What happens to the other organisms in a food chain when an organism in the middle of the food chain is lost?

The organisms higher on the food chain will start to fall, as it is like a domino effect. The lower half of the food chain would thrive with no predators, and they would begin to overproduce and therefore overpopulate leading to overconsumption of the areas natural resources such as berries or whatever it is that they eat. With this, the ecosystem will be affected greatly as well over a period of time. The organisms at the top of the food chain would greatly decrease as well. After the majority of the natural resources were gone, the organism which was thriving from lack of predators will die as there will no longer be sustainable resources to eat.

We can plant more trees and plants.