# Determine the secondary production (1st order consumers) of a small forest ecosystem with an area of 10 km2

Determine the secondary production (1st order consumers) of a small forest ecosystem with an area of 10 km2, if it is known that in May – September, an average of 20 kcal of solar energy per month is supplied to this ecosystem per 1 cm2. No more than 1% of the incoming energy is used for photosynthesis, and plants spend about 500 calories to create 1 g of organic matter. Consumables without damage to plants can consume no more than 10% of pure primary production.

1) For five months (from May to September), 20 kcal • 5 = 100 kcal of solar energy is supplied to 1 cm2. And the entire forest area is 10 km2 or 10 ^ 11 cm2. Let’s calculate how much energy is supplied to the entire ecosystem: 100 kcal • 10 ^ 11 = 10 ^ 13 kcal.
2) 1% is spent on photosynthesis, i.e.
10 ^ 13 kcal: 100 = 10 ^ 11 kcal = 10 ^ 14 cal.
At the same time, 500 calories of energy are spent on the formation of 1 g of carbohydrates. This means that plants can synthesize 10 ^ 14 calories: 500 cal = 2 • 10 ^ 11 g of primary production.
3) 10% of net primary production is available to consumers of the 1st order, i.e. 2 x 10 ^ 10 g or 20,000 tons.
Answer: 20,000 tons.

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