Nitrogen enrichment suppresses other environmental drivers and homogenizes salt marsh leaf microbiome

DALEO, PEDRO; ALBERTI, JUAN; JUMPPONEN, ARI; VEACH, ALLISON; IALONARDI, FLORENCIA; IRIBARNE, OSCAR; SILLIMAN, BRIAN

ECOLOGY

ECOLOGICAL SOC AMER

Año: 2018

0012-9658

Microbial community assemblyis affected by a combination of forces that act simultaneously, butthe mechanisms underpinning their relative influences remain elusive.This gap strongly limits our ability to predict human impacts onmicrobial communities and the processes they regulate. Here, weexperimentally demonstrate that increased salinity stress, food webalteration and nutrient loading interact to drive outcomes in saltmarsh fungal leaf communities. Both salinity stress and food webalterations drove communities to deterministically diverge, resultingin distinct fungal communities. Increased nutrient loads,nevertheless, partially suppressed the influence of other factors asdeterminants of fungal assembly. Using a null model approach,we found thatincreased nutrient loads enhanced the relative importance ofstochastic over deterministic divergent processes; without increasednutrient loads, samples from different treatments showed a relatively(deterministic) divergent community assembly whereas increasednutrient loads drove the system to more stochastic assemblies,suppressing the effect of other treatments. These results demonstratethat common anthropogenic modifications can interact to controlfungal community assembly. Furthermore, our results suggest that whenthe environmental conditions are spatially heterogeneous (as in ourcase, caused by specific combinations of experimental treatments),increased stochasticity caused by greater nutrient inputs can reducethe importance of deterministic filters that otherwise causeddivergence, thus driving to microbial community homogenization.