population of woodlice = (35 ...

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Result

Lincoln Index

Total population = (S1 x S2)/ m

Total population of woodlice = (35 x 39)/ 2

= 682.5

Approximately 683 woodlice are present in this area.

This method is reliable if I assume that

The marked woodlouse mix evenly with the unmarked;
Being caught the first time does not increase or decrease the likelihood of the woodlouse being caught the second time;
There are no births or immigrations between marking and recapture;
The marked woodlice behave in the same way as the unmarked and suffer no ill effects from the mark.

Results obtained from other groups are as follows:

Evaluation

From my result above, the number of woodlouse caught in the second sample is more than the number of woodlouse caught in the first sample. This may be as a result of an improvement in my woodlice catching skills or as a result of an in thorough sampling of the area. The number of marked woodlice caught in the second sample was low. This may have been as a result of migration and emigration. Woodlice may move to areas drier and better than the sampled area. The area being sampled is part of the school ground and so may have been disturbed therefore altering our result.

The number of woodlouse caught by the green group was higher in the second sample and they had the highest number of marked woodlice in their second sample. This may have been as a result of migration of woodlouse into this area as it was drier and well sheltered.