Echidnas would not have a major impact to the Environment, considering they are so small and would only mainly eat ants, not plants and bushes. After all Echidnas are Native to Australia and aren't found anywhere else on the planet.
they are helpful not harmful to plants
If it is harmful it will not survive long
Harmful: Winds can destroy structures. Helpful: Winds can power windmills.
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yes they kill more harmless insects than harmful ones.
the organism's environment
it is helpful in one way but harmful in another
mushrooms are helpful because they break down dead organisms and are "clean-up" the environment.
Helpful. They eat other smaller animals that overpopulate the jungle. So, in that way, yesss :)
it can be helpful or harmful
sometimes they are helpful and harmful.
We build houses. its as simple as that we build buildings on their terrotory and that of course is helpfil to us but harmful to them.