Experimental research has well established that biodiversity has a large effect on the delivery of multiple ecosystem services (multifunctionality), and thus on human well-being. However, it remains unclear how land use intensity mediates biodiversity-ecosystem functioning interactions in real world ecosystems. In order to understand the importance of biodiversity loss on ecosystem multifunctionality, it is crucial to quantify the relative strengths of direct land-use effects and indirect effects mediated by biodiversity and functional composition. The Biodiversity Exploratories project has conducted exemplary research investigating the effects of land use intensity on biodiversity and ecosystem functioning in temperate grasslands and forests over more than 10 years. We sampled 15 ecosystem functions or services (ecosystem services hereafter) and nine trophic groups, including 4,600 above- and below-ground taxa in 150 grasslands and 150 forests plots differing in land-use intensity. We also introduced multifunctionality measures in which ecosystem services were weighted according to realistic land-use objectives.
In grasslands, we found that land-use intensification reduced diversity across multiple trophic levels. This loss of diversity affects ecosystem functioning and services because high species richness in multiple trophic groups (multitrophic richness) is needed for high multifunctionality. Multitrohic diversity had stronger positive effects on ecosystem services than richness in any individual trophic group. On average, three trophic groups influenced each ecosystem service, with each trophic group influencing at least one service. Multitrophic richness was particularly beneficial for ‘regulating’ and ‘cultural’ services, and for multifunctionality, whereas a change in the total abundance of species or biomass in multiple trophic groups positively affected supporting services. Multitrophic richness and abundance drove ecosystem functioning as strongly as abiotic conditions and land-use intensity.
In forests, we found that management determined the number and type of ecosystem services provided and biodiversity levels. Intensive forestry, characterized by dense, conifer forests, provided only a few services and involve larger trade-offs between services. Open old-grown unmanaged forests provided the largest number of ecosystem services and supported higher levels of biodiversity, especially when they were mixed forests including oaks and conifers.
Finally, by using novel measures of multifunctionality, in which services were weighted according to management objectives, we were also able to show that the relationships between land use, biodiversity, functional composition and multifunctionality depend greatly on the services required. Therefore, a combination of forests and grasslands of different land use intensity provide multiple ecosystem services and support higher levels of biodiversity at the landscape scale.