La Bourse / Volume VII / Nº VII.03 / Quiz, reflection, essays

A watercolour of hills in bands of gold, rust and green, wildflowers in the foreground. — Plate VII.03 · Quiz, reflection, essaysThe Strip Through the Middle.The forest at the edge of the farm was worth two hectares of coffee for every hectare of itself. The same trees, cut into strips and put through the middle, could have been worth eight. Nobody moved them, because nobody had computed the multiplier.

ASSESSMENT · Chapter VII.03 — Biodiversity as Infrastructure

Three instruments: a ten-point quiz, eight reflection questions, five essay prompts. The quiz checks comprehension rather than recall. The reflections are private and first-person. The essays are arguable from more than one side.

THE QUIZ — ten points

Four on recall.

1. Write the marginal-hectare formula and define each term.

V = L · Y₀ · Δ · P · φ — leverage (crop hectares served per habitat hectare), unserved yield in tonnes per hectare, the proportional yield uplift, the farmgate price per tonne, and the attribution share. One mark for the expression, one for identifying L as the term set by placement rather than by quantity.

2. State the two half-decay distances measured by Ricketts and colleagues, and say what each governs.

Visitation rate falls by half at about 0.6 km from natural habitat; pollinator richness at about 1.5 km. Visitation governs how much service a given block receives; richness governs how stable that service is across seasons and weather. Credit any answer that notes the service has a measurable spatial decay, which is what makes habitat sizeable and priceable.

3. Of the 115 leading global food crops, how many depend on animal pollination, what share of production volume do they represent, and what share of value did Gallai and colleagues attribute to insect pollination?

87 of 115 — 75.7 per cent of crops; about 35 per cent of production by volume; €153 billion, or 9.5 per cent of the value of world crop production for human food.

4. Name the four mechanisms of the United States 2008 Compensatory Mitigation Rule, and say which one England's biodiversity net gain regime already has.

Performance-linked credit release, bonded financial assurance, a long-term stewardship endowment, and a preference for advance mitigation. England has the thirty-year securement and a public register — the durability leg — and none of the other three.

Four on application.

5. A colleague presents the figure "$4.5 billion a year in pest control by native insects" as the business case for a habitat programme on a 400-hectare farm. What is wrong with the move, and what is the right use of the number?

Divided across 160 million hectares of US cropland it is $28.12 per hectare per year — below a single insecticide pass, and far too small to carry a farm-level decision. It is a policy number, useful for arguing about a national research budget, and it does not descend to a field. The stronger answer also notes the generality problem: enemies rise in complex landscapes in 74 per cent of studies but pest pressure falls in only 45 per cent.

6. A grower has 157 hectares of habitat in two blocks at the farm boundary and is being advised to buy a further 60 hectares. What should they do first, and why?

Compute L. At Finca Santa Fe the geometric ceiling was 7.9 and the measured value implied 2.07 — a gap of 3.8 times produced entirely by placement. Since V is linear in L, redistributing the existing habitat into strips through the blocks can be worth several times what buying more at the boundary is worth, and it costs nothing. Full marks require noting that quantity is a factor of one and configuration is a factor of four.

7. Explain why the English biodiversity net gain price of roughly £25,000 a unit should not be read as evidence that a hectare of habitat is worth £100,500.

Because the compliance price is set by the cost of the developer's alternative — planning refusal — not by the service the habitat provides. The measured agronomic value of the same hectare runs $739 to $3,360 a year against a compliance price of $8,303 a year: two markets in one asset, priced off unrelated variables. A landowner selling into the compliance market is selling a permit; the agronomic value is a separate asset they have not sold.

8. The biodiversity–function curve saturates: the sixteenth species adds one eighth of what the second adds, and only 12 per cent of polycultures beat their best single species. Why is this not fatal to the case for high richness?

Because every such curve was fitted to one function, in one year, in one place. Isbell and colleagues found 84 per cent of 147 species promoted functioning at least once across many functions, years and sites. Modelling each context as drawing about twelve species from the pool, twenty-two contexts reproduce the observed 84 per cent. The saturation is in the denominator, not the field.

Two that require the arithmetic to be done.

9. A coffee farm has 80 hectares of habitat. Mapping the one-kilometre service radius shows 320 hectares of coffee inside it. Unserved yield is 1.0 t/ha, the measured uplift is 20 per cent, attribution is agreed at 0.70, and coffee is $3,000 a tonne. Compute the value per hectare of habitat, capitalise it at 7 per cent, and say whether it beats a pasture alternative returning $150 a hectare. Show your working.

L = 320 / 80 = 4.0. V = 4.0 × 1.0 × 0.20 × 3,000 × 0.70 = $1,680 per hectare per year. Capitalised: 1,680 / 0.07 = $24,000 per hectare. Against pasture at $150, it beats it 11.2 times over. The point of the question is that the answer is a per-hectare land rent, and a land rent can be lent against. Credit any answer that also tests the price sensitivity: at $1,320/t it is $739, still 4.9 times pasture; at $6,000/t it is $3,360.

10. A scheme requires one hectare of created wetland per hectare destroyed. Moreno-Mateos and colleagues measured created wetlands at 23 per cent below reference on biogeochemical function. What offset ratio holds function constant, and what is the loss embedded in the one-to-one rule? Then state the design change that addresses delivery rather than ratio.

Delivered function is 100 − 23 = 77 per cent, so the ratio required is 1 / 0.77 = 1.30 hectares created per hectare lost. A one-to-one rule writes a 23 per cent loss into the instrument before anybody fails to comply. The design change is performance-linked credit release: under the US 2008 rule about 15 per cent of credits issue on approval and site protection and the other 85 per cent against ecological milestones, so a credit cannot be sold before the habitat exists. The strongest answer distinguishes the two failures — ratio is an equivalence problem, release timing is a delivery problem, and fixing one does not fix the other.

REFLECTION — eight questions, for one person and a pen

These are not for a room. Write the answers by hand if you can; the slowness is the point.

Think of a piece of ground you have decided about — kept, cleared, sold, built on. What price was in the air that month, and would you have decided the same way at a different point in the cycle?

Where in your own work are you carrying something at its alternative-use value rather than at what it actually produces? Answer about a person or a relationship before answering about an asset.

What have you been arguing for on principle that you have never tried to price? What would it cost you, in hours, to find out?

Recall a number you used because it was large, without dividing it by anything. What would the division have shown?

Think of something in your life whose value depends almost entirely on where it sits rather than how much of it there is. What would moving it be worth, and what has stopped you?

When did you last claim the whole of an improvement that several things produced? What would your honest φ have been?

What are you treating as replaceable that takes decades to form? Name one thing, and one way you would know if you were wrong.

Where have you accepted a promise where you would normally have asked for a milestone? What made that reasonable at the time, and is it still?

ESSAY PROMPTS — five

Each is arguable from more than one side. Each requires at least one source the chapter cites and at least one it does not.

1. The derivative problem. The chapter argues that the marginal value of a hectare of habitat is a derivative on a commodity price, and that a clearing decision taken in a trough is a permanent bet against mean reversion. Argue either that the correct response is a contractual one — indexed royalties, price floors, long-dated covenants — or that it is a regulatory one, because private contracts cannot bind land across the ownership changes of a full commodity cycle. Use Ricketts and colleagues (2004), and one source on commodity price cycles or long-dated agricultural contracting that the chapter does not cite.

2. Is the Dasgupta framework the right container? The Review measures natural capital per head falling 40 per cent while produced capital doubled, and asks for accounting prices it acknowledges do not exist. Argue either that inclusive wealth accounting is the only framework that can put biodiversity into a finance ministry's decisions, or that its substitutability assumptions make it structurally unable to represent non-substitutable systems. Engage Dasgupta (2021) directly, and at least one published critique — Spash and Hache is a starting point, not the only one.

3. The offset market as a permit market. The chapter claims England's biodiversity net gain price is set by the developer's alternative and is not an ecological signal. Argue whether a compliance market that prices a permit rather than a service can nonetheless produce good ecological outcomes — and what would have to be true of its rules for that to hold. Use zu Ermgassen and colleagues, and one source on emissions trading or transferable development rights that the chapter does not cite.

4. Pest regulation: absent evidence or absent effect? Karp and colleagues found landscape composition explained little variation in pest and enemy abundance across 132 studies and 6,759 sites. Argue either that this is a measurement problem — wrong scale, wrong taxa, wrong response variable — or that it is a real finding about the contingency of the service, and say what would change your mind. Use Karp et al. (2018) and Dainese et al. (2019), and one agronomic or integrated-pest-management source the chapter does not cite.

5. What is a hectare of created wetland? Moreno-Mateos and colleagues measured a 23 per cent functional deficit persisting a century after restoration. Argue whether the right conclusion is a higher offset ratio, a categorical prohibition on offsetting slow-forming systems, or a shift of the whole instrument from compensation to avoidance — and price your answer, at least roughly. Use Moreno-Mateos et al. (2012) and Curran et al. (2014), and one source on restoration ecology or the mitigation hierarchy that the chapter does not cite.