Through the process of photosynthesis, plants capture energy from sunlight and use it to combine carbon dioxide and water to produce carbohydrates and oxygen. The photosynthesis carried out by all the plants in an ecosystem is called the gross primary production (GPP). About 48–60% of the GPP is consumed in plant respiration. The rest is known as the net primary production (NPP). Total photosynthesis is limited by a range of environmental factors. These include the amount of light available, the amount of leaf area a plant has to capture light (shading by other plants limits photosynthesis), the supply of carbon dioxide and water, and suitable temperatures for carrying out photosynthesis.