Identify the ecosystem with the lowest productivity.

Net Primary Productivity $(NPP)$ is defined as .....

............. of an ecosystem is the rate of production of organic matter during photosynthesis.

The net primary productivity of the oceans is ............ .

Distinguish between:
$(a)$ Litter and detritus
$(b)$ Primary and secondary productivity

Which of the following ecosystems will be more productive in terms of primary productivity? Justify your answer: $A$ young forest,a natural old forest,a shallow polluted lake,an alpine meadow.