# Organisms and Populations

**Exponential Growth Equation**

**N**

N

N

r = intrinsic rate of natural increase;

e = base of natural log.

_{t}=N_{0}e^{rt}where as :N

_{t}= Population density after time t;N

_{0}= Population density after time 0;r = intrinsic rate of natural increase;

e = base of natural log.

**Logistic Growth Equation**

**$${dN \over dt} = rN ({ k-N \over k}) $$ Where as:**

N = Population density at time t;

r = Intrinsic rate of nutual increase;

k = Carring capicty

N = Population density at time t;

r = Intrinsic rate of nutual increase;

k = Carring capicty

**Population Density**

**$${N _{t+1}} ={ N _t} +[{(B + I) - (D + E)} ] $$ Where as:**

N

N

B = Birth

D = Death

I = Immigration

E = Emmigration

N

_{t+1}= Population density at time t+1;N

_{t}= Population density at time t;B = Birth

D = Death

I = Immigration

E = Emmigration