A conceptual framework of the dynamic C and N coupling under global change (IMAGE) Science China Press Caption NPP, net primary productivity; GEP, gross ecosystem productivity. Credit ©Science China Press Usage Restrictions Use with credit. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.