Distinguish recycling from ecological recovery

Put the boundary around the claim

The starting local pools contain 100 g N. Removing half the plant nitrogen exports 15 g N and leaves 15 in plants. Soil and detritus still contain 40 and 30. Local nitrogen is now 85 g; adding the exported account restores the full 100 g ledger.

Export is different from transferring damaged plant material into local detritus. The first crosses the boundary; the second retains nitrogen inside it. Neither is equivalent to destroying atoms.

Follow recovery without creating matter

With 50% export and one update, uptake is 0.2 × 40 = 8 g N, litter transfer is 0.1 × 15 = 1.5 g N, and mineralization is 0.1 × 30 = 3 g N. New pools are soil 35, plants 21.5 and detritus 28.5 g N. They still total 85 g N locally, plus 15 exported.

Plant nitrogen has increased from its immediate post-export value. That does not mean the original local nitrogen total has returned. Redistribution can increase one pool while the overall deficit remains.

Predict an endpoint: compare 0% and 50% export at the same update count. Can ten steps of internal recycling replace the exported 15 g N? Identify a process outside this model that could add nitrogen to the local boundary.

At 100% export, this model sets uptake to zero because no plant pool remains. It does not include seeds, surviving untracked roots or immigration. Failure to regenerate in that case follows from the model’s assumptions, not a prediction that real disturbed habitats cannot recover. For partial export, uptake capacity remains fixed despite the smaller plant pool, another deliberate simplification.

Define ecological recovery before measuring it

Disturbance can alter species composition, structure and ecosystem processes. Succession describes community change over time; it does not guarantee an exact return to the previous community. Primary succession begins on newly exposed substrate; secondary succession retains legacies such as soil or organisms from an earlier community. Background: community dynamics.

Choose an outcome before assessing recovery: nutrient retention, plant cover, species composition and productivity answer different questions. The nitrogen model measures only its defined pools. It contains no species or recruitment mechanism and therefore cannot test community succession.

For a follow-up observational study, compare repeated measurements at affected and suitable reference sites, document pre-disturbance evidence if available, and record site differences and concurrent environmental change. A green-looking site alone does not establish restored nutrient storage or biodiversity. Propose at least two measurements that would distinguish redistribution from replacement of exported matter.