--- title: the stocks and flows of natural capital canonical_url: https://ensurance.app/guide/the-stocks-and-flows-of-natural-capital markdown_url: https://ensurance.app/guide/the-stocks-and-flows-of-natural-capital.md subtitle: "fifteen kinds of place, nineteen kinds of work, and the one number that joins them" category: natural-capital --- # the stocks and flows of natural capital *fifteen kinds of place, nineteen kinds of work, and the one number that joins them* The **stocks and flows of natural capital** are the two halves of one account. The UN's ecosystem accounting standard calls the stocks ecosystem assets and the flows ecosystem services. In plainer words, a stock is a living system that holds value in place: a forest, a wetland, a reach of river, a strip of coastal marsh, with an extent, a character and a condition. A flow is what that system does every year: water held and released, soil kept on the slope, a street cooled, a field pollinated, a storm surge blunted. We use the shorter words because stocks and flows are what a balance sheet and an income statement already are. Take the Demille wetland in Florida, 83 acres of forested wetland. The stock is the wetland. The flows are what it does in a year: water held, water cleaned, habitat kept, and the rest of the work a wetland does whether or not anyone values it. [RealValue](/manual/natural-capital?from=guide) makes the flow legible in dollars beside what the stock costs to hold. [Ensurance](/?from=guide) funds the stock. It is not the number. Those who depend on the flows fund the asset that makes them, and the asset kept whole keeps making them. [Ensure the asset to ensure the flows](/guide/ensure-the-asset-to-ensure-the-flows?from=guide) is that loop in full. :::johnson **the stock is the place. the flow is the work.** — Fifteen kinds of place, nineteen kinds of work, and one number that puts what the work was valued at beside a stated cost of the place. [see the stocks and the flows →](/natural-capital?from=guide) ::: ## what a stock is, and what a flow is A **stock** accumulates. It is what you would find if you walked the ground: the trees, the saturated soil, the channel, the dune. You can ask how much of it there is (its extent), what kind it is (its character) and how well it is working (its condition). It is measured at a point in time. A **flow** circulates. It is produced by the stock, year after year, and leaves it. You cannot find a flow by standing on the parcel; you find it downstream, downwind, in the next field, in the hospital admissions that did not happen. It is measured per year. The two are not interchangeable, and the mistake that costs the most is booking one as the other. [A stock is not an income](/guide/a-stock-is-not-an-income?from=guide) walks that mistake through three cases. This series stays on the other side of it: how the stocks and the flows were defined, where their numbers come from, and what the one number that joins them is for. ## why one vocabulary Nobody at BASIN invented the idea of natural capital stocks and flows. The System of Environmental-Economic Accounting, the Millennium Ecosystem Assessment, TEEB, CICES, IPBES, the Ecosystem Services Valuation Database, FEMA's benefit-cost toolkit, TNFD, ENCORE and the IUCN typologies all carry a version of it. The problem is that they disagree. They disagree about how many kinds of ecosystem there are, about how many services an ecosystem provides, about what to call each service, and about how to group them. So the framework behind RealValue read more than 120 of those classification and valuation frameworks and asked one question of each: what does it count, and under what name? From the land cover and ecosystem typologies, 27 were read and 7 kept. From the ecosystem services frameworks, more than 50 were read and 9 cross-referenced. The result is two short lists, each of which crosswalks to the systems that matter for valuation, real assets and disclosure, so that an acre read in this account can be followed into an ecosystem account, a property record or a nature-related disclosure without losing its lineage. The method and every source are in the [BASIN Field Manual appendix](https://docs.basin.global/appendix/land-cover-classification-and-ecosystem-typologies). ## the fifteen stocks Every acre of land, coast and near-shore water is one of these, or a mix of them. The framework is land-centric by design; the open and deep ocean were set aside in the first version, and Marine Systems was added so the list reaches the shelf. - **Cultivated & Developed.** Farmland and built land, altered for food and habitation. - **Urban Open Space.** Vegetated ground inside a city: parks, greenways, the planted lot. - **Rural Open Space.** Vegetated ground outside the city that is not forest, grassland or wetland: pasture edges, buffers, hedgerows. - **Rivers & Lakes.** Flowing and standing fresh water and the channel that carries it. - **Inland Wetlands.** Ground that is periodically saturated: swamps, marshes, peatlands, bogs, floodplains. - **Tropical Forests.** Closed-canopy forest at low latitudes, warm and humid all year. - **Temperate Forests.** Forest with seasons, deciduous to evergreen, in both hemispheres. - **Boreal Forests.** The taiga: spruce, fir and pine under long winters. - **Coastal Systems.** Tidal wetlands, beaches and dunes, the transition between land and sea. - **Marine Systems.** The shelf, the open water and the seafloor beyond the coast. - **Grasslands.** Ground dominated by grasses, natural or semi-natural, grazed or not. - **Shrublands.** Ground dominated by shrubs, usually on thin soils. - **Polar & Alpine.** Tundra, ice and the high mountains. - **Desert.** Low rainfall, extreme temperatures, drying wind. - **Subterranean.** Caves, aquifers and the ground beneath the surface. Each is a page at [/natural-capital/stocks](/natural-capital/stocks?from=guide), and the 2025 post [the 15 ecosystem types that underpin your portfolio](/guide/15-ecosystem-types-natural-capital-stocks?from=guide) carries the list with a line on what each one yields. The list is flat on purpose. The source typologies sort ecosystems into realms and biomes, and those layers are useful to an ecologist; they are one more thing to learn for a landowner, a lender or a city staffer who needs to know what kind of place this is. [Every acre is one of fifteen things](/guide/every-acre-is-one-of-fifteen-things?from=guide) shows how land cover becomes an ecosystem type and why the list stops where it does. ## the nineteen flows Every stock does some of these, and a healthy one does many at once: - **Raw Materials.** Timber, fiber and the materials a place yields. - **Food.** Crops, catch, game and grazing. - **Energy.** Biomass, the head of water, the wind over the ground. - **Water Abundance.** Water stored and released when it is needed. - **Healthy Soils.** Soil formed and kept fertile. - **Medicinal & Genetic.** The compounds and the gene pool. - **Climate Stability.** Carbon held and local heat moderated. - **Clean Air.** Particles and gases filtered. - **Clean Water.** Water filtered and waste broken down. - **Risk Resilience.** Floods, storms, fire and heat blunted. - **Pollination.** Crops and wild plants fertilized. - **Erosion Control.** Soil kept on the slope and out of the channel. - **Pest & Disease Control.** Predators and competitors keeping outbreaks down. - **Habitat.** The nursery and the home range. - **Recreation & Experiences.** The walk, the hunt, the swim. - **Research & Learning.** What the place teaches. - **Aesthetic & Sensory.** The view, the quiet, the smell of rain. - **Art & Inspiration.** What the place makes people make. - **Existence & Legacy.** Knowing it is there, and leaving it to someone. Each is a page at [/natural-capital/flows](/natural-capital/flows?from=guide), and the 2025 posts [the 19 ecosystem services your business depends on](/guide/19-ecosystem-services-natural-capital-flows?from=guide) and [ecosystem stocks and flows: the natural capital vocabulary for TNFD](/guide/ecosystem-stocks-flows-natural-capital-tnfd?from=guide) carry the list with a line on who depends on each. The Millennium Ecosystem Assessment, TEEB, CICES and SEEA group these services (provisioning, regulating, cultural, and in the MEA supporting); we keep the list flat, name the flow and value it. Beside the nineteen, the original framework carries two real asset benefits, Land Utilization and Resource Utilization: the income a property already earns from rent, grazing, timber, crops or energy. They are the income side of the same account, and they are reconciled against Food, Energy and Raw Materials so that a harvest sold is never counted twice. [Nineteen things a place does](/guide/nineteen-things-a-place-does?from=guide) shows how fifty frameworks reduced to one list. ## where the numbers come from A flow gets a dollar figure the way an appraisal gets a comparable: from a record of what the same kind of work was valued at somewhere else, adjusted for here. The records are published. The Ecosystem Services Valuation Database held 9,500 of them from more than 1,100 studies in its 2020 global update, each with its method. FEMA's 2022 ecosystem service values put dollars per acre per year on nine land cover types and fourteen services inside the benefit-cost toolkit that federal hazard mitigation projects must pass. [Where the dollar per acre comes from](/guide/where-the-dollar-per-acre-comes-from?from=guide) reads both, and says what a transferred value can and cannot carry. Then the number meets the place. [The same acre is not the same acre](/guide/the-same-acre-is-not-the-same-acre?from=guide) is about extent, character and condition: a drained wetland and a wet one share a row in the basis and do not share a number. ## the one number Flows over stocks: the annual flows value divided by a stated stock basis, shown as a percentage. It is built the way a real estate cap rate is built, and it is read differently: it compares places, conditions and interventions, and it says what a year of the work was valued at beside the price of keeping the place. It is not a yield. For the Demille wetland the flows are valued at $1,449,703 a year, most of it public-goods value rather than cash, our estimate; over the entrust value of $294,250 that is 493%, and over the project cost of $267,500 it is about 542%. The two answer different comparisons, which is why the basis always travels with the rate. [Flows over stocks](/guide/flows-over-stocks?from=guide) builds it, names its bases, and says what the gap between the two figures is and is not. ## what the account is for The account is instrumental. It exists so that a living system can be seen by the people and institutions that move money, in the units they already use, so that the money can go to the system before it fails rather than to the loss after. The ledger is not the system; [what natural capital actually is](/guide/what-natural-capital-actually-is?from=guide) holds that line. The number is a bridge, never the worth; [a valuation is not the worth](/guide/a-valuation-is-not-the-worth?from=guide) holds that one. "BASIN is not financializing nature," Jeff Stephens says in the Field Manual's opening on why to value nature at all. "We are naturalizing finance." ## frequently asked questions ### what are the stocks and flows of natural capital? A stock is a living system that holds value in place, measured at a point in time: a forest, a wetland, a river reach, a marsh, with an extent, a character and a condition. A flow is what that system does every year, measured per year: held water, kept soil, cooler air, pollinated crops, blunted storms. The UN's SEEA EA calls them ecosystem assets and ecosystem services. ### how many stocks and flows are there? The framework behind RealValue uses fifteen ecosystem stocks and nineteen ecosystem service flows, each a flat list, synthesized from more than 120 classification and valuation frameworks. The original framework adds two real asset benefits, land and resource utilization, for the income a property already earns, which is why some pages say 21; the RealValue flows page counts 18 because food, energy and raw materials are carried as income when they are sold. ### is this the same as SEEA ecosystem accounting? It uses the same two ideas and many of the same sources. SEEA EA is a national statistical standard built for countries and large areas. RealValue applies the stocks and flows to one parcel at a time, in dollars per acre per year, beside the cost of the real asset. [An account is not a forest](/guide/an-account-is-not-a-forest?from=guide) covers the difference. ## next Start with the places: [every acre is one of fifteen things](/guide/every-acre-is-one-of-fifteen-things?from=guide). If you hold or finance land and want to know which stocks are on it and what they do, [investors](/solutions/investors?from=guide&topic=stocks-and-flows) shows how the account is used. If you can already name the place, [tell us which](/contact?from=guide&topic=stocks-and-flows). ## sources [Natural capital, the ensurance manual](/manual/natural-capital?from=guide) — stocks, flows, the natural cap rate and the Demille example. [The framework, the ensurance manual](/manual/framework?from=guide) — the fifteen, the nineteen, the crosswalks and the sources. [BASIN Field Manual, Core Benefits Framework](https://docs.basin.global/core-benefits/core-benefits-framework) — the review of more than 120 frameworks; the stocks and the 21 core benefits. [BASIN Field Manual, Land Cover Classification & Ecosystem Typologies](https://docs.basin.global/appendix/land-cover-classification-and-ecosystem-typologies) — 27 typologies read, 7 kept. [BASIN Field Manual, Ecosystem Services Classification](https://docs.basin.global/appendix/ecosystem-services-classification) — more than 50 frameworks read, 9 cross-referenced. [BASIN Field Manual, Ecosystem Services Valuation Database](https://docs.basin.global/appendix/ecosystem-services-classification/ecosystem-services-frameworks/ecosystem-services-valuation-database-esvd) — 9,500 value records from more than 1,100 studies in the 2020 update. [BASIN Field Manual, FEMA Ecosystem Service Value Updates](https://docs.basin.global/appendix/ecosystem-services-classification/ecosystem-services-frameworks/fema-ecosystem-service-value-updates) — nine land cover types, fourteen priced services, the Benefit-Cost Analysis Toolkit. [BASIN Field Manual, Why put a value on nature?](https://docs.basin.global/realvalue/why-put-a-value-on-nature) — the Jeff Stephens line. [United Nations et al. 2021. System of Environmental-Economic Accounting, Ecosystem Accounting (SEEA EA).](https://seea.un.org/ecosystem-accounting) — ecosystem assets and ecosystem services as stocks and flows. ## the series 1. [the stocks and flows of natural capital](/guide/the-stocks-and-flows-of-natural-capital?from=guide) (read first) 2. [every acre is one of fifteen things](/guide/every-acre-is-one-of-fifteen-things?from=guide) 3. [nineteen things a place does](/guide/nineteen-things-a-place-does?from=guide) 4. [where the dollar per acre comes from](/guide/where-the-dollar-per-acre-comes-from?from=guide) 5. [the same acre is not the same acre](/guide/the-same-acre-is-not-the-same-acre?from=guide) 6. [flows over stocks](/guide/flows-over-stocks?from=guide) 7. [ensure the asset to ensure the flows](/guide/ensure-the-asset-to-ensure-the-flows?from=guide)