Explanation:

NPP stands for Net Primary Productivity. It is the amount of organic matter produced by plants in an ecosystem, after accounting for the energy used during respiration. NPP is an important measure of ecosystem productivity and can be used to estimate the amount of available energy for higher trophic levels.

The incorrect statement is option C, which states that NPP is limited by light and available nutrients in an aquatic ecosystem. This statement is incorrect because:

NPP Limiting Factors
- NPP is limited by a variety of factors, including light, temperature, water, and nutrients. These factors can vary depending on the ecosystem, and can change over time due to natural or human disturbances.
- In aquatic ecosystems, light is an important limiting factor for NPP. Photosynthesis requires light energy, and the amount of light available can determine the rate of photosynthesis and therefore NPP. However, nutrients can also be a limiting factor in some aquatic ecosystems, particularly in areas with high levels of runoff or pollution that can cause nutrient imbalances.
- In terrestrial ecosystems, NPP is often limited by nutrients, particularly nitrogen and phosphorus. These nutrients are necessary for plant growth and can become limiting if they are not available in sufficient quantities.

Formula for NPP

The formula for NPP is NPP = GPP - R, where GPP is Gross Primary Productivity and R is the energy used by plants during respiration.

- GPP is the total amount of organic matter produced by plants through photosynthesis, before accounting for respiration losses.
- R is the amount of energy used by plants during respiration. This energy is used to power cellular processes and is necessary for plant growth and maintenance.

High NPP in Tropical Rainforest

- Tropical rainforests have very high NPP due to their warm, wet climate and abundant sunlight. These conditions allow for year-round plant growth and high rates of photosynthesis.
- However, despite their high NPP, tropical rainforests are also subject to high rates of deforestation and other disturbances. These disturbances can have negative impacts on ecosystem productivity and can lead to declines in biodiversity and other ecosystem services.