Soil pH and drought affect nutrient resorption of Leymus chinensis in the Inner Mongolian grasslands along a 1200-km transect

Plants retain and reabsorb nutrients as a resource conservation strategy. However, studies demonstrating the patterns of nutrient resorption for a single species across a broad spatial scale in grassland ecosystems are still scarce, and our understanding of how environmental changes modify these patterns remains limited.

We established a 1200-km transect in Inner Mongolia, China, and selected the local dominant species of Leymus chinensis to explore the spatial patterns and predictors of nutrient resorption.

Nitrogen (NRE) and phosphorus resorption efficiency (PRE) decreased with increasing latitude, while they increased with elevation across our transect. The average values of NRE and PRE were 63.7% and 70.2%, respectively. The NRE of L. chinensis was lower than its PRE, suggesting that the L. chinensis in Inner Mongolian generally suffers from P deficiency. Soil pH and the Standardized Precipitation Evapotranspiration Index of current growing season (SPEIgs) emerged as the primary predictors influencing spatial variations in nutrient resorption. NRE and PRE increased with soil pH and decreased with SPEIgs, emphasizing that nutrient resorption is particularly sensitive to changes in nutrient and water availability. Moreover, soil contributed significantly more than climatic factors in driving large-scale changes in nutrient resorption.

Soil pH and SPEIgs co-regulated the spatial patterns of nutrient resorption. L. chinensis was at phosphorus limitation in the study area. Soil characteristics can better explain the variation of nutrient resorption than climate factors, highlighting that the soil is a critical aspect when predicting the relative vulnerability of natural communities to environmental changes.