| The species of plants that play a vital role in controlling the relative abundance of other species in a community are called |
| a) | Edge species | b) | Keystone species |
| c) | Pioneer species | d) | Seral species |
| (b)Within biological communities, some species may be important in determining the ability of large number of other species to persist in the community. These crucial species have been termed keystone species. These have often considerably low abundance and biomass as compared to dominant species but their removal or decrease in number causes serious disruption in the functions of community, e.g., top predators, grey wolves in grasslands, etc. |