Question 1

What is biodiversity net gain?

Accepted Answer

A requirement that development must leave biodiversity **measurably better** than before — in England, a legally mandated minimum uplift, calculated with a defined metric and secured for a long period.

**The principle.** Previously, planning required developments to avoid or mitigate harm where possible. Net gain goes further: the development must produce a **quantified improvement** over the pre-development baseline.

**How it is measured.** Through a **statutory biodiversity metric** converting habitat into **biodiversity units**, based on:

**Habitat type** and its distinctiveness.

**Condition**, assessed against published criteria.

**Area** — or length, for hedgerows and watercourses, which are assessed separately.

**Strategic significance** of the location.

For habitat created or enhanced, the metric also applies **risk multipliers** for **difficulty of creation**, **time to target condition** — habitats taking decades to establish are discounted heavily — and **distance** from the impact site.

**The mitigation hierarchy still applies first**, and this matters: avoid harm, then minimise, then restore, and only then compensate. **Net gain is not a licence to destroy habitat and pay for it elsewhere**, though that is the concern most frequently raised.

**How gain is delivered**, in order of preference: **on site**; **off site**, on land the developer provides or buys units for; or by purchasing **statutory biodiversity credits** from government, priced deliberately high to make it the last resort.

**The 30-year requirement** is the significant provision — habitat created must be **secured and maintained for at least 30 years**, through a legal agreement or conservation covenant, with monitoring and reporting.

**The criticisms:**

**Metrics simplify ecology.** A unit of one habitat is not ecologically equivalent to a unit of another, however the arithmetic balances.

**Created habitat frequently fails**, and monitoring and enforcement capacity is limited.

**Irreplaceable habitats** — ancient woodland, peat — cannot be recreated at all, and are excluded from the trading arrangements for that reason.

**Baselines can be degraded in advance**, which the rules attempt to prevent.

**Local authority capacity** to assess and enforce is a recurring concern.

Question 2

What are ecosystem services?

Accepted Answer

The benefits people obtain from ecosystems — a framework for making nature's contribution visible in decisions that would otherwise treat it as worth nothing. The four categories, from the Millennium

Question 3

What does a red list conservation status mean?

Accepted Answer

An assessment of a species' risk of extinction, made by the IUCN against published quantitative criteria — and it is a measure of risk, not of rarity, abundance or importance, which is the

Question 4

What is a keystone species?

Accepted Answer

A species whose effect on its ecosystem is disproportionately large relative to its abundance — so removing it causes changes far beyond what its numbers would suggest. The origin. The concept comes

Question 5

What is a marine protected area, and do they work?

Accepted Answer

An area of sea where human activity is restricted for conservation. They work when they are genuinely protected, enforced, and large enough — and a great many are none of those things, which is why

Question 6

What is the difference between climate mitigation and adaptation?

Accepted Answer

Mitigation reduces the cause. Adaptation reduces the harm. Both are necessary, and treating them as alternatives is a mistake that has cost real time. Mitigation means limiting climate change itself

Question 7

What is a wildlife corridor, and do they work?

Accepted Answer

A strip of habitat connecting otherwise isolated areas, allowing animals to move between them — and the evidence that connectivity matters is strong, while the evidence about specific corridors is

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