Which of the following is not a characteristic of a stable community?

Tilman found that plots with more species showed less year-to-year variation in total biomass. He also showed that in his experiments, increased diversity contributed to higher productivity.  Various groups of interacting organisms in a particular region are included in community. A community is said to be stable when its populations size of all species remains same over a period of time. In other words, the population is not showing much change or variation and is able to withstand any hardships or changes in the environment. A stable community is not affected by invasion of other organisms including alien species. It resists loss of biodiversity.