Community history modifies how plant diversity shapes beta multifunctionality

Research on ecosystem multifunctionality (EMF) has mainly quantified the magnitude of multiple functions within local communities (alpha multifunctionality [alpha-EMF]), whereas less is known about variation in function profiles among communities (beta multifunctionality [beta-EMF]). We asked how plant diversity affects variation in ecosystem function profiles among communities and whether this relationship depends on community history. We analyzed 5-year means of six ecosystem functions from 240 subplots in the DELTa-BEF, short for DEterminants of Long-Term Biodiversity Effects on Ecosystem Functioning Experiment, comparing new communities without experimental plant or soil history, resown communities retaining soil history, and old communities with continuous plant and soil histories. We adapted a variance-based beta diversity framework to quantify beta-EMF and partition it into local contributions to beta multifunctionality (LCBM) and function contributions to beta multifunctionality (FCBM). Plant diversity increased alpha-EMF in all treatments, with stronger increases in resown and old than in new communities. Richness was not detectably related to LCBM in new communities but was associated with lower LCBM in resown communities and higher LCBM in old communities, with the clearest contrast between the resown and old treatments. Leaf area index contributed more to beta-EMF than expected under equal contributions (20.2%), whereas basal respiration contributed less (13.2%); the other four functions did not differ from the equal-contribution expectation. Thus, similar gains in local multifunctionality can be accompanied by contrasting patterns of spatial functional heterogeneity, depending on community history. Partitioning beta-EMF into local and function contributions provides a practical way to identify which communities and functions contribute to spatial heterogeneity.