Here we see a food pyramid that shows how the Kilocalories pass up the food chain.

     The first trophic level is occupied by the primary producers, which are the plants.  Plants make food through photosynthesis. The limiting factor for these plants is the shortage of water, so they produce fewer than 200 Kilocalories of food for the animals for each square meter each year.

    The primary consumers, who eat the plants, occupy the second trophic level. These animals have very little to eat, and are small. Many are insects, or reptiles, who are cold blooded and who use less energy to maintain their bodies than mammals and birds do. As food for predators, they provide about 20 Kilocalories per square meter per year for predators.

     The predators are the secondary consumers. They occupy the third trophic level. Again we see cold-blooded animals, such as snakes, insect-eating lizards, and tarantualas. Only about 2 Kilocalories per square meter per year are stored in their bodies. In the harsher desert environments, they are the top predators.

    In areas where deserts get more rain, more plant material is produced and a few tertiary consumers may be able to survive. They form a fourth trophic level.

Cold Desert Energy Pyramid

Introduction to Desert Biomes

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