Data for: Male, female and mixed-sex poplar plantations support divergent soil microbial communities

Mixed-species forests are often more productive than monocultures because
of a lower niche overlap and higher taxonomic and functional diversity of
soil microbial communities. Males and females of dioecious plants have
sex-specific adaptations to diverse habitats. The potential of using
sexual differences in establishing more diverse poplar plantations has not
been explored in degraded areas. We conducted a series of greenhouse and
field experiments to investigate how belowground competition, soil
microbial communities and seasonal variation nitrogen content differ among
female, male and mixed-sex Populus cathayana plantations. In the
greenhouse experiment, female neighbors suppressed the growth of males
under optimal nitrogen conditions. However, male neighbors enhanced δ15N
of females under inter-sexual competition. In the field, the root length
density, root area density and biomass of fine roots were lower in female
plantations than in male or mixed-sex plantations. Bacterial networks of
female, male and mixed-sex plantations were characterized by different
composition of hub nodes, including connectors, module and network hubs.
The sex composition of plantations altered bacterial and fungal community
structures according to Bray-Curtis distances, with 44% and 65% of
variance explained by the root biomass, respectively. The total soil
nitrogen content of mixed-sex plantation was higher than that in female
plantation in spring and summer. The mixed-sex plantation also had a
higher β-1,4-N-acetyl-glucosaminidase activity in summer and a higher
nitrification rate in autumn than the other two plantations. The seasonal
soil N content, nitrification rate and root distribution traits
demonstrated spatiotemporal niche separation in the mixed-sex plantation.
We argue that a strong female-female competition and limited nitrogen
content could strongly impede plant growth and reduce the resistance of
monosex plantations to climate change and the mixed-sex plantations
constitutes a promising way to restore degraded land.