The source of energy is the plants because with out the plants the small animals will not have anything to eat. If the small animals die then the middle size animals won't have anything to eat. So the big animals will not have anything to eat so they will die. Some of the factors that may limit population growth is when the big animal (Hawk) eat the middle size animals (Lizard) when they keep eating each other the animals will not get over populated and the population will not grow.
The Argentine cactus moth it lives in the trees and they will live in the trees for along time and after a while they will kill the cactus. This can harm a lot of animals. The plants have small bugs so when they die the small bugs die too. Then the small animals won't have anything to eat.
The Argentine cactus moth it lives in the trees and they will live in the trees for along time and after a while they will kill the cactus. This can harm a lot of animals. The plants have small bugs so when they die the small bugs die too. Then the small animals won't have anything to eat.