Question

Read the following statements (A - D) related to the importance of species diversity in an ecosystem and identify the correct statement.

• A. Communities with more species, generally tend to be less stable than those with less species
• B. Communities with more species, shows less productivity
• C. Communities with less species, generally tend to be more stable than those with more species
• D. Communities with more species show less year to year variation in total biomass

Answer 1

The correct option is D Communities with more species show less year to year variation in total biomass

David Tilman was an American ecologist who showed that stability of a community depends on its species richness. He performed long-term ecosystem experiments using outdoor plots in grassland ecosystems. He found that the plots with more species showed less year to year variation in total biomass and increased diversity contributed to higher productivity. Hence option b is incorrect and option d is correct.

Many ecologists believe that communities with more species tend to be more stable than those with less species. For example, if only lions and rabbits are present in an ecosystem, the lions would always need to depend on the rabbits for food. This would lead to a decline in the number of rabbits and finally they will go extinct. Eventually, the lions would also starve to death. Hence option a and c are incorrect.