The accuracy of pyramid numbers and pyramid of biomass depends on the specific ecosystem being considered and the data available for its construction.

Regarding the ecosystem with the lowest net primary production (NPP) per square meter, typically, deserts have the lowest NPP. Deserts have limited water availability and extreme temperature fluctuations, which restrict plant growth and primary productivity. As a result, there is relatively little biomass produced in deserts compared to other ecosystems like forests or grasslands. This scarcity of plant biomass limits the energy available to support higher trophic levels, resulting in lower overall NPP per square meter in desert ecosystems.

Dr Gaurav H Tandon thank you for your contribution to the discussion

A pyramid of energy is the most accurate representation of the energy flow through a food chain as it indicates how much energy is lost at each trophic level. The biomass of organisms in each trophic level is measured and presented in a pyramid of biomass. It is more accurate as the organism's size is taken into account. Pyramids of number show the number of organisms at each stage in a food chain. Pyramids of biomass show the mass of organisms at each stage in a food chain. An inverted pyramid is where the mass of producers is higher than that of consumers. A pyramid of biomass helps in quantifying the biomass at each trophic level. This pyramid indicates the amount of energy flow at each level and the role that various organisms play in the transfer of energy. The pyramid shape is used because it can represent energy available at every trophic level. The level will always get smaller as you go up the pyramid. The pyramid shape is also used because it represents the number of organisms at each trophic level. Although pyramids of number are pyramid-shaped there are two important exceptions. Pyramids will be upside down or inverted if there are a lot of small animals feeding on a large plant. They are also inverted where an animal has a large number of small parasites feeding on it. Most primary productivity of the ocean is carried out by free-floating phytoplankton. Thus, open oceans have the lowest net primary productivity.The most productive ecosystems are the tropical rain forests with dense and evergreen vegetation. It is productive throughout the year and has an annual net primary productivity of 9000 kcal per square metre per year. The regions of high ecological productivity represented by shallow water areas, moist forest alluvial plains and regions of intensive farming. The regions of low ecological productivity represented by arctic snow-covered wastelands deserts and Deep Ocean areas. Gross productivity is the overall rate of energy capture. Net productivity is lower: it's gross productivity adjusted for the energy used by the organisms in respiration/metabolism, so it reflects the amount of energy stored as biomass. Energy transfer between trophic levels is not very efficient.