Primary Productivity:
Tropical rainforests are among the best of environments that let plants grow to their absolute limit. Their perfect climatic conditions allow plants to grow as large as they can and thus it's growth and productivity (total amount of organic matter produced per unit area per unit time) is higher than that of other vegetative biomes.
There are various ways to analyse productivity within a biome. Gross Primary Productivity (GPP) is the rate at which the primary producers in an ecosystem convert the sun's energy into chemical energy known as biomass. GPP is measured as the amount of energy produced per unit area over a given amount of time. e.g. kilocalories per square metre per year (kcal/m squared/yr).
Some of this chemical energy must be used for activities like respiration, reproduction and growth. Net Primary Productivity (NPP) is the rate at which the producers use photosynthesis to produce and store chemical energy minus the rate at which they use some of that energy for their own respiration. The NPP is a measure of how quick an organism can turn the chemical energy into energy available to consumers within the ecosystem. NPP is the main food supply for humans and other animals.
There are various ways to analyse productivity within a biome. Gross Primary Productivity (GPP) is the rate at which the primary producers in an ecosystem convert the sun's energy into chemical energy known as biomass. GPP is measured as the amount of energy produced per unit area over a given amount of time. e.g. kilocalories per square metre per year (kcal/m squared/yr).
Some of this chemical energy must be used for activities like respiration, reproduction and growth. Net Primary Productivity (NPP) is the rate at which the producers use photosynthesis to produce and store chemical energy minus the rate at which they use some of that energy for their own respiration. The NPP is a measure of how quick an organism can turn the chemical energy into energy available to consumers within the ecosystem. NPP is the main food supply for humans and other animals.
From the second diagram displayed above, we can deduce that tropical rainforests are the second largest primary producers on the planet and the largest primary producer on land at about 170 billion kcals per year. Oceans are only ahead of tropical rainforests by 20 billion kcals and yet they cover 11 times the area on the planet than tropical rainforests (oceans - 70%, tropical rainforests - 6%). Tropical rainforests have such a high NPP because of its geological position which is perfect for being bathed in huge amounts of solar radiation and also having the perfect climate for plant growth.