Why do you ask numerous questions that are more like student exam questions? As a professor in agronomy you must surely know the answer to what you are asking?

Dr James Weldon thank you for your contribution to the discussion

There are two main reasons why ecosystem productivity increases from the polar regions towards the tropics:

• Temperature: Plants need warmth to grow, and the tropics receive more sunlight and have warmer temperatures than the polar regions. This allows plants to grow faster and produce more biomass.
• Sunlight: The tropics receive more sunlight than the polar regions, which gives plants more energy to photosynthesize and produce food.

In addition to these two factors, tropical ecosystems also tend to have more nutrients available than polar ecosystems. This is because tropical soils are often more weathered and have a higher organic matter content.

All of these factors contribute to the higher productivity of tropical ecosystems. Tropical rainforests, for example, are the most productive ecosystems on Earth, producing more biomass per unit area than any other type of ecosystem.

Higher biodiversity in the tropics

There are a few reasons why tropical regions have more biodiversity than temperate and polar regions:

• More stable environment: Tropical regions tend to have more stable temperatures and rainfall patterns than temperate and polar regions. This makes it easier for plants and animals to adapt and thrive.
• More niches: Tropical ecosystems are more complex and have more niches for different species to fill. For example, a tropical rainforest has many different layers, from the forest floor to the canopy, and each layer provides a different habitat for different species.
• More time to evolve: Tropical regions have been warm and humid for millions of years, which has given plants and animals more time to evolve and diversify.

As a result of these factors, tropical regions are home to a vast array of plant and animal life. For example, the Amazon rainforest is home to an estimated 10% of the world's known species.

It is important to note that there are some exceptions to these general trends. For example, some polar ecosystems, such as the Antarctic, are very productive due to the abundance of phytoplankton. Additionally, some temperate ecosystems, such as kelp forests, are also very productive. However, overall, the tropics are the most productive and biodiverse ecosystems on Earth.

Dr Murtadha Shukur thank you for your contribution to the discussion

The higher temperatures in the tropics cause higher rates of metabolism, ecological dynamics and coevolutionary processes, which generate and maintain higher biodiversity.

Dr Gemechu Fufa Arfasa thank you for your contribution to the discussion

Tropics receive more solar energy which contributes to greater productivity and hence greater biodiversity due to greater availability of food. Less seasonal variations promote niche specialization and lead to a greater species diversity. The productivity of the ecosystem increases from the polar region towards the tropics because of the suitable temperature and increasing sunlight. Tropics have more species biodiversity than that of the Polar Regions. The maximum biodiversity in the tropical reason is due to the following reasons: Prolonged evolutionary time : The tropics have remained undisturbed in the past and therefore evolved more species diversity. The productivity of the ecosystem increases from the polar region towards the tropics because of the suitable temperature and increasing sunlight. Tropical regions are always nutrient-limited and show low productivity. Polar Regions are light limited in the winter and only display production during the late spring and summer months when light is available. Northern temperate regions have a spring bloom, and a smaller autumn bloom (PW). Availability of solar energy is what limits photosynthesis productivity in polar oceans. Productivity is low and limited because of lack of nutrients. The sun is more directly over head > light penetrates deeper into tropical ocean than in temperate and polar waters. In Tropical Rainforests, water, sunlight, and high temperatures are consistent and a dense concentration of plants is present, causing both the GPP and NPP to be very high. So, high levels of productivity increase biomass.Water, sunlight, and high temperatures are constant in tropical rainforests, and there is a dense population of plants, resulting in a very high GPP and net primary productivity.In terrestrial ecosystems Tropical rain-forests show the highest productivity. In aquatic ecosystems, coral reefs have the highest productivity. It is generally seen that there is more biodiversity in the tropical region than the temperate region because of a variety of factors: First is the constant temperature and climate. The temperate region has a severe climate which makes it very hard for animals to survive in such extreme climatic condition.Tropics receive more solar energy which contributes to greater productivity and hence greater biodiversity due to greater availability of food. Less seasonal variations promote niche specialization and lead to a greater species diversity. The higher temperatures in the tropics cause higher rates of metabolism, ecological dynamics and co evolutionary processes, which generate and maintain higher biodiversity. This encourages niche specialization and high species richness. The maximum biodiversity is found in tropical rain forests as they are less seasonal; they are neither too hot nor too cold and are more predictable. Therefore, this is the correct option. These kinds of environments help in promoting niche specialization and also lead to greater species diversity.