Suppose a fox in a food web feeds only on rabbits, squirrels, mice and birds, all of which feed exclusively on plant material. Assuming that a fox’s daily caloric requirement is 800 kcal, and that only 10 percent of the energy at one trophic level can be passed to the next trophic level. How many square meters of plant material are required to support the fox, if the net primary productivity of the plant material is 8,000 kcal/m2/yr? Hint: draw the food chain to determine how many kcal/m2/yr the fox receives to determine how much land he needs and remember the 10% rule!

square metres of plant materials required to support the fox = 3650 m²

Explanation:

From the given information:

the daily caloric requirement of the fox = 800  

In a year, we have = 800 kcal × 365 /year = 292,000 kcal/year

Also, only 10% of the energy at a particular trophic level can be passed onto the next.

the net productivity of the plant material = 8000 kcal/m²/yr

So, using 10% of energy at a particular level, the fox only need 80 kcal/m²/yr

The objective is to determine in square meters, how many materials are required to support the fox.

square metres of plant materials required to support the fox =

= 3650 m²