Biodiversity-ecosystem function relationship in natural grassland communities

Background/Question/Methods

Ecologists have debated the nature of the biodiversity-ecosystem function relationship for over 50 years. Previous evidence points towards a generally positive relationship, where an increase in biodiversity leads to increases in ecosystem functions and stability. Most experimental evidence for significant relationships between diversity and function or stability has come from communities in which diversity itself is experimentally manipulated, so it is important to relate these findings to real ecosystems in which diversity is established by natural processes. Utilising the natural gradient in plant species richness present in grasslands at Silwood Park we tested whether function (measured in terms of aboveground plant production and soil invertebrate biomass) is dependent upon plant diversity (using both taxonomic and phylogenetic diversity measures) across multiple years.

Results/Conclusions

A weak positive correlation was identified between primary production and species richness in one year only. Primary production itself varied considerably across years and in response to a simulated extreme weather event, but this variation was independent of species richness. Depending on the measure, stability of soil invertebrates correlated with either plant diversity or plant biomass. Communities dominated by more phylogenetically similar species produced greater plant biomass and less invertebrate biomass. Whilst all diversity measures poorly correlate with primary production it appeared plant diversity (in any measure) was more closely correlated with invertebrate biomass. The main implication of this work is for ecologists to test theories (based on empirical evidence) in naturally occurring communities. Natural communities are complex systems, but as we show they are not completely idiosyncratic.