What would happen to the garden ecosystem if there were no more earthworms?

If there were no earthworms then there would be nothing which can convert the dead organic matter into "Inorganic solvents" which is used by Plants for their nutrition through the soil.
So, in that case, ecosystem cycle would not complete, & it will get disturbed by high amount 'cause producers will be affected.

Hope this helps!

The return of the wolf to yellowstone national park will probably affect the bird population to some degree, not significantly. while wolves will hunt birds when necessary, they prefer to hunt larger prey. the bird population will most likely only be affected when hunting is scarce for the wolves. birds of prey will also probably not be affected as much as other birds who spend more time on the ground hunting for food as the tend to spend more time in the air or in trees since they do not need to stay on the ground for long due to the nature of the way they hunt.