The second SEEA-derived headline indicator covers services provided by ecosystems. It is conceptually harder than extent, because extent is observable from above, whereas services are relationships involving something an ecosystem supplies and someone who benefits. Both ends have to be identified before anything can be counted.
Supply and Use, in Physical Units First
A services account records, for each service, what ecosystems supplied and what economic units used.
| Service type | Example | Physical unit |
|---|---|---|
| Provisioning | Timber, fish, water abstracted | m³, tonnes, m³ |
| Regulating | Flood mitigation, carbon retention, pollination | Varies by service |
| Cultural | Recreation visits | Visitor-days |
The discipline that keeps this credible is that physical accounting comes first. Monetary valuation, where it happens at all, sits on top of a physical account rather than replacing one.
This ordering matters because valuation is contested and physical supply generally is not. A flood-mitigation service measured in cubic metres of retained runoff is a hydrological quantity. The same service expressed in currency embeds assumptions about avoided damages that reasonable people dispute and if the physical layer is solid, the dispute stays confined to the valuation step.
The Modelling Reality
Almost no regulating service is directly measured at national scale. They are modelled using data from land cover, terrain, climate, and biophysical relationships.
Tooling exists for exactly this, and platforms built for SEEA application package the models so that national teams are not implementing hydrology from first principles. That is a genuine enabler and it carries the usual caveat: a modelled service inherits the model's assumptions, and the model was probably calibrated somewhere else.
The honest presentation is to report modelled services as modelled, state the model and its provenance, and resist the presentational pull toward showing them with the same confidence as a measured timber harvest.
Why the Extent Account Has to Come First
A services account allocates services to ecosystem assets. Which means it needs those assets defined, mapped and classified, which is the extent account.
If extent is still being compiled, the services work has to proceed on interim spatial layers and be revisited when the final map exists. That is a normal sequencing constraint on parallel workstreams, and it is worth stating explicitly in the documentation, because a services account built on an interim extent layer is provisional in a way its output tables do not advertise.
The Use Side Is the Harder Half
Identifying supply is a biophysical question. Identifying use requires linking an ecosystem to the households, industries or government units that benefit, which is an economic-statistics question.
Water is the clearest illustration. A forested catchment supplies regulated flow; the users are downstream irrigators, a water utility, a hydropower operator. Attributing supply to those users requires knowing the hydrological connection and the economic structure, and those datasets live in different institutions.
Which is, in the end, the argument for doing this inside a statistics office. Nobody else routinely holds both halves.
Turn climate goals into a verified portfolio
TREEO connects the full carbon cycle, encompassing eligibility, simulation, real time monitoring, and registry ready reporting, while combining expert consulting with dMRV technology so the evidence exists before anyone asks for it.
