Data for: Leaf N-S of wetland plants in western China

Salinization alters the elemental balance of wetlands and induces
variations in plant survival strategies. Sulfur (S) plays vital roles in
serving regulatory and catalytic functions in stress resistance of plants.
Yet, how plant S and its relationships with nitrogen (N) vary across
natural environmental gradients are not well documented. We collected 1366
plant samples and 230 water and sediment samples from 230 wetlands in
Tibetan Plateau and adjacent arid regions of western China, to analyze the
effects of environmental variables on plant S accumulation and N-S
correlations. We found that plant S correlated with N in unimodal
patterns. Salinity, rather than temperature or nutrient supply, promoted
disproportionate accumulation of S but limited N uptake, inducing
decoupling of N-S correlation in plants. Towards high salinity, the faster
increasing rates of total S than that of glutathione, the most abundant
organic-S compound in plant resistance, provided potential evidences
explaining the decoupled plant N-S correlation. A salinity of 3.9‰ was
calculated to be a threshold at which substantial changes in plant N-S
correlation occurred. We designed a conceptual model to illustrate the
mechanisms driving variations of N-S correlation in plants and
environments along salinity gradient. In addition, salinity reduced
species richness and drove community reassembly by filtering species with
high S concentrations at community scale. Our study addressed the critical
roles of S in plant resistance under adverse conditions. Studies on
biogeochemical cycles of S and N in wetland ecosystems will further
enhance our understanding of plant responses to future climate change.