There is a delicate balance in all enviorments and ecosystems and I know there is a many organisms in this food web but if one gets taken out ,it will throw off the whole system . there might be too little or too much of something! For an example if the grass wasn't there then the herbivores and omnivores would have to go to another plant and what if they eat that all up? The cycle would have to repeat and since the animals that eat the plant would die then the animals that eat them would die out and the decomposers would have nothing to eat!