Real-Life Math
"Math is used extensively in biogeography when one has to do mapping,"
says Margaret North, a biogeographer. "A simple use of statistics in biogeography
is when one uses the quartering method."
You are a biogeographer who
has been hired by the government to create a map of all the animals and vegetation
in a region called Burns Bog. It is a huge area and there are many kinds of
vegetation and life in the bog. You decide the best method of surveying the
area is to use the quartering method.
The quartering method is the
best way to calculate and catalog all the species, both animal and plant,
in a given area. You set up 4 points in the area, then count and record the
animal and plant species close to each point.
To take a sample of the
trees, for instance, the closest tree to each point is chosen. The species
and diameter of each of these 4 trees is recorded. Then the distance between
the point and each of the 4 trees is measured. The sum of these divided by
4 equals "d," the mean distance.
Here's some of the data you can
calculate when using the quartering method.
Mean distance
-- average distance between sample and point
Relative density -- percentage
of number of individual species compared to total number of individuals in
all species
Here's some of the data you've gathered
from Burns Bog:
Total number of distances taken is 4
Sum
of all the distances is 100 acres
Number of individuals of each species
= 20 frogs, 80 cats, 90 dogs, 10 snakes
Number of individuals of all species
= 200
Here are some formulas you will be using:
Mean
distance (d) = Sum of all distances / Total number of distances taken
Relative
density = (Number of individuals of the species / Number of individuals
of all species) x 100
Calculate the mean distance
and the relative density of the frogs.