Multiple Diversity Facets of Crucial Microbial Groups in Biological Soil Crusts Promote Soil Multifunctionality

Landscape in Zhangye Danxia Geopark, covered by biological soil crusts (Image by IHB)

A research group from the Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences elaborated how the microbial diversity characteristics of the key carbon-nitrogen-fixing groups in biological soil crusts affect the multi-dimensional functional level of dryland ecosystems. The results were published in Global Ecology and Biogeography.   

With the increasing impact of global change, biodiversity is rapidly decreasing. The potential for biodiversity loss to impair ecosystem functions and service has received widespread attention. The emerging consensus seems to be that higher level of biodiversity is needed to maintain the simultaneous execution of multiple ecosystem functions. However, the relationship between microbial diversity and multifunctionality among different taxonomic groups is not consistent. Therefore, only considering the diversity characteristics at the community level may obscure many internal connections.  

For this, researchers used biological soil crusts as a model system. On the basis of the classic biodiversity-ecosystem function relationship (BEF), considering that the relationship between different taxonomic groups of microorganisms and ecological functions is not highly conservative, they proposed a research framework based on functional group to assess the potential relationship between the diversity and abundance of the key functional groups in biocrusts and the ecosystem multifunctionality.  

The results showed that the integrated biodiversity index of carbon-nitrogen-fixing groups in biological crusts could predict the level of multifunctionality better than richness. The divergence in diversity characteristics at different levels determined the unique role of each functional group on soil multifunctionality. 

In addition, the evaluation of functional significance at the species level could provide important clues for the trade-offs and redundancy among various functional groups, which explained different patterns of diversity effects. Phylogeny dissimilarity was the dominant factor for phototrophs to promote ecosystem functions, while for diazotrophs, richness was the most important factor. 

On the whole, the results suggested that multiple facets of diversity should be considered in assessing the impact of biodiversity. Compared with the community level, the multifaceted diversity within-functional group was a strong predictor of ecosystem functions. The finding provides a new perspective for further understanding the relationship between biodiversity and ecosystem functions.