Effects of grazing prohibition on - and -type denitrifier communities in salt marshes.

INTRODUCTION

Grazing prohibition is an effective management practice to restore salt marsh functioning. However, the effects of grazing exclusion on denitrifying microbial communities and their controlling factors in salt marshes remain unclear.

METHODS

In this study, we surveyed soil physicochemical properties and above- and below-ground biomass and using quantitative polymerase chain reaction and Illumina MiSeq high-throughput sequencing technology to determine the relative abundance, composition, and diversity of nitrite reductase - and -type denitrifying bacterial communities associated with grazing prohibition treatments and elevations.

RESULTS

The abundance of -type denitrifiers increased with grazing prohibition time, whereas the abundance of -type denitrifiers remained unaltered. Moreover, -type denitrifiers were more abundant and diverse than -type denitrifiers in all treatments. Grazing prohibition significantly altered the operational taxonomic unit richness, abundance-based coverage estimator, and Chao1 indices of the -type denitrifying bacterial communities, whereas it only minimally affected the structure of the -type denitrifying bacterial community.

DISCUSSION

The results imply that the community, rather than , should be the first candidate for use as an indicator in the process of salt marsh restoration after grazing prohibition. Substances of concern, total nitrogen, and salinity were the key environmental factors affecting the abundance and community composition of and denitrifiers. The findings of this study provide novel insights into the influence of the length of grazing prohibition and elevation on - and -type denitrifying bacterial community composition in salt marshes.