why are raiforest are considered to be stronger ecosystem than corn field?

Answer 1

What do you mean by "stronger ecosystem"?

Rainforests have higher species richness than agricultural fields, and appropriately they have many more extinctions each year. Based on likelihood of extinction I'd say a rainforest is the "weakest" ecosystem.

Crows are an excellent example of how robust general ecosystems are. If a corn field gets harvested any crows living there will simply move to somewhere else because they occupy such a wide niche. If a rainforest gets harvested many of the species living there will have no new habitat to move into because they require such special conditions.

Diversity is a popular buzzword that often gets abused by people who think anything with more diversity must be better. Although it may be true in other fields, ecosystem diversity has not been proven to be necessarily beneficial. Disagree? Show me a peer reviewed study.

Answer 2

One word - diversity.

A rainforest has hundreds if not thousands of different species of plants, insects, and animals living in its environment. Some interdependant, some independant, some parasitic, some symbiotic.
The extinction of one species will not likely destroy the entire habitat (given time) because other species would evolve to fill the niche left.

A corn field has just a few species - corn, a few weeds, some insects, and crows. If one or another of these few species were to vanish, the entire habitat could be destroyed.

Answer 3

lindajune - High Five.

I was going to post the exact same thing.