Primary community assembly on land - the missing stages: why are the heterotrophic organisms always there first?

1 It is proposed that as a general rule primary community assembly by autotrophs is preceded by a previously unrecognized heterotrophic phase that may be instrumental in facilitating the establishment of green plants and consolidating the assembly process. 2 This heterotrophic stage, of variable duration, involves the allochthonous input of both dead organic matter and living invertebrates sufficient to allow the initial establishment of functioning communities comprised of scavenging detritivores and predators. 3 Evidence for deposition of such materials onto newly exposed land surfaces and the development of such animal communities is summarized for a variety of sites and substrates worldwide. 4 It is suggested that these heterotrophic communities conserve nutrients, particularly nitrogen, and facilitate the establishment of green plants.