Microbial community structure and functions differ between native and novel (exotic-dominated) grassland ecosystems in an 8-year experiment.
Sielaff A.C., U. R. N., Hofmockel K.S., Xu X., Polley W. and Wilsey, B. J.. 2018.
Abstract
Aims Grasslands dominated by non-native (exotic) species have replaced purely native-dominated areas in many parts of the world forming 'novel' ecosystems. Altered precipitation patterns are predicted to exacerbate this trend. It is still poorly understood how soil microbial communities and their functions differ between high diversity native- and low diversity exotic-dominated sites and how altered precipitation will impact this difference.
Methods We sampled 64 experimental grassland plots
in central Texas with plant species mixtures of either all
native or all exotic species; half with summer irrigation.
We tested how native vs. exotic plant species mixtures
and summer irrigation affected bacterial and fungal
community composition and structure, the influence of
niche vs. neutral processes for microbial phylotype co-
occurrence (C-score analysis), and rates of phosphorus
and nitrogen mineralization across an 8-year
experiment.
Results Native and exotic-dominated plots had significantly different fungal community composition
and structure, but not diversity, throughout the length
of the study, while changes in bacterial communities
were limited to certain wet and cool years. Nitrogen
and phosphorus mineralization rates were higher un-
der native plant mixtures and correlated with the
the abundance of particular fungal species. Microbial
communities were more structured in exotic than
native grassland plots, especially for the fungal
community.
Conclusions The results indicate that conversion of native
to exotic C4 dominated grasslands will more strongly
impact fungal than bacterial community structure. Further-
more, these impacts can alter ecosystem functioning be-
lowground via changes in nitrogen and phosphorus
cycling.
Key Words
Grasslands .Exotic plants . Fungi .Bacteria . Microbial diversity. Mineralization . Neutral/niche processes
