IB ESS Formulas

Net primary productivity

calculated by subtracting respiratory losses (R) from gross primary productivity (GPP).

NPP = GPP - R

Gross secondary productivity (GSP)

the total energy or biomass assimilated by consumers and is calculated by subtracting the mass of fecal loss from the mass of food consumed

GSP = food eaten - fecal loss

Net secondary productivity (NSP)

calculated by subtracting respiratory losses (R) from GSP.

NSP = GSP - R

CBR (crude birth rate)

= no of births / population size x1000

CDR (crude death rate)

=# of deaths / population size x 1000

NIR (natural increase rate)

= CBR - CDR/10 (migration is ignored)

TFR (total fertility rate)

= average no of children/woman

DT (doubling time)

= time in years to double the population size

Respiration

glucose + oxygen -> carbon dioxide + water

Photosynthesis

carbon dioxide + water -> glucose + oxygen

Lincoln index

- measures the abundance of motile organisms using capture-mark-recapture

n1*n2/ nm

- n1 is the number caught in the first sample

- n2 is the number caught in the second sample

- nm is the number caught in the second sample that were marked.

Simpson diversity index

- measures species diversity in two similar habitats. Remember, higher the value of D, greater the diversity. A lower value in one habitat may indicate human impact.

D= N(N-1)/ (n-1)

- D is the Simpson diversity index.

- N is the total number of organisms of all species found.

- n is the number of individuals of a particular species.

% change

= change (final - original)/ original number × 100