Ecosystem Energy Flow Simulation

About this experiment

Follow energy stored in producers, herbivores, carnivores and apex consumers. Change their initial stores and transfer efficiencies, shut off primary production, and account for every input and departure.

Learning goals

Distinguish stored energy from the rate of energy transfer.
Explain why only part of a departing store enters the next trophic level.
Check the complete energy budget before and after input stops.

How to use it

1Run ten days with primary production and inspect each trophic level.
2Select a consumer base and change its incoming transfer efficiency.
3End primary production now and follow the existing energy through the chain.
4Record tracked stores and losses to verify their sum against initial energy plus input.

The model

E ˙_{0} = G (t) - k_{0} E_{0}

Primary production supplies the producer store.

E ˙_{i} = η_{i - 1} k_{i - 1} E_{i - 1} - k_{i} E_{i}

Consumers receive only a fraction of the preceding turnover.

i \sum E_{i} + L = i \sum E_{i} (0) + \int_{0}^{t} G (u) d u

Tracked energy plus cumulative departures equals initial energy plus primary input.

Assumptions

Stores are continuous energy inventories per unit area, not organism counts. Primary production enters the producer store at a fixed rate while enabled.
Turnover coefficients for producers through apex consumers are 0.20, 0.15, 0.10 and 0.08 per day. They are illustrative constants.
A selected fraction of each lower-level departure enters the next level. The rest enters a cumulative loss store, as does all apex turnover.
Loss includes heat and untracked organic waste; the model does not resolve decomposer recycling. Positive matrix-exponential propagation preserves nonnegative stores and the complete budget.
Bar heights are logarithmic. Altering a planned production cutoff compares different histories; ending production now preserves all energy already captured.

Try this in class

Q1Can a consumer store briefly increase after primary production stops?
Q2Why is a stored-energy ratio different from a transfer efficiency?

Frequently asked questions

Is transfer efficiency always ten percent?

No. Ten percent is the initial illustrative setting. Each incoming consumer efficiency can be changed independently.

Does the loss store contain only heat?

No. It also includes material and chemical energy leaving the tracked food chain, which this simplified model does not recycle.