The best replacement for ecosystem is biome.

The best alternatives to ecosystem are rated as following:
★★★★★  biome
★★★★  habitat
★★★  community
★★★  environment
★  biosphere
★  ecology
★  ecosystem
★  population
  ecological community
  biomes
  biome bigger
  apple ecosystem
  landscape
  freshwater ecosystem
  saltwater ecosystem
  aquatic ecosystem
  eco system
  food chain
  complex ecosystem
  habitat biome

Your alternative for ecosystem is not listed? Suggest!
Speaking about ecosystem, one probably shouldn't forget about decomposers.

Other search terms related to ecosystem and their ratings are:
★★★★★ decomposers
★★★ biotic and abiotic factors
★★★ predators
★ greatest number of members
organisms
You have in mind a companion for ecosystem and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of ecosystem in all years. Click on graph for more.
ecosystem
biome
habitat