--- title: "Ecosystem Energy Budgets: GPP, NPP and Transfer Efficiency" description: "Gross primary production is what producers capture, net primary production is what remains after their own respiration, and only a small share reaches the next trophic level. The numbers are why food " canonical: https://lightmysky.com/learn/science/ecosystem-energy-budgets-gpp-npp-and-transfer-efficiency-mt_D81CKcOdBI source: https://lightmysky.com/learn/science/ecosystem-energy-budgets-gpp-npp-and-transfer-efficiency-mt_D81CKcOdBI.md retrieved: 2026-09-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Ecosystem Energy Budgets: GPP, NPP and Transfer Efficiency Gross primary production is what producers capture, net primary production is what remains after their own respiration, and only a small share reaches the next trophic level. The numbers are why food chains stay short. Subject: Science · Area: Organisms & Life Processes · Ages 17 to 18 Page: https://lightmysky.com/learn/science/ecosystem-energy-budgets-gpp-npp-and-transfer-efficiency-mt_D81CKcOdBI ## Ready when they can - Calculates net primary production from gross production and respiratory loss. - Works out percentage energy transfer between two trophic levels from given data. - Explains where the energy that fails to transfer actually goes. ## Lesson: Where the Energy Goes GPP is the total chemical energy producers fix per area per time. Plants burn some of it in their own respiration just to stay alive. NPP equals GPP minus respiration, and NPP feeds every herbivore and everything above. Only about a tenth of the energy at one level becomes new biomass at the next. A rabbit burns most of its grass in respiration, loses some in urine and faeces, and never eats the roots. Short chains and narrow pyramid tops follow. **Example.** Work the transfer as a percentage: energy in new biomass above, divided by energy available below, times 100. Grass holding 20000 units with 2000 reaching new rabbit tissue means 10 percent. **Tip.** Use a chain for the maths and the web for the full story. One grass plant feeds rabbits, grasshoppers, and voles while the fox eats all three, so removing one species ripples in several directions. **Recap.** Subtract respiration from GPP for NPP, expect about a tenth to move up, and trace the rest to heat, waste, and uneaten parts. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Energy Loss Between Levels](https://lightmysky.com/learn/science/energy-loss-between-levels-mt_BOG5zRYtQz) - [Anaerobic Routes and the ATP Yield Compared](https://lightmysky.com/learn/science/anaerobic-routes-and-the-atp-yield-compared-mt_LBZ4laMfqb) - [Respiration: Energy Yield, Oxygen Debt and Fermentation](https://lightmysky.com/learn/science/respiration-energy-yield-oxygen-debt-and-fermentation-mt_mvnCjThdTH) ## Opens up - [The Nitrogen Cycle and the Microbes That Drive It](https://lightmysky.com/learn/science/the-nitrogen-cycle-and-the-microbes-that-drive-it-mt__K1J47NhWj) - [Optimal Foraging and the Currency of a Behavioural Decision](https://lightmysky.com/learn/science/optimal-foraging-and-the-currency-of-a-behavioural-decision-mt_9iNYB7d1Rh)