Spatial variation in leaf potassium concentrations and its role in plant adaptation strategies

Abstract Potassium (K) is an essential element for regulating plant growth and physiological metabolism. However, little information is available on large-scale spatial variations in leaf potassium concentrations (LKC) in different plant species, the variations in LKC, and the mechanism underlying these variations. Here, we measured LKC in 2781 plant species sampled from 78 typical ecosystems (including forests, grasslands, and deserts) in China. The average LKC was 18.30 g kg−1, and the minimum and maximum LKC were 0.35 and 52.65 g kg−1, respectively. The LKC differed significantly among plant life forms and climate zones. In addition, LKC had a significant spatial variation in China. The LKC increased with increasing latitude and was mainly affected by climatic variables, especially temperature, but was not constrained by phylogeny. Higher LKC was observed in lower-temperature regions, indicating a cold adaptation mechanism. Our finding demonstrated that LKC plays a role in plants’ adaptation mechanisms at a large scale and extend the physiological function of LKC from leaves to biomes. Furthermore, it may provide a database for studying the basic model of N fluxes across ecological gradients.