Q. How can a great biological diversity protect an ecosystem from environmental damage? Why are less biodiverse ecosystems at risk of suffering deep biological harm if submitted to even small changes?

In the ecosystems with more biodiversity the food webs and the ecological interactions among living beings are more complex and diverse and in these ecosystems environmental changes can be more easily compensated by the multiplicity of available foods, resources and survival options. In the ecosystems with less biodiversity the individuals are more dependent on some beings that serve them as food and they interact with a tiny number of different species. In these ecosystems in general abiotic factors are restrictive and the species are more specialized to such conditions and more sensitive to environmental changes so even small environmental harm can cause big disturbances in the equilibrium of the ecosystem.