Trait value of Stipa krylovii populations in control and drought treatments

Understanding patterns of intraspecific trait variation can help us
understand plant adaptability to environmental changes. To explore the
underlying adaptation mechanisms of zonal plant species, we selected seven
populations of Stipa krylovii, a dominant species in the Inner
Mongolia Steppe of China, and evaluated the effects of phenotypic
plasticity and genetic differentiation, the effects of climate variables
on population trait differentiation, and traits coordinated patterns under
each soil moisture treatment. We selected seeds from seven populations of
S. krylovii in the Inner Mongolia Steppe, China, and carried out a soil
moisture (2) × population origin (7) common garden experiment at Tianjin
City, China, and measured ten plant traits of S. krylovii.
General linear analyses were used to analyze how soil moisture and
population origin affect each trait variation, Mantel tests were used to
analyze population trait differentiation - geographic distance (or
climatic difference) relationships, regression analyses were used to
evaluate the trait-climatic variable relationships, and plant trait
networks (PTNs) were used to evaluate the traits coordinated patterns.
Both soil moisture and population origin showed significant effects on
most of the traits. Aboveground biomass, root-shoot ratio, leaf width,
specific leaf area, and leaf nitrogen (N) content were significantly
correlated with climate variables under the control condition. Specific
leaf area and leaf N content were significantly correlated with climate
variables under drought conditions. By PTNs, the hub trait(s) was plant
height under the control treatment and were aboveground biomass, root
length, and specific leaf area under drought conditions. This study
indicates that both phenotypic plasticity and genetic differentiation can
significantly affect the adaptability of S. krylovii. In addition, soil
moisture treatments show significant effects on trait-climate
relationships and trait-coordinated patterns. These findings provide new
insights into the adaptive mechanisms of zonal species in the semi-arid
grassland region.