Data from: Unique roles of functional group of submerged macrophytes on ecosystem functions

The presence of submerged plant communities and the restoration of their
diversity have critical impacts on aquatic ecosystem function, especially
in eutrophic lakes. However, we lack a holistic understanding of how
specific species and functional groups and their richness of submerged
macrophytes affect the community productivity and water quality in aquatic
ecosystems, and how these effects vary across water nutrient gradients.
Here, we performed a mesocosm experiment by manipulating species richness
and functional richness from a species pool of 22 submerged macrophytes to
test what are the ecological implications of shifts in macrophyte
diversity under two nutrient levels. The results showed that species
richness significantly enhanced community productivity only at low
nutrient levels, while functional richness had no marked effects on
community productivity across nutrient levels. The improvement of water
quality by increasing submerged plant diversity (species and functional
group richness) is often efficient, despite its context-dependent effect
(e.g., nutrient level, specific parameters). Specifically, our results
demonstrated a remarkable role in distinct functional groups (FG). That
is, the presence of a particular functional group characterized by high
leaf dry mass content (LDMC) and small specific leaf area (SLA)
significantly enlarged the reduction of total nitrogen (TN) across
nutrient levels, as well as the reduction of total phosphorus (TP) and
chemical oxygen demand (COD" "Mn")at low nutrient llevels
Additionally, the presence of FG characterized by long florescence and
great SLA significantly affected nitrate reduction at high nutrient level
and the reduction of TN, "COD" "Mn", and conductivity
at low nutrient level. The presence of FG, characterized by low LDMC and
short shoot height, significantly enhanced the reduction of dissolved
oxygen and pH. Our findings highlighted that the unique contributions of
functional groups of macrophyte communities to water quality improvement
should be taken into account when designing restoration strategies.