Abstract
Anti-seasonal drying-wetting cycles since 2010 have substantially altered its soil and vegetation status in the drawdown zone of China’s Three Gorges Reservoir (TGR). Such alternations may thus affect the composition and functioning of soil microbial communities, including the beneficial arbuscular mycorrhizal fungi (AMF), which enhance plant performance. Moreover, limited information is available if AMF communities are different in soils and roots, particularly under contrasting land-use changes. By combining the Illumina Miseq sequencing with bioinformatics analyses, AMF communities in both rhizosphere soils and roots of a stoloniferous and rhizomatous C4 perennial of Cynodon dactylon were characterized under three land-use types: (1) crop cultivated, (2) non-cultivated non-disturbed, and (3) disturbed non-cultivated land. A total of 35 and 26 AMF taxa were respectively detected from C. dactylon rhizosphere soils and roots from these three land-use types, which had endured four anti-seasonal drying/summer-wetting/winter cycles. Contrasting differentiations in the AMF community composition and structure were displayed in the C. dactylon rhizosphere soils and roots, and between land-use types. Nonmetric multidimensional scaling analyses revealed that AMF communities significantly correlated to soil organic carbon in the rhizosphere soils and roots of C. dactylon, to land-use types only in rhizosphere soils, whereas to soil moisture only in roots. Our results highlight the effects of soil nutrients and land-use changes on AMF community composition and diversity under the canopy of C. dactylon in TGR. The identified dominant AMF taxa can be employed to vegetation restoration in such degraded habitats globally.
Highlights
The water table between 145 m and 175 m of the newly-formed drawdown zone has created a total area of ~400 km2 water body along the Three Gorges Reservoir (TGR) since the completion of a 185 m high dam in the middle stream of Yangtze River in 2010 [1]
Had some degree of either specialization or restriction to land-use types. These findings have indicated that the arbuscular mycorrhizal fungi (AMF) communities in drying-wetting environments would include some specific AMF taxa in the TGR region and some common taxa existing in other habitats
In the drawdown zone of the TGR, higher AMF diversity and distinctive AMF taxa were displayed in rhizosphere soils than in roots of a C4 C. dactylon under three contrasting land-use lands
Summary
The water table between 145 m and 175 m (impounded level) of the newly-formed drawdown zone has created a total area of ~400 km water body along the Three Gorges Reservoir (TGR) since the completion of a 185 m high dam in the middle stream of Yangtze River in 2010 [1]. As a consequence of flood control and hydropower manipulation, a 30 m hydro-logically seasonal up-and-down regime has been switched down to less than 140 m water table by emptying the downstream water during the natural flooding (wetting) in summer, but up to 175 m water table by storing the water during the natural un-flooding (drying) in winter. After such a conversion of drying-wetting cycles, plant species adapted to previously terrestrial habitats have almost completely degraded or die Diversity 2019, 11, 197; doi:10.3390/d11100197 www.mdpi.com/journal/diversity.
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