How often are ecosystems top-down controlled? Experiments in grassland, grasshopper, and bird systems over time and space.

ABSTRACT: Ecosystems are frequently considered to be controlled by predation (top-down). Experiments examined this in four bird/spider/grasshopper/prairie habitats over 34 years, employing in each habitat three 100 m² bird exclosures and controls (121 habitat/year cases) where plant, grasshopper, and spider abundances were measured. Top-down control (plants decrease and grasshoppers increase with bird exclusion) was observed in only 13.2% of cases, while plants increased and grasshoppers decreased in 33.1% of cases, plants decreased and grasshoppers decreased in 25.6% of cases, and plants increased and grasshoppers increased in 28.1% of cases. Therefore, top-down control was not common and system responses were not constant, but varied among sites, years, and directionally over time with

SUBMITTER: Belovsky GE 

PROVIDER: S-EPMC11583287 | biostudies-literature | 2024 Nov

REPOSITORIES: biostudies-literature