How biodiversity determines the level of ecosystem function is one of the core issues in ecology. The concept of species diversity is composed of multi-dimensional characteristics, including community composition, phylogenetic evolution and interaction relationship, in addition to species quantity (richness).    

At present, a major challenge that ecologists facing is how to predict the influence of biodiversity decline on ecological multifunctionality from the view of multidimension. This problem has hampered the efforts of using biodiversity theory to guide practices in ecological restoration.   

Researchers from Institute of Hydrobiology (IHB) of Chinese Academy of Sciences studied the photosynthetic autotrophic functional group, comprising mainly of terrestrial cyanobacteria, in the arid region of northwest China. They revealed the potential associations between the multifaceted diversity of cyanobacteria and the multifunctional level of soil ecosystem. The results were recently published online in the international journal of Molecular Ecology.   

By identifying on the abundant and rare species of photosynthetic bacteria in biocrust, the research team quantified species richness, evenness, and phylogenetic distance by the high throughput sequencing method. They also analyzed the topological architecture of the co-occurrence network, as a proxy of interaction intensity.    

Meanwhile, soil multifunctionality was evaluated by using seven key individual functional variables, i.e., potential productivity, belowground biomass, soil nitrogen/phosphorus content, plant-available nutrients, soil carbon stock, and water-holding capacity.   

Researchers found that, while phototrophic richness is not positively related with the maxima of multifunctional performance, interspecies facilitation and compositional identity are particularly stronger but often neglected predictors.    

They also revealed a significant positive correlation of species functional importance with its topological feature in co-occurrence networks, highlighting a potential mechanism by which species interaction promotes multifunctionality.   

The findings gave a comprehensive view of how soil constructive species drive multifunctionality and contribute to guide management efforts of ecological restoration according to the theory of biodiversity-functionality relationship. 

 
Sampling sites, functional characteristics, and the identification of abundant and rare phototrophic species. (Image by IHB)