In this NetLogo example a system is setup to include a finite amount of vegetation (green patches) and a variable number of consumers (turtles).

 

The consumers use energy by move randomly and consuming food to supplement lost energy. Eating is simulated by a change in patch colour once overlaid by a turtle. If the consumers’ energy level reaches zero they die and disappear from the system. 

 

Food quantity decreases over time and follows the exponential decay pattern:

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A = A0 e ^ (k t)       (if  k < 0 )

 

A : Population at time t

A0 : Initial Population

k : Growth constant

t : Time